trasal/dadatrigger

psrdada ringbuffer setup for triggering events and dumping to disc

Dadatrigger

This code is written for the AA-Alert project. (c) 2017 Jisk Attema, Netherlands eScience Center, ASTRON

Based on the PSRdada software.

Initial version of data flow pipeline

This is a work in progress; see the start.sh script. Documentation and instructions coming soon(ish).

DADA header information

Meta data for the generated output is taken from various locations:

• the FITS file templates
• commandline arguemnts
• DADA header blocks

The start.sh script should get most values from the system (via QPID?), generates the necessary dada headers, and passes commandline arguments.

The table below describes the required keys in the DADA headerblock:

DADA header key	used by	standard name (QPID?)	description	Units
NCHAN	filterbank, amber	NCHANNELS	Number of frequency channels	1
MIN_FREQUENCY	filterbank, fits, amber		Lowest frequency
CHANNEL_BANDWIDTH	filterbank, fits, amber		Bandwidth per channel
BW	filterbank		Total bandwidth
TSAMP	filterbank, amber			s
RA	filterbank
DEC	filterbank
SOURCE	filterbank		Name of the source	-
AZ_START	filterbank
ZA_START	filterbank
MJD_START	filterbank
NBIT	filterbank			1
FILE_SIZE	dbdisk		Expected final file size (?)	bytes
SAMPLES_PER_BATCH	amber		Normally 12500 or 25000	1
UTC_START	dbevent, dbdisk		Start of the observation	%Y-%m-%d-%H:%M:%S (UTC)
RESOLUTION	dbevent		Page size (events are an integer mulitple of this)	bytes
BYTES_PER_SECOND	dbevent		Data rate	bytes

TODO:

• MIN_FREQUENCY, CHANNEL_BANDWIDTH, NCHAN, TSAMP, NBIT are all constant per experiment (ie. defined as part of the science case and mode). Having them as a parameter here is confusing, because changing it here will at most crash the codes; it will not do what you want.
• Link stuff to QPID
• Are we missing keys?

dadatrigger's Issues

Mapping between keys in README and keys in the interface doc

I took the table from the README from this repo and tried mapping the keys for the start_observation command from table 1 in the Interface Specification from MAC to SC3+4. Looks like there is some difference between the two. Since Markdown pasting in Slack doesn't work, I just put it in an issue over here. I don't really mind where we discuss it further, as long as we are consistent in doing so :).

Interface fields in bold are implemented by APERTIF but do not appear in the interface document.

DADA header key	Interface Field	Type	Qpid	cfg
NCHAN	arts.survey.nrChannels	int
MIN_FREQUENCY	arts.survey.frequencyChannel0	float
CHANNEL_BANDWIDTH	arts.survey.channelBandwidth	float
BW
TSAMP
RA	task.beamSet.0.compoundBeam.X.phaseCenter [0]	float
DEC	task.beamSet.0.compoundBeam.X.phaseCenter [1]	float
SOURCE	task.source.name	str	X
AZ_START
ZA_START
MJD_START
NBIT
FILE_SIZE
SAMPLES_PER_BATCH
UTC_START	task.startTime
RESOLUTION
BYTES_PER_SECOND
	task.taskID	str	X
(N/A)	arts.survey.mode	str	X
	arts.survey.zappedChannels	int []
	arts.survey.nrChunks	int
	arts.survey.nrSamplesPerChunk	int
	arts.survey.DMs	float []
	arts.survey.integrationSteps	int []
	arts.survey.threshold	float