MCRDS Data Format May 3, 2006

File Type Header Data file type –32 byte string (“Data-MCRDS”) terminated with null character ‘\0’. Characters after termination undefined. –2 bytes unsigned short representing year –1 byte unsigned character representing subyear version –5 bytes reserved

Data Header Block struct HeaderBlock { int dataType; double sampFreq;% 120 MHz int prfCount;% PRF = 1/(prfCount*1e-7) int numAve;% # of hardware integrations (i.e. coherent averages) int rxAtten[8][2][4]; int rxBlank[8][1][4]; char calModeEn;% always false char numWaveforms; char pad[2];% reserved int calNumOfPnts;% not used during data collection double calStartFreq;% not used during data collection double calStopFreq;% not used during data collection double calDelay;% not used during data collection double calDuration;% not used during data collection };

Fields of interest: Rx mode rxAtten and rxBlank –Each of the eight receivers are loaded with 4 different modes. The modes for each receiver are independent of one another. E.g. mode 1 for receiver 2 can be different than mode 1 for receiver 3. –A mode is defined by the settings of the two digital step attenuators and the blank delay line selection. The receiver has a single blanking switch, but two different control lines that can be selected. –During any given pulse period, all receivers must be in the same mode number. I.e. the radar does not allow receiver 2 to be in mode 1 while receiver 3 is in mode 2.

Fields of interest: Waveforms The radar system transmits a set of waveforms defined by the radar operator. The radar loads this sequence of waveforms into the system. For example: –3 us linear FM chirp, radar mode 0 Receiver gain settings are set to allow capture of the surface echo and both transmit amplifiers are enabled. –10 us linear FM chirp, radar mode 1 Receiver gain settings set to maximize dynamic range while keeping the lowest noise figure possible and satisfying our A2D dithering req. Transmit antenna one enabled. –10 us linear FM chirp, radar mode 2 Receiver gain settings set to maximize dynamic range while keeping the lowest noise figure possible and satisfying our A2D dithering req. Transmit antenna five enabled. When the radar is enabled, each of the waveforms and radar modes is run in sequence. –E.g. With three waveforms the effective PRF of an individual waveform becomes PRF/3

Waveform Headers (part of data header block) struct WaveformHeaderBlock { double startFreq;% 20 MHz (USB mixing with 120 MHz LO to 140 MHz) double stopFreq; % 40 MHz (USB mixing with 120 MHz LO to 160 MHz) double pulseDuration;% arbitrary (but most likely 1 us, 3 us or 10 us) double calFreq;% 0 (disabled during data collection) double calDelay;% unused double calDuration;% unused char bandSelect;% 0 for 150 MHz band, 1 for 450 MHz band char zeroPiMod;% 0 for no modulation, 1 for zero-pi modulation char txMult;% unused char rxMode;% 0, 1, 2, or 3 char txAmpEn[2];% [0] control tx amp 0, [1] controls tx amp 1 char pad[2]; int mod0Count;% transmitter blanking control line int mod1Count;% transmit amplifier blanking control line int numSam[4];% number of samples for each DAQ to capture (4 daqs, each with 2 channels) int sampleDelayCount[4];% delay for DAQ begins capturing char recordEn[8];% per channel record enable int recordDelay[8];% per channel recording window start sample int recordNumSam[8];% per channel recording number of samples int blankDelay0Count;% receiver blank control line 0 int blankDelay1Count;% receiver blank control line 1 }; COUNTS ARE DEFINED AS 10 MHz clock cycles (0.1 us) and are relative to the AWG trigger. The transmit waveform is delayed by 1 us. Therefore “zero-time” has a count of 10.

AWG Block For predistortion and non-ideal linear FM chirps –We are not using this data block for May 06.

Data Block 4 byte integer for data type (data type is 2 for data blocks) 8 bytes for computer time stamp –4 bytes for seconds since epoch (Jan 1, 1970) –4 bytes for microseconds 8 bytes for radar time (free-running 10 MHz counter on the radar board) –Used to precisely synchronize to the 1 pps provided by the Wallop’s Flight Facility group. 4 bytes for DAQ errors –1 byte per DAQ –Byte is zero when there is no error –Most common error is a FIFO error which causes a reset of the FIFOs and a few dropped records Binary data follows (2 byte unsigned samples) –12 bit DAQ, 64 integrations = 18 bits –2 bits dropped = 16 bit sample

Overview Data Block 0Datatype (=2) Computer Time Radar Time DAQ 0 DAQ Error Bytes Data Block 1 Data Block 2 DAQ 1 DAQ 2 Waveform 0 Waveform 1 Waveform 2 Sample 0 Sample 1 Sample 2 File Type Data Header