Skip to end of metadata
Go to start of metadata

The PSRDADA format is used internally within the MWAX correlator and beamformer components. It is not user-facing.

Pre Correlator

KeywordValid values or ExampleUsed ByDescription
HDR_SIZE4096PSRDADARequired by PSRDADA - size of header in bytes (should always be 4096)
POPULATED0 | 1mwax_db2correlate2db

Used to ensure the correlator does not read an incomplete file.

0 means the file is not yet complete, 1 means the file is ready for consumption

OBS_ID1244973688mwax-db2fitsObs_id of this observation
SUBOBS_ID1244973688mwax-db2fitsGPS second of this part of the observation. Increments in 8 sec intervals
MODE

HW_LFILES

VOLTAGE_START

NO_CAPTURE

mwax_db2correlate2db

mwax-db2fits

This matches the "mode" from the existing metadata database/schedule. (HW_FILES == Correlation mode, VOLTAGE_START == voltage capture, NO_CAPTURE = create subfiles, but do not send to correlator)
UTC_START2018-10-11-05:26:14

PSRDADA

mwax-db2fits

Required by PSRDADA. This is the UTC start date/time of the subobservation(?). Used by mwax-db2fits to append a human readable date/time to the filename produced.
OBS_OFFSET0 (n seconds since start of observation)

PSRDADA

mwax-db2fits

Required by PSRDADA. I believe this is the number of seconds offset from the start of the observation. First subobservation will have this set to 0. Second subobservation will be 8, etc.

NBIT

8mwax_db2correlate2dbBits per sample (should always be 8)
NPOL2

mwax_db2correlate2db

mwax-db2fits

Polarisations per tile (i.e. rf_chains) (should always be 2)


NTIMESAMPLES64000mwax_db2correlate2dbNumber of timesamples in each input sub-block of a subobservation (nominally sub-blocks are 50 ms)
NINPUTS256 | n rfinputsmwax_db2correlate2dbNumber of signal paths present in the input subobservation file, to be correlated (must be <= NINPUTS_XGPU)
NINPUTS_XGPU256 | n rfinputs in multiples of 16mwax_db2correlate2dbNumber of signal paths actually correlated by xGPU (must be a multiple of 16; must match the number of paths that xGPU has been configured for)

APPLY_PATH_WEIGHTS

0 | 1mwax_db2correlate2dbShould scalar path weights be applied prior to correlation (for gain normalisation and/or sub-arraying)
APPLY_PATH_DELAYS0 | 1mwax_db2correlate2dbShould fractional path delays be applied prior to correlation (for phasing up to a correlation pointing centre)
INT_TIME_MSEC200 - 8000

mwax_db2correlate2db

mwax-db2fits

Correlator integration time (milliseconds)
FSCRUNCH_FACTOR40 (1 - 6400)

mwax_db2correlate2db

mwax-db2fits

Correlator frequency scrunch factor: number of ultrafine 200 Hz fine channels to average together
APPLY_VIS_WEIGHTS0 | 1mwax_db2correlate2dbShould data occupancy weights be applied to normalise the output visibilities

TRANSFER_SIZE

5275652096

PSRDADA

mwax_db2correlate2db

Total number of bytes of input data for one subobservation (of nominally 8 seconds)

PROJ_ID

G0008mwax-db2fitsProject ID of observation
EXPOSURE_SECS8 (in incremements of 8 seconds)mwax-db2fitsDuration of observation in seconds
COARSE_CHANNEL76 (0 - max receiver channel number == 255)mwax-db2fitsReceiver channel number 
CORR_COARSE_CHANNEL9 | (1 - coarse channel max)mwax-db2fitsCorrelator channel number - which correlator channel "index" is this? e.g. first channel would be 1. In a 24 channel system, last channel would be 24. This would map to gpubox01-24 in the legacy Correlator
SECS_PER_SUBOBS8

mwax_db2correlate2db

mwax-db2fits

Number of seconds per subobservation

UNIXTIME

1539235574mwax-db2fitsUnix time of the start of this observation. This field is used by mwax-db2fits to provide a UNIX timestep for each integration throughout the observation.
UNIXTIME_MSECmwax-db2fitsUnix time milliseconds offset of the start of this observation. This will always be 0 with the current setup, but is here for completeness.

FINE_CHAN_WIDTH_HZ

10000mwax-db2fitsCorrelator output fine channel width in Hz
NFINE_CHAN128

mwax_db2correlate2db

mwax-db2fits

Correlator output number of fine channels
BANDWIDTH_HZ1280000mwax-db2fitsCoarse channel passband width in Hz, i.e. the channel spacing

SAMPLE_RATE

1280000mwax_db2correlate2dbSample rate of input data in samples/s (whether critically-sampled or oversampled)
MC_IP0.0.0.0mwax-db2fitsMulticast IP for this coarse channel (for debug purposes)
MC_PORT0mwax-db2fitsMulticast port for this coarse channel (for debug purposes)
MC_SRC_IP0.0.0.0Not used (yet)Multicast source IP of data for this coarse channel (for debug purposes)

Post Correlator changes

KeywordValid values or ExampleUsed ByDescription

NBIT

32mwax-db2fitsBits per complex visibility component (real | imaginary)
NTIMESAMPLES1 - 40 (for 8 s subobservations)?Number of integration times (visibility sets produced) per subobservation

TRANSFER_SIZE

n bytes

mwax-db2fits

Total number of bytes of output data for this 8 second subobservation. Calculated by:

bytes = visibilities + weights

visibilities = integrations * baselines * fine channels * polarisations * bytes_real * bytes_imaginary

weights = integrations * baselines  * polarisations * bytes_real 

  • No labels