Data Set Information
DATA_SET_NAME MAGELLAN BISTATIC RADAR CALIBRATED DATA V1.0
DATA_SET_ID MGN-V-RSS-4-BSR-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview : This archive contains calibrated data from Magellan (MGN) Bistatic Radar (BSR) experiments conducted on 5 June 1994 at S-Band (13 cm wavelength) using the NASA Deep Space Network (DSN) 70-m antenna near Madrid, Spain (DSS 63). During these experiments the specular point crossed Maxwell Montes. The results indicated that the surface material in the Maxwell area behaved as a semi-conductor (13 mhos/m) [PETTENGILLETAL1996]. Parameters : Raw data from the MGN BSR experiments were archived in the PDS (DATA_SET_ID : MGN-V-RSS-1-BSR-V1.0), but no 'higher level' products followed during the Magellan era. In conjunction with analysis of new BSR data collected using the Venus Express spacecraft [SIMPSONETAL2008], the old MGN S-Band data from Maxwell were reprocessed. This new data set contains time samples which have been calibrated in amplitude (PRR directory). A second set of files (PRT directory) has the major sources of Doppler shift and other frequency effects removed, so that the echo centroid appears near 12500 Hz in the 25000 Hz bandwidth. The PRR and PRT data are complex double precision time samples in binary files; the right-circularly polarized (RCP) and left-circularly polarized (LCP) files are coherent. The SPC directory contains 10-second averages of power spectra and voltage cross-spectra derived from the samples in the PRT directory. The cross-spectra are between the two received polarizations (RCP and LCP). The SPC files are in ASCII format. There are three SPC files -- one for each MGN orbit. The rows in an SPC file are ordered by increasing time; within each time step, the rows are ordered by increasing frequency. All of the spectra have 1024 frequency bins with 24.4 Hz resolution. The archive also includes ancillary data: power spectra used to 'equalize' (flatten) the receiver spectral response (SRF directory), polynomial coefficients to calibrate the amplitude (GNC directory) and frequency (SC1 and SC2 directories) of the samples, and files useful in understanding the Magellan BSR experimental geometry (BSP and SRG directories). Processing : The data flow in creating the calibrated files is illustrated in the diagram below. The text, which follows, describes the steps. ODR | | 8-bit real samples | V RCP -------- LCP ----------| PREPMO |---------- | -------- | 16-bit samples | | 16-bit samples | | --------- --------- | PREPFND | | PREPFND | --------- --------- | | | PRP file | PRP file | 64I/64Q | 64I/64Q | | --------- --------- SRF --->| FND | | FND | <--- SRF --------- --------- | | | PRQ file | PRQ file | 64I/64Q | 64I/64Q | | --------- --------- GNC --->| GAIN | | GAIN | <--- GNC --------- --------- | | to <------- PRR file | | PRR file -------> to ARCHIVE 64I/64Q | | 64I/64Q ARCHIVE V V --------- --------- | STEER | <------ SC1 ------>| STEER | --------- --------- | | PRS file | | PRS file 64I/64Q | | 64I/64Q V V --------- --------- | STEER | <------ SC2 ------>| STEER | --------- --------- | | to <------- PRT file | | PRT file -------> to ARCHIVE 64I/64Q | | 64I/64Q ARCHIVE | ---------- | |-------->| FNDXLOOK |<--------| | ---------- | | | | V | Average V --------- | Cross --------- | FNDLOOK | | Spectrum | FNDLOOK | --------- | --------- | | | Average | V | Average RCP Power| ------------ | LCP Power Spectrum ------->| BSRMAT2TAB |<------- Spectrum ------------ | | SPC file V to ARCHIVE The ODR (Original Data Record) files are from the raw data archive (MGN-V-RSS-1-BSR-V1.0). Program PREPMO unpacks the 8-bit real samples and stores them in 16-bit words with separate files for RCP and LCP. Program PREPFND was designed to reduce the bandwidth of 16-bit sample streams by powers of 2 using a bandpass set at an arbitrary location within the original bandwidth. Here we are not interested in reducing bandwidth; but the program does allow us to convert from 16-bit real samples to double precision complex samples (64I/64Q) in a format which can be used as input to other software. The 'preprocessed' files from PREPFND have the file name extension PRP. The FND program does roughly the same thing as PREPFND except that (1) it expects complex double precision input and (2) it allows the user to 'equalize' the spectrum. The input time samples are Fourier transformed, the spectrum is divided by the square root of a noise power spectrum (SRF file), and the inverse transform is taken to create new time samples. To reduce instabilities in the inversion, there is 50 percent overlap in the transforms and only the central 50 percent of the time samples from each operation are retained. Since there is no overlap at the beginning of the first block and at the end of the last block, a few samples at the beginning and end of the file must be thrown away. Output files from FND have a flat frequency response over the central 80 percent of the window if the reference noise power spectrum (SRF) is representative of