Read utilties for CHIME/FRB Open Data Release.

pip install cfod

Note: Currently only Python 2.7 is supported.

To read a single data file from the data release,

from cfod import chime_intensity as ci
fn = `astro_5941664_20180406203904337770_beam0147_00245439_02.msgpack`
intensity, weights, fpga0, fpgaN, binning, frame0_nano, nrfifreq, rfi_mask = ci.unpack_data(fn)

where:

• intensity is a 2D Intensity array.
• weights are the corresponding 2D array weights to the intensity array.
• fpga0 (int) is start fpga count of the data chunk. (Internally used to track time, can be ignored). The fpga count increments at the rate of 2.56us.
• fpgaN (int) is number of fpga counts in the data chunk read
• binning (int) is the downsampling of the data from the ringbuffer
• frame0_nano is the conversion from fpga timestamp to utc timestamp (Currently not supported.)
• nrfifreq is the number of frequences masked by the realtime rfi system (Currently not supported.)
• rfi_mask is currently not supported

To read multiple data files at once, you can use the following command,

from cfod import chime_intensity as ci
fns = ['file1', 'file2', 'file3']
intensity, weights, fpga0s, fpgaNs, binning, rfi_mask, frame0_nanos = ci.unpack_datafiles(fns)

To convert .msgpack files into filterbank .fil format you can run msgpack2fil from the command line (scripts are installed through pip). You need to provide a pathname wildcard in quotation marks. To see all command line options run help:

msgpack2fil --help

CHIME/FRB data has 16384 frequency channels but PRESTO and sigproc by default allocate memory for only a maximum of 4096 channels. You would need to update reader.h and header.h in sigproc and recompile before trying to read a 16384 filterbank file, or you can let msgpack2fil subband data by at least a factor 4 (using the --fscrunch argument). Make sure to provide a DM for subband dedispersion (using the --subdm argument) to mitigate subband smearing.

pip uninstall cfod