027587- 1-T DESIGN AND IMPLEMENTATION OF A C-BAND SINGLE ANTENNA POLARIMETRIC ACTIVE RADAR CALIBRATOR James J. Ahne Kamal Sarabandi Fawwaz T. Ulaby Radiation Laboratory University of Michigan Ann Arbor, Michigan

TABLE OF CONTENTS DEDICATION.................................. 1. ACKNOWLEDGMENTS....................... iii. LIST OF FIGURES............................. vi. LIST OF TABLES.............................. viii. LIST OF APPENDICES......................... ix. CHAPTER ABSTRACT............................... 1 I. INTRODUCTION..................... 2 II. PARC THEORY / DESIGN CRITERIA... 3 2.1 PARC Radar Cross Section 2.2 Antenna Design 2.2.1 C-Band Antenna Specifications 2.2.2 C-Band Antenna System Performance 2.2.3 Summary of Horn Performance 2.3 GLoop Design 2.3.1 Delay Line 2.3.2 Amplifiers 2.3.2.1 Input Power Calculations 2.3.2.2 Feedback Oscillations 2.3.3 Attenuation Switches ii

2.4 Control and RF Detection Circuitry 2.4.1 Control Circuitry / Control Panel 2.4.1.1 LED Battery Power Monitor 2.4.1.2 Battery Over-discharge Protection 2.4.1.3 Automatic System Activation Timers 2.4.1.4 Voltage Regulation 2.4.1.5 Auxiliary Switching Capability 2.4.1.6 External Source Hook-up 2.4.1.7 Recharge Ports 2.4.2 Detection Circuitry 2.5 Temperature Stabilization 2.6 Assembled Prototype II. EXPERIMENTAL RESULTS............ 43 3.1 Anechoic Chamber Tests 3.1.1 SAPARC Time Domain Response 3.1.2 0~ Orientation Test 3.1.3 45~ Orientation Test 3.2 GLoop Measurements 3.3 Thermal Gain Testing 3.4 Field Deployment Conditions 3.4.1 Battery Capacity 3.4.2 All-Weather Performance IV. CONCLUDING REMARKS............ 69 APPENDICES REFERENCES iii

LIST OF FIGURES Figure 2.1 Basic PARC Configuration 2.2 SAPARC System Block Diagram 2.3 Magnitude and Phase Patterns For a Two Antenna PARC 2.4 a Side View of the C-Band Tapered Square Horn Antenna 2.4 b Adapter Flange For the C-Band Tapered Square Horn Antenna 2.4 c Frontal View of the C-Band Tapered Square Horn Antenna 2.5 Depiction of Adequate and Inadequate Beamwidths For a Horn Antenna 2.6 Multipath Contribution Scenarios For Horn Antennas With and and Without Significant Sidelobes 2.7 C-Band SAPARC Antenna System 2.8 The Effects of Placing a Delay Line Within the PARC System 2.9 C-Band 0.141 Inch Semi-rigid Microporous Coaxial Delay Line 2.10 S11 Time Domain Response of the C-Band Delay Line 2.11 S21 Frequency Domain Response of the C-Band Delay Line 2.12 JPL AIRSAR Fly-by Geometry 2.13 NASA SIR-C Fly-by Geometry 2.14 SAPARC Control Printed Wiring Assembly (Unstuffed) 2.15 SAPARC Control Printed Wiring Assembly (Stuffed) 2.16 Blueprint of the SAPARC Front Control Panel 2.17 SAPARC Front Control Panel 2.18 a Internal Components of the C-Band SAPARC Unit 2.18 b C-Band SAPARC Disassembled for Transport 2.18 c' Fully Assembled C-Band SAPARC 3.1 Frequency Domain Response of GLoop 3.2 Detailed Frequency Response of GLoop 3.3 Frequency Domain Response of the 50 dB Attenuator 3.4 C-Band POLARSCAT Test Equipment iv

3.5 Anechoic Chamber Measurements at the University of Michigan's Radiation Laboratory 3.6 0~ and 45~ Orientation Modifications 3.7 SAPARC Time Domain Response 3.8 SAPARC 0~ Orientation Phasor Polarizations 3.9 SAPARC 0~ Orientation RCS Azimuthal Patterns (SIR-C Mode) 3.10 SAPARC 45~ Orientation Phasor Polarizations 3.11 SAPARC 45~ Orientation RCS Azimuthal Patterns (SIR-C Mode) 3.12 SAPARC 45~ Orientation Phase Patterns (SIR-C Mode) 3.13 Phasor Diagrams for the 45~ Orientation 3.14 C-Band SAPARC Thermal Gain Variations 3.15 Battery Capacity Test (1.0 A Load, 22~ C) 3.16 Full Load Battery Capacity Test (1.2 A Load, 22~ C) 3.17 Cold Weather Battery Capacity Test (1.2 A Load, -10~ C) D. 1 Cross Polarization Isolation Test Set-up D.2 a Sw Time Domain Plot of a 14" Calibration Sphere D.2 b Sw Frequency Domain Plot of a 14" Calibration Sphere (With Background Subtraction) D.2 c Shh Time Domain Plot of a 14" Calibration Sphere D.2 d Shh Frequency Domain Plot of a 14" Calibration Sphere (With Background Subtraction) D.2 e Shv Time Domain Plot of a 14" Calibration Sphere D.2 f Shv Frequency Domain Plot of a 14" Calibration Sphere (With Background Subtraction) D.2 g Svh Time Domain Plot of a 14" Calibration Sphere D.2 h Svh Frequency Domain Plot of a 14" Calibration Sphere (With Background Subtraction) v

LIST OF TABLES Table 2.1 C-Band Antenna Characteristics 2.2 JPL AIRSAR Parameters 2.3 NASA SIR-C Parameters 2.4 Thermal Variations of Key SAPARC Components 3.1 C-Band POLARSCAT Parameters 3.2 Marker Identification for Figure 3.2 3.3 Magnitude and Position Values for the Markers Shown in Figure 3.2 vi

LIST OF APPENDICES Appendix A B C D E OMT Specifications Amplifier Specifications Control Circuitry Schematics Cross Polarization Isolation Tests Measurement and Calibration Programs vii V~l

ABSTRACT This report serves as a documentation of the design parameters and performance characteristics of a C-band single antenna polarimetric active radar calibrator (SAPARC) developed for JPL and NASA at the University of Michigan's Radiation Laboratory. The device is one of four which are currently being constructed for future JPLINASA Synthetic Aperture Radar (SAR) missions. The report includes details of the SAPARC's RF and digital / analog electronics design, as well as test results from a number of anechoic chamber measurements. Application notes and suggestions are also included throughout. 1

CHAPTER I INTRODUCTION Active and passive radar calibrators are often used in conjunction with airborne and space borne polarimetric imaging SAR platforms. When strategically placed, these devices serve as ground-based calibration targets with specified radar cross sections (RCS). Trihedrals / corner reflectors are by far the most common type of calibration device used; however, their physical size and weight make them undesirable for field deployment. The drawbacks associated with trihedrals are two-fold. First, an actual deployment of the device can be physically awkward and inconvenient. Trihedrals can be as large as 12 ft by 12 ft by 12 ft, and they can weigh up to 300 pounds. In addition to their cumbersome size and weight, trihedrals tend to act like large rain and snow collectors, thus complicating the chances of performing an accurate calibration. The second drawback is a bit more subtle, but just as significant. The accuracy of an external calibration of a radar system directly relies on the knowledge of the scattering matrix of the calibration target. Although it is possible to estimate the elements of the scattering matrix of a calibration target analytically, manufacturing tolerances may leave a fair amount of uncertainty in the estimated values. Therefore, it is necessary to measure the calibration targets against a precise calibration target, such as a metallic sphere. This reveals the second drawback of passive calibrators with large physical dimensions, namely that the far field condition and uniform illumination criteria are difficult to meet in the laboratory. Hence, it becomes difficult to accurately define the performance characteristics of passive calibrators of this size and type. Polarimetric active radar calibrators (PARCs), on the other hand, tend to be much smaller and easier to handle than their passive counterparts. A PARC also yields better calibration measurements since its SAR image can be translated over a dark background, thus providing a higher signal to background ratio. As a result of these advantages, 2

PARCs are rapidly becoming the calibration device of choice for future space borne missions. As a final point, PARCs traditionally are designed with two antennas which can cause severe degradation in their performance, as will be explained later. Here a new design for the C-band PARC is used which requires a single antenna. The purpose of this report is to outline of the theory, design, and implementation of the C-band single antenna PARCs developed for NASA and JPL at the University of Michigan. The content of this project reflects the modifications and improvements made to previous PARC and SAPARC units (specifically, an L-band SAPARC prototype built by Sarabandi and Oh for the University of Michigan's Radiation Laboratory [1] ). Currently, the C-Band SAPARCs are tentatively planned for field deployment in October 1993, where they will be used as calibration devices for NASA's SIR-C (Shuttle Imaging Radar -C) mission. 3

CHAPTER II PARC THEORY / DESIGN CRITERIA In its simplest form, a PARC consists of a receive antenna, an amplifier, and a transmit antenna (see Figure 2. 1). With this configuration, the PARC merely acts like a repeater, whereby an incoming radar signal is received, amplified, and re-transmitted back to the SAR platform. Variations on this simple design do, however, lead to a variety of merits. Figure 2.2 depicts the modifications which are employed in this project's SAPARC units. The most notable difference is the addition of a delay line along with an orthogonal mode transducer (OMT) / single antenna implementation. The device now serves as a specialized type of repeater, where the signal is captured with respect to one polarization and re-transmitted via its opposite polarization. The pre-amplifier and power amplifier ensure the proper amplification of the signal, while the delay line electrically delays the signal for reasons which will be given later. As a final note, the switches provide the attenuation needed for applicability to SIR-C as well a JPL AIRSAR missions. 2.1 PARC Radar Cross Section The fundamental equation defining the radar cross section (RCS) of a PARC is given by =G GTGRX [2] o'4op [2] where GT and GR are the transmit and receive antenna gains, and GLoop is the net loop gain associated with the gains and losses from the system's amplifiers, switches, and delay line. Generally speaking, a larger RCS is more desirable. Hence, the driving 4

GR GT Receive Antenna Transmit Antenna Gamp Figure 2.1: Basic PARC Configuration

Microwave Switches 44 dB SIR-C Pre-Amplifier SIRE et AM "% Orthogonal Mode Transducer Tapered Square Horn Antenna G 15 dB Delay Line 41.5 dB Control Circuitry System Acitvation Timers LED Battery Power Monitor Battery Over-discharge Protection Voltage Regulation Oscillation / SAR Fly-by Detection Detection Circuitry Figure 2.2: C-Band SAPARC Block Diagram

impetus behind most PARC designs is the maximization of GLoop GT, and GR. These parameters, in turn, are limited by beamwidth requirements, transducer isolation performance, and physical size and weight considerations. The following sections address each of these parameters in more detail. 2.2 Antenna Design In the design of early PARC systems, two antennas, one for transmit and one for receive, were employed to achieve the necessary isolation between the receiver and transmitter modes of the PARC. The transmit and receive antennas were placed in close proximity to one another to meet the compactness requirement of the PARC design. However, since the antennas are in the near field of each other, the RCS pattern of the PARC becomes asymmetric and causes ripples in the phase and amplitude responses which tend to mar the PARC's performance [1] (see Figure 2.3). In order to counter these setbacks and yet to meet the compactness requirement, a single antenna PARC was considered. In this design, the PARC employs a dual polarized horn antenna with a very good polarization isolation and low return loss for both polarization channels. Wide bandwidth and beamwidth with high cross polarization isolation can be achieved through the implementation of an OMT (Orthogonal Mode Transducer) in conjunction with a piecewise tapered square horn. The geometry of a piecewise tapered horn is shown in Figures 2.4a, 2.4b, and 2.4c. The waveguide discontinuity at a flared intersection excites higher order waveguide modes which are proportional to the flare angle. Since the waveguide is square, the higher order modes can couple energy into the orthogonal channel (TE10 to TEoi, for example). It was noticed that when the flare angle is less than 50, the energy transfer from between the orthogonal channels is minimized. However, in order to get the desired aperture over a reasonable length, the square horn can be flared (with angles less than 50) at many points along its length, thereby simulating an exponential taper. Note that the length of each section should be longer than the wavelength. 7

50. 40. 30. 20. 10. 0. I - - I I I I1 I I I ~- -^o -... - _r -*': — *Q —.-.,0-''" LC,: = _ E C) L/ c4 do -10. -20. -30. I I I — tn LCD 180. 150. 210. 120. 90. 60. 2 I F I -P-. <hh ( v -- 0 --- - - -— A - - -.-..o i i -40. -50. I W. IV -0 ---- -.. o. -— A — o ~ — -- h,, I I I i 30. -60. w -70. 0. - -30. -40. -80. -4( I., I I I ~... - 3. -30. -20. -10. 0. 10. 20. 30. 40. -20. 0. 20. 40. Incidence Angle (Degrees) Incidence Angle (Degrees) Figure 2.3: Magnitude and Phase Patterns for a Two Antenna PARC System

-.015 Ar A.25 5.00 2.9640 10.0~ 2.9640 15.00 2.9640 2.9390 4.5274 3.1 (/~~~~~ ff ^ ^ ~~~~~~~~~~~200 6.6850 t1.0 * All tolerances +-0.03 inches (unless noted otherwise) * All angle tolerances +-1.0 degrees * All dimensions are in inches and all values pertain to inner dimensions as shown Figure 2.4a: Side View of the C-Band Tapered Square Horn Antenna

View A-A 3.75 * All dimensions are in inches * All tolerances +-0.03 inches * All angle tloerances +-0.5 degrees Figure 2.4b: Adapter Flange for the C-Band Tapered Square Horn Antenna

* All angle dimensions +-0.5 degrees * All pertinent dimensions given for side view Figure 2.4c: Frontal View of the C-Band Tapered Square Horn Antenna

2.2.1 C-Band Antenna Specifications The goal of the SAPARC's antenna design is to reduce the RF mismatch and cross-talk (i.e. cross polarization generation) while at the same time providing adequate gain, beamwidth, and bandwidth. For the C-band SAPARC, the primary concern of the design was the trade-off between the reciprocal parameters of antenna gain and beamwidth. Physical size and weight were not major factors due to the relatively small wavelength of the C-band system. From a practical point of view, the scattering matrix of the SAPARC must be rather insensitive to orientation angles, i.e. a SAPARC should be immune to possible pointing errors). Thus, one of the design goals is to achieve a two-way antenna beamwidth of around 200. Note that the relatively large beamwidth ensures a successful calibration even if the SAPARC is not directly within the line of sight of the SAR platform. Figure 2.5 demonstrates pictorially the importance of having a wide antenna beamwidth. A secondary goal was to reduce the sidelobes radiating from the aperture, thereby minimizing the effect of multipath reflections to and from the SAPARC's ground-based position. Multipath contributions yield inaccurate RCS responses since unwanted electromagnetic energy is effectively being collected by the SAPARC antenna system (see Figure 2.6). The nominal RCS response, however, is measured within an anechoic chamber where multipath contributions are negligible. Hence, measurements taken within anechoic chamber and field environments may differ considerably. Using an antenna with small sidelobes is advantageous in that multipath contributions will be reduced; thus, measurements taken during actual field deployment conditions will more closely resemble measurements taken within the chamber environment. One of the project's early prototypes incorporated the use of a corrugated horn with a square aperture. Note that corrugated horns generally offer improved performance since they reduce the sidelobes in the antenna pattern. Unfortunately, this prototype yielded a high degree of co-polarized mismatch and extremely poor cross polarization isolation. The concept of employing a dielectric lense was also tried; however, the costs of 12

Flight Path Adequate SAPARC antenna beamwidth Flight Path.6 Inadequate SAPARC antenna beamwidth Figure 2.5: Depiction of Adequate and Inadequate Beamwidths for the Tapered Square Horn

OdB 13dB Multipath Contribution Received at 13 dB Below Main Beam Large Sidelobes OdB Multipath Contribution \ \r ^30dB Received at 30 dB,.t^~ (^^ ^Below Main Beam Negligible Sidelobes Figure 2.6: Multipath Contribution Scenarios for Horn Antennas With and Without Significant Sidelobes

constructing adequate lenses or custom made corrugated horns became much too prohibitive. Therefore, it was decided that the most economically feasible design would forego the multipath considerations. Due to the high costs involved, first a prototype horn (made from copper plated printed circuit board material) was constructed and found to yield a one way 3 dB antenna pattern beamwidth of 260. The physical dimensions of the prototype horn was chosen to be 28 cm in length with a square aperture of 17.6 cm by 17.6 cm (3.11X by 3.11X). Based on these promising results, a final design was implemented using four equi-length sections flared in 5~ steps. As shown in Figure 2.4, the overall length of the horn is 30.11 cm with an aperture of 16.98 cm by 16.98 cm (3k by 3X). This final design also incorporated rounded aperture edges which, in theory, reduce the diffraction effects inherent with the abrupt edges of a typical horn [3]. For the center frequency of 5.3 GHz, the radius of curvature for the rounded edge was chosen to be 2.83 cm, which corresponds to a X / 2 radius of curvature. As a final point, the C-band SAPARC's design employs an OMT purchased from Atlantic Microwave (model # OM1370). This device provides cross polarization isolation of better than 50 dB with a VSWR smaller than 1.5 over the frequency range of 5.2 - 5.9 GHz. A VSWR of 1.07 to 1.08 is the typical value for this OMT. See Appendix A for the detailed OMT test specifications. Figure 2.7 depicts the completed horn and OMT combination. 2.2.2 C-Band Antenna Performance The results from the final design varied from fair to excellent. The largest disappointment came in the form of the narrow 3 dB beamwidths demonstrated in Figures 3.24 and 3.26 (0~ and 450 Orientations). As shown in these pattern measurements, the antenna provides two way beamwidths of 15~ for both orientations. Although these beamwidths are relatively narrow, the overall capabilities of the SAPARC will not be degraded. 15

Figure 2.7: C-Band SAPARC Antenna System

The horn design does, however, provide exceptional cross polarization isolation between the receive and transmit ports. Appendix D outlines the steps taken in measuring the horn's cross polarization performance. These measurements were conducted within the UM Radiation Laboratory's anechoic chamber, as shown in Figure D. 1. Figures D.2 a - h reflect the time and frequency domain responses taken with a Hewlett Packard 8510 network analyzer. Note that the frequency domain plots incorporated time gating and background subtraction over a frequency range of 5.0 - 5.6 GHz. From the plots given in Figure D.2, we can deduce that the antenna system (horn and OMT combination) yields a cross polarization isolation exceeding 42 dB. This quality of the horn is instrumental in providing the SAPARC's 38 dB of overall cross polarization isolation (Figure 3.24) and relatively high GLoop gain. Note the 4 dB discrepancy between the system'sRCS cross polarization isolation and the is aolation resulting from the antenna system alone (measured independently). One possible explanation is that the system's RCS cross polarization isolation was measured in conjunction with another horn and OMT combination (i.e. the radar's antenna system) which similarly possesses a finite isolation capability. The antenna system isolation measurements, on the other hand, used a metal sphere which theoretically acts like a perfectly pure reflective polarizer, i.e. the sphere cannot de-polarize incident electromagnetic waves (as can an imperfect horn antenna). Therefore, it is reasonable to expect that the 4 dB discrepancy is due, at least in part, to the imperfections of the radar's antenna system. Other sources of calibration error may contribute to the discrepancy as well. Finally, it should be noted that the maximization of GLoop is dependent upon the level of isolation between the receive and transmit ports on the antenna. Refer to Figure 2.1. From this simple diagram, one can see how a feedback scenario results whenever a small fraction of energy is coupled from the transmit antenna to the receive antenna. The coupled electromagnetic wave is then repeatedly amplified as the energy continues along the feedback loop. Eventually, the coupled energy will increase to a magnitude which saturates the amplifiers. For obvious reasons, this situation cannot be tolerated for a PARC design. Therefore, the antenna system's cross polarization isolation must be large enough to prevent the occurrence of a feedback loop. 17