the receiver filtering. Names of files coming from FND have extension PRQ. The GAIN program uses polynomial coefficients from a GNC file to compute an amplitude scale factor for the time samples in a PRQ file. The coefficients account for changes in attenuator settings in the receiver system and also include a scale factor so that an output power spectrum is absolutely calibrated in units of zeptowatts (10^-21 W). Output files from GAIN have file name extension PRR. Note to Users: To ensure that scaling between Stanford and other processing software is the same, compare your output with the following calculations of average noise power density. The first 10 seconds of the file was Fourier transformed (1024-point spectra), the 244 power spectra were computed and averaged, and then the frequency bins indicated were averaged. Bins from both the lower and upper halves of the spectrum were included and care was taken to avoid spacecraft, echo, and interference signals. Units of power density are zeptowatts per hertz (where 1 zW : 10^-21 W). PRR File Noise Bins Average Noise Power Density ------------ ------------------- --------------------------- 4156130B.PRR 121-173 and 743-892 0.30199+/-0.00136 zW/Hz 4156161D.PRR 321-460 and 777-916 0.27723+/-0.00106 zW/Hz 4156191B.PRR 121-260 and 777-916 0.33472+/-0.00128 zW/Hz The STEER program uses polynomial coefficients to synthesize a digital signal which is 'mixed' with the bistatic radar samples. In the first STEER operation, the coefficients are computed to predict the frequency of the directly propagating carrier from the spacecraft to the DSN antenna in the 25000 Hz bandwidth. Within the STEER program, it is the predicted phase which is actually computed at each sample time. When the predicted phase is subtracted from the sample phase, the frequency of the entire spectrum is shifted. If the prediction is perfect, the directly propagating carrier will be shifted to exactly 12500 Hz, the center of the frequency window. All other signals in the spectrum will be shifted an equal amount, effectively 'rotating' the spectrum so that signals shifted out of the high end of the window reappear at the low end. The first STEER operation uses coefficients from the SC1 directory; output files from this processing have file name extensions PRS. In the second stage of STEER processing, the frequency differential between the carrier and the surface echo is computed from polynominal coefficients in the SC2 directory. In the output the centroid of the surface echo is moved to the center of the frequency window. Output files from this step have files names with extensions PRT. The FNDLOOK program computes average power spectra from time samples in the PRT file. If the amplitude scaling has been carried out correctly in the GAIN step, the spectra will accurately reflect the power reaching the receiver in each frequency bin of the spectrum. The FNDXLOOK program computes the average cross spectrum between the RCP and LCP receiver channels. If R(f) is a single voltage spectrum from the RCP receiver and conj{L(f)} is the complex conjugate of the corresponding voltage spectrum from the LCP receiver, then the cross spectrum is R(f)*conj{L(f)} and a time average of the cross spectrum can be denoted as Because the cross spectrum is a complex number, its average is computed by averaging the real part of the individual spectra, averaging the imaginary part of the individual spectra, and constructing a new complex value from the averages of the two parts. Note: Because the processing steps are identical for the RCP and LCP signals (and the SC1 and SC2 coefficents are applied in the same way), the PRT files for RCP and LCP remain coherent. There may be small errors in the frequencies of the surface echoes, but both RCP and LCP have the same errors and a cross-correlation of the PRT files from each channel will show the same phase relationship as was true at the receiving antenna. BSRMAT2TAB takes the RCP power spectra, the LCP power spectra, and the cross spectra and constructs an ASCII file in which they are organized first according to time and secondly by frequency. Each row in the output (SPC) file contains an RCP power, an LCP power, a magnitude of the cross spectrum, and a phase of the cross spectrum for a single time and frequency. The design of the SPC file allows for inclusion of both X-Band and S-Band values; since no X-Band data were included in this reprocessing effort, the X-Band columns have been set to zero. Data : PRR Data: Amplitude-corrected time samples are a primary data type for this archive; these are found in the PRR directory. A power spectrum computed from a PRR file should be absolutely calibrated in units of zeptowatts (10^-21 W). PRR files have a single header record followed by many data records containing double-precision complex time samples. Each file is defined as a pair of PDS TABLE objects with the first TABLE corresponding to the header record and the remaining (data) records making up the second TABLE. A typical PRR file