HDR_SIZE

4096

PSRDADA

Required by PSRDADA - size of header in bytes (should always be 4096)

POPULATED

0 | 1

mwax_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_ID

1244973688

mwax-db2fits

Obs_id of this observation

SUBOBS_ID

1244973688

mwax-db2fits

GPS second of this part of the observation. Increments in 8 sec intervals

MODE

MWAX_CORRELATOR

MWAX_VCS

NO_CAPTURE

mwax_db2correlate2db

mwax-db2fits

This matches the "mode" from the existing metadata database/schedule.

UTC_START

2018-10-11-05:26:14

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_OFFSET

0 (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

8

mwax_db2correlate2db

Bits per sample (should always be 8)

NPOL

2

mwax_db2correlate2db

mwax-db2fits

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

NTIMESAMPLES

64000

mwax_db2correlate2db

Number of timesamples in each input sub-block of a subobservation (nominally sub-blocks are 50 ms)

NINPUTS

256 | n rfinputs

mwax_db2correlate2db

Number of signal paths present in the input subobservation file, to be correlated (must be <= NINPUTS_XGPU)

NINPUTS_XGPU

256 | n rfinputs in multiples of 16

mwax_db2correlate2db

Number 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 | 1

mwax_db2correlate2db

Should scalar path weights be applied prior to correlation (for gain normalisation and/or sub-arraying)

APPLY_PATH_DELAYS

0 | 1

mwax_db2correlate2db

Should fractional path delays be applied prior to correlation (for phasing up to a correlation pointing centre)

APPLY_PATH_PHASE_OFFSETS

0 | 1

mwax_db2correlate2db

Should path phase offsets be applied prior to correlation (for fringe-stopping, in conjunction with applying path delays)

APPLY_COARSE_DERIPPLE

0 | 1

mwax_db2correlate2db

Should coarse PFB channeliser de-ripple be applied within the F-stage, prior to cross-correlation within the F-stage, prior to cross-correlation (key/value pair not currently implemented)

DR_PARAM

NULL | deripplev1

mwax_db2correlate2db

If APPLY_COARSE_DERIPPLE==1 then this value tells db2correlate2db which deripple settings to use (key/value pair not currently implemented)

INT_TIME_MSEC

200 - 8000

mwax_db2correlate2db

mwax-db2fits

Correlator integration time (milliseconds)

FSCRUNCH_FACTOR

40 (1 - 6400)

mwax_db2correlate2db

mwax-db2fits

Correlator frequency scrunch factor: number of ultrafine 200 Hz fine channels to average together

APPLY_VIS_WEIGHTS

0 | 1

mwax_db2correlate2db

Should 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

G0008

mwax-db2fits

Project ID of observation

EXPOSURE_SECS

8 (in incremements of 8 seconds)

mwax-db2fits

Duration of observation in seconds

COARSE_CHANNEL

76 (0 - max receiver channel number == 255)

mwax-db2fits

Receiver channel number 

CORR_COARSE_CHANNEL

9 | (1 - coarse channel max)

mwax-db2fits

Correlator 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_SUBOBS

8

mwax_db2correlate2db

mwax-db2fits

Number of seconds per subobservation

UNIXTIME

1539235574

mwax-db2fits

Unix 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_MSEC

0 

mwax-db2fits

Unix 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

10000

mwax-db2fits

Correlator output fine channel width in Hz

NFINE_CHAN

128

mwax_db2correlate2db

mwax-db2fits

Correlator output number of fine channels

BANDWIDTH_HZ

1280000

mwax-db2fits

Coarse channel passband width in Hz, i.e. the channel spacing

SAMPLE_RATE

1280000

mwax_db2correlate2db

Actual sample rate of input data in samples/s (whether critically-sampled or oversampled).

MC_IP

0.0.0.0

mwax-db2fits

Multicast IP for this coarse channel (for debug purposes)

MC_PORT

0

mwax-db2fits

Multicast port for this coarse channel (for debug purposes)

MWAX_U2S_VER

X.Y.Z

mwax_db2fits

Version number of mwax_u2s used to capture the UDP packets for this subfile

MWAX_SUB_VER

1

mwax_u2s

Version number of subfile format. A value of 2 indicates the presence of the following fields:

IDX_PACKET_MAP

(OFFSET)+(SIZE)¹

mwax_u2s

Location and size of packet map in block 0 metadata0 metadata - note that the packetmap has been present in subfiles going back to some time in 2023, but the offsets have only been correct since u2s version 2.10 (rolled out ~ may 7 2024)

IDX_METAFITS

(OFFSET)+(SIZE)¹

mwax_u2s

0+0

deprecated/never implemented. Ignore if present. Location and size of copy of metafits file at time of the observation (the key/value pair exists but the metafits info is not currently written). This was dropped before we ever implemented the embedding, older subfiles may contain spurious entries.

IDX_DELAY_TABLE

(OFFSET)+(SIZE)¹

mwax_u2s

Location and size of delay table in block 0 metadata

IDX_MARGIN_DATA

(OFFSET)+(SIZE)¹

mwax_u2s

Location and size of margin data section in block 0 metadata

IDX_OCCUPANCY_TABLE

(OFFSET)+(SIZE)¹

mwax_u2s

Location and size of data occupancy table in block 0 metadata (this key/value pair is currently not implemented)