2.23 Summary of Horn Performance Physical Characteristics Electrical Characteristics Aperture Size: Length: Weight: Material: Manufacturer: 16.98cm X 16.98cm 30.11 cm 3.5 lbs. Aluminum Midwest Enterprises Gain: 15.93 dB 2-Way 3 dB Beamwidth: 15~ Cross Polarization Isolation: 42 dB Table 2.1: C-Band Antenna System Characteristics 2.3 GLoop Design 2.3.1 Delay Line At the heart of any PARC system is the GLoop component of the RCS. As mentioned above, a PARC can enhance a calibration measurement by translating its SAR response over a dark background (i.e. a background with a specular surface, such as an airport runway or a large body of water -- See Figure 2.8). This technique is easily implemented by adding a low loss delay line between the receiver and transmitter, as shown in Figure 2.2. When calculating the length of the delay line, a number of system parameters had to be incorporated in order to insure an adequate SAR delay. The slant range resolution, ry, is given as 6.67 m for JPL's AIRSAR. As shown in Figure 2.8, the SAPARC should "appear" as if it is situated directly over a body of water. The quantity Ap corresponds to the distance between the physical location of the PARC and its desired SAR image position. An acceptable Ap is approximately 10 pixels (i.e. 10 range bins); therefore, Ap = 10r, = 66.7m 18

Physical Location of SAPARC SAR Flight Direction Physical Location of SAPARC SAPARC Response 0 co em "a u) Water Terrain Time Figure 2.8: The Effects of Placing a Delay Line Within the PARC System

Figure 2.9: C-Band 0.141 Inch Semi-rigid Microporous Coaxial Delay Line

Figure 2.10: S11 Time Domain Response of the C-Band Delay Line r o i= rq X X-: 1: - >ss-AL; I I I.. 1, i " I 1 A i i ----: ' Q c *tI I.- N ~___________________.__.__.__ (l. 1L I I I 1 I I I_ t 0 * <

Figure 2.11: S21 Frequency Domain Response of the C-Band Delay Line I rI fX~~~~~~~~~~~~~~~~~~~~~~~ i w"t <~~~~~~ ^_^ ____ __________~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ N N I I n: L U UO < 0 m X M -0 >>S.a (x O q 11. 1 I I rr O I: /\

With Ap now known, the delay D can be found through the simple relationship c where c is the speed of light in free space. Lmin, the minimum length of line needed, is L = D = Ap.69c) = 46.02m = 150.99ft C Note that Vcoax is the velocity of the wave within a coaxial medium. The minimum length of line required is approximately 151 feet, yet in actuality, all of the L- and C-band SAPARCs developed for this project use line lengths of 200 feet (therefore guaranteeing a sufficient delay). Figures 2.9 and 2.10 show the coil of delay line and its corresponding S 1 time domain response for the C-band SAPARC. At C-band frequencies, the losses associated with any delay line tend to be quite severe. These losses were minimized by using 0.141 inch semirigid microporous coaxial cable (manufactured in 25 ft-long pieces by Precision Tube, Inc.). The total attenuation resulting from the eight 25 ft-long sections was measured with a Hewlett Packard 8510 Network Analyzer, and was found to be approximately 41.4 dB (see Figure 2.11). Note that the measured loss and the losses quoted by the manufacturer, namely 22 dB, differed by almost 20 dB. It is assumed that this difference results from the losses associated with the 16 connectors. 2.3.2 Amplifiers The role of amplification in a PARC is to increase the RCS of the antenna system and to compensate for the losses associated with the PARC's delay line and other passive components. The amplifier gain of a SAPARC system must be chosen such that the amplifier operates in the linear region. Amplifier saturation may occur for two reasons: 1. saturation due to high levels of input power received from the SAR platform, and 2. saturation due to feedback oscillations. The latter of the two results from a finite receive 22

and transmit channel isolation (determined by the performance of the OMT and horn antenna). 2.3.2.1 Input Power Calculations In order to insure that the amplifiers would not be saturated by the received RF, a number of preliminary calculations were made using the Friis transmission formula and known system parameters for JPL's AIRSAR and NASA's Shuttle Imaging Radar (SIR-C). Tables 2.2 and 2.3, respectively, summarize the JPL AIRSAR and NASA SIR-C parameters. Peak Power Average Power Wavelength Antenna Gain Altitude Incidence Angles Pixel Resolution Pt = 1 kW (60 dBm) Pt = 19 W (42.79 dBm) X = 0.0566 m G = 23.3 dB 15,000 - 40,000 ft (4,572 - 12,192 m) 20~ - 70~ 3.03 m or 12.01 m (1 or 4 Look Azimuth) 6.67 m (Slant Range) Table 2.2: JPL AIRSAR Parameters Peak Power Wavelength Antenna Gain Altitude Incidence Angles Pixel Resolution Pt = 2.2 - 2.25 kW (63.42 - 63.52 dBm) X = 0.0566m Unknown (Assume G = 20 dB) 200 - 225 km 150 - 55~ 10 - 60 m Range Resolution Table 2.3: SIR-C Parameters 24

For JPL's AIRSAR system, the following Friis transmission calculations are applicable. Figure 2.12 depicts the geometry of a typical fly-by, where h is the height of the platform and R is the corresponding range (i.e. distance between the SAR and the calibration unit). The values used in this calculation are for the "worst case" scenario with respect to possible amplifier saturation. Therefore, the dimensions correspond to the case where the maximum amount of power will be received by the SAPARC. AIRSAR Platform { (Transmitter) 200 R= 4.865 km h= 4.572 km SAPARC (Receiver) Figure 2.12: JPL AIRSAR Fly-by Geometry The general form of the Friis transmission formula is P,= PTI4 GTGR [4] whereas h R = = 4.8654km cos(O) PT = 1KW = 60dBm 4rR) 4 (4.8654km)) =-120.67dB GT = 23.3dB GR= 15dB 25

Therefore, the maximum input power received by the first stage amplifier will be PR = 60 + 23.3 + 15 -120.67 = -22.37dBm Similarly, NASA's SIR-C system, shown in Figure 2.13, will yield the following results. SIR-C Platform &- (Transmitter) h = 200 km R = 207 km SAPARC (Receiver) Figure 2.13: NASA SIR-C Fly-by Geometry The Friis transmission formula gives PR PT( )R GTGR [4] whereas h R = c( 207.05km cos(o) PT = 2.25KW = 63.52dBm '= X4122 0 7.05k6m = -153.25dB t4 JR t4n(207.05an)) GT 20dB GR 15dB 26

Therefore, the maximum input power received by the first stage amplifier will be PR = 63.52 -153.25 + 20 + 15 = -54.73dBm The gain of the first stage amplifier (i.e. the pre-amplifier) is at most 44 dB (see Appendix B). Hence, the first stage amplifier must be capable of producing the following output power levels in order to insure operation within the linear range of the amplifier. AIRSAR Pout = PR + Gpreamp = -22.37dBm + 44 dB = 21.63 dBm SIR-C Pout = PR + Gpreamp = -54.73 dBm + 44 dB = -10.73 dBm As shown in Figure 2.2, an additional attenuator of 10 dB was added to the front end of the pre-amplifier as an extra precaution to deter possible saturation during AIRSAR calibrations. Note that the 1 dB compression point for this amplifier is approximately 15 dBm. Adding an attenuator "in front" of the amplifier degrades the signal to noise ratio; however, in this case, the signal level is much higher than the thermal noise, thus the effect of the additional attenuator is negligible. As will be pointed out in the next section, the noise inherent within the loop can lead to internal oscillations. Therefore, minimizing the noise will theoretically lead to a maximization of GLoop. Yet, in light of the seriousness of amplifier saturation, it was agreed that the benefits resulting from this potentially lower noise performance could not outweigh the assurance that the preamplifier is operating within its proper linear range. 2.3.2.2 Feedback Oscillations An equally serious problem can arise when the system is driven into a state of feedback oscillation. Section 2.3.2.1 alluded to the fact that noise inherent within the system can be amplified just as easily as any incoming RF signal. Oscillations result whenever the amplified noise exceeds the isolation of the antenna system. For the C-band SAPARC design, the net GLoop gain must not exceed 42 dB (the antenna system's cross polarization isolation). 27

Since GLoop must be less than 42 dB, it follows that GLoop = GAmp + LLine < 42 dB Rearranging this equation gives GAmp < GLoop + LLine = 42 dB + 42 dB Therefore GAmp < 84 dB Due to the relatively high loss of the delay line, a second amplifier is needed to help boost the signal before it is transmitted back to the SAR platform. As was done with the preamplifier, care must be taken to insure that the second stage amplifier is not driven into saturation. For this reason, the IdB compression point of the power amplifier was chosen to be 29 dBm. 2.33 Attenuation Switches The principle goal of the attenuation switch (see Figure 2.2 and Appendix C, pg. 6) is to reduce the loop gain thereby allowing the SAPARC to be used for both JPL AIRSAR and NASA SIR-C missions with the maximum allowable RCS. As pointed out in Section 2.3.2.1, JPL's AIRSAR, which flies at significantly lower altitudes than SIR-C, has a correspondingly higher risk for saturating the SAPARC's amplifiers. Conversely, an excessively large GLoop can lead to the saturation of the SAR platform's own receiver. The original goal was to insert (via the microwave switches) a 10 dB pad within the GLoop path for AIRSAR calibrations. This pad could then be "switched out" for SIR-C applications; however, it was found that the system would occasionally slip into a feedback oscillation mode whenever the 10 dB pad was out of the GLoop line. These oscillations occurred most prevalently whenever the amplifiers were not warmed up, thus implying that the loop gain was right on the fringe of its maximum limit (the amplifiers can exhibit a 1-2 dB drift in gain between initial turn-on and steady state / room temperature operation). Reducing the loop gain by 3 dB eliminated this problem altogether for operating temperatures of 200 C and greater. (See section 3.3 for cold 28

weather operation). Hence, for SIR-C usage, the Mini-Microcircuits switches insert a 3 dB attenuator into the loop, whereas a 10 dB attenuator is inserted for the JPL AIRSAR calibrations. The Miteq pre-amplifier and power amplifier tandem provide approximately 96 dB of gain, which is well above the limit shown above in Section 2.3.2.2 (see Appendix B). Hence, this explains why an attenuator must be added in front of the first stage amplifier since doing so makes GLoop less than the cross polarization isolation of the antenna system. It would appear as if a 13 dB (i.e. 96dB - 13 dB = 83 dB < Gamp max = 84 dB) attenuator is required; however, a trial and error approach showed that a 3 dB attenuator is sufficient to prevent feedback oscillations. Note that the results shown throughout this report reflect the SAPARC's operation within the SIR-C mode. Similar results can easily be found for the AIRSAR case by simply subtracting 7 dB from the overall SIR-C RCS measurements. 2.4 Control and RF Detection Circuitry The control and RF detection circuitry serves a two-fold purpose. First, it provides the necessary switching and timing functions for the various power loads; secondly, the circuits display the operating status of the entire system, thereby alerting the user of changes in battery capacity and calibration readiness. The system is comprised of three major components: the Control Printed Wiring Assembly (PWA), the Detection PWA, and the Control Panel. A more detailed description of each of these subsystems is given in the following sections. 2.4.1 Control Circuitry / Control Panel The single antenna PARCs developed through this project feature custom made control and detection circuits. The features of the control circuitry are as follows: 29

Figure 2.14: SAPARC Control Printed Wiring Assembly (Unstuffed)

Figure 2.15: SAPARC Control Printed Wiring Assembly (Stuffed)

C-BAND PARC SYSTEM STATUS POWER RESET ~u POWER ON RESET OK m SYSTEM ACTIVE ~D RF INPUT/OUTPUT BATTERIES POWER EXTERNAL TIMER CONTROL LEVELS SOURCES I I C( ON ( OFF/ RECHARGE INDIVIDUAL CHARGING ( DNFIGURATION PARALLEL RECHARGE PORTS ~ m 12V 12V BATTERY BATTERY 1 2 ON DISPLAY ~ OFF COMPLETELY CHARGED COMPLETELY DISCHARGED SOURCE 1 SOURCE 2 ON OFF m + 12V 12V SOURCE 1 SOURCE 2 TIME ON I 1 TIME OFF I ' I ON BYPASS ) PC OFF TIME SET\ - SET ALARM ON L OFF TIME SET - SET ALARM ON - OFF ON )WER ) OFF IN OUT DETECTION CIRCUITRY I I RESET CALIBRATION COMPLETED SAR APPLICATION SIR-C AJPL AIRSAR Figure 2.16: Blueprint of the SAPARC Control Panel

Figure 2.17: SAPARC Front Control Panel

* LED Battery Power Monitor * Auxiliary Switching Capability * Battery Over-discharge Protection * External Source Hook-up * Automatic System Activation Timers * Recharge Ports for Internal Sources * Voltage Regulation * Easy Detachability for Maintenance Most of the circuitry (for the functions listed above) is mounted on the Control PWA. This board was designed with EE Designer, a PWA layout software package which can be run on most IBM pc's. The PWA was then manufactured by L. Ross industries in Ann Arbor. (See Figures 2.14 and 2.15). As a final note, the entire Control PWA / Detection PWA combination can be removed from the system chassis by disconnecting the 50 - pin connector. Before doing so, however, it is advised that the user first disconnect the internal supplies by removing the 7A fuses; the "BATTERIES" switch must then be turned on, and the "POWER RESET" button depressed (for 10 seconds) so that all residual charge held by the internal capacitance of the system can be safely discharged. (See Figure 2.16 and 2.17, both of which depict the front control panel). 2.4.1.1 LED Battery Power Monitor The LED display mounted on the control panel is driven by a differential amplifier circuit which monitors the gradual drop in voltage of each separate lead acid battery (see Appendix C, pg. 3). Preliminary tests showed that this drop is a linear function of time, whereby the safe operating range exists between 10V < V < 12.5V (refer to the battery operating curves given in Figures 3.12, 3.13, and 3.14). The entire system becomes fully loaded whenever the LED display is activated, thus yielding a more accurate measurement of the battery's remaining capacity. Note that under room temperature conditions, the Yuasa 7 A-hr 12V batteries can operate for up t6 5.5 hours (under a full load of 1.2A) before the lower operating voltage threshold is reached. Colder temperatures will significantly limit this capacity; at -100C, the system can only operate for 4.5 hours before the same lower threshold causes the system to shut down. 34

The LED display is currently set to measure a voltage range of 10.5V < V< 12.5V for each supply. This range can be adjusted for supplies 1 and 2 by tweaking the potentiometers R8 and R17, respectively. 2.4.1.2 Battery Over-discharge Protection In conjunction with the LED bar graph display, the discharge protection circuitry similarly monitors the supply voltages through the use of comparitors (see Appendix C, pg. 4). When the lower voltage threshold is reached (i.e. 10V), power to the entire system will be shut off, thus protecting the lead acid batteries from excessive discharging. (The battery's capacity is severely degraded whenever this lower voltage threshold is exceeded for extended periods of time.) This lower threshold can be easily adjusted by tweaking potentiometers R3 and R15 (for supplies 1 and 2, respectively). 2.4.1.3 Automatic System Activation Timers The system's built-in activation timers can control the operation interval for the SAPARC. In almost all practical situations, the SAPARC needs to be on for a relatively short period of time which can be programmed using the activation timers, thus prolonging the SAPARC's use by conserving battery capacity (see Appendix C, pp. 5-6). Two separate clocks are used: one for activating the high load components, and one for deactivating the entire circuit. The wiring design consists of a number of buffers and opto-isolators which connect the output of the timers (i.e. piezo-electric connections) with the rest of the control circuitry. Note that these connections were made with shielded 20 gauge wire; the first prototype, which did not use shielded wire, experienced occasional transient responses resulting from the switching of the high load components (e.g. amplifiers, heater, etc.). Proper shielding and the use of opto-isolators eliminated this problem altogether. The timer activation mode can be bypassed for manual operation as well. In the manual mode, the system loads are all activated for immediate and constant operation, thus making this mode ideal for testing purposes. When deploying the SAPARC within a field environment, one should use the bypass in order to insure that the system cannot be 35

driven into a feedback state. Feedback oscillations will occur whenever an object is placed within the SAPARC's antenna beam pattern. Hence, a low-lying tree branch or other similar object may drive the system into an oscillation state. Using the bypass allows the user to "see" if any objects are within range of causing such problems. If the system can operate correctly in the bypass state, then the user will have confidence that the SAPARC will also work while in the automatic mode. As a last note, the activation timers are independently powered by small cell 1.25V batteries. These cells can be easily replaced by removing the top cover on the SAPARC chassis. A small plastic cover on the clock units must also be removed in order to gain access to the battery compartments. 2.4.1.4 Voltage Regulation The various subsystems within the SAPARC require supply voltages of ~15V, ~8V, and +5V. The +5V and ~8V regulation is performed by basic 7800 series regulators, whereas the ~15V modes are supplied from DC-DC converters (one on the Detection PWA, and the second on the Control PWA - see Appendix C, pp. 3,4, and 7). The +15V DC-DC converter possesses an efficiency of greater than 80%; hence, the converter outperforms conventional voltage regulation by a considerable margin (i.e. in terms of efficient power use). It should also be noted that conventional regulators cannot supply the relatively large amount of current which is required for the operation of the amplifiers and other possible auxiliary loads. 2.4.1.5 Auxiliary Switching Capability As mentioned above, the Control PWA is configured so that additional loads can be added (and thus controlled) as the user sees fit (see Appendix C, pg. 2). The voltage output for these auxiliary ports includes ~15V and +24V. Possible loads include recording devices which can monitor the RF power levels received during SAR fly-bys, thereby providing a means for measuring the pattern of the SAR's illuminating footprint. 36

The Detection PWA does provide a correlation between detected RF and a specific DC output voltage. This capability may be utilized for use with recording devices. Heaters can also be connected to this circuit; however, testing has shown that their use is of little value for reliable temperature stabilization. (See section 2.5). 2.4.1.6 External Source Hook-up The user can bypass the internal battery supplies by employing the use of the external hook-up jacks located on the front control panel (see Figures 2.16 and 2.17, as well as Appendix C, pg. 1). If external sources are to be used, simply flip the "EXTERNAL SOURCES" switch to the ON position. Hit the "POWER RESET" pushbutton and continue the system operation in the normal fashion. As a final note, DO NOT CONNECT THE GROUNDS FROM THE EXTERNAL BATTERIES TOGETHER. 2.4.1.7 Recharge Ports The user can also recharge the internal batteries via the recharging ports located on the front control panel (see Figures 2.16 and 2.17, as well as Appendix C, pg. 1). Two different port types are provided for the support of varying recharging devices. When recharging, have the "BATTERIES" switch in the OFF / RECHARGE position. The "CHARGING CONFIGURATION" switch permits the user to charge the batteries individually or together in a parallel mode. 2.4.2 Detection Circuitry The Detection PWA was acquired from an existing two-antenna PARC system developed by Applied Microwave (see Appendix C, pg. 7). This subsystem monitors the power levels which exist at the output of the power amplifier. The threshold for this detection has been set low enough (Pmin detection = -48.6 dBm) so that oscillations as well as SAR fly-bys can be recorded. In the original circuit design, a detection would illuminate a 37

small red bulb; in addition to this, a.25A circuit breaker switch (which serves as a permanent recording device) has been added to signal the user that a successful calibration is complete. Note that the circuit breaker takes approximately 60 seconds to trip once a detection is made. When deploying the SAPARC, the user must be certain that feedback oscillations will not occur during the calibration. Therefore, one must always monitor the detection lamp during final setup preparations. (Recall that the SAPARC system is extremely sensitive to adjacent objects which may reside within the antenna's beamwidth. These objects include nearby bushes, tree limbs, etc.). If a feedback scenario is present, simply press the RESET to clear the Detection PWA circuitry. Continue to re-position the SAPARC as needed so that no errant detections are made. 2.5 Temperature Stabilization During the initial design phase, one of the primary goals was to develop a system which was insensitive to changes in the ambient temperature. It was assumed that the most sensitive devices would be those which are active, namely the preamp and power amp. To this end, a 24W hybrid heater had been placed on the amplifier combination. Unfortunately, the temperature stabilization tests showed that the most sensitive device was the passive delay line, and not the amplifiers as first suspected. The following test results demonstrate this fact: 38

