PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT PUBLICATION_DATE = 2007-06-01 NOTE = "Description of the CALIB directory contents for the MRO SHARAD EDR/RDR archives." END_OBJECT = TEXT END CALIB Directory Contents In SHARAD ground processing, the range processing of each echo is performed by computing the FFT of the discretely sampled pulse echo, by multiplying it by the complex conjugate of the FFT of the discretely sampled transmitted signal (which is called reference chirp) and then by performing the IFFT of the result: because of the properties of Fourier transform pairs, this is equivalent to the computation of a correlation in the time domain. The CALIB directory contains reference chirps for the MRO SHARAD EDR/RDR archives, plus the documentation describing how they have been produced. It has been found that amplitude and phase of the reference chirp are a function of the temperatures of both transmitter and receiver. From ground tests, the behavior of the chirp has been determined, and is reported here in the form of 40 binary files. Each file contains the FFT of the base-banded reference chirp for a given combination of transmitter and receiver temperatures. Such combination of transmitter and receiver temperatures is indicated in the file name. For example, the file called REFERENCE_CHIRP_M05TX_M20RX.DAT contains the reference chirp for a transmitter temperature of -5 degrees C (as denoted by the mnemonic M05TX) and a receiver temperature of -20 degrees C (as denoted by the mnemonic M20RX). To choose the correct reference chirp for range compression, it is necessary to read the transmitter and receiver temperatures as reported in the auxiliary data of each data product, and then to select the chirp whose transmitter and receiver temperatures most closely match those found in the data product. Reference chirps are contained in binary files as 4096 floating point numbers, each 4 bytes long and stored in least significant byte first (LSB) order. The first 2048 values represent the real part of the reference chirp, while the remaining 2048 values constitute its imaginary part. Reference chirps are expressed as complex spectra in the Fourier frequency domain. Frequency spacing between samples is (80/3 MHz) / 4096 = 6.51 kHz. Chirps are in base band, and spectra are ordered in increasing frequency order. Zero frequency corresponds to sample 1025. To use the reference chirps for range compression of raw data, the following steps need to be performed: - Extend the length of the vector containing the raw data samples from 3600 to 4096 through zero padding. - Multiply the raw data by the complex exponential of 2.Pi.i.F_c.t where the dot denotes multiplication and Pi is pi, i is the imaginary unit, F_c is equal to (80/3 - 20) MHz, and t is a vector 4096 samples long containing linearly increasing values starting from zero, and each spaced 3/80 microseconds apart from the next. - Compute the FFT of the result. - Select only the central 2048 samples of the complex spectrum, that is from sample 1025 to sample 3072 if spectrum samples are ordered for increasing frequency. - Multiply the result by the complex conjugate of the reference chirp. - Compute the IFFT of the result ------------------------------------------------------------------------------ The files listed below are found in this directory. CALIBRATION_PLAN.LBL - PDS label for CALIBRATION_PLAN.PDF. CALIBRATION_PLAN.PDF - Adobe Acrobat version of the Mars Reconnaissance Orbiter SHAllow RADar Calibration Plan. CALINFO.TXT - The file you are reading. REFERENCE_CHIRP_M05TX_M20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -5 degrees C and the temperature of the receiver is at -20 degrees C. REFERENCE_CHIRP_M05TX_P00RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -5 degrees C and the temperature of the receiver is at 0 degrees C. REFERENCE_CHIRP_M05TX_P20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -5 degrees C and the temperature of the receiver is at +20 degrees C. REFERENCE_CHIRP_M05TX_P40RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -5 degrees C and the temperature of the receiver is at +40 degrees C. REFERENCE_CHIRP_M05TX_P60RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -5 degrees C and the temperature of the receiver is at +60 degrees C. REFERENCE_CHIRP_M10TX_M20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -10 degrees C and the temperature of the receiver is at -20 degrees C. REFERENCE_CHIRP_M10TX_P00RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -10 degrees C and the temperature of the receiver is at 0 degrees C. REFERENCE_CHIRP_M10TX_P20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -10 degrees C and the temperature of the receiver is at +20 degrees C. REFERENCE_CHIRP_M10TX_P40RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -10 