sigpyproc.io.pfits

sigpyproc.io.pfits#

PSRFITS header and data reading.

This module contains classes for reading PSRFITS headers and data.

Classes

`Backend`	Backend information.
`PFITSFile`	Handle a PSRFITS file.
`PrimaryHdr`	Primary header information.
`Receiver`	Receiver information.
`SubintHdr`	Sub-integration header information.

class sigpyproc.io.pfits.Backend(*, name, phase, dcc, delay, tcycle, configfile)[source]#

Bases: object

Backend information.

Attributes:

namestr: Name of the backend instrument.
phase: float: Phase convention of backend.
dcc: float: Downconversion conjugation corrected.
delay: float: Backend propn delay from digi. input.
tcycle: float: Native cycle time of correlation system.
configfile: str: Name of a configuration file used to set up the backend system.

name#

phase#

dcc#

delay#

tcycle#

configfile#

class sigpyproc.io.pfits.PFITSFile(filename)[source]#

Bases: object

Handle a PSRFITS file.

Parameters:

filenamestr: Filename of the PSRFITS file.

Attributes:

filename: Name of file.
pri_hdr: Primary header object.
sub_hdr: Sub-integration header object.
bitsinfo: Bits information object.

Methods

`read_freqs`(isub)	Read the Channel centre frequency from the PSRFITS SUBINT table.
`read_offsets`(isub)	Read channel data offset (DAT_OFFS) column from the SUBINT table.
`read_scales`(isub)	Read channel data scale factor (DAT_SCL) column from the SUBINT table.
`read_subint`(isub, *[, scloffs, weights])	Read the digitised data from the PSRFITS SUBINT table.
`read_subint_pol`(isub, *[, poln_select, ...])	Read the given polarization format from the PSRFITS SUBINT table.
`read_subints`(startsub, nsubs, *[, ...])	Read the given polarization format from a range of PSRFITS SUBINT table.
`read_weights`(isub)	Read channel weight (DAT_WTS) column from the SUBINT table.

property filename#

Name of file.

Returns:

str: Filename of the PSRFITS file.

property pri_hdr#

Primary header object.

Returns:

PrimaryHdr: Primary header.

property sub_hdr#

Sub-integration header object.

Returns:

SubintHdr: Subint header.

property bitsinfo#

Bits information object.

Returns:

BitsInfo: Bits information.

read_subints(startsub, nsubs, *, poln_select=1, scloffs=True, weights=True)[source]#

Read the given polarization format from a range of PSRFITS SUBINT table.

Parameters:

startsubint: Index of start row (subint) to read from the SUBINT table.
nsubsint: Number of subints to read from the SUBINT table.
poln_selectint, optional: 1=PP+QQ, 2=PP,QQ, 3=(PP+QQ)^2 4=PP,QQ,PQ,QP, by default 1.
scloffsbool, optional: Apply scales and offsets when unpacking data, by default False.
weightsbool, optional: Apply weights when unpacking data, by default False.

Returns:

ndarray: Subint (row) data in float32 if scloffs or weights applied, otherwise in uint8 with shape (nsamps, nchan).

read_subint_pol(isub, *, poln_select=1, scloffs=True, weights=True)[source]#

Read the given polarization format from the PSRFITS SUBINT table.

Parameters:

isubint

Index of row (subint) to read from the SUBINT table.

poln_selectint, optional

Polarization index to select, by default 1.

Available options:

1=PP+QQ
2=PP,QQ
3=(PP+QQ)^2
4=PP,QQ,PQ,QP

scloffsbool, optional

Apply scales and offsets when unpacking data, by default True

weightsbool, optional

Apply weights when unpacking data, by default True

Returns:

ndarray: Subint (row) data in float32 if scloffs or weights applied, otherwise in uint8 with shape (nsamps, nchan).

read_subint(isub, *, scloffs=True, weights=True)[source]#

Read the digitised data from the PSRFITS SUBINT table.

Parameters:

isubint: Index of row (subint) to read from the SUBINT table.
scloffsbool, optional: Apply scales and offsets when unpacking data, by default True.
weightsbool, optional: Apply weights when unpacking data, by default True.

Returns:

ndarray: Subint (row) data in float32 if scale_and_offset or weights applied, otherwise in uint8 with shape (nsamps, npol, nchan).

read_freqs(isub)[source]#

Read the Channel centre frequency from the PSRFITS SUBINT table.

Parameters:

isubint: Index of row (subint) to read from the SUBINT table.

Returns:

FrequencyChannels: Centre frequency for each channel in MHz (NCHAN).

read_weights(isub)[source]#

Read channel weight (DAT_WTS) column from the SUBINT table.

Parameters:

isubint: Index of row (subint) to read from the SUBINT table,

Returns:

ndarray: Weights for each channel in the range 0-1 (NCHAN).

read_scales(isub)[source]#

Read channel data scale factor (DAT_SCL) column from the SUBINT table.