Ambient Temp Lower Extreme Difference (20~ C) (-10~ C) in Component Measurement Measurement Measurement Power Amp Gain 51.12 dB 50.46 dB 0.66 dB (with heater) Preamp Gain 43.33 dB 42.67 dB 0.66 dB (with heater) Delay Line 42.53 dB 39.39 dB 3.14 dB Loss Total Line Loss 53.94 dB 49.67 dB 4.27 dB (without amps) (with 1OdB pad) Table 2.4: Thermal Variations of Key SAPARC Components As shown above, temperature stabilization would require either a number of high power heaters or a variable attenuator / gain feedback circuit. The former of these alternatives is somewhat impractical since it would require excessive amounts of battery power. Similarly, the latter option is too expensive for a practical implementation. An acceptable solution requires a mapping of the GLoop component of the RCS as a function of temperature. Such a mapping is shown in Section 3.3. The goal, then, is to accurately record the system's temperature during an actual field test. The temperature (recorded as a function of time) will then be compared to the GLCop vs. Temperature chart from Section 3.3. Hence, an accurate description of the system's total RCS can be calculated for the exact fly-by time of the SAR platform. 39

An automatic measurement is obtained through the use of a Dickson 24-hour Temperature Recorder. This device is nestled within the delay line loop located at the base of the SAPARC chassis. For an actual field deployment scenario, the user must activate the temperature recorder while noting the exact time of initial operation. Once this is done, the user is free to leave the deployment area while the rest of the equipment remains in its automated mode. 2.6 Assembled Prototype Figures 2.18 a-c show the SAPARC in its completed state. Note how the horn antenna is detachable for quick and easy transport of the device. 40

Figure 2.18a: Internal Components of the C-Band SAPARC

Figure 2.18b: C-Band SAPARC Disassembled For Transport

4).:.:.::...::::. A::. X 4) U 00 4) Cr rz..........~~~~~................................................................_.. CT4 CT _L

CHAPTER III EXPERIMENTAL RESULTS As mentioned in Chapter 1, the accuracy of a SAR calibration is highly dependent upon the measured performance of the calibration device. Hence, the measurements taken in accordance with this project must adhere to the following goals: * Accurate measurement of the scattering matrix for the 0~ and 45~ antenna orientations. * 0.2 dB accuracy in the mapping of the thermal gain variations. * Overall characterization of SAPARC performance with respect to field deployment conditions, including extremes in temperature, all-weather performance, and battery capacity. 3.1 GLoop Measurements Figures 3.1 and 3.2 depict the S21 frequency responses of GLop for room temperature operation (22~ C). For this measurement, a 50 dB attenuator was placed on the receive channel of the SAPARC in order to prevent amplifier saturation. The frequency response for this attenuator is similarly shown in Figure 3.3. From these measurements, GLoop is found to be 44.08 dB. However, as section 3.3 will show, GLoop is highly dependent upon the SAPARC's operating temperature. To find the correct value of GLoop for each SAR calibration, one must refer to the thermal variation chart shown in Figure 3.14. The SAPARC anechoic chamber tests were performed at room temperature 44

(approximately 220 C). Figure 3.9 (SAPARC RCS for the 00 Orientation) shows that the maximum achievable value for the RCS is 40 dBsm. Using this data in conjunction with the theoretical equation given in section 2.1, the gain of the C-band antenna system is found to be 15.93 dB. The following calculations demonstrate this result. a=G GTGR2P2 -GP 41 where a = 40dBsm Gop = 44.08dB GT = GR= GAn,, 2 (0.0566m)2 _ 4n 4Xn Rearranging the equation gives AG,,e= 2 = (40.OdBsm- 44.08dB + 35.94dB) GLP 41X G,', = 15.93dB The equations above demonstrate how the user can easily find the RCS of the SAPARC for any given operating temperature. In other words, when the operating temperature is known, the corresponding value of GLop will also be known, and hence so will the RCS of the SAPARC unit. The equations are similarly applicable to the 45~ SAPARC orientation. For this case, simply subtract the 6 dB difference from the 0~ orientation antenna results described above. 3.2 Anechoic Chamber Tests The University of Michigan Radiation Laboratory maintains a fully equipped 60-foot 45

long, tapered anechoic chamber which is used for conducting antenna pattern measurements and for measuring the scattering characteristics of man-made and natural targets. This chamber is ideal for making accurate measurements of the SAPARC's RCS within a relatively noise-free environment. A major component of the Radiation Laboratory's polarimetric radar measurement facility is the LCX POLARSCAT system. The parameters of the C-band subsystem are as follows: Center Frequency Frequency Bandwidth Antenna Type Antenna Gain Beamwidth Far Field ( 2d2 / X ) XPOL Isolation Calibration Accuracy Measurement Precision (N>1 Phase Accuracy 5.3 GHz 0.5 GHz Dual Polarized Pyramidal Horn 25.3 dB 8.0~ 5.8 m 45dB +0.3dB 00) + 0.4 dB ~30 Table 3.1: C-Band POLARSCAT Parameters A large percentage of this system consists of Hewlett Packard components, including an HP 8753 Network Analyzer and HP 9000 Computer with an additional disc drive. Using computer control, polarimetric measurements of the phase and magnitude responses can be taken with respect to changes in target elevation and azimuth angles (Figure 3.4). The chamber experiments required a center frequency of 5.3 GHz with a 600 MHz bandwidth. Calibrations were performed by using a 14" metallic sphere in accordance with a calibration technique developed by Sarabandi [5] (See Appendix E). Time gating was also employed, whereby a gate span of 10 ns (centered on the target's response) provides an automatic subtraction of background scatterers. 46

Ml only REF -5.0 dB 1 10.0 dB/ V -5.7512 dB I og MAG c A hp MARKER 1 Z 3 HzI.. ____.......................... X................ _. qQ -t CD u2 0 O CD 3 0 0 ~ CD O CD 0 % 0 START STOP 5. 000000000 GHz 5.600000000 GHz

Figure 3.2: Detailed Frequency Domain Response of GLoop N N I I toLto 0 a rr <: O is) - n U) |-& (Inn{ m "o m \ 'o ff IV r-I _ N. 0) C I rI a o in Li 1,.4 W '- rr,.q

Figure 3.3: Frequency Domain Response of the 50 dB Attenuator ~~I ''~ ~ '~ N N l! J I I I CDi6 0) a: --- N t — >-.. _ __ __ (____ o -:) 11:1> ___._ _ <nlO ~ ~l t Q 1 * conW >- Q e H.

Figure 3.4: C-Band POLARSCAT Test Equipment

3m / C = | ~ ~ ~ 0 0 1 HPRelay _ X, Actuator I oo 1 — I I]- L- Iii0 0 HP8753 Network I _____ | [ - ___ Analyzer HP 9000 Computer Figure 3.5: Anechoic Chamber Measurements at the University of Michigan's Radiation Laboratory

0~ 45~ Orientation Orientation I N^ Old Center 7.07 cm 7.07 cm New 7.07 cmCenter New Center Note: SAPARC must be moved up by 7.07 cm and mounted to the left by 7.07 cm Counterweight m 75 Ibs s 2 layers of Styrofoam sheets Styrofoam Upper g pedestal l. aChamber Block (Lower Pedestal) -4 — Plywood - -- Turntable --— 7 cm 0~ Orientation Upper Pedestal Position Turntable Center 45~ Orientation Upper Pedestal Position Sphere Calibration Lower Pedestal Position Turntable Center Figure 3.6: 0~ and 45~ Orientation Modifications

A block diagram of the measuring facility is given in Figure 3.5. Figure 3.6 shows the configurations used for the 0~ and 45~ Orientation tests. 3.1.1 SAPARC Time Domain Response Section 2.3 mentioned that a SAR calibration can be enhanced by time shifting the PARC's radar response so that it appears to originate over a dark background (refer to Figure 2.8). Recall that a 200 foot delay line is incorporated into the SAPARC design to accomplish such a feat. The effect of this delay is clearly shown in Figure 3.7, the time domain response of the C-band SAPARC system. As an addendum, Tables 3.2 and 3.3 provide an identification and quantification of the five markers given in Figure 3.7. Marker Identification 1 Leakage (i.e. cross talk) between the receive and transmit horns used in the measurement 2 Backscatter from the SAPARC's antenna and chassis (physical location of the SAPARC) 3 Primary time-delayed SAPARC response 4 First delayed multipath reflection 5 Response due to the ringing of the SAPARC unit Table 3.2: Marker Identification for Figure 3.2 Marker 1 2 3 4 5 Magnitude (dB) -100.39 -87.40 -36.31 -79.59 -49.37 Time Delay (ns) Referenced to Measured Marker 1 53.75 0.00 143.75 90.00 408.75 355.00 502.50 448.75 672.50 618.75 Electrical Distance (m) Referenced to Measured Marker 1 16.11 0.00 43.10 26.99 122.54 106.43 150.65 134.54 201.61 185.50 Table 3.3: Magnitude and Position Values for the Markers Shown in Figure 3.2 53

M1 only log MAG REF -30.0 dB 3 10.0 dB/ V -36.312 dB lhp A C/) > - — m i-A'T~~ 'T 0I + START 0.0 s STOP 1. 0 s

The values given in Tables 3.2 and 3.3 lead to a number of important conclusions. First, the electrical length of the delay line is found to be the difference between markers 2 and 3, namely 265 ns. This, in turn, corresponds to an electrical length of 79.44 m; hence, the SAPARC's SAR response has effectively been translated by nearly 80 m (i.e. approximately 260 feet). Also note the ringing effect (marker 5) where a replica of the original SAR response is periodically repeated every 263.75 ns, or 79.1 m. The subsequent replicas are a product of the limited isolation of the OMT. During the transmission of the first SAR response, a small amount of leakage RF makes its way through the SAPARC loop where it is amplified, delayed, and re-transmitted as another SAR response. Figure 3.7 shows how each of the recurring responses will decay by approximately 13 dB; hence, this process continues until the net amount of leakage becomes negligible. When processing the imaging data, the ringing effect inherent with each SAPARC allows for easy identification and location of the calibration system, thus providing another advantage over passive calibration devices. Marker 4 shows the delayed response of the first multipath reflection. The distances between markers 1 and 2 and markers 3 and 4 are virtually identical; therefore, it is believed that the response labeled by marker 4 corresponds to a component of the original signal which experienced multiple reflections from the SAPARC horn / chassis and the receive / transmit antennas on the radar platform. In other words, this signal originally reached the SAPARC unit where it was then reflected back towards the radar platform. Once reaching the platform, the signal was then reflected back again towards the SAPARC. Upon reaching the SAPARC for the second time, the signal was received, delayed, amplified, and re-transmitted back to the radar platform. Similar multipath signals are shown throughout Figure 3.7. As a final point, the SAPARC provides an exceptional signal to noise ratio (SNR). The difference between the SAR response (labeled as marker 3) and the anechoic chamber's noise floor is over 70 dB. A 50 dB signal to clutter ratio (i.e. the difference between markers 2 and 3) is also shown to be quite extraordinary. These relatively large values of SNR will prove to be very beneficial for actual SAR calibrations. 55

3.12 0~ Orientation Test The 0~ orientation of a SAPARC refers to the case when there is no polarization mismatch between the radar's antenna and the SAPARC antenna. In this mode, the SAPARC provides a calibration of cYhv, where a received vertically polarized signal is amplified, delayed, and transmitted back to the radar with a horizontal polarization. The phasor polarizations are given in Figure 3.8. Figure 3.9 demonstrates the measured azimuthal pattern response for this orientation. As shown, the SAPARC yields a maximum RCS response of 40 dBsm with a 150 half-power beamwidth (for the ohv case). (Note that the traditional convention of listing the target's polarimetric RCS as cxy where x and y refer to the received and transmitted polarizations, respectively, is used.) A cross polarization isolation of 38 dB exists between Yhv and Yvv, 'hh, thereby giving credence to the excellent cross polarization isolation performance of the horn / OMT design described in section 2.2. As a final point, the Ovh response reveals the "noise floor" inherent with this measurement. This RCS response is characterized by a 100% polarization mismatch for both the radar and SAPARC antennas, and hence the extremely low RCS response of -40 to -60 dBsm is expected. 3.1.3 45~ Orientation Test The 450 orientation is accomplished by rotating the SAPARC horn as demonstrated in Figure 3.10. Doing so allows a complete calibration of the Scattering Matrix since each transmit and receive combination, namely <vv, GMhh, Ghv, and ovh, yields the same RCS azimuthal pattern response with a half-power beamwidth of 15~. Figure 3.11 depicts the RCS azimuthal pattern response for the 450 orientation. Note how each trace is symmetric and virtually equal over a 400 beamwidth, as expected. Also note how the peak RCS of 34 dBsm is exactly 6 dB below the 0~ orientation response of 40 dBsm. Again, this result is in excellent agreement with the theoretical expectations (the two 450 polarization mismatches, one for transmit and the second for receive, correspond to a total loss in power of 1/2 * 1/2 = 1/4 = 6 dB). 56

Transmit Receive y X Radar Antenna Polarizations SAPARC Antenna Polarizations Figure 3.8: SAPARC 0~ Orientation Phasor Polarizations

Figure 3.9: SAPARC 00 Orientation RCS Azimuthal Patterns (SIR-C Mode) 50.0 40.0 30.0 20.0-. 10.0,'' 0.0 -10.0 Q s -20.0 E\. -50.0 I s ~ co / ^-'v \ \ -20.0r,.s -60.0\ l -70.0.................... -40.0 -30.0 -20.0 -10.0 0.0 10.0 20.0 30.0 40.0 Azimuth Angle (Degrees), V O --- hh ahV

Tv Rv --- Th ---- - - Rh y X Radar Antenna Polarizations SAPARC Antenna Polarizations Tv: Transmit Vertically Polarized Wave Component Rv: Receive Vertically Polarized Wave Component Th: Transmit Horizontally Polarized Wave Component Rh: Receive Horizontally Polarized Wave Component Figure 3.10: SAPARC 45~ Orientation Phasor Polarizations

Figure 3.11: SAPARC 450 Orientation RCS Azimuthal Patterns (SIR-C Mode 40.0. 30.0 20.0 - - 10.0 -0.0. / ';-/ \ \ -40.0 -30.0 -20.0 -10.0 0.0 10.0 20.0 30.0 40.0 Azimuth Angle (Degrees) -40.0 -30.0 -20.0 -10.0 0.0 10.0 20.0 30.0 40.0~~~~~~~' r~~Aimt nle (Dges

Figure 3.12: SAPARC 45~ Orientation Phase Patterns (SIR-C Mode) 200.0 I I I i I I I I I I a.. 180.0 160.0 140.0 120.0 100.0 80.0 60.0 40.0 20.0 0.0 I I r r 5 rrr, r r,* LCIIIIIIIIII r j rrr r rr \r I r I.! Ohh - w v --- —--- vh - -— ~ — - hv-wv:.OI %. 11%.., ~ ~ C~CIIII n! W - I I -20.0 -' -40.0 I...... I.... I I I -30.0 -20.0 -10.0 0.0 10.0 20.0 30.0 40.0 Azimuth Angle (Degrees)

V R T y \/j45.0~ H x Radar Antenna SAPARC Receive SAPARC Antenna SAPARC Transmit (vv )hv Ovh 4hh (hv - vv = 0~ R Component In Phase T Component In Phase (vh - Ovv = 1 80~ R Component 180~ Out of Phase T Component In Phase Ohh - Ovv = 180~ R Component 180~ Out of Phase T Component In Phase Figure 3.13: Phasor Diagrams for the 45~ Orientation

The phase responses shown in Figure 3.12 are also noteworthy. Theoretically, we expect Phv - vw =0~ Phh - Ow = Pvh - Ovv = 180~ over an 800 beamwidth. The phase diagrams in Figure 3.13 help to explain these results. Section 2.2 referred to the drawbacks encountered when using a two-antenna PARC system; more specifically, these problems include pattern asymmetry and ripples in the phase and magnitude responses. Figure 2.3 is an example of one two-antenna system tested by Sarabandi and Oh [1]. By comparing Figure 2.3 with those in Figures 3.11 and 3.12, one can easily see the notable SAPARC improvements in magnitude and phase performance. 3.3 Thermal Gain Testing Section 2.5 alluded to the fact that PARC's are susceptible to gain variations due to changes in the ambient temperature. Countering these thermal gain variations is formidable task; therefore, it is much easier to compensate for the changes in the SAPARC's RCS by mapping the GLoop dependency on ambient temperature. The thermal gain tests were performed at ERIM (Environmental Research Institute of Michigan) where a temperature-controllable refrigerator could be obtained. Figure 3.14 reflects the results of the experiment whereby GLoop is plotted over a temperature range of -20~C to 50~C. The user of the device must remember, however, that component aging may alter the overall performance of GLoop. Therefore, periodic calibrations of GLOOp vs. temperature is recommended. As a final note, special precautions must be taken when operating the SAPARC in cold weather scenarios. Currently, the system is configured to provide the 63

Figure 3.14: C-Band SAPARC Thermal Gain Variations 60 50 ' 40 y = 48.324 - 0.18322x RA2 = 0.998 30... I. I -20 0 20 40 60 Temperature (~C)

maximum allowable RCS for temperatures of 20~C or greater (see section 2.3.3). However, Figure 3.14 clearly shows how GLoop can increase by as much as 7 dB for temperatures below 20~C. Therefore, the user is encouraged to use the JPL AIRSAR mode of operation whenever cold operating temperatures are anticipated. Recall that the AIRSAR mode uses a microwave switch to insert 7 dB of attenuation into the loop, thereby providing the needed cold weather protection against feedback oscillations. 3.4 Field Deployment Conditions 3.4.1 Battery Capacity The SAPARC units developed through this project require two 12V, 7 Amp*H lead acid batteries. The power demands on Supply 2 (see Appendix C, pg. 1) is given as follows: SAPARC Operating Condition Current Draw Power Demand Timing Circuitry On 0.37 A 4.44 W System Active 1.09 A 13.08 W System Active with LED Display On 1.20 A 14.40 W Table 3.4: Power Demands on Supply 2 Figure 3.15 (1 A case) depicts the capacity performance of the Yuasa 12V battery used in the SAPARC design. Figure 3.16 shows the results for the full load case (i.e. a current draw of 1.2 A). Under full load conditions, the SAPARC can operate (at temperatures above 20~C) for up to 5.5 hours; longer operating times are achievable when using the Activation Timers. Figure 3.17 shows the marked decrease in capacity during cold weather operation. During this test, the Yuasa 12V battery was subjected to a temperature of -100C while providing a current of 1.2 amps. Under these conditions, the SAPARC's full load operating time is reduced by one hour, therefore, the user must take special precautions when planning to operate the SAPARC in cold climates. 65

Cap ac i ty Test: Yuasa 7. 0 RH 14 13 0)12 rd +, o 1 1 > I I I r a a a I a a ' I a a a I a a I I I I a I a a a I a a a I ' a I I I a I I I ' ~8 a.,,,,,,,,,,,,,,,,,,,,,,,,,,,, i\,,,,.,,...! I 9 i. 0 1 2 3 4 hou rs 5 6 e 1 apsed 7 8 9 10 Figure 3.15: Battery Capacity Test (1.OA Load, 22~C)

Cap ac i ty Test: Yu as a 7 0 RH 1 1 0) O-) rd -p ol 1 9 L 0 1 2 3 4 5 8 7 8 9 hours e apsed Figure 3.16: Battery Capacity Test (1.2A Load, 22~C)

