PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM RECORD_BYTES = 32 /* Largest actual record in the file */ FILE_RECORDS = 230 ^SPREADSHEET = "ODY2004040_S253.CSV" DATA_SET_ID = "MER1-M-RSS-1-EDR-V1.0" TARGET_NAME = "MARS" INSTRUMENT_HOST_NAME = "MARS EXPLORATION ROVER 1" INSTRUMENT_NAME = "RADIO SCIENCE SUBSYSTEM" INSTRUMENT_ID = "RSS" PRODUCER_ID = "DSN" PRODUCT_CREATION_TIME = 2004-02-10T00:00:00 PRODUCT_TYPE = UHFD PRODUCT_ID = "ODY2004040_S253.CSV" ORIGINAL_PRODUCT_ID = "ody2004040_S253.asc" START_TIME = 2004-02-09T05:05:18 STOP_TIME = 2004-02-09T05:24:25 HARDWARE_MODEL_ID = "C/TT-505" DESCRIPTION = "Ultra-High Frequency Doppler (UHFD) files are the results of measurements made by the UHF radio system on the Mars Odyssey Orbiter (ODY). The ODY UHF radio system uses a reference frequency near 401 MHz. The reference frequency is multiplied by the ratio 160/147 to generate a signal near 437 MHz which can be used to transmit commands to vehicles on Mars such as MER 1 and MER 2, and receives signals back at 401 MHz. The ODY UHF radio measures the difference in frequency between the reference and received carrier frequencies which provides a (Doppler) measure of the relative velocity of the surface vehicle. Each UHFD file contains ASCII records with 4 fields; commas are used to separate fields within each record. The first field of each record is the time of the measurement in seconds past the J2000 reference epoch (which is 2000-01-01T12:00:00 UTC). The second field of each record is an integer flag which indicates the reference frequency. The third field is an integer flag which indicates data quality (0 indicates valid, 1 indicates bad); the fourth field is the frequency difference measurement in Hz. The measurement is the absolute value of the difference of the received frequency minus the reference frequency. For Mars Odyssey, the only available reference frequency is 401.584625 MHz. The frequency of the signal transmitted by ODY is a fixed multiple, 160/147, of the reference frequency. For the MER radio operating in coherent mode, the received frequency is multiplied by a fixed multiple, 147/160, to generate the signal transmitted back to the orbiter. For example, when ODY is directly overhead the rover, the signal received from MER and the ODY reference frequency are the same and the measurement is zero, indicating zero velocity of the rover relative to ODY along the line of sight to the orbiter. In general, the absolute value of the velocity along the line of sight is (to first order in v/c) v = (c/2) *F(measurement)/F(reference) where c is the speed of light. The size of each record is variable; the maximum record size consists of 14 characters for the TIME field, 1 character for the LO FLAG field, one character from the DATA QUALITY field, 11 characters for the FREQUENCY field, three single-character delimiters (comma), plus ASCII carriage-return and line-feed at end of each record." OBJECT = SPREADSHEET ROWS = 227 ROW_BYTES = 32 /* Largest actual record in the file */ FIELDS = 4 FIELD_DELIMITER = "COMMA" OBJECT = FIELD NAME = "TIME" DATA_TYPE = "ASCII_REAL" FIELD_NUMBER = 1 BYTES = 14 /* Maximum item bytes */ DESCRIPTION = "The time of the measurement in seconds past the J2000 reference epoch (which is 2000-01-01T12:00:00 UTC)." END_OBJECT = FIELD OBJECT = FIELD NAME = "LO FLAG" DATA_TYPE = "ASCII_INTEGER" BYTES = 1 FIELD_NUMBER = 2 DESCRIPTION = "Flag which indicates the reference local oscillator (LO) frequency against which the frequency of the received carrier is measured. For ODY, the flag is always '1' since only one reference frequency is available." END_OBJECT = FIELD OBJECT = FIELD NAME = "DATA QUALITY" DATA_TYPE = "ASCII_INTEGER" BYTES = 1 FIELD_NUMBER = 3 DESCRIPTION = "Flag which indicates data quality (0 indicates valid, 1 indicates bad). Data may be flagged as 'bad' due either to telemetry indicating a bad receiver condition or to telemetry integrity checks indicating errors in telemetry record from ODY to the DSN containing the measurement data." END_OBJECT = FIELD OBJECT = FIELD NAME = "FREQUENCY" DATA_TYPE = "ASCII_REAL" BYTES = 11 /* Maximum item bytes */ FIELD_NUMBER = 4 DESCRIPTION = "Frequency difference measurement in Hz." END_OBJECT = FIELD END_OBJECT = SPREADSHEET END