Parameters:

isubint: Index of row (subint) to read from the SUBINT table.

Returns:

ndarray: Data scale factor for each channel (NCHAN * NPOL).

read_offsets(isub)[source]#

Read channel data offset (DAT_OFFS) column from the SUBINT table.

Parameters:

isubint: Index of row (subint) to read from the SUBINT table.

Returns:

ndarray: Data offset for each channel (NCHAN * NPOL).

class sigpyproc.io.pfits.PrimaryHdr(filename)[source]#

Bases: object

Primary header information.

Parameters:

filenamestr: Filename of the PSRFITS file.

Attributes:

header: astropy.io.fits.Header: Primary header.
observer: str: Observer name(s).
project_id: str: Project name.
telescope: str: Telescope name.
location: astropy.coordinates.EarthLocation: Antenna location.
receiver: Receiver: Receiver information.
backend: Backend: Backend information.
ibeam: int: Beam number.
obs_mode: str: Observation mode.
date_obs: astropy.time.Time: Observation start date.
freqs: FrequencyChannels: Frequency channels.
chan_dm: float: On-line (normally coherent) dedispersion measure.
source: str: Source name or label for an observation.
coord: astropy.coordinates.SkyCoord: Source coordinates.
tstart: astropy.time.Time: Observation start time.

property header#: astropy.io.fits.Header: Primary header.

property observer#: str: Observer name(s).

property project_id#: str: Project name.

property telescope#: str: Telescope name.

property location#: astropy.coordinates.EarthLocation: Antenna location.

property receiver#: Receiver: Receiver information.

property backend#: Backend: Backend information.

property ibeam#: int: Beam number.

property obs_mode#: str: Observation mode.

property date_obs#: astropy.time.Time: Observation start date.

property freqs#: FrequencyChannels: Frequency channels.

property chan_dm#: float: On-line (normally coherent) dedispersion measure.

property source#: str: Source name or label for an observation.

property coord#: astropy.coordinates.SkyCoord: Source coordinates.

property tstart#: astropy.time.Time: Observation start time.

class sigpyproc.io.pfits.Receiver(*, name, nrcvr, basis, hand, sa, rph, tracking_mode, tracking_angle)[source]#

Bases: object

Receiver information.

Attributes:

namestr: Name of the receiver.
nrcvrint: Number of receptors.
basisstr: Basis of receptors.
hand: int: Hand of receptor basis.
sa: float: Symmetry angle of receptor basis.
rph: float: Reference source phase.
tracking_mode: str: Tracking mode of the receiver platform.
tracking_angle: float: Position angle tracked by the receiver.

name#

nrcvr#

basis#

hand#

sa#

rph#

tracking_mode#

tracking_angle#

class sigpyproc.io.pfits.SubintHdr(filename)[source]#

Bases: object

Sub-integration header information.

Parameters:

filenamestr: Filename of the PSRFITS file.

Attributes:

header: astropy.io.fits.Header: SUBINT header.
subint_width: int: Width of subint table in bytes.
nsubint: int: Number of rows (subints) in subint table.
poln_type: str: Polarisation identifier (e.g., AABBCRCI, AA+BB).
poln_state: str: Polarisation state (e.g., Coherence).
npol: int: Number of polarisation products in the DATA table.
tsamp: float: Time per bin or sample (seconds).
nbits: int: Number of bits per sample.
zero_off: float: Zero offset for data (the nominal data zero in digitiser units).
signint: int: Flag to indicate that the data values are signed integers.
subint_offset: int: Subint offset for contiguous SEARCH-mode files.
nchans: int: Number of frequency channels for each polarisation in the DATA table.
chan_bw: float: Channel bandwidth in MHz.
channel_offset: int: Channel offset for contiguous SEARCH-mode files.
subint_samples: int: Number of samples per subint or table row.
nsamples: int: Total number of valid samples in a search-mode file.
subint_shape
sub_hdr
tsubint: float: Time per subint or table row (seconds).
offs_sub: float: Time since the observation start at the centre of first subint (s).
azimuth: astropy.coordinates.Angle: Azimuth (degrees).
zenith: astropy.coordinates.Angle: Zenith (degrees).
freqs: sigpyproc.utils.FrequencyChannels: Frequency channels for first subint.

property header#: astropy.io.fits.Header: SUBINT header.

property subint_width#: int: Width of subint table in bytes.

property nsubint#: int: Number of rows (subints) in subint table.

property poln_type#: str: Polarisation identifier (e.g., AABBCRCI, AA+BB).

property poln_state#: str: Polarisation state (e.g., Coherence).

property npol#: int: Number of polarisation products in the DATA table.

property tsamp#: float: Time per bin or sample (seconds).

property nbits#: int: Number of bits per sample.

property zero_off#: float: Zero offset for data (the nominal data zero in digitiser units).

property signint#: int: Flag to indicate that the data values are signed integers.

property subint_offset#: int: Subint