Capac i ty Test: Yu as a 7.8 RH 14 13 0) m12 - ol2 >. a ' I ' '' I ' I a I I ' ' I ' ' ' II a................... ~.... " - I........!;,.,,..I I...!.. ~.~.!....... I 10 r N 0iL 1 2 3 4 hou rs 5 G e apsed 7 8 10 Figure 3.17: Cold Weather Battery Capacity Test (1.2A Load, -10~C)

3.4.2 All-Weather Performance Ideally, the SAPARC can be used in all types of weather; of course, there are a number of practical limitations which concern the aperture on the horn antenna. Obviously, rain and snow can accumulate inside the horn / OMT, and thus the calibration would be ruined. In order to compensate for this occurrence, a polyethylene film (e.g. Saran Wrap) was placed over the aperture to serve as a radome. This film was very effective in keeping water out of the horn / OMT combination; however, an accumulation of water droplets on the radome eventually lead to a feedback oscillation scenario (see Sections 2.3.2.2 and 2.4.2). Therefore, applying a thin-filmed polyethylene radome is suggested for weatherproofing the horn, OMT, and waveguide adapters. Yet, do not expect the SAPARC to operate correctly in adverse weather conditions. As a sidenote, if the rainfall ceases and the radome is allowed to dry, the SAPARC will "break-out" of its oscillation mode and return to its normal operating condition. The only notable change is that the detection circuitry will be triggered prematurely. Finally, the chassis of the SAPARC unit should be shrouded with a rain tarp to prevent excess exposure to the elements. 69

CHAPTER IV CONCLUDING REMARKS The report outlines the design and performance characteristics of the first single antenna polarimetric active radar calibrator (SAPARC) prototype developed for NASA's SIR-C mission at the University of Michigan's Radiation Laboratory. In addition to this specific unit, a second C-band and two L-band versions are currently being constructed as part of a continuation of this project. This first C-band prototype possesses a nominal RCS of 34 dBsm with a 3 dB beamwidth of 150. One of its best attributes, however, is the fact that it can outperform conventional PARCs though its implementation of a single dual-polarized antenna. More specifically, the pattern asymmetry and phase and magnitude ripples are eliminated through the use of this design. In addition to these RF characteristics, the prototype is also noteworthy in that it provides a number of features which accommodate prolonged operation intervals and useful system status updates. In the future, subsequent modifications to this basic design will hopefully lead to more accurate and convenient calibrations of SAR platforms. 70

APPENDIX A OMT SPECIFICATIONS

TEST RESULTS JSTOMER UN.O NO 't \ _ PART NO. JSTOMER P.O. NO. V 2' ATL. REF.NO. _r X ORTHOGONAL MODE JUNCTION [STED BY 5L t DATE 2'A\-o1 F*5^^ CJ^_ |_______ catalog number: C;-, -- erial requency VS R ISOLAumber in MHz H port E port TION:i A 1O c \ TS IO c I, I \ c. I \ I D'-t S Ic LO,5u E \ o C <,0 D E __E _____ B E A _ cification limits 1B \'' o dB maximum maximium minmum \ t____ E ___o___dB _ serial frequency VSWR ISOLAnumber In WMz H port E port TION A B C D | 1..,_1 A B C D D ___I___ A B _______ C_ D A B C D E A B D D ______I___I E Port E Port H Port tyle 1 H Port Style 2 _~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I TLANTIC MICROWAVE CO POIRA1 iON )UTE117 * BOLTON, MASS. 01740:I (F17 t77Q0-cc * Tu'Ys tqi.-Q.Ri 1, AT ATLANTIC I rV-I 5-18-88 TR-107 REV. A CUSTOMER COPY 0 FILE COPY 0

APPENDIX B AMPLIFIER SPECIFICATIONS

I -- UI 100 Davids Drive, Hauppauge, N.Y. 11788-2034 PROJECT No: P38858 MODEL No: AFS5-05000560-60-8P-5 SERIAL No: 249372 CUSTOMER: UNIVERSITY OF MICHIGAN P.O. No: F33091 TEL: (516) 436-7400 TELEX: 6718148 FAX 516-436-7430 IMPORTANT - MUST USE HEAT SINK IF CASE TEMPERATURE EXCEEDS 70~C SPECIFICATIONS AT +23~ C: OUTPUT POWER @ ldB FREQUENCY: 5.0 to 5.6 GHz GAIN COMPRESSION: +8 dBm MIN. GAIN: 40 dB VOLTAGE: +15 VOLTS MEASURED MAX.GAIN FLATNESS: +/- 1 dB CURRENT: 150 mA MAX. VSWR INPUT: 2:1 MAX. NOISE FIGURE: 6.0 dB MAX. VSWR OUTPUT: 2:1 HOUSING No: 113110 NOTE: TEST DATA TAKEN WITH CASE TEMP. OF +23'C FREQUENCY GAIN VSWR OUTPUT POWER. — ~ NOISE FIGURE (dBm) (@ ldB GAIN (GHz) (dB) IN OUT (dB) COMPRESSION) 5.0 44.0 1.28 1.71 1.30 +14 5.1 44.5 1.31 1.69 1.26 +14 5.2 44.6 1.32 1.65 1.39 +15 5.3 44.4 1.34 1.56 1.45 +15.5 5.4 44.2 1.35 1.50 1.61 +15 5.5 43.4 1.38 1.38 1.39 +16 5.6 42.6 1.36 1.29 1.46 +16,...... -;ZLLICU TESTED BY: DATE: 06/02/92 (DONALD MAURICE)

SPECIFICATIONS Project P30,885 Internal Transfer Customer P/N _ Model A t^-5 e. - 5056 - o Zc Serial No. 24C- 1 1- - Frequency (GHz) 5,0-5.( Ghzo Output Power (dBm) at 1 dB Compression i Z9. C) ) G, r l-, Gain (dB) o - G I, Voltage 415 V Gain (dB) _^ z o Jd,n O____ 415 /zc~ Gain Flatness (dB) IT Measured Gai__n_ Fl____d -1.J5( rJl Current (mA) B9-21Q TA VSWR Input/Output Noise Figure (dB) /.o c _o_ Noise Temp 'K TEST DATA +7Z~c_ Frequency Gain VSWR N. F. Noise Po at Po (GHz) (dB) In Out dB temp 'K 1dB comp. hard satu. + $.1 C0|Ct4cAO.) |: Ie |. |3. \ 2< = o I Q Io 1 1 1+30 I I,3 ce 1.Q1 lj?,P~ 22 ~1 I 1 _______ 5,(g _ oV^ __ ___I 3.0 I1 1 130 1 _....................... i, X Tested By ----- ~ Date 41 t9 MITEQ INC. * 100 Davids Drive * Hauppouge, New York 11788-2086 * Tel. (516)436-7400

OOtL-9E9T(91S) l')l 9 9802-88LIT >iJO MSaN 'aOnoddnoH * ^AIJa SPIA'OQ 00 * OONI 031IW, --- —.- -.- Al - i. a A^lyNf ------.- As pa3psai -- i c3j )ll I I HLOEMONVO NIV3 L lb)-V *'ON OlJaS 4 w lapowl d Z- ZI~ O~- - = v - y -Nd "Nawo.sn3 JaJsu.Jj l oUJa.UI 13rn5LIAI Y ~ F 3.arOJd

APPENDIX C CONTROL CIRCUITRY SCHEMATICS

Control Ponel Power Connections I SW2-A c, C SWI -A Source I SWI SWI-t 3' 2> To Control 34 ^> PWA 34:' SWI (Battery Power) Position I: On Position 2: Off/Recharge SW2 (External Sources) Position I: Off Position 2: On SWIO (Charging Configuration) Open: Individual Closed: Parallel Connector References A = 50 Pin Connector B = 9 Pin Connector Control Panel C = 9 Pin Connector Timing Circuit On On A-33 > To Control PWA Source 2

Relay Circuitry I SW5 -A +12V _- - A-33 > Power Reset +24V l <e A-24 N ---NO o Token Fr +24YV __________________________________________ ' On Contr +24V T " A-32 > A-34 > I II From Control i-' 22 3 Panel 4,4, CR2 CR1 I } ( uioU 12 3 20 Battery Power rom SV2-A-C roI Panel Hybrid A-35 - -- B-4 a + - HeaterH Chossis GND

Battery Power Threshold Detection Circuitry VA SW3-C Display Power On/Off A-19 >4-e~~ ----~ A-2O +24V Node A-19: o --- << A-20 "-o On PWA Closed:On; Open:Off Source I 10 Segment LED Display Unit R8 IOOK Pot R IOOK P A-I A-2 A-3 A-4 A-5 A-6 A-7 A-8 A-9 Source 2 10 Segment LED Disploy Unit A-10 3 - I A-I 4 -- A-I I i A-12 A-143 A-16 A- 1 4 A-l 5 ) A- 17 O, A - I8 - 10

Battery Power Threshold Detection Circuitry - Part 2 Power On LED - +24V Node On Control PWA A-29 U6 oss is C3 0. 33u F C5 0.33uF.2 Ch GND m22 Ohm +5V Node On Control Panel +24V Node On Control PWA UIO l 4, l l U8 I I [Timer Act ivot ion Circuitry] U5

Timer Act ivat ion Circuitry A-31 Open: Off SW3-A - Disploy On/ Off Closed: Open I;: A-23 ). +5V R24 160 Ohm U9 3 On Control PWA T 6 U13 U14 Timer On (Micronta Alarm Clock) A-35 A-36 +5V Node On Control Ponel U5 C-6 C-7 Timer Off (Micronto Alorm Clock) C-4 C-5 C-8 C-9 + C Nodes On C A-25 Contro l Pane l GND A-25 " - o SRW5e-B - Power Reset R20 160 Ohm A-30 Reset OK LED _ U5 Power On LED/ Reloy 4

Microwave Switch Connections SW7 SAR Appl icat ion Q AI o X Al ~C| ------- iFrom A-40 )- -8V Reg Deteee ction ()) A2 --- PWA 0 1 BSwitch Positions "-... "('C: JPL Airsar ~B82 _ ~ ': SIR-C B-2 B-I RF Amps/ Heater Connections From PWA -< A-35 <-< --- B-4 > — To Heater (+24V Node) From PWA -< A-36 <-4 — - B-3 --- To Amplifiers (RF) (+15V Node) SWII & SW12 (Timer Controls) 3 Pole - 4 Position Rotary Switch Timer Switch Replocement Pos it ions 1234 Connection Pads Inside Of Timer I C I LDIZ Funct ion Time Set Alarm Set Run - Alarm On Run - Alarm Off Connected Pad.s C, D A, C, D C B, C Pos it ion 2 3 4 0 0 0 D A NC B 0 0 0 NC D NC NC I NC 0 0 0 NC NC NC NC NC NC NC NC

Modificotions Made To Applied Microwave's Detection Circuitry +15V Node On Detection PWA SW9 R35 680 Ohm: Out Node On o Detection PWA R36. 330 Ohm. t 0. 25 Amp o+24V -. ----/ — (Token From SW2-A-C / Circuit Breoker On Control PWA) R39 Power Res istor 47 Ohm '-39 I T5 Power Tronsistor LM31 IN U21 A +12 V (Token From SW2-B-C On Control Panel) Lamp -8V For RF Switches Detect ion Reset: RST Node On Detec ion PWA L____< N C. SW8 A-37 ' - Detection Reset N-.OI -15V Node c On Detection PWA A-40 <( SW7

GROUND CONNECTIONS. p -< < A-42 <- A-43 <- A-44 -; A-45 — 4 A-46 -c A-47 -4 A-48 " -A-49 A-50 LI Control GND PWA ~ --- —---- -- - -- --------- I.14 44 44 44 4.4- i I Chassis GND Control PWA GND POWER CONNECTIONS Defection PWA GND COM Node on I V Detection PWA I ___/- t +12V Node on -12V Node on IDetection PWA Detect ion PWA L-__-_-_-_-_______ _ ____ _ _ _ ___ _ j_2 +12V Node On Control PWA&J

APPENDIX D CROSS POLARIZATION ISOLATION TESTS

14" Calibration Sphere 1 3 feet HP 8510 NWA Note: Amplifier Used for Cross Polarization Measurements Only G = 38.7 dB Figure D.1: Cross Polarization Isolation Test Measurements

Figure D.2a: Svv Time Domain Plot of a 14" Calibration Sphere -0 <D( C a), r mCO ^ a CO r LL I <. frei:>L, Im Wi co. Z ol O~ r-q 9&

Figure D.2b: Sw Frequency Domain Plot of a 14" Calibration Sphere (With Background Subtraction) -- -- -— 1 F- - -- ] m e W.o.... sIn < LL I 03 (m,~~~~ xt L 0i N N I I L(D~ G C ID ID G t - Cn C CD I-I< 0 in (n

522 REF -50.0 dB 1 10.0 dB/ V -54 939 dB I og MAG A A *17 0q co (5 _sn o _- Et0 0:t "'2 o::r: 5D D START STOP 0.0 s 50.0 ns

Figure D.2d: Shh Frequency Domain Plot of a 14" Calibration Sphere (With Background Subtraction) N N I I (D & S t0 0 I a n LD Si Cl 1 -< 0 in -) ID m aim m8N r-I Ln a S I in in I in NLL I N LL LOTDr U < C3

Figure D.2e: Shv Time Domain Plot of a 14" Calibration Sphere ~xn \ COri c I Hs'~ r13 L E.. 0 UI ^ u>^d prI t ~._...f~ ~ II _in_< (n Ef ). -qLL IQ <(D J <

Figure D.2f: Shv Frequency Domain Plot of a 14" Calibration Sphere (With Background Subtraction) N I I CL & D S)S~ E<r0 I-I — (fU) 0 m m 'N a -0 m r-i q S Lf) I in LL I N W LUr cam u < 3

Figure D.2g: Svh Time Domain Plot of a 14" Calibration Sphere __ - S = -_ I < I C) O W I _|t Ic_ ~~~~~~~~~~~~~~~(- ' --- — a > co~~~~~~~~~~~~~~~~~~ m \ T0 -I in ID ' I,"q (D tn NLL I r-q (F) -jr 0 * a CL <l a f\ u <

Figure D.2h: Svh Frequency Domain Plot of a 14" Calibration Sphere (With Background Subtraction) N N II LD D CD CD CD 00D 0I) 0 -QtIn -- (flU) 01 co tn C CO I Ut O MIL n I tf) ('4LL I r- W (Il Zr:> U < C

APPENDIX E MEASUREMENT AND CALIBRATION PROGRAMS

C ********************************************************************** c C Appendix E C HPUX Data File Conversion Program C C JPL AIRSAR / NASA SIR-C SAPARC Project C C James J. Ahne C Radiation Laboratory C Department of Electrical Engineering and Computer Science C University of Michigan, Ann Arbor, MI 48109-2122 C C ******************************************************************* C C Read raw data and write converted data for Calibration by a Sphere. C COMPLEX TARGET(81,4,20) REAL RAW(42) INTEGER NPTS, NTRACE CHARACTER POL(4)*2 C DATA POL/'VV','HH','HV','VH'/ C C Read raw real data and convert to complex data for calculation. C OPEN(1,FILE- '152319gc') NP-4 NPTS-20 NTRACE-81 DO 10 IT-1,NTRACE DO 10 IP-1,NP READ(1,*) (RAW(K),K-1,NPTS*2) DO 14 J-1,NPTS J2-J*2-1 14 TARGET(IT, IP, J) -CMPLX (RAW (J2),RAW(J2+1)) 10 CONTINUE C COMPLEX Z PI-4.*ATAN(1.) X-REAL(Z) Y-AIMAG(Z) PHASE-(180./PI) *ATAN2 (Y,X) RETURN END C C C C CLOSE (1) Open files for outputs. OPEN (10,FILE-'cparc_sirc_45af' ) DO IT-1,NTRACE DO IP-1,NP WRITE(10,*)'NT- ',IT,'POL- ',POL(IP) DO I-1,NPTS WRITE(10,*)TARGET(IT,IP,I) ENDDO ENDDO ENDDO CLOSE (10) STOP END ****FUNCTION PHASE(Z)*************** FUNCTION PHASE(Z) ****************************************************************** C C C C C C C C

iiiiii~~~~i:'I rii::::::::i:::i:I: t.......................................... C ******~~~~~~~*********************........................... c c C Appendix E Scatterometer Calibration Program JPL AIRSAR / NASA SIR-C SAPARC Project James J. Ahne Radiation Laboratory Department of Electrical Engineering and Computer Science University of Michigan, Ann Arbor, MI 48109-2122 C C C C * ***** ***** ******************* C C (THIS PROGRAM CALIBRATES THE SCATTEROMETERS USING THE NEW METHOD) C COMPLEX C,A,A11,A12,A21,A22 COMPLEX EW0O(20),EHHO(20),EVH0(20),EHVO (20) COMPLEX EVVM(20), EHHM(20), EVHM(20),EHVM (20) COMPLEX EWS(150,20),EHHS (150,20),EVHS(150,20),EHVS (150,20) COMPLEX EVVU(150,20),EHHU(150,20),EVHU(150,20),EHVU(150,20) COMPLEX Sl1(150,20),S22(150,20),S12(150,20),S21(150,20) complex SIG11,SIG22,SIG12,SIG21 character*l,char COMPLEX SO(20) open(9,file-'sph_14') open(10,file-'sph_dat.22') open(ll,file-'mntdat.22') C open(12,file-'sap_bg') Backgound Data - Not Applicable For Parc open(13,file-'cparc_sirc_45af') PI-4. *ATAN(1.) ndata-20 ntrace-81 C cir-(0.6945+1.333)/(1.994+2.424) C READ THEORETICAL VALUE OF SPHERE DO I-l,ndata READ(9,*)DUM,SO (I) ENDDO C SPHERE DATA READ(10,103) DO I-l,ndata READ (10, *) evvO (I) ENDDO READ (10,103) DO I-1,ndata READ(10,*)ehhO(I) ENDDO READ (10,103) DO I-1,ndata READ(10,*)ehvO(I) ENDDO READ(10,103) DO I-1,ndata READ (10, *)evhO (I) ENDDO READ(11,103) DO I-1,ndata READ (11, *)evvm (I) EVVO (I)-EVV (I)-evvm(I) ENDDO READ(11,103) DO I-1,ndata READ(ll,*)ehhm(I) ).ft: -l:.......... EhhO (I) -Ehh (I) -ehhm(I) ENDDO READ(11,103) DO I-l,ndata READ(ll,*)ehvm(I) EhvO(I)-EhvO(I) -ehvm(I) ENDDO READ (11,103) DO I-l,ndata READ (11, *)evhm(I) EvhO(I)-EvhO (I)-evhm(I) ENDDO do i-l,ndata print *,20*alog10(cabs(evv0(i))),20*aloglO(cabs(ehv0(i))), & 20*aloglO(cabs(evhO(i))),20*aloglO(cabs(ehhO(i))) enddo pause C BACKGROUND DATA C do itrace-1,ntrace C READ(12,103) C DO I-l,ndata C READ(12,*)X,Y C EVWS(ITRACE,I) -CMPLX (X,Y) C ENDDO C READ(12,103) C DO I-l,ndata C READ (12,*)X,Y C EHHS (ITRACE, I) -CMPLX (X,Y) C ENDDO C READ(12,103) C DO I-l,ndata C READ(12,*)X,Y C EHVS(ITRACE,I) -CMPLX (X, Y) C ENDDO C READ(12,103) C DO I-l,ndata C READ(12,*)X,Y C EVHS(ITRACE, I)-CMPLX(X,Y) C ENDDO C enddo C UNKNOWN DATA DO ITRACE-1,ntrace READ(13,103) 103 FORMAT(1X) DO I-l,ndata READ (13, *)evvu (itrace, i) C EVVU (ITRACE, I) -CMPLX (X,Y) -EVVS (ITRACE, I) ENDDO READ(13,103) DO I-l,ndata READ(13,*)ehhu(itrace,i) C EHHU(ITRACE,I)-CMPLX (X,Y)-EHHS(ITRACE,I) ENDDO READ(13,103) DO I-l,ndata READ(13,*)ehvu(itrace,i) C EHVU(ITRACE,I)-CMPLX(X, Y)-EHVS(ITRACE,I) ENDDO READ (13,103) DO I-l,ndata READ (13, *)evhu (itrace, i) C EVHU (ITRACE, I) -CMPLX (X, Y) -EVHS (ITRACE, I) ENDDO ENDDO