contains 16 minutes of data with a complex I/Q pair of samples every 40 microseconds (25000 samples per second). A single (binary) complex sample requires 16 bytes for storage; the volume of a 16-minute file is 383975424 bytes. File names have the form ydddhhMC.PRR where y is the one-digit year (4), ddd is the three-digit day of year (156), hh is the two-digit hour, and M is the tens of minutes when the file started. C is a letter denoting frequency band and polarization of the data in the file; valid choices are B for S-Band RCP and D for S-Band LCP. Each PRR file is accompanied by a detached ASCII PDS label which describes both the content and format of the file and has file name ydddhhMC.LBL. PRT Data: Amplitude-corrected time samples which have also been corrected for the major sources of Doppler shift and other frequency effects are the second primary data type; these are found in the PRT directory. The corrections for Doppler and other frequency effects should place the surface echo centroid in the range 10000-15000 Hz, where the total bandwidth is 25000 Hz. The structure and naming of PRT files is identical to that for PRR files except for the file name extension (PRT). Each PRT file is accompanied by a detached PDS label which describes both the content and format of the file and has file name ydddhhMC.LBL. SPC Data: The third type of primary data is the SPC file. These are ASCII files containing power spectra, cross-spectrum magnitudes, and cross-spectrum phases. There are three SPC files -- one for each MGN orbit. The first 8 or 12 rows in an SPC file contain a header (a PDS TABLE object) listing source files (receiver channel, PRP file name, SRF file name, and GNC file name). The remaining rows contain the power and voltage cross-spectra measurements (a second PDS TABLE). The rows are ordered by time; within each time step, the rows are ordered by frequency. Columns in the data part of an SPC file give: spectrum number center time for the average spectrum (seconds) frequency bin number frequency corresponding to the bin number (Hz) average X-Band RCP power (set to zero in this archive) average X-Band LCP power (set to zero in this archive) average S-Band RCP power (zeptowatts) average S-Band LCP power (zeptowatts) average X-Band cross-spectrum magnitude (set to zero) average X-Band cross-spectrum phase (set to zero) average S-Band cross-spectrum magnitude (zeptowatts) average S-Band cross-spectrum phase (radians) All of the spectra have 1024 frequency bins with 24.4 Hz resolution. For the first BSR orbit there are 192 time steps of 10 seconds each; for the second and third orbits, there are 288 time steps of 10 seconds each. SPC files have names of the form ydddhhMB.SPC where 'y', 'ddd', and 'M' are the same as for PRR files and 'B' indicates that these are the second versions created of each file. The 'A' versions were preliminary and have not been included in the archive. Ancillary Data : Ancillary files were used directly in the calibration process (GNC, SC1, SC2, and SRF directories) or could be used during interpretation (BSP and SRG directories). They are described briefly below in the order in which they might be encountered during calibration. The SRF directory contains power spectra for the RCP (4156134B.SRF) and LCP (4156134D.SRF) channels which were used to 'equalize' (flatten) the spectral response of the filters in the receiving system. Each file is a 1024-point power spectrum computed from 227 seconds of noise data. Since the filtering is entirely digital, there is no reason to believe that the RCP and LCP noise power spectra would differ; but separate SRF files have been derived for the two channels. Standard deviation of individual frequency bins is about 1.3 percent of the mean. Each file includes an attached PDS label. The GNC directory contains ASCII files of coefficients for polynomials used to adjust the amplitude of the samples from a single receiver channel. The gain calibration accounts for changes in receiver attenuator settings and the system temperature of the channel. File 4156130B.GNC contains gain coefficients for all S-RCP observations on 5 June 1994; file 4156130D.GNC contains coefficients for all S-LCP observations. Each GNC file is accompanied by a detached PDS label having the same file name except for the extension (LBL). The SC1 directory contains ASCII files of coefficients for polynomials used to adjust the frequency of the directly propagating carrier signal so that it is approximately centered in the 25000 Hz output bandwidth. Each SC1 file covers approximately 16 minutes in (nominally) one second steps and is valid for both RCP and LCP. The SC1 files were created in the 1990's and were reformatted for archive in 2008. File names have the form ydddhhmm.SC1 where 'y' and 'ddd' are the same as for PRR files and 'hh' and 'mm' give the start hour and minute, respectively, for the data in each file. Each SC1 file is accompanied by a PDS detached label having the same name except for the extension (LBL). The SC2 directory