MCRDS Data Format

1
MCRDS Data Format

• May 3, 2006

2
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

3
Data Header Block

• struct HeaderBlock
• int dataType
• double sampFreq 120 MHz
• int prfCount PRF 1/(prfCount1e-7)
• int numAve of hardware integrations (i.e.
  coherent averages)
• int rxAtten824
• int rxBlank814
• char calModeEn always false
• char numWaveforms
• char pad2 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

4
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.

5
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

6
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 txAmpEn2 0 control tx amp 0, 1
  controls tx amp 1
• char pad2
• int mod0Count transmitter blanking control
  line
• int mod1Count transmit amplifier blanking
  control line
• int numSam4 number of samples for each
  DAQ to capture (4 daqs, each with 2 channels)
• int sampleDelayCount4 delay for DAQ begins
  capturing
• char recordEn8 per channel record enable

7
AWG Block

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

8
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 Wallops 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

9
Overview
File Type
Data Header
Data Block 0
Datatype (2)
Waveform 0
Sample 0
Computer Time
Data Block 1
Waveform 1
Sample 1
Radar Time
Data Block 2
Waveform 2
Sample 2
DAQ Error Bytes
DAQ 0
DAQ 1
DAQ 2