...........:..:::::::::::::::::::::....::........:.:........:..................................:.....:::::::::::::::::::..:::...............:::...... -:::........................................................................... ~:::::i~::::::..::-::::~;,i::= -~-::::::-::::. ~;:-;-......~..~~....;...::...:.:..:.....~ C C c C 4 C C c c C This c & & do itrace-l,ntrace print *,20*aloglO (cabs(evvu(ITRACE,4))), 20*alogl0 (cabs (ehvu (itrace, 4))), 20*alogl0 (cabs (evhu (itrace, 4))), 20*alogl0 (cabs (ehhu (itrace,4))) enddo is a calibration based on cl-c2 DO ITRACE-1, NTRACE DO I-l,ndata A-EVHO (I) *EHVO (I) / (EVVO (I) *EHH0 (I)) C-(1-CSQRT(1-A))/CSQRT(A) All- (EVVU (ITRACE, I) /EVVO (I)) * (1+C**2} *SO (I) A22- (EHHU (ITRACE, I)/EHH0 (I)) * (1+C**2) *SO (I) A12- (EVHU (ITRACE, I) /EVHO (I)) * (2*C) *S0 (I) A21- (EHVU (ITRACE, I) /EHV0 (I)) * (2*C) *SO (I) S12 (ITRACE, I) -(A12+C**2*A21-C* (All+A22) ) / (1-C**2) **2 S21 (ITRACE, I) - (A21+C**2*A12-C* (All+A22)) / (l-C**2) **2 Sll (ITRACE, I) -(All+C**2*A22-C* (A12+A21)) / (1-C**2) **2 S22 (ITRACE, I) (A22+C**2*All-C* (A12+A21)) / (l-C**2) **2 ENDDO PRINT *,ITRACE ENDDO open(15,file-'cparcirsrcam45af') open(16,file-'cparcrc _rcph_45af') C C The variable I now sets the frequency (for 20 data points, C use 1-10 -- chooses the center frequency) 1-10 C C 10 print*,'input psi' read*,psi psi-psi*3.1415/180. sigll-sll (41,10)*cos (psi) **2sin (psi) *co (psi) * (s12 (41,10) & +s21(41,10)) +s22(41,10)*sin(psi)**2 sig22-sll (41,10) *sin (psi) **2+sin (psi) *cos (psi) * (s12 (41,10) 6 +s21 (41,10))+s22(41,10)*cos(psi) **2 sigl2-sin(psi)*cos(psi) * (sll(41,10)-s22 (41,10))-sin (psi)**2 & *s21(41,10)+cos(psi)**2*s12(41,10) sig21-sin (psi)*cos(psi) * (sll(41,10)-s22(41,10) ) -sin(psi)**2 & *s12(41,10)+cos(psi)**2*s21(41,10) print*, cabs (sigll), cabs (sig22), cabs(sigl2), cabs (sig21) read*, nk if(jnk.eq.0)goto 10 angmax-40.0 angmin —40.0 print*, ntrace dang-(angmax-angmin) / (ntrace-1) do itr-l,ntrace ang-angmin+(itr-1)*dang C sigll-sll (itr, i) *cos (psi) **2-sin (psi) *cos (psi) * (s12 (itr, i) & +s21(itr,i)) +s22(itr,i)*sin(psi)**2 sig22-sll (itr, i) *sin(psi)**2+sin (psi) *cos (psi) * (s12 (itr, i) & +s21(itr,i))+s22(itr,i)*cos (psi)**2 sigl2-sin (psi) *cos (psi) * (sll (itr, i) -s22 (itr, i) ) -sin (psi) **2 & *s21 (itr, i) +cos (psi) **2*s12 (itr, i) sig21-sin(psi) *cos(psi)* (sll (itr, i)-s22 (itr, i) ) -sin(psi)**2 & *s12(itr,i)+cos(psi)**2*s21(itr,i) sll(itr, i)-sigll s22 (itr, i) -sig22 s12 (itr, i)-sig2 s21 (itr, i) sig21 WRITE(15,*)ANG,10.*ALOG10(4.*PI*cabs(Sll(ITR, I)) **2) &,10.*ALOG10 (4.*PI*cabs (S22(ITR, I) ) **2) &,10.*ALOG10(4.*PI*cabs (S12(ITR,I))**2) &,10.*ALOG10 (4.*PI*cabs(S21(ITR, I))**2) WRITE (16, *)ANG, PHASE (S22 (ITR, I)/Sll (ITR, I) ) &,PHASE (S12 (ITR, I)/S1l (ITR, I)) &,PHASE(S21 (ITR, I)/Sll(ITR, I)) ENDDO STOP END C****************************************************************** C FUNCTION PHASE(Z) C C****************************************************************** COMPLEX Z PI-4.*ATAN(1.) X-REAL(Z) Y-AIMAG(Z) PHASE-(180./PI) *ATAN2 (Y,X) if(phase.lt.-100.0) phase-phase+360 RETURN END

:~**^ v* we s. e- * - wo S -w *X * W** *Z****y \ **v* * ' Xw ~t'2 i'`== & M::~~t ):::: rB o {Z*b*;~: ~ X -~: ~ @; 1********************************t********** ****************! Appendix E HP Basic Scatterometer Measurement Program *! ~ ~ JPL AIRSAR / NASA SIR-C SAPARC Project James J. Ahne Radiation Laboratory Department of Electrical Engineering and Computer Science! University of Michigan, Ann Arbor, MI 48109-2122!****************************************************************************** 10 ********************************************************************* 20 L/C/X POLARIMETER MEASUREMENT PROGRAM 30 FILE: SAPARC 4 40 ****************************************************************** 50 1 LAST EDIT: Sep 22, 1992 Change for C-Band SAPARC measurements 60 1 70 ************************************************************************ 80 OPTION BASE 1 90 COM /Paths/ eNwa,eNwa_datal,eNwa_data2,Netwrk analyzer, Hpib, Relay 100 COM /Constants/ Vel,Zero(3),Exec_key$[2] 110 COM /System_config/ INTEGER Printerflag,Debug_flag,Version$[12],ModeS[10],Outtyp eS[10),Sound$(3],Bell$(l),Target$[30],Ref_target$[30] 120 COM /Sys_l/ FreqS(3) [1],Freqcent (3),Freq_span(3),Gate_cent (3),Gate_span(3) 130 COM /Sys_2/ PolS(4) [2],PolswS(3,4) [8] 140 COM /Sys_3/ INTEGER Fdisp,P_disp 150 COM /Sys_4/ DriveaS(15],DrivebS[15],DrivecS[15],INTEGER Preamble,Bytes 160 COM /Sys_5/ INTEGER Nskip,Ndata 170 COM /Sys_6/ Ref angle,Angle,AngleS[10],Beam(3),INTEGER Npts,Ntrace,Averagefactor 180 COM /Sys_7/ INTEGER Meas_flag(3) 190 COM /Com4/ INTEGER Rotation_state,REAL Incangle,Current_angle,Start_angle,Stop_an gle, homele,ldho e, INTEGER Sets_per_pos 200 COM /Status/ INTEGER Sc,Connect_flg,E_flg,Debug_flg,Response$[80] 210 1 220 1 230 INTEGER F,I,J,P,T,Meas_flag_old(3),Exit_flag,Nt,Nst,Nskh,Npt 240 DIM Sky_cal_file$(3) [14],Old_target_name$[30] 250 DATA "L","C","X" I FREQUENCY 260 DATA "VV","HH","HV",VH" I POLARIZATION 270 DATA 1.25,1.2,1.5 1 FREQ CENT 280 DATA.3,.6,.5 I FREQSPAN 290 DATA 12.5,9.0,6.2 I BEAMWIDTH 300 DATA "?*B3456","?*A34B56","?*A4B356,"?*A3B456" I L 310 DATA "?*B3456n,"?*A56B34","?*A6B345","?*A5B346" I C 320 DATA "?*A34B56","?*B3456","?*A3B456","?*A4B356" I X 330 DATA ":,700,0",":,700,1",":MEMORY,0,7" I DRIVEA,B,C 340 DATA 200E-9,200E-9,200E-9 I GATE CENTERS 350 DATA 10E-9,10E-9,10E-9 I GATE SPANS 360 READ FreqS(*) 370 READ Pol$(*) 380 READ Freq_cent(*) 390 READ Freq_span(*) 400 READ Beam(*) 410 READ PolswS(*) 420 READ Drive_aS,Drive_bS,DrivecS 430 READ Gate cent(*),Gate_span(*) 440 PRINT Measflag (*) 450 1 460! Set up error handling routine. 470 480 LOAD KEY "NOKEY:MEMORY,0,1" 490 500 510 520 530 540 550 560 570 580 590 600 610 620 630 640 650 660 670 680 690 700 710 720 730 740 750 760 770 780 790 800 810 820 830 840 850 860 870 880 890 900 910 920 930 940 950 960 970 980 990 1000 1010 1020 1030 1040 1050 1060 1070 1080 1090 1100 1110 1120 MASS STORAGE IS "JIM CPARC:,700,0"!! Initialize important parameters. I DEG Rotationstate —l Current_angle-0. MAT Measflag- (1) ModeS-"FAST ACQ" F_disp-2 P_disp-3 Printer_flag-0! Hp_bus_init IF Printer_flagl-! THEN Out_typeS-"PRINT/DISC" Vel-2.99792458E+8 Ntrace-81 Npts-401 Nskip-20 Ndata-20 Average_factor-4 AngleS-"0" Angle-0 Ref_angle-0 TargetS-"" Sound$-"ON Debug_flag-0 BellS-CHRS(7) ExeckeyS-CHRS(255) &CHR (88) VersionS-"Version 8.0 Exitflag-0 Print bannerl! System_memory-VAL(SYSTEMS("AVAILABLE MEMORY")) IF FNAsk("INITIALIZE RAM DISK?") THEN INITIALIZE DrivecS,0 INITIALIZE DrivecS,INT((System memory)/512) ELSE ASSIGN @Isitthere TO DrivecS;RETURN Outcome IF Outcome-0 THEN CAT DrivecS;NO HEADER,COUNT Entries IF Entries-0 THEN INITIALIZE Drive_cS,0 END IF ASSIGN @Isitthere TO * END IF! Config_and_poll OUTPUT @Nwa;"TIMDTRANON;LOGM;CONT;" OUTPUT @Nwa;"POIN401;"! OUTPUT @Relay;"?*B1256A34" Seriesinit Start loop: Print banner4 ON KEY 0 LABEL ON KEY 1 LABEL ON KEY 2 LABEL ON KEY 3 LABEL ON KEY 4 LABEL ON KEY 5 LABEL...f ",FNTraplevel " REFERENCE CAL",FNTrap_level " TARGET RUN ",FNTrap_level " SET FREQUENCY",FNTrap_level " ANGLE ",FNTrap_level " TARGET NAME ",FNTrap_level GOSUB Null GOSUB Reftarget GOSUB Acq_target GOSUB Freqset GOSUB Set_angle GOSUB Set target

1130 ON KEY 6 LABEL " * OF TRACES ",FNTrap_level GOSUB Set traces 1140 ON KEY 7 LABEL " * OF POINTS ",FNTrap_level GOSUB Set points 1150 ON KEY 8 LABEL "# OF AVERAGES ",FNTrap_level GOSUB Set averagE 1160 ON KEY 9 LABEL " QUIT ",FNTrap level GOTO Quitfastac 1170 GOSUB Allocate matrix 1180 LOOP 1190 EXIT IF Exit_ flag-l 1200 END LOOP 1210 GOSUB Deallocate mtrx 1220 Exitflag-0 1230 GOTO Start loop 1240 1250 Null: RETURN 1260 1 1270 1.......... 1280 1 1290 Ref_target: I Acquire a reference target data set. 1300 1310 OFF KEY 1320 Clear crt 1330 OUTPUT eNwa;"TIMDTRANON; LOGM; GATEOFF;" 1340 OUTPUT eNwa;AUTO; ELED 100NS; STAR ONS; STOP 300NS;" 1350 PRINT TABXY(1,10;"Please point scatterometer assembly to referen 1360 PRINT TABXY(1,12);-Press CONTINUE when ready..." 1370 PAUSE 1380 GOSUB Setates 1390 OUTPUT eNwa;"TIMDTRANOFF; POLA; AVERFACT";VAL$(Averagefactor);-; 1400 OUTPUT eNwa;"AVERO ON 1410 INPUT "Enter the reference target angle: ", ef angle 1420 P 1430 Get the reference target response. 1440 1 1450 FOR T-1 TO Ntrace 1460 FOR F-1 TO 3 1470 IF Meas_flag(F) THEN 1480 Freqset(F) 1490 Freq_sw(F) 1500 OUTPUT eNwa;"GATEOFF;" 1510 OUTPUT eNwa;"GATECENT";VAL$(Gatecent (F));"S;" 1520 OUTPUT eNwa;"GATESPAN";VAL$(Gate_span(F));"S;" 1530 OUTPUT eNwa;"GATEON;" 1540 OUTPUT eNwa;"TIMDTRANOFF;POLA;" 1550 FOR P-1 TO 4 1560 Pol sw(F,P) 1570 OUTPUT eNwa;"FORM3;NUMG";VAL$(Average_factor+l);";WAIT" 1580 OUTPUT eNwa;"WAIT; OUTPFORM;" 1590 ENTER @Nwa_datal;Preamble,Bytes,Trace(*) 1600 MAT Target_response(P,*)- Trace 1610 NEXT P 1620 Nskh-Nskip+l 1630 FOR P-1 TO 4 1640 FOR Nt-Nskh TO Npts STEP Nskip 1650 Nst-INT(Nt/Nskip) 1660 Target_data (T,P,Nst)-Target_response(P,Nt) 1670 NEXT Nt 1680 NEXT P 1690 END IF 1700 NEXT F 1710 NEXT T 1720 Store_file(Target_data(*),"REF",FNTimestamp$,F) 1730 1740 i Get the reference target mount response. 1750 1760 BEEP::::::::::~~:::::; *:.j:' *..'.. ':':':.... -...i.i.i.i.!.i.i.l...ii..ii i.... i i.... i....................i........................... 1770 PRINT TABXY(1,10);"Please remove the reference 1780 PRINT TABXY(1,12);"Press CONTINUE when ready... 1790 PAUSE Q o1800 Clearcrt 1810 PRINT TABXY(1,14);"Data for the mount is being < 1820 FOR T-1 TO Ntrace 1830 FOR F-1 TO 3 1840 IF Measflag(F) THEN 1850 Freqset(F) 1860 Freqsw(F) 1870 OUTPUT @Nwa;"GATEOFF;" 1880 OUTPUT eNwa;"GATECENT";VAL$(Gatecent 1890 OUTPUT eNwa;"GATESPAN";VAL$(Gatespar 1900 OUTPUT @Nwa;"GATEON;" _ ---- 1910 FOR P-l TO 4 1920 Pol sw(F,P) 1930 OUTPUT @Nwa;"FORM3;NUMG";VAL$(Average 1940 OUTPUT @Nwa;"WAIT; OUTPFORM;" 1950 ENTER @Nwa_datal;Preamble,Bytes,Trace 1960 MAT Target_response(P,*)- Trace 1970 NEXT P 1980 Nskh-Nskip+l ce target." 1990 FOR P-1 TO 4 2000 FOR Nt-Nskh TO Npts STEP Nskip 2010 Nst-INT(Nt/Nskip) 2020 Target data(T,P,Nst)-Targetre f" 2030 NEXT Nt 2040 NEXT P 2050 END IF 2060 NEXT F 2070 NEXT T 2080 Store_file(Target_data(*), MNT",FNTimestamp$,F) 2090 Polsw(Fdisp,P_disp) 2100 DISP "Reference target mount response saved." 2110 Exitflag-l 2120 RETURN 2130! 2140! 2150! 2160 Acq_target: 2170 2180 OFF KEY 2190 Clear crt 2200 OUTPUT @Nwa;"TIMDTRANON; LOGM; GATEOFF;" 2210 OUTPUT @Nwa;"ELED 100NS; STAR ONS; STOP 300NS;" 2220 PRINT TABXY(1,10);"Please point scatterometer ass 2230 PRINT TABXY(1,12);"Press CONTINUE when ready..." 2240 PAUSE 2250 GOSUB Set_gates 2260 OUTPUT @Nwa;"TIMDTRANOFF; POLA; AVERFACT";VAL$(Av 2270 OUTPUT @Nwa;"GATEOFF;AVEROON;" 2280 2290! Get the target response. 2300 2310 FOR T=1 TO Ntrace 2320 2330! Get angles 2340 2350 IF T=l THEN 2360 Rotation_state — 2370 ELSE 2380 Rotation_state-2 2390 END IF 2400 SELECT Rotationstate target from its mount." collected.... " t(F));"S;" n(F));"S;" afactor+l);";WAIT" s(*) sponse(P,Nt) sembly at surface target." verage_factor);";"