contains ASCII files of coefficients for polynomials used to adjust the frequency of the surface echo so that it is approximately centered in the 25000 Hz output bandwidth. It is assumed that the directly propagating carrier was centered in the previous processing step, so this is a differential frequency correction. Each SC2 file covers a single MGN orbit in (nominally) 10 second steps and is valid for both RCP and LCP. The SC2 files were created in the 1990's and were reformatted for archive in 2008. File names have the form ydddhhmm.SC2, where the components have the same meaning as for SC1 files. Each file is accompanied by a PDS detached label having the same name except for the extension (LBL). The BSP directory contains the spacecraft and planetary ephemerides for 5 June 1994 (4156156A.BSP). The spacecraft ephemerides were derived from a Magellan 'SPK' file (CYCLE6.BSP), obtained from the Navigation and Ancillary Information Facility (NAIF) at the NASA Jet Propulsion Laboratory (JPL). The spacecraft ephemerides were then merged with the JPL DE-421 solar system ephemeris (DE421.BSP), also obtained from NAIF. The BSP file is accompanied by a PDS minimal label which points to additional information on NAIF, its products and tools, and documentation on this 'SPK' file. The SRG directory contains a single file (4156156A.SRG) summarizing the MGN BSR experiment geometry at one minute time increments over eight hours starting at 1994-06-05T13:00:00. This is an ASCII file containing a single header row followed by 480 data rows. The SRG file is accompanied by a PDS label (4156156A.LBL) which describes the content and format of the data file. The SRG header row gives: 01) DSN antenna number (63) 02) input BSP file name (4156156A.BSP) 03) assumed spherical radius of Venus (6051800 m) 04) assumed speed of light in vacuum (299792458 m/s) 05) latitude of a specific target (arbitrarily set to +70 deg)) 06) longitude of a specific target (arbitrarily set to 0 deg) 07) time spacing between rows in the data table (60 seconds) The SRG data rows contain the following. 'Specific target' is the surface point with latitude and longitude given in positions 5-6 of the header row. 'Backscatter point' is where a line drawn from the DSN antenna through the spacecraft (and beyond) would intercept the surface. The raypath closest approach (RCA) point is where such a line would be closest to Venus if there were no intercept and if Venus were between the DSN and spacecraft. The specular point is where spacecraft-to-surface-to-DSN mirror-like reflection would occur. If the spacecraft is in occultation, these points are not meaningful; existence of the backscatter point precludes existence of the RCA point. Vectors are in J2000 coordinates, distances are in meters, velocities are in m/s, and angles are in degrees. 01) Earth received time (ERT, seconds from midnight UTC) 02) corresponding transmit time at Venus (seconds from midnight) 03) Venus north pole vector (x,y,z components) 04) Venus fixed-body x-axis (x,y,z components) 05) Venus fixed-body y-axis (x,y,z components) 06) Venus center to DSN antenna vector 07) Venus center to MGN spacecraft vector 08) MGN spacecraft to DSN antenna vector 09) Venus center to specific target vector 10) Specific target to DSN antenna vector 11) Specific target to MGN spacecraft vector 12) Incidence angle at the specific target 13) Scattering angle at the specific target 14) Spacecraft-target-DSN angle 15) Venus center to backscatter point vector 16) Latitude of the backscatter point 17) Longitude of the backscatter point 18) Venus center to RCA point 19) Latitude of the RCA point 20) Longitude of the RCA point 21) Venus center to specular point vector 22) Incidence angle at the specular point 23) Reflection angle at the specular point 24) Latitude of the specular point 25) Longitude of the specular point 26) Partial derivative of (12) with respect to Venus radius 27) Partial derivative of (13) with respect to Venus radius 28) Partial derivative of (14) with respect to Venus radius 29) Partial derivative of (16) with respect to Venus radius 30) Partial derivative of (17) with respect to Venus radius 31) Partial derivative of (22) with respect to Venus radius 32) Partial derivative of (23) with respect to Venus radius 33) Partial derivative of (24) with respect to Venus radius 34) Partial derivative of (25) with respect to Venus radius Coordinate System : In general the J2000 inertial reference frame is used. But the radio data are not dependent on frames, and the NAIF software allows easy translation among coordinate systems. The only file for which a coordinate system matters is the SRG file. Software : No software is included with this archival data set. Media/Format : This archival data set was transferred to TDK and Taiyo Yuden DVD+R media using a Dell computer with a Plextor PX712A writer. The software was Padus Disc Juggler running under the Windows XP2 operating system. Discs have been produced in the UDF-Bridge format with ISO 9660 Level 1 compatibility.