degrees C and the temperature of the receiver is at +40 degrees C. REFERENCE_CHIRP_M10TX_P60RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -10 degrees C and the temperature of the receiver is at +60 degrees C. REFERENCE_CHIRP_M15TX_M20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -15 degrees C and the temperature of the receiver is at -20 degrees C. REFERENCE_CHIRP_M15TX_P00RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -15 degrees C and the temperature of the receiver is at 0 degrees C. REFERENCE_CHIRP_M15TX_P20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -15 degrees C and the temperature of the receiver is at +20 degrees C. REFERENCE_CHIRP_M15TX_P40RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -15 degrees C and the temperature of the receiver is at +40 degrees C. REFERENCE_CHIRP_M15TX_P60RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -15 degrees C and the temperature of the receiver is at +60 degrees C. REFERENCE_CHIRP_M20TX_M20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -20 degrees C and the temperature of the receiver is at -20 degrees C. REFERENCE_CHIRP_M20TX_P00RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -20 degrees C and the temperature of the receiver is at 0 degrees C. REFERENCE_CHIRP_M20TX_P20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -20 degrees C and the temperature of the receiver is at +20 degrees C. REFERENCE_CHIRP_M20TX_P40RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -20 degrees C and the temperature of the receiver is at +40 degrees C. REFERENCE_CHIRP_M20TX_P60RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at -20 degrees C and the temperature of the receiver is at +60 degrees C. REFERENCE_CHIRP_P00TX_M20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at 0 degrees C and the temperature of the receiver is at -20 degrees C. REFERENCE_CHIRP_P00TX_P00RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at 0 degrees C and the temperature of the receiver is at 0 degrees C. REFERENCE_CHIRP_P00TX_P20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at 0 degrees C and the temperature of the receiver is at +20 degrees C. REFERENCE_CHIRP_P00TX_P40RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at 0 degrees C and the temperature of the receiver is at +40 degrees C. REFERENCE_CHIRP_P00TX_P60RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at 0 degrees C and the temperature of the receiver is at +60 degrees C. REFERENCE_CHIRP_P20TX_M20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +20 degrees C and the temperature of the receiver is at -20 degrees C. REFERENCE_CHIRP_P20TX_P00RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +20 degrees C and the temperature of the receiver is at 0 degrees C. REFERENCE_CHIRP_P20TX_P20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +20 degrees C and the temperature of the receiver is at +20 degrees C. REFERENCE_CHIRP_P20TX_P40RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +20 degrees C and the temperature of the receiver is at +40 degrees C. REFERENCE_CHIRP_P20TX_P60RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +20 degrees C and the temperature of the receiver is at +60 degrees C. REFERENCE_CHIRP_P40TX_M20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +40 degrees C and the temperature of the receiver is at -20 degrees C. REFERENCE_CHIRP_P40TX_P00RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +40 degrees C and the temperature of the receiver is at 0 degrees C. REFERENCE_CHIRP_P40TX_P20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +40 degrees C and the temperature of the receiver is at +20 degrees C. REFERENCE_CHIRP_P40TX_P40RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +40 degrees C and the temperature of the receiver is at +40 degrees C. REFERENCE_CHIRP_P40TX_P60RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +40 degrees C and the temperature of the receiver is at +60 degrees C. REFERENCE_CHIRP_P60TX_M20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +60 degrees C and the temperature of the receiver is at -20 degrees C. REFERENCE_CHIRP_P60TX_P00RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +60 degrees C and the temperature of the receiver is at 0 degrees C. REFERENCE_CHIRP_P60TX_P20RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +60 degrees C and the temperature of the receiver is at +20 degrees C. REFERENCE_CHIRP_P60TX_P40RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +60 degrees C and the temperature of the receiver is at +40 degrees C. REFERENCE_CHIRP_P60TX_P60RX.DAT - Reference chirp to be used for range processing of the received signal when the temperature of the transmitter is at +60 degrees C and the temperature of the receiver is at +60 degrees C.