2410 CASE -0 3050 1 ON KEY 7 LABEL " ",FNTrap_level GOSUB Nu 2420 Clear_crt 3060 1 ON KEY 8 LABEL " ",FNTrap_level GOSUB Nu 2430 PRINT TABXY(1,4);"When ready for measurement, press CONTINUE." 3070 1 ON KEY 9 LABEL " CANCEL ",FNTrap_level GOTO Can 2440 BEEP 3080! LOOP 2450 PAUSE 3090 I EXIT IF Exit_flag-1 2460 Clear_crt(3,16) 3100 I END LOOP 2470 PRINT TABXY(1,4);"Collecting data... " 3110 GOSUB Set_c 2480 CASE ELSE 3120 GOTO Store_band 2490 PRINT TABXY(1,4);"Current angle is ";Current_angle;" degrees." 3130 RETURN 2500 Rotate_target! 3140 Set_l: OFF KEY 0 2510 WAIT 1 3150 Meas_flag (1)-1 2520 Clear crt(3,16) 3160 F_disp-l 2530 PRINT TABXY(1,4);"Collecting data..." 3170 RETURN 2540 END SELECT 3180 Set_c: OFF KEY 1 2550 FOR F-1 TO 3 3190 Meas_flag(2)-1 2560 IF Measflag(F) THEN 3200 F_disp-2 2570 Freqset (F) 3210 RETURN 2580 Freq_sw(F) 3220 Set_x: OFF KEY 2 2590 OUTPUT @Nwa;"GATEOFF;" 3230 Meas_flag(3)-1 2600 OUTPUT @Nwa;"GATECENT";VAL$S(Gate_cent(F));"S;" 3240 F_disp-3 2610 OUTPUT eNwa;"GATESPAN";VAL$(Gatespan(F));"S;" 3250 RETURN 2620 OUTPUT @Nwa;"GATEOON; WAIT;" 3260 Store band: Print_banner4 2630 PRINT Npts,Ntrace,Ndata,Nskip 3270 Exit flag-l 2640 FOR P-1 TO 4 3280 GOSUB Allocate_matrix 2650 Pol _sw(F,P) 3290 RETURN 2660 OUTPUT 9Nwa;"NUMG";VAL$(Average_factor);";WAIT; FORM3; OUTPFORM;" 3300 Cancel_band:! 2670 ENTER @Nwa_datal;Preamble,Bytes,Trace(*) 3310 MAT Meas_flag- Meas_flag_old 2680 MAT Target_response(P,*)- Trace 3320 Exit_flag-l 2690 NEXT P 3330 GOSUB Allocate_matrix 2700 Nskh-Nskip+l 3340 RETURN 2710 FOR P-1 TO 4 3350! 2720 FOR Nt-Nskh TO Npts STEP Nskip 3360! --- —------------------------------------------- 2730 Nst-INT(Nt/Nskip) 3370! 2740 Target_data(T,P,Nst)-Target_response(P,Nt) 3380 Set_angle:! 2750 NEXT Nt 3390 INPUT "Enter measurement angle: ",Angle 2760 NEXT P 3400 Angle$-VAL$(Angle)&CHR$(179)&" "! Degree sign. 2770 END IF 3410 Print_banner4 2780 NEXT F 3420 RETURN 2790 PRINT "# OF TRACES LEFT-",Ntrace-T 3430! 2800 NEXT T 3440! --------------------------------- 2810 Store_file(Target_data(*),"GND",FNTimestampS,F) 3450! 2820 DISP "Surface target data saved." 3460 Set_target:! 2830 BEEP 3470 LINPUT "Enter target type or name: "',Targets 2840 Rotation state-4 3480 TargetS-TRIMS (TargetS) 2850 Rotate_target 3490 TargetS-Target$&RPT$S(" ",30-LEN(TargetS)) 2860 WAIT 5 3500 Print_banner4 2870 BEEP 3510 RETURN 2880 OUTPUT @Nwa;"CONT;" 3520! 2890 Exit flag-1 3530...... --- —-----------------—.......................................................... 2900 RETURN 3540! 2910! 3550 Set_traces:! 2920! ------------------------------------- 3560 INPUT "Enter the number of traces( or angles) desired 2930 1 3570 GOSUB Deallocate_mtrx 2940 Freq_set: GOSUB Deallocatemtrx 3580 GOSUB Allocate_matrix 2950 OFF KEY 3590 Print_banner4 2960 MAT Meas_flag_old- Meas_flag 3600 RETURN 2970 MAT Meas_flag- (0) 3610! 2980! Exit_flag-0 3620! --- —---------------------- 2990! ON KEY 0 LABEL " L BAND ",FNTrap_level GOSUB Set_l 3630 Set_points:! 3000 1 ON KEY 1 LABEL " C BAND ",FNTrap_level GOSUB Set_c 3640 INPUT "Enter the number of sample points (Npts,201): ' 3010 I ON KEY 2 LABEL " X BAND ",FNTrap_level GOSUB Set_x 3650 OUTPUT @Nwa;"POIN "&VAL$(Npts)&";" 3020 1 ON KEY 4 LABEL " STORE ",FNTrap_level GOTO Store_band 3660 INPUT "Enter the data points to be stored (Ndata,10):' 3030 1 ON KEY 5 LABEL " ",FNTrap_level GOSUB Null 3670 Nskip=INT(Npts/Ndata) 3040 1 ON KEY 6 LABEL " ",FNTrap_level GOSUB Null 3680 Bytes-16*Ndata 11 11 cel band ( > 3 ):, Nt race,Npts *,Ndata

CT.-..=.5.t;r~;~.'~ I''' 'a:zsIs22~~ z~~: I ~~~~ ~~ tzi '.5-:::..i::':...:::::: ==~.~.~.==~.~SZ' ==.szs ~~~ ~-~~~~~-~~~ ~~ i --- ~~~~~~~ ~2;.,....... ~~'"~~.5'..:~.,i~~;~~~~ ":S2"~~ "' ~'2~'~~:f~:~:~s'~'.~'.`.~ss':.::::::5c.-.~, —~ ---~~5 ---.~.~:~:':: 3690 Printbanner4 3700 GOSUB Deallocatemtrx 3710 GOSUB Allocate matrix 3720 RETURN 3730 1 3740 1 ---- ---------------------------------— ~ 3750 1 3760 Setaverage: 1 3770 INPUT "Enter averaging factor: ",Average_factor 3780 Printbanner4 3790 RETURN 3800 1 3810 1~ 3820 1 3830 Allocate matrix: I Allocate storage space for data. 3840 3850 Systemmemory-VAL(SYSTEMS("AVAILABLE MEMORY")) 3860 Avail traces-MIN(Ntrace,INT(Systemmemory-50000-3*4*16.*Npts)/(3*4*16.*Ndata)) 3870 IF Avail traces<Ntrace THEN 3880 BEEP 3890 PRINT TABXY(1,16);"Memory has capacity for only ";Availtraces;" traces." 3900 PRINT "Press CONTINUE key to continue" 3910 PAUSE 3920 Ntrace-Avail traces 3930 END IF 3940 ALLOCATE COMPLEX Trace(Npts),Target_response(4,Npts) 3950 ALLOCATE COMPLEX Target_data(Ntrace,4,Ndata) 3960 RETURN 3970 Deallocatemtrx: I Return to main program. 3980 1 3990 DEALLOCATE Target_response(*),Trace(*) 4000 DEALLOCATE Targetdata(*) 4010 RETURN 4020 1 4030! --- —----------------------------------------------------------------- 4040 1 4050 Set_gates: I Set gate centers and spans. 4060 1 4070 FOR F-1 TO 3 4080 IF Meas_flag(F) THEN 4090 Freq_set(F) 4100 Freq_sw(F) 4110 P-3 4120 Pol sw(F,P) 4130 OUTPUT @Nwa;"TIMDTRANON; LOGM;" 4140 OUTPUT eNwa;"ELED 100NS; STAR ONS; STOP 300NS; WAIT;" 4150 OUTPUT eNwa;"FORM3; OUTPACTI;" 4160 ENTER @Nwa;Gate cent (F) 4170 OUTPUT eNwa;"MARKOFF;" 4180 OUTPUT @Nwa;"CONT;" 4190 OUTPUT @Nwa;"GATESPAN";VALS(Gate_span(F));"S;" 4200 OUTPUT @Nwa;"GATECENT";VALS(Gate_cent(F));"S;" 4210 OUTPUT eNwa;"KEY41; KEY59; KEY58; KEY59;" 4220 LOCAL eNwa 4230 DISP "Adjust gate center to suit, and press CONTINUE." 4240 PAUSE 4250 OUTPUT @Nwa;"OUTPACTI;" 4260 ENTER @Nwa;Gatecent (F) 4270 OUTPUT eNwa;"GATESPAN";VAL$(Gate_span(F));";" 4280 OUTPUT @Nwa;"KEY41; KEY59; KEY58; KEY4;" 4290 LOCAL @Nwa 4300 DISP "Adjust gate span to suit, and press CONTINUE." 4310 PAUSE 4320 OUTPUT @Nwa;"OUTPACTI;" 4330 4340 4350 4360 4370 4380 4390 4400 4410 4420 4430 4440 4450 4460 4470 4480 4490 4500 4510 4520 4530 4540 4550 4560 4570 4580 4590 4600 4610 4620 4630 4640 4650 4660 4670 4680 4690 4700 4710 4720 4730 4740 4750 4760 4770 4780 4790 4800 4810 4820 4830 4840 4850 4860 4870 4880 4890 4900 4910 4920 4930 4940 4950 4960 ENTER @Nwa;Gate_span(F) END IF NEXT F RETURN! Quitfastacq:! End of program DISP "PROGRAM EXIT" GOSUB Deallocatemtrx LOAD KEY "EDITKEY:MEMORY,0,1" STOP END!! ************************************************************************* DEF FNAsk(PromptS) OFF KEY DISP PromptS; INPUT "",Yn$ Yn$-UPC$(Yn$ [1, 1) SELECT Yn$ CASE -"Y" RETURN 1 CASE -"N",-" RETURN 0 CASE ELSE RETURN 0 END SELECT FNEND! I**************************************************************************! DEF FNFilelocS(FileS,Dir$) INTEGER C! for the location of the ':' in DirS (minus 1) LET C-POS(DirS,":")-1 IF C<-0 THEN RETURN TRIMS(FileS&DirS) ELSE RETURN DirS[1,C]&RPTS("/",DirS[C,C]<>"/")&File$&Dir$[C+1,LEN(Dir$)] END IF FNEND! Fileloc! *********************************************************************** DEF FNTimestampS(OPTIONAL Time format) DIM Time_digitsS[4],Year_digitsS[6] DIM MachinetimeS[8],Machine_dateS[11] REAL Timedatenow Timedatenow-TIMEDATE MachinedateS-DATES(Timedatenow) MachinetimeS-TIMES(Timedate_now) Time_digitsS-MachinetimeS[1,2]&Machine_time$[4,5] Year_digits$[1,2 -Machinedate [10,11] IF Machine_date$[1,1]-" " THEN Machine_dateS[1,1]-"0"! SELECT MachinedateS[4,6] CASE -"Jan" Year_digits$[3,4]-"01" CASE -"Feb" Year_digits$[3,41-"02" CASE -"Mar"

4970 4980 4990 5000 5010 5020 5030 5040 5050 5060 5070 5080 5090 5100 5110 5120 5130 5140 5150 5160 5170 5180 5190 5200 5210 5220 5230 5240 5250 5260 5270 5280 5290 5300 5310 5320 5330 5340 5350 5360 5370 5380 5390 5400 5410 5420 5430 5440 5450 5460 5470 5480 5490 5500 5510 5520 5530 5540 5550 5560 5570 5580 5590 5600 I I CASE CASE CASE CASE CASE Year digits$[3,41-"03" -"Apr" Yeardigits$[3,41-"04" -"May" Year digits$[3,4]-"05" -"Jun" Yeardigits$ [3,41-"06" -"Jul' Year_digitsS 3,4]-"07" -"Aug" 5610 5620 5630 5640 5650 5660 5670 5680 5690 5700 IF POS(Na_ident$,"8720B") IF POS(Na_ident$,"8753A") IF POS(Na_ident$,"8753B") LOCAL @Nwa PRINT PRINT Naident$ PRINT Netwrkanalyzer I Clearcrt PRINT PRINT THEN Netwrkanalyzer-4 THEN Netwrk analyzer-5 THEN Netwrk analyzer-6 Yeardigits$(3,41-"08" CASE -"Sep" Year dioits$(3,41-"09" CASE -"Oct" Yeardigits$[3,41-"10" CASE -"Nov" Year digits$[3,41-"11" CASE -"Dec" Yeardigits$[3,4]-"12" END SELECT I Year digits$[5,6]-Machine_date$([,2] SELECT NPAR CASE -0 RETURN Year_digits$(5,6]&Time_digits$ CASE -1 IF Time format-i THEN RETURN Yeardigits$&Time_digits$ END IF IF Time format-2 THEN RETURN Yeardigits$[3,6]&Time_digits$ END IF END SELECT FNEND l I************************************************************************ 1 DEF FNTrap_level RETURN VAL(SYSTEMS("SYSTEM PRIORITY"))+1 FNEND ************************************************************************* SUB Config_and_poll COM /Paths/ @Nwa,eNwa datal,eNwadata2,Netwrk_analyzer, Hpib,eRelay COM /System/ System memory I I Find out what's out there. ALLOCATE Device list (0:31) [20] ALPHA PEN 4 KBD LINE PEN 3 KEY LABELS PEN 5 Clear crt Netwrk analyzer-O ALLOCATE NaidentS[80] System_memory-VAL(SYSTEM$ ("AVAILABLE MEMORY")) I How much memory for RAM-DISK PRINT "AVAILABLE MEMORY: ";System_memory;" BYTES" ON TIMEOUT 7,4 GOTO Nona! In case there is no network analyzer Isna: OUTPUT @Nwa;"FORM4; OUTPIDEN;" ENTER @Nwa_data2;Naident$ IF POS(Na_identS,"8510A") THEN Netwrk_analyzer-l IF POS(Na_identS,"8510B") THEN Netwrk_analyzer-2 IF POS(Na_ident$,"8720A") THEN Netwrk_analyzer-3 5710 IF Netwrk_analyzer-0 THEN 5720 5730 5740 Nona: BEEP 5750 OFF CYCLE 5760 PRINT TABXY(1,5);"There is no active network analyzer on the HPIB bus." 5770 PRINT TABXY(1,6);"Please check connections, and press the RUN key." 5780 PRINT 5790 PRINT TABXY(1,7);"If you DO NOT want to use a network analyzer, press the CONTINUE key." 5800 PAUSE 5810 END IF 5820 5830 5840 Check_hpib:! Check the rest of the bus 5850 ON TIMEOUT 7,.01 GOTO Nothing 5860 5870 FOR Device-700 TO 731 5880 DISP "Checking for device at address: ";Device 5890 Devicelist$(Device-700)-"NOTHING" 5900 ASSIGN @What is it TO Device 5910 Outcome-SPOLL(@Whatis it) 5920 Devicelist$(Device-700)-"SOMETHING" 5930 PRINT Device,"SOMETHING HERE","spoll: ";Outcome 5940 ASSIGN @Whatisit TO * 5950 Nothing:! Skip to next device 5960 NEXT Device 5970 5980 OFF TIMEOUT 7 5990 ASSIGN @What is it TO * 6000 IF DevicelistS(1)-"SOMETHING" THEN 6010 DISP "Position the printer to Top-Of-Form and press CONTINUE..." 6020 PAUSE 6030 PRINTER IS PRT 6040 PRINT CHR$(27) &-"&lL";! Set Page Breaks 6050 Printerflag-i 6060 PRINTER IS CRT 6070 END IF 6080 DEALLOCATE Na ident$ 6090 DEALLOCATE Device list$(*) 6100 ABORT @Hpib 6110 SUBEXIT 6120 SUBEND 6130 6140! * ********************************************************************** 6150 6160 SUB Hp_businit 6170 COM /Paths/ @Nwa,@Nwadatal,@Nwadata2,Netwrkanalyzer,@Hpib,@Relay 6180 COM /Sys1l/ Freq$(*),Freqcent(*),Freqspan(*),Gate_cent(*),Gatespan(*) 6190 COM /Sys_2/ Pol$(*),Polsw$(*) 6200 COM /System config/ INTEGER Printer_flag,Debug_flag,Version$,Mode$,Outtype$,Soun dS,BellS,TargetS,Ref targetS 6210 6220 This subroutine configures the HP-IB bus and presets the HP8510.

................................................................................. ri cr~~~~~~::::...................................................................................... '~+'.f= '.-.......................................................................................................................... 6230 1 6240 ASSIGN eHpib TO 7 6250 ASSIGN eNwa TO 716 6260 ASSIGN @Nwa datal TO 716;FORMAT OFF 6270 ASSIGN eNwa data2 TO 716;FORMAT ON 6280 ASSIGN eRelay TO 710 6290 REMOTE SHpib 6300 ABORT @Hpib 6310 CLEAR eNwa 6320 IF Debug_flag-l THEN OUTPUT eNwa;"DEBUON;" 6330 IF Debug_flag-0 THEN 6340 OUTPUT @Nwa;"DEBUOFF;" 6350 OUTPUT eNwa;"TITL """&Freq$(2)&" BAND " 6360 END IF 6370 SUBEND 6380 6390 ************************************************************ 6400 1 6410 SUB Series init 6420 COM /System_config/ INTEGER Printerflag,Debug_flag,VersionS,ModeS,Out_type$,Sound $,Bell5,TargetS,Ref targetS 6430 DIM Input$[80] 6440 6450 This subroutine prints a header for the printout and sets the system 6460 I date and time. 6470 1 6480 IF Printer_flag-l THEN PRINTER IS PRT 6490 PRINT CHR$(12) 6500 Set clock 6510 1 LINPUT "ENTER MEASUREMENT SERIES TITLE",InputS 6520 I PrefaceS-"*"&RPT$(" ",9) 6530 I PRINT RPT$("*",70) 6540 1 PRINT PrefaceS&InputS 6550 1 LINPUT "ENTER OPERATOR NAME",Input$ 6560 1 PRINT Preface$&InputS 6570 PRINTER IS CRT 6580 PRINT 6590 PRINT 6600 PRINT PrefaceS&"MEASUREMENT SERIES STARTED AT "&TIMES(TIMEDATE) 6610 PRINTER IS CRT 6620 SUBEND 6630 1 6640 ******************* ************************************************* 6650 6660 SUB Set clock 6670 OPTION BASE 1 6680 INTEGER I 6690 DIM Chrono$(12),MonthS(12)([3 6700 Exec_keyS-CHRS(255)&CHR$(88) 6710 READ MonthS(*) 6720 DATA "JAN","FEB","MAR","APR", MAY","JUN","JUL","AUG", SEP", OCT","NOV","DEC" 6730 OUTPUT KBD;"SCRATCH KEY "&Exec_key$; 6740 Clearcrt 6750 PRINT " Current system date: ";DATES(TIMEDATE) 6760 PRINT " Current system time: ";TIMES(TIMEDATE) 6770 PRINT 6780 Ask: LINPUT "Enter date and time (YYMMDDHHMMss):",Chrono$ 6790 IF ChronoS-"" AND DATES(TIMEDATE)<>" 1 Mar 1900" THEN 6800 Clearcrt 6810 SUBEXIT 6820 END IF 6830 Year$-VAL$(1900+VAL(Chrono$[1,2) ) 6840 IF (VAL(Chrono$[3,4])<-0 OR VAL(Chrono$(3,4])>12) THEN 6850 BEEP I 6860 6870 6880 6890 6900 6910 6920 6930 6940 6950 6960 6970 6980 6990 7000 7010 7020 7030 7040 7050 7060 7070 7080 7090 7100 7110 7120 7130 7140 7150 7160 7170 7180 7190 7200 7210 7220 7230 7240 7250 7260 7270 7280 7290 7300 7310 7320 7330 7340 7350 7360 7370 7380 7390 7400 7410 7420 7430 7440 7450 7460 7470 7480 7490 PRINT "Incorrect month value." GOTO Ask END IF YearS-MonthS(VAL(ChronoS[3,4]))&" "&YearS YearS-Chrono$[5,6]&" "&YearS SET TIMEDATE (DATE(YearS)) IF (VAL(Chrono$[7,8]))>23 THEN BEEP PRINT "Incorrect hour value." GOTO Ask END IF Day$-Chrono$S7, 8)":" IF VAL(Chrono$[9,10])>59 THEN BEEP PRINT "Incorrect minute value." GOTO Ask END IF DayS-DayS&Chrono$[9,10])&":" IF (LEN(Chrono$)>10 AND LEN(ChronoS)-12) THEN IF VAL(Chrono$[11,12])>59 THEN BEEP PRINT "Incorrect seconds value." GOTO Ask END IF DayS-Day$&Chrono$[11,12] ELSE DayS-DayS&"00" END IF SET TIME TIME(DayS) Clearcrt SUBEXIT SUBEND!!t********************************************************************* SUB Fix error SELECT ERRN CASE ELSE PRINTER IS CRT PRINT "ERROR ";ERRN PRINT ERRMS PRINT " PROGRAM IS PAUSED. FIX ERROR, IF POSSIBLE, AND CONTINUE." PAUSE END SELECT SUBEND!! ************************************************************************ SUB Clearcrt(OPTIONAL INTEGER Startline,Numoflines) INTEGER I DIM ClearlineS[80] Clear lineS-" IF NPAR-0 THEN OUTPUT KBD;CHRS(255)&CHR$(75); ELSE PRINT TABXY(1,Start line);"";RPT$(Clear_line$,Num_of_lines) PRINT TABXY(1,Start line);""; SUBEXIT END IF SUBEND!! ************************************************************************