DATA_SET_RELEASE_DATE 2008-10-31T00:00:00.000Z
START_TIME 1994-06-05T12:00:00.000Z
STOP_TIME 1994-06-05T12:00:00.000Z
MISSION_NAME MAGELLAN
MISSION_START_DATE 1989-05-04T12:00:00.000Z
MISSION_STOP_DATE 1994-10-12T12:00:00.000Z
TARGET_NAME VENUS
TARGET_TYPE PLANET
INSTRUMENT_HOST_ID MGN
INSTRUMENT_NAME RADIO SCIENCE SUBSYSTEM
INSTRUMENT_ID RSS
INSTRUMENT_TYPE RADIO SCIENCE
NODE_NAME Geosciences
Radio Science
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE Overview : This data set is the result of reprocessing the Magellan S-Band bistatic radar data collected at DSS 63 on 5 June 1994. These observations were the most useful for assessing the behavior of the anomalously reflecting materials at high elevation on Venus [PETTENGILLETAL1996]. Data collected at X-Band on 5 June 1994 were not processed because there was little evidence that an echo had been captured (high absorption by the neutral atmosphere at 3.6 cm wavelength). No data collected on the same date at DSS 14 were processed -- pointing errors at that ground station reduced signals by as much as 10 dB. Data from other dates were not processed because the targets or viewing geometry appeared to be less promising. Review : This archival data set was reviewed by a peer review panel prior to its acceptance by the Planetary Data System (PDS). The peer review was conducted by the PDS Geosciences Node in accordance with PDS procedures. Data Coverage and Quality : Eight quasi-specular tracks were observed using two 70-m DSN antennas on 5-6 June 1994. Each track extended from south of the Venus equator to beyond Maxwell Montes in the north. The objective was to observe changes in reflected signal amplitude and dispersion as the specular point moved over different surface units. Of particular interest was Maxwell Montes, targeted five days earlier in a spotlight bistatic experiment. Real-time observation of echoes at S-band and possible detection (with intense non-real-time processing) of X-band echoes were predicted for 5 June 1994. Data were collected during six orbits using DSS 63 near Madrid; data from four orbits were collected using DSS 14 near Goldstone. Madrid began by receiving S-RCP and S-LCP on the first orbit, switched to X-RCP and X-LCP on the second, and continued to alternate on successive orbits thereafter. Previous experience had shown that attempting to record both S-Band and X-Band signals at 25000 samples per second at a single antenna led to errors. On the fifth orbit, DSS 14 began with X-RCP and X-LCP (while DSS 63 collected S-RCP and S-LCP), and alternated thereafter. Tuning predictions for the open-loop receivers were calculated at Stanford; owing to a sign error, the predictions failed to achieve the desired result, but real-time corrections to the tuning (manual frequency offsets) were sufficient to keep the S-band signal within the passband for all but parts of the first DSS 63 orbit. S-band echoes were observed in real time from DSS 63; no X-band echoes were seen. At DSS 14 an error in ground antenna pointing reduced signal levels considerably; those data have very little value when compared with with the data from DSS 63. Some of the tapes received from DSS 63 had truncated records; these errors only affected the X-Band recordings. About half of the tapes received from DSS 14 were unreadable. The tables below summarize the data which were reprocessed and have been included in the calibrated data archive. All were from 5 June 1994, collected at DSS 63 using S-Band (13 cm wavelength). The notation 4156130{B,D}.PRR means that the S-RCP file name is 4156130B.PRR and the S-LCP file name is 4156130D.PRR. The 'missing' PRT files included only times when there was no surface echo. : Start Stop Calibrated Complex Calibrated Complex Time Time Time Time Samples Samples with Echo Centered (ERT) (ERT) (PRR Directory) in Spectrum (PRT Directory) ---------- ---------- ------------------- -------------------------- 13:09:31 13:25:30 4156130{B,D}.PRR 4156130{B,D}.PRT 13:25:31 13:41:30 4156132{B,D}.PRR 4156132{B,D}.PRT 13:41:31 13:48:39 4156134{B,D}.PRR 15:58:12 16:14:11 4156155{B,D}.PRR 4156155{B,D}.PRT 16:14:12 16:30:11 4156161{B,D}.PRR 4156161{B,D}.PRT 16:30:12 16:46:11 4156163{B,D}.PRR 4156163{B,D}.PRT 16:46:12 16:54:17 4156164{B,D}.PRR 19:10:25 19:26:24 4156191{B,D}.PRR 4156191{B,D}.PRT 19:26:25 19:42:24 4156192{B,D}.PRR 4156192{B,D}.PRT 19:42:25 19:58:24 4156194{B,D}.PRR 4156194{B,D}.PRT 19:58:25 20:00:23 4156195{B,D}.PRR : : Start Stop Calibrated Power Number Number of Time Time and Voltage of Frequency Bins (ERT) (ERT) Cross-Spectra Time per (SPC Directory) Steps Time Step ---------- ---------- ---------------- ------ -------------- 13:09:31 13:41:31 4156130B.SPC 192 1024 15:58:12 16:46:12 4156155B.SPC 288 1024 19:10:25 19:58:25 4156191B.SPC 288 1024 : For the three orbits which were reprocessed, the data are reasonably good. But several points are worth noting: (1) Interfering signals originating on Earth passed through the frequency range occupied by the surface echo; but the geometry was slightly different on each orbit. At most, only the data from the first BSR orbit were seriously compromised when the interfering signal passed through the surface echo at the same time (13:31) as the specular point was moving across Maxwell Montes. (2) The masers on both S-Band channels were unstable on time scales of seconds to minutes. The S-RCP gain variation was relatively unimportant, but variations in the S-LCP gain of as much as 1 dB made the attempt at absolute calibration only marginally successful and produced false polarization signatures for noise which should have been random. Forcing the background noise to be the same on both channels might be a better procedure in a future analysis even though it would lead to small errors in the inferred polarization of the surface echoes. (3) The GNC coefficients were chosen to give a 15 dB correction to sample values when S-RCP attenuation was increased or decreased by 15 dB, the nominal value. The result is perfectly accurate in the sense that no discontinuity can be seen in the output S-RCP sample values after correction. On S-LCP a 15 dB GNC correction proved too much, so 14.5 dB was used instead. In retrospect, this was too little; a GNC correction of 14.75 dB appears to have been the best choice. Since the S-LCP channel was already known to be unstable at the 1 dB level, no attempt was made to recalibrate the amplitudes to remove the 0.25 dB discontinuities and they can be seen in the PRR and PRT data. (4) The frequency calibration, following procedures which have easily located Voyager and other signals to 1 Hz, put Magellan BSR echoes into the desired 10000-15000 Hz window but without much additional precision. The most likely source of frequency error is drift of Magellan's on-board frequency reference, perhaps affected by temperature as the spacecraft maneuvered to maintain equal illumination in the horizontal and vertical polarization planes. The apparent frequency of the echo peak and its drift (as it appears in the SPC files) is listed below. Note that drift of the echo does not invalidate the cross-spectrum values because the same phase corrections were applied to both polarizations; however, the bin location of any given cross-spectrum value will be offset, just as the bins of the S-RCP and S-LCP power spectra will be offset. : Experiment Start Start End End Average Time Frequency Time Frequency Drift (s) (Hz) (s) (Hz) (Hz/s) ---------- ----- --------- ----- --------- ------- 1 47580 14150 48980 12500 -1.18 2 58700 13250 60100 12000 -0.89 3 69900 13000 71200 12100 -0.69 : (5) [PETTENGILLETAL1996] reported 1-second averaging to obtain echo properties. Partly because of software limitations, the integration used here was 10 seconds. (6) In spite of the issues listed above, the calibrated data do show an excess of RCP echo power when the specular point was over Maxwell Montes, and especially when it was near Cleopatra Patera. Limitations : The limitations in this data set follow from the quality of the execution, which is described above under Data Coverage and Quality.
CITATION_DESCRIPTION Simpson, R.A., Magellan Bistatic Radar Calibrated Data V1.0, MGN-V-RSS-4-BSR-V1.0, NASA Planetary Data System, 2008.
ABSTRACT_TEXT Calibrated data from three orbits of S-Band (13 cm wavelength) Magellan bistatic radar data collected with NASA antenna DSS 63 on 5 June 1994 when the specular point crossed Maxwell Montes. Similarly processed data were used by Pettengill et al. (SCIENCE, 272, 1628-1631, 1996) to infer existence of a semiconductor layer covering anomalously reflecting regions at high altitude on Venus. This new data set includes calibrated time samples of receiver output as well as calibrated power spectra and voltage cross spectra (between the two received polarizations). The data set was written to three DVD+R volumes for delivery to the NASA Planetary Data System (PDS).
PRODUCER_FULL_NAME RICHARD A. SIMPSON
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