~:~:::::::::'~;::':' ::::::8i:::M....2 ~'~'~'~:'"'' '~'~::::~;~~t~:~:~~::~:~:t~ fi::: "' ''' .........~n f:tts~~ ~.sr~.~.s~~~ ~~ i iS3i 7500 SUB Print bannerl 7510 Clear crt 7520 PRINT 7530 PRINT 7540 PRINT TABXY(3,16); ************************************************ 7550 PRINT TABXY(4,16); * * 7560 PRINT TABXY(5,16);"* LCX * 7570 PRINT TABXY(6,16);"* UNIVERSITY OF MICHIGAN RADIATION LAB * 7580 PRINT TABXY(7,16);'* L/C/X MEASUREMENT PROGRAM 7590 PRINT TABXY(8,16);"* (VERSION 8.0) * 7600 PRINT TABXY(9,16);"* * 7610 PRINT TABXY(10,16); * May 21, 1990 * 7620 PRINT TABXY(11,16); * *" 7630 PRINT TABXY (12,16);"************************************************" 7640 SUBEXIT 7650 SUBEND 7660 1 7670 *********************************************************************** 7680 1 7690 SUB Print banner2 7700 PRINT "Don't use Print banner2." 7710 SUBEND 7720 1 7730 ******************** *********** 7740 1 7750 SUB Print banner3 7760 PRINT "Don't use Printbanner3." 7770 SUBEND 7780 1 7790 *********** ******************************************** 7800 1 7810 SUB Print banner4 7820 COM /Paths/ eNwa,eNwa_datal,eNwa_data2,Netwrk_analyzer,eHpib,SRelay 7830 COM /Constants/ Vel,Zero(*),Execkey$ 7840 COM /Systemconfig/ INTEGER Printer_flag,Debug_flag,VersionS,ModeS,Outtype$,Soun dS,BellS,TargetS, Reftarget 7850 COM /Sys_l/ FreqS(*),Freq_cent(*),Freq_span(*),Gate_cent(*),Gatespan(*) 7860 COM /Sys_2/ PolS(*),PolswS(*) 7870 COM /Sys_3/ INTEGER F_disp,P_disp 7880 COM /Sys_4/ Drive_aS,Driveb$,Drive_cS,INTEGER Preamble,Bytes 7890 COM /Sys_5/ INTEGER Nskip,Ndata 7900 COM /Sys_6/ Ref_angle,Angle,AngleS,Beam(*),INTEGER Npts,Ntrace,Average_factor 7910 COM /Sys_7/ INTEGER Meas_flag(*) 7920 1 7930 1 7940 OFF KEY 7950 Clear crt 7960 PRINT 7970 PRINT 7980 PRINT " PARAMETER CURRENT VALUE" 7990 PRINT 8000 PRINT " FREQUENCY 8010 FOR F-1 TO 3 8020 IF Measflag(F) THEN PRINT Freq$(F)&" "; 8030 NEXT F 8040 PRINT " 8050 PRINT " 8060 PRINT " ANTENNA ANGLE "&Angle$ 8070 PRINT " TARGET TYPE "&TargetS 8080 PRINT " MEASUREMENT MODE "&Mode$&" 8090! PRINT " CURRENT DISPLAY "&FreqS(F_disp)&" "&PolS(P_d isp); 8100 PRINT " 8110 PRINT " # OF TRACES/SET ";Ntrace 8120 PRINT " # OF SAMPLE POINTS ";Npts 8130 PRINT " # OF DATA POINTS ";Ndata 8140 PRINT " (to be stored) 8150 PRINT " # OF AVERAGES ";Average_factor 8160 SUBEXIT 8170 SUBEND 8180 1 8190 ************************ ******** 8200 1 8210 SUB Storefile(COMPLEX Matrix(*),File_typeS,FilenameS,INTEGER F) 8220 8230 COM /Sys_l/ FreqS(*),Freq_cent (*),Freq_span(*),Gate_cent(*),Gate_span(*) 8240 COM /Sys_2/ PolS(*),Polsw$(*) 8250 COM /Sys_5/ INTEGER Nskip,Ndata 8260 COM /Sys_6/ Ref_angle,Angle,AngleS,Beam(*),INTEGER Npts,Ntrace,Average_factor 8270 COM /Sys_7/ INTEGER Meas_flag(*) 8280 COM /Systemconfig/ INTEGER Printer_flag,Debug_flag,VersionS,Mode$,Out_type$,So undS, Bell$,Target$, Reftarget$ 8290 8300 8310 INTEGER Records_per_set,T 8320 REAL Bytes_perset 8330 DIM Suffix$[2] 8340 ALLOCATE COMPLEX Trace(Ndata) 8350 8360 8370 DISP "Saving file." 8380 SELECT File_typeS 8390 CASE -"SKY"! Sky data. 8400 Bytes_per_set-16*Ndata 8410 Recordsper_set-4*SUM(Meas_flag)*Ntrace 8420 IF SUM(Measflag)-3 THEN 8430 Suffix$-"SA" 8440 ELSE 8450 FOR F-1 TO 3 8460 IF Meas_flag(F)-1 THEN 8470 Mf-F 8480 END IF 8490 NEXT F 8500 SuffixS-"S"&Freq$(Mf) 8510 END IF 8520 GOSUB Savehpux 8530! GOSUB Savetraces 8540 8550 8560 CASE -"REF" 8570 Bytes_per_set-16*Ndata 8580 Records_perset-4*SUM(Meas_flag)*Ntrace 8590 IF SUM(Meas_flag)-3 THEN 8600 SuffixS-"RA" 8610 ELSE 8620 FOR F-1 TO 3 8630 IF Measflag(F)-l THEN 8640 Mf-F 8650 END IF 8660 NEXT F 8670 SuffixS-"R"&Freq$(Mf) 8680 END IF 8690 GOSUB Save_hpux 8700!GOSUB Savetraces 8710 8720 8730 CASE -"MNT" 8740 Bytes per set-16*Ndata

8750 8760 8770 8780 8790 8800 8810 8820 8830 8840 8850 8860 8870 8880 8890 8900 8910 8920 8930 8940 8950 8960 8970 8980 8990 9000 9010 9020 9030 9040 9050 9060 9070 9080 9090 9100 9110 9120 9130 9140 9150 9160 9170 9180 9190 9200 9210 9220 9230 9240 9250 9260 9270 9280 9290 9300 9310 9320 9330 9340 9350 9360 9370 9380 Recordsper_set-4*SUM(Meas_flag)*Ntrace IF SUM(Meas_flag)-3 THEN Suffix$-"MA" ELSE FOR F-1 TO 3 IF Meas_flag(F)-1 THEN Mf-F END IF NEXT F Suffix$-"M"&Freq$(Mf) END IF GOSUB Save_hpux I GOSUB Save traces! CASE -"GND" Bytes_per_set-16*Ndata Records_per_set-Ntrace*4*SUM(Meas_flag) IF SUM(Meas_flag)-3 THEN Suffix$-"GA" ELSE FOR F-1 TO 3 IF Meas_flag(F)-l THEN Mf-F END IF NEXT F Suffix$-"G"&Freq$ (Mf) END IF GOSUB Save_hpux I GOSUB Save traces END SELECT DEALLOCATE Trace(*) SUBEXIT Save_averaged: I I Save the reference data file.! IF NOT Debug_flag THEN CREATE BDAT Filename$&Suffix$&Drive_c$,Records_per_set,Bytesperset END IF Base record-0 FOR F-1 TO 3 IF Meas_flag(F)-l THEN IF Debug_flag THEN ASSIGN eDisc TO PRT OUTPUT eDisc;"FILE: ",Filename$,Suffix$ OUTPUT eDisc USING Image_l;Version$,Freqcent(F),Freqspan(F) OUTPUT eDisc USING Image_2;Ndata,Average_factor OUTPUT eDisc USING Image_3;Ref_targetS,T FOR P-1 TO 4 OUTPUT eDisc USING Image_4;Pol$(P),Gate_cent(F),Gate_span(F) MAT Trace- Matrix(1,P,*) OUTPUT @Disc;Trace(*) NEXT P ELSE ASSIGN eDisc TO Filename$&Suffix$&Drive_c$;FORMAT OFF OUTPUT eDisc, Base_record+l;Version$,Freq_cent (F),Freq_span(F) OUTPUT eDisc,Base_record+l;Ndata,Average_factor OUTPUT eDisc,Base_record+l;Ref_target$,T FOR P-l TO 4 OUTPUT eDisc, Baserecord+P;PolS(P),Gate_cent(F),Gate_span(F) MAT Trace- Matrix(l,P,*) OUTPUT eDisc,Base record+P;Trace(*) 9390 NEXT P 9400 Baserecord-Baserecord+4 9410 END IF 9420 END IF 9430 NEXT F 9440 ASSIGN @Disc TO * 9450 RETURN 9460 I 9470 ------------------------------- 9480! 9490 Savehpux: 9500! Save data in HP-U) 9510 9520 IF NOT Debug_flag THEN 9530 CREATE Filename$&Suffix$S 9540 END IF 9550 IF Debug_flag THEN 9560 ASSIGN @Disc TO PRT 9570 FOR T-l TO Ntrace 9580 FOR F-1 TO 3 9590 IF Meas_flag(F)-l THEN 9600 FOR P-l TO 4 9610 MAT Trace- Matrix 9620 OUTPUT @Disc;Trace 9630 NEXT P 9640 END IF 9650 NEXT F 9660 NEXT T 9670 ELSE 9680 ASSIGN @Disc TO FilenameS$ 9690 FOR T-1 TO Ntrace 9700 FOR F-1 TO 3 9710 IF Measflag(F)-l THEN 9720 FOR P-l TO 4 9730 MAT Trace- Matrix 9740 OUTPUT @Disc;Trac 9750 NEXT P 9760 END IF 9770 NEXT F 9780 NEXT T 9790 END IF 9800 ASSIGN @Disc TO * 9810 RETURN 9820 9830! --- —-------------------------- 9840 9850 Savetraces: 9860! Save the ground ta 9870 9880 IF NOT Debugflag THEN 9890 CREATE BDAT Filename$&Suf 9900 Baserecord-0 9910 END IF 9920 IF Debug_flag THEN 9930 ASSIGN @Disc TO PRT 9940 OUTPUT @Disc;"FILE: ";File 9950 OUTPUT @Disc USING Image_5 9960 OUTPUT @Disc USING Image_3 9970 FOR T-1 TO Ntrace 9980 FOR F-1 TO 3 9990 IF Meas_flag(F)-l THEN 10000 OUTPUT @Disc USING Ima 10010 FOR P-1 TO 4 10020 OUTPUT @Disc USING X format. &Drive_cS,240000 (T,P,*) e(*);Suffix$&DrivecS;FORMAT ON (T,P,*) ce (*) _- _ - -_ - -_ - -_ - -_ - -_ - -_ - -_ - -_ - -_ - -_ - -_ - -_ - -_ - -_ - -_ - -_ - -_ - -_ - -_ - -_ - arget data file. ffix$&Drive_c$,Records_per_set,Bytesperset ename$;Suffix$; Ndata, Nt race 3;Target$ ige_l;Version$,Freq_cent(F),Freq_span(F); Image 4;Pol$(P),Gate_cent (F),Gatespan (F),T

.......................................... 9M.2,22K............................................................................................... --------...........::::::::^*::::::::::::::::::::::i:::::::::^:::::::::::^::*:::::::::::::::::::::::::::::::::::::::;::::;::;:::;:::;::;:::j:::;::;:;::;:::;:;:;:::::::::::::::::::::::::::::::::::::::::::: 10030 MAT Trace- Matrix(T,P,*) 10040 OUTPUT eDisc;Trace(*) 10050 NEXT P 10060 END IF 10070 NEXT F 10080 NEXT T 10090 ELSE 10100 ASSIGN eDisc TO Filename$&Suffix$S&Drive_c$;FORMAT OFF 10110 I OUTPUT eDisc,l;Ndata,Ntrace 10120 1 OUTPUT eDisc,;Target$ 10130 FOR T-1 TO Ntrace 10140 FOR F-1 TO 3 10150 IF Meas_flag(F)-1 THEN 10160 1 OUTPUT SDisc,Base_record+l;;Version$,Freqcent (F),Freq_span(F) 10170 FOR P-1 TO 4 10180 I OUTPUT @Disc,Base record+P;Pol$(P),Gatecent(F),Gate_span(F),T 10190 MAT Trace- Matrix(T,P,*) 10200 OUTPUT eDisc,Base_record+P;Trace(*) 10210 NEXT P 10220 Base_record-Baserecord+4 10230 END IF 10240 NEXT F 10250 NEXT T 10260 END IF 10270 ASSIGN @Disc TO * 10280 RETURN 10290 1 10300 1 --- —-----------------— ______ --- —--------------- 10310 1 10320 Image_ 1:IMAGE (IX,12A,5X,"FREQ CENTER: ",2D.4D,5X,"FREQ SPAN: ",2D.4D) 10330 Image_2:IMAGE ("NUMBER OF POINTS: ",5D,5X,"NUMBER OF AVERAGES: -,5D) 10340 Image_3:IMAGE ("TARGET: ",30A,"GATING TARGET TYPE: 0,2D) 10350 Image_4:IMAGE ("POLARIZATION: ",2A,5X,"GATE CENTER: ",SD.14DE,/,5X,"GATE SPAN: ",S D.14DE,"TRACE: ",3D) 10360 Image_5:IMAGE ("NUMBER OF POINTS: ",5D,5X,"NUMBER OF TRACES: ",5D) 10370 Image_6:IMAGE (SX,SD.14DE,5X,SD.14DE) 10380 SUBEND 10390 1 10400 l************************************************************************* 10410 1 10420 SUB Freq_set(INTEGER Ifreq) 10430 COM /Paths/ @Nwa,@Nwa_datal,@Nwa_data2,Netwrk_analyzer,@Hpib,@Relay 10440 COM /Sysl/ Freq$(*),Freq_cent(*),Freq_span(*),Gate_cent(*),Gate_span(*) 10450 1 10460! This subroutine sets the transmit frequency for the HP8753. 10470! 10480 IF Ifreq-1 THEN 10490 OUTPUT @Nwa;"POWEO" 10500 ELSE 10510 OUTPUT 9Nwa;"POWE-10" 10520 END IF 10530 SELECT Netwrk analyzer 10540 CASE -3,-4,-5,-6 10550 OUTPUT @Nwa;"TIMDTRANOFF;" 10560 CASE -1,-2 10570 OUTPUT eNwa;"FREQ;" 10580 END SELECT 10590 OUTPUT @Nwa;"CENT "&VAL$(Freq_cent(Ifreq))&" GHZ;" 10600 OUTPUT @Nwa;"SPAN "&VAL$(Freq_span(Ifreq))&" GHZ;" 10610 SUBEND 10620! 10630 l**************************************** 10640! 10650 SUB Freq_sw(INTEGER Ifreq) 10660 COM /Paths/ @Nwa,@Nwa_datal,@Nwa_data2,Netwrk_analyzer,@Hpib,@Relay 10670 SELECT Ifreq 10680 CASE 1 10690 OUTPUT @Relay;"?*A2Bl" 10700 CASE 2 10710 OUTPUT 8Relay;"?*AlB2" 10720 CASE 3 10730 OUTPUT eRelay;'?*B12' 10740 END SELECT 10750 WAIT.1 10760 SUBEND 10770! 10780!************************************************************************ 10790! 10800 SUB Pol_sw(INTEGER Ifreq,Ipol) 10810 COM /Paths/ @Nwa,@Nwa_datal,@Nwa_data2,Netwrk_analyzer,@Hpib,@Relay 10820 COM /Sys_l/ Freq$(*),Freq_cent(*),Freq_span(*),Gate_cent(*),Gate span(*) 10830 COM /Sys_2/ Pol$(*),Polsw$(*) 10840! 10850! This subroutine sets the transmit and receive polarization by 10860! sending the proper command over the HPIB to the polarization 10870! relays. 10880! 10890 OUTPUT @Relay;Polsw$(Ifreq,Ipol) 10900 OUTPUT @Nwa;"TITL "" "&Freq$(Ifreq)&" BAND - "&Pol$(Ipol)& """" 10910 WAIT.1 10920 SUBEND 10930! 10940!************************************************************************ 10950 1 10960 SUB Rotate_target 10970 OPTION BASE 1 10980 COM /Com4/ INTEGER Rotation_state,REAL Inc_angle,Current_angle,Start_angle,Stop_ang le, Old_home_angle,INTEGER Sets_per_pos 10990 COM /Status/ INTEGER Sc,Connect_flg,E_flg,Debug_flg,Response$[80] 11000 INTEGER Fs_flag,Ss_flag,Speed,Imc_status,Confirm_answer 11010! 11020! 11030 Confirm answer-1 11040 Imc_status-0 11050 Debug_flg-0 11060 Fs flag —l 11070 Ssflag —1 11080 Clear_crt(3,16) 11090! 11100! 11110 SELECT Rotation_state 11120 CASE — 1 11130 IF FNAsk("Do you wish to use the rotator?") THEN 11140 Connect_flg-0 11150 GOSUB Init_imc 11160 GOSUB Init_graph_pos 11170 GOSUB Manual loop 11180 PRINT "Set Auto Mode Please....." 11190 ELSE 11200 Rotation state"0 11210 GCLEAR 11220 GRAPHICS OFF 11230 END IF 11240 CASE -0 11250 SUBEXIT 11260 CASE -1 11270 GOSUB Check_position 11280 GOSUB Print anoles ii

-4m -.:m K. - - -: 't... 11290 GOSUB Manual_loop 11300 CASE -2 11310 GOSUB Check_position 11320 GOSUB Auto 11330 CASE -3 11340 GOSUB Check_position 11350 GOSUB Manualloop 11360 GOSUB Auto 11370 CASE -4 11380 GOSUB Check position 11390 GOSUB Go home 11400 CASE -5 11410 GOSUB Check_position 11420 Rotation state-1 I Switch to manual mode. 11430 END SELECT 11440 SUBEXIT 11450 1 11460 1 11470 Init imc: I Initialize the IMC unit. 11480 GOSUB Check 4 fault 11490 PRINT TABXY(1,3);"INITIALIZING IMC" 11500 Clear crt(4,15) 11510 Comm("4WB") I Set warm boot (clear flags). 11520 PRINT TABXY(1,4);"WB" 11530 Comm("4EB") I Clear IMC buffer. 11540 PRINT TABXY(1,4);"EB" 11550 Encoder ratio-4096 I 32000 11560 Comm("4ER"&VAL$(Encoder ratio)) I Load encoder ratio. 11570 PRINT TABXY(1,4);"ER"&VAL$ (Encoder_ratio) 11580 IF FNAsk("Do you wish to set home at the current position?") THEN 11590 Comm("4RS",Confirm answer) 11600 ENTER Response$;Old_home_angle 11610 Oldhome_angle-Old_home_angle/93.3 11620 Comm("4PIZO") I Set IMC at 0. 11630 PRINT TABXY(1,4);"PIZ"&RPT$(" ",LEN(VAL$(Encoder_ratio))) 11640 Comm("4PIAO") I Set IMC at 0. 11650 PRINT TABXY(1,4);"PIA" 11660 Current_angle-0 11670 END IF 11680 Comm("4SP100') I Set speed to (50pps). 11690 PRINT TABXY(1,4);"SP "&RPT$(" ",LEN(VAL$(Encoder ratio))) 11700 Comm("4AC500")! Set acceleration (500ppsA2). 11710 PRINT TABXY(1,4);"AC ' 11720 Comm("4DC500")! Set deceleration (500pps^2). 11730 PRINT TABXY(1,4);"DC " 11740 GOSUB Check_position 11750 Rotationstate-1 11760 Clearcrt 11770 1 11780 1 11790 PRINT TABXY(1,4);"DONE INITIALIZING IMC" 11800 PRINT TABXY(1,5);"Turntable currently in manual mode." 11810 PRINT TABXY(1,6) 11820 Print_angles:l 11830 PRINT TABXY(1,7);"Current angle is: ";Currentangle;" degrees." 11840 PRINT TABXY(1,8);"Starting angle is: ";Start_angle;" degrees." 11850 PRINT TABXY(1,9);"Stopping angle is: ";Stop_angle;" degrees." 11860 RETURN 11870 1 11880 1 11890 Manual_loop:I Main activation loop. 11900 LOOP 11910 ON KEY 0 LABEL "FAST SLEW CW ",FNTrap_level GOSUB Fs_cw 11920 ON KEY 1 LABEL "FAST SLEW CCW ",FNTrap_ level GOSUB Fs_ccw 11930 11940 11950 11960 11970 11980 11990 12000 12010 12020 12030 12040 12050 12060 12070 12080 12090 12100 12110 12120 12130 12140 12150 12160 12170 12180 12190 12200 12210 12220 12230 12240 12250 12260 12270 12280 12290 12300 12310 12320 12330 12340 12350 12360 12370 12380 12390 12400 12410 12420 12430 12440 12450 12460 12470 12480 12490 12500 12510 12520 12530 12540 12550 12560 ON ON ON ON ON ON ON ON GO' END I! Fs cw:! IF ELS ENE RETURN KEY 5 LABEL "SLOW SLEW CW ",FNTraplevel GOSUB Ss_cw KEY 6 LABEL "SLOW SLEW CCW ",FNTrap_level GOSUB Ss_ccw KEY 2 LABEL "MANUAL CONTROL",FNTrap_level GOSUB Manual KEY 3 LABEL "TARGET GO HOME",FNTrap_level GOSUB Go_home KEY 4 LABEL "STOP ROTATION ",FNTrap_level GOSUB Stop_turn KEY 7 LABEL "SET AUTO MODE ",FNTrap_level GOSUB Set_auto KEY 8 LABEL "SET TARGET HOME",FNTrap_level GOSUB Set_position KEY 9 LABEL "RETURN ",FNTrap_level GOTO Quit SUB Check_position LOOP `-X.w o.-. ~ ~N.. wq...,.t Fast slew clockwise. Fs_flag<0 THEN Comm ( "4 SP 500") Comm("4SFN") Fs_flag —l*Fs_flag Clear_crt(3,15) PRINT TABXY(1,15);"ROTATING CW (FAST)" SE Comm("4ST") Fs_flag —l*Fs_flag Clear crt(3,15) PRINT TABXY(1,15);"ROTATION STOPPED" GOSUB Check_position ) IF! --- —-------------------------------------------------! Fs_ccw:! Fast slew counterclockwise. IF Fs_flag<0 THEN Comm("4ST") Comm ("4 SP 500") Comm("4SRN") Fs_flag —l*Fs_flag Clear_crt(3,10) PRINT TABXY(1,15);"ROTATING CCW (FAST)" ELSE Comm("4ST") Fsflag —l*Fsflag Clear_crt(3,15) PRINT TABXY(1,15);"ROTATION STOPPED" GOSUB Checkposition END IF RETURN Sscw: Slow slew clockwise. --- —--------------------------------------------- SsIcw:! Slow slew clockwise. IF Ss flagcO THEN Comm ("4ST") INPUT "Speed?",Sp Comm("4SP"&VAL$ (INT (Sp))) Comm ("4SFN") Ssflag —l*Ss_flag Clear_crt(3,15) PRINT TABXY(1,15);"ROTATING CW (SLOW)" ELSE Comm( "4ST") Ss_flag —l*Ss_flag Clear_crt(3,15) PRINT TABXY(1,15);"ROTATION STOPPED"

12570 GOSUB Check_position 12580 END IF 12590 RETURN 12600 1 12610 -------------------------------- 12620 1 12630 Ssccw:I Slow slew counterclockwise. 12640 IF Ss_flag<0 THEN 12650 INPUT "Speed?",Sp 12660 Comm("4SP"&VAL$(INT(Sp))) 12670 Comm("4SRN") 12680 Ss_flag —l*Ss_flag 12690 Clearcrt(3,15) 12700 PRINT TABXY(1,15);"ROTATING OCW (SLOW)" 12710 ELSE 12720 Comm("4ST") 12730 Ss_flag —l*Ss_flag 12740 Clearcrt(3,15) 12750 PRINT TABXY(1,15);"ROTATION STOPPED" 12760 GOSUB Check_position 12770 END IF 12780 RETURN 12790 1 12800 1 -------------------------------- 12810 1 12820 Manual: INPUT "ANGLE (IN DEGREES)-?",Inc angle 12830 INPUT "SPEED? (-100 —500 RECOMMENDED)",S 12840 Comm("4SP"&VAL$(Speed)) 12850 Auto: SELECT Rotationstate 12860 CASE -4 12870 GOSUB Go_home 12880 Rotationstate-2 12890 GOTO Auto 12900 CASE ELSE 12910 Angl2-Inc_angle*93.3 12920 Angll-INT(Angl2) 12930 IF Angl2-Angll>-.5 THEN Angll-Angll 12940 1 Current angle-Current_angle+Inc_ang 12950 Inc angle$-VAL$(Angll) 12960 Comm("4IM"&Inc angleS) 12970 Comm("4RFI") 12980 END SELECT 12990 Imc status-0 13000 Clear_crt(3,7) 13010 PRINT TABXY(1,14);"ROTATING TARGET, PLEA 13020 I 13030 1 13040 WHILE NOT BIT(Imcstatus,0) I 13050 Comm("4RS",Confirm answer) 13060 ENTER Response$;Imcstatus 13070 PRINT TABXY(1,15);DVAL$(Imc_status 13080 GOSUB Check_position 13090 WAIT 1 13100 END WHILE 13110 Imc_status-0 13120! 13130! 13140 Clear crt(3,16) 13150 PRINT TABXY(1,16);"CURRENT TARGET POSITI 13160 WAIT 2 1 Wait for target settling. 13170 RETURN 13180 1 13190 1 — Speed L+1 [le,SE WAIT." 13200! 13210 Stop_turn:Comm("4ST") 13220 WHILE NOT BIT(Imc_status,0) 13230 Comm("4RS",Confirm_answer) 13240 ENTER ResponseS;Imc_status 13250 WAIT.1 13260 END WHILE 13270 Clear_crt(3,16) 13280 PRINT TABXY(1,15);"ROTATION STOPPED" 13290 GOSUB Checkposition 13300 Imc_status-0 13310 RETURN 13320 1 13330 1 --------------------------— ~13340 1 13350 Setauto: Comm("4SP500") 13360 GOSUB Checkposition 13370 Clear_crt(3,16) 13380 PRINT TABXY(1,3);"Current starting a 13390 PRINT TABXY(1,4);"Current increment a 13400 PRINT TABXY(1,5);"Current stopping a 13410 PRINT TABXY(1,6);"Current rotation s 13420 PRINT TABXY(1,7);RPT$(" ",80) 13430 PRINT TABXY(1,8);"Rotator positioned 13440 INPUT "Enter starting angle value (dE 13450 INPUT "Enter increment angle (degrees 13460 INPUT "Enter stopping angle (degrees) 13470 INPUT "Enter rotation speed of target 13480 Speed-INT(Speed) 13490 Comm("4SP"&VAL$ (Speed)) 13500 IF ABS(Start_angle-Current_angle)>.l 13510 PRINT TABXY(1,9);RPT$(" ",80) 13520 PRINT TABXY(1,10);"Rotating target 13530 Temp_angle-Inc_angle 13540 Inc_angle-Start_angle-Current_angl 13550 GOSUB Auto 13560 Inc angle-Temp_angle 13570 END IF 13580 Rotation_state-2 13590 Clear_crt 13600 PRINT TABXY(1,20);"Turntable is in au key)" 13610 RETURN 13620! 13630! --- —----------------------------------------- 13640! 13650 Set_position:INPUT "LOCK IN CURRENT TARGET POSI 13660 IF Yn$-"Y" OR Yn$-"y" THEN 13670 Comm("4RS",Confirm answer) 13680 ENTER Response$;Old_home_angle 13690 Old_home_angle-Old_home_angle/93 13700 Comm("4PIAO")! Set absolute pos 13710 Comm("4PIZ0")! Set incremental 13720 Current_angle-0 13730 ELSE 13740 PRINT "POSITION WAS NOT SET." 13750 END IF 13760 RETURN 13770! 13780! --- -------------------- ------- 13790! 13800 Go_home: IF Speed<200 THEN Speed-200 13810 Comm("4SP"&VAL$(Speed)) 13820 Comm("4AM0")! Move to zero absolute p! Wait for motor to stop. angle: ";Start_angle;" degrees" angle: ";Inc_angle;" degrees" angle: ";Stop_angle;" degrees" speed: ";Speed d at: ";Current_angle;" degrees" egrees): ",Start_angle s): ",Inc_angle: ",Stop_angle t (-500 recommended): ",Speed THEN t to starting angle..." le itomatic mode. (press the RETURN soft I Wait for motor to stop.;,2) ON IS ";Current_angle;" DEGREES. TION AS REFERENCE POSITION?",Yn$.3 ition to zero. postition to zero. osition. I

13830 Comm("4RAN") I Initiate movement. 13840 Comm("4MW") I Make sure the move is completed. 13850 Imc status-0 13860 Clear crt(3,15) 13870 PRINT TABXY(1,14);"ROTATING TARGET TO HOME POSITION, PLEASE WAIT." 13880 WHILE NOT (BIT(Imc status,0) AND BIT(Imcstatus,5)) 13890 GOSUB Check_status 13900 PRINT TABXY(1,15);"CURRENT STATUS: ";DVAL$(Imc_status,2) 13910 GOSUB Check_position 13920 WAIT.1 13930 END WHILE 13940 Clear crt (3,16) 13950 PRINT TABXY(1,15);"TARGET AT HOME POSITION." 13960 GOSUB Check_position 13970 Imcstatus-0 13980 RETURN 13990 1 14000! --- —------------------------------------------------------------------- 14010 1 14020 Checkstatus:! Keep an eye on the Whedco controller status. 14030 Comm("4RS",Confirm answer) 14040 ENTER Response$;Imc_status 14050 RETURN 14060 1 14070 1 ---- ----- ---------------------- ---------------------- 14080 1 14090 Check_position:l Get the current turnstile position in degrees. 14100 Comm("4RP",Confirm answer) 14110 ENTER Response$;Motor_position 14120 Current_angle-Motor_position/93.3 14130! Current_angle-Current_angle+Inc_angle 14140 PRINT TABXY(1,16);"CURRENT TARGET POSITION IS ";Current_angle;" DEGREES. 14460 ---------------------------------------------- 14470! 14480 Init_graph_pos: I Creates a graphical depiction of where the target is. 14490! 14500 GINIT 14510 GCLEAR 14520 GRAPHICS ON 14530 SHOW 0,100,0,100 14540 PENUP 14550 MOVE 90,70 14560 PEN 1! Draw circle 14570 POLYGON 12,360,360 14580 PENUP 14590 MOVE 90,70 1 Draw old home orientation. 14600 PEN 2 14610 DRAW 90+11*COS(Old_home_angle),70-11*SIN(Old_home_angle) 14620 PENUP 14630 MOVE 90,70! Draw current home orientation. 14640 PEN 4 14650 DRAW 90,58 14660 PENUP 14670 MOVE 90,70 I Draw current target orienation. 14680 PEN 3 14690 X_pos-90+11*COS(Current_angle) 14700 Y_pos-70-11*SIN(Current_angle) 14710 DRAW X_pos, Y_pos 14720 RETURN 14730! 14740!. --- —------------------------ 14750! 14760 Draw_positions: I Draws out the angular orienations. 14770 MOVE 90,70! Draw old home orientation. 14780 PEN 2 14790 DRAW 90-11*SIN(Old_home_angle),70-11*COS(Old_home_angle) 14800 PENUP 14810 MOVE 90,70! Draw current home orientation. 14820 PEN 4 14830 DRAW 90,58 14840 PENUP 14850 DISABLE 14860 MOVE 90,70 1 Draw current target orienation. 14870 PEN -3 14880 DRAW X_pos,Y_pos 14890 MOVE 90,70 14900 PEN 3 14910 X_pos-90-ll1*SIN(Current_angle) 14920 Y_pos-70-ll1*COS(Current_angle) 14930 DRAW X_pos,Y_pos 14940 PENUP 14950 ENABLE 14960 RETURN 14970! 14980. --- —------------------------------------------------------------------ 14990! 15000 Quit:! 15010 SUBEXIT 15020 SUBEND 15030! 15040 ************************************************************************* 15050 15060 SUB Comm(C$,OPTIONAL INTEGER Confirm_answer) 15070! 15080! PROGRAM MODULE: Comm 15090! 14150 14160 14170 14180 14190 14200 14210 14220 14230 14240 14250 14260 14270 14280 14290 14300 14310 14320 14330 14340 14350 14360 14370 14380 14390 14400 14410 14420 14430 14440 14450 RETURN 1 ---I...... GOSUB Draw_positions Check 4 fault: I Check the IMC for a fault condition and correct or! notify the user if necessary. Comm ("4FC",Confirm answer) ENTER Response$;Fault$ SELECT Fault$ CASE -"Power failure" I Loss of power RETURN CASE -"Force DAC" I Force DAC command was given BEEP PRINT "Force DAC command was given..." DISP "Press CONTINUE to resume..." PAUSE RETURN CASE -"Over-current"! Over-current condition exists. BEEP PRINT "An over-current condition has been detected on the IMC." PRINT PRINT "Cycle the power to the IMC until the OV-CUR LED goes out" DISP "Press CONTINUE to reinitialize the IMC" PAUSE GOSUB Init_imc RETURN END SELECT RETURN!

................................ 15100 15110 15120 15130 15140 15150 15160 15170 15180 15190 15200 15210 15220 15230 15240 15250 15260 15270 15280 15290 15300 15310 15320 15330 15340 15350 15360 15370 15380 15390 15400 15410 15420 15430 15440 15450 15460 15470 15480 15490 15500 15510 15520 15530 15540 15550 15560 15570 15580 15590 15600 15610 15620 15630 15640 15650 15660 15670 15680 15690 15700 15710 15720 15730 )I )I )I )I )I )I )I )I )I I I I I I I I I I I PURPOSE: Modified version of the Comm module to be used for direct two way communication with the WHEDCO IMC stepping motor controller. UPDATE: 3.0 Version 3.0 checks to see if the card being used is the HP98628A (Datacomm) or the HP98626A (Serial). Depending on which card is used, the appropriate registers are selected. OPTION BASE 1 COM /Status/ INTEGER Sc,Connect_flg,E_flg,Debug_flg,Response$ INTEGER Baud_rate, B,Num chars, Response_flg, Indexl DIM Input$[256],Term$S[256],In$[256] BUFFER,From_232$[256] DIM Num chars$[61,Num ltrs$[6]1,Out$(2561 BUFFER DIM White_print$([1],Crlf$([2 IF Debug_flg THEN PRINT TABXY(1,1);"ENTERING Comm ON ERROR GOSUB Error l IF Connectflg THEN After_init Sc-30 ASSIGN eFindit TO Sc;RETURN Outcome IF Outcome-0 THEN ASSIGN @Find_it TO * CONTROL Sc,0;1 I Res CONTROL Sc,3;1 I Asy CONTROL Sc,0;1 I Set CONTROL Sc,8;1+2 I Set CONTROL Sc,16;0 I Di CONTROL Sc,17;0 I Dis CONTROL Sc,18;0 I Di CONTROL Sc,19;0! Di CONTROL Sc,20;14 I TX CONTROL Sc,21;14! RX CONTROL Sc,22;0 I No CONTROL Sc,23;0 I No CONTROL Sc,34;2 I 7 CONTROL Sc,35;0 I 1 CONTROL Sc,36;1 IODE Connect_flg-1 ELSE Sc-8 ASSIGN @Find_it TO * ASSIGN @Findit TO Sc;RETURN Outcome IF Outcome<>0 THEN PRINT "RS-232 card not installed. ASSIGN SFindit TO * STOP END IF ASSIGN @Find_it TO * RESET Sc CONTROL Sc,0;1 I Rese CONTROL Sc,3;Baud_rate I Set CONTROL Sc,4;8+2! UART CONTROL Sc,5;3! UART CONTROL Sc,12;128+32+16 Disa STATUS Sc,3;B Conf Connect_flg-1 END IF After_init:1 White_print$-CHR$(136) Crlf$-CHR$ (13) &CHR$ (10) PRINT CHR$(128)&CHR$(136);! Set up... -....... -.. 15740 15750 15760 15770 15780 15790 15800 15810 15820 15830 15840 15850 15860 15870 15880 15890 15900 15910 15920 15930 15940 15950 15960 15970 15980 15990 16000 16010 16020 16030 )] 16040 16050 16060 16070 16080 16090 16100 16110 16120 16130 16140 16150 16160 16170 ASSIGN eScreen TO CRT ASSIGN @Kbd TO KBD ASSIGN @Rx TO BUFFER In$ ASSIGN 8Tx TO BUFFER Out$ ASSIGN @Uartout TO Sc ASSIGN @Uart in TO Sc Response_flg-0 Response$-""! 1 ENABLE INTR Sc! Enable interrupt on card. TRANSFER @Tx TO @Uart_out;CONT! Enable transfer buffers. TRANSFER @Uart_in TO @Rx ON INTR Sc,FNTrap_level GOSUB Read_loop I Process card interrupts. IF C$<>"" THEN GOSUB Send_com! Send command out to controller. ELSE GOTO Quit! If null command, exit quick. END IF!! Reset command acknowledge flag. I Null out response string. Wait for it:WHILE NOT Response_flg GOSUB Read_loop IF NPAR-2 THEN LOOP! Waiting for acknowledgement.! We are waiting for data to be! sent by the Whedco controller. set RS-232 interface. ync link protocol. t Async toggle. t RTS and DTR lines. sable connection timeout. sable no activity timeout. sable NO CARRIER timeout. sable transmit timeout. baud speed - 9600 baud speed - 9600 handshake with Whedco. hardwired handshake. )its/character. stop bit. ) parity. GOSUB Read loop IF (POS(Response$,"*")) THEN Response$-Response$(POS(Response$, "* "), LEN(Responses Response_flg-l END IF EXIT IF ((Response_flg-i) AND (POS(Response$,Crlf$))) END LOOP ELSE WHILE NOT ((POS(Response$,"*")) OR (POS(Response$,"?"))) GOSUB Read_loop END WHILE Indexl-POS (Response$, "*") IF Indexl-0 THEN! Must be a "?" (Whedco command error).! Must be a "?" (Whedco command error). E_flg-1! Notify via error flag. Response_flg-1 ELSE! Normal command interpretation. E_flg-0 Response_flg-1 END IF END IF END WHILE GOTO Quit Please install and reboot." et the RS-232 interface. the baud rate. r 8 bits/char. ODD parity. r DTR line active. able CD,DSR,CTS Eirm speed to user. 16180 16190 16200 16210 16220 16230 16240 16250 16260 16270 16280 16290 16300 16310 16320 16330 16340 16350 16360 Read loop:! Read in serial data from Whedco. STATUS @Rx,4;Num_chars! IF Num_chars-0 THEN RETURN! Num_chars$-", "&VAL$(Num_chars)&"A"! ENTER @Rx USING Num_chars$;From_232$ Response$-Response$&From_232$ RETURN! Number of characters to receive, if 0 try again. Set up the IMAGE for ENTER.! Transfer contents.! Build up dialogue. I Update pointers. the screen.

REFERENCES [1] Ulaby, Fawwaz T. Lecture Notes on "Remote Sensing II: Radar", pg. 58. February 13, 1992. [2] Sarabandi, Kamal, et al. "Performance Characterization of Polarimetric Active Radar Calibrators and a New Single Antenna Design", IEEE Transactions on Antennas and Propagation, Vol. 40, No. 10, October 1992. [3] Burnside, Walter D. "An Aperture-Matched Horn Design", IEEE Transactions on Antennas and Propagation, Vol. AP-30, No. 4, July 1982. [4] Balanis, Constantine A. Antenna Theory: Analysis and Design, New York: John Wiley and Sons, 1982. [5] Sarabandi, Kamal, et al. "A Convenient Technique for Polarimetric Calibration of Radar Systems," IEEE Transactions on Geoscience and Remote Sensing, Vol. 28, pp. 1022-1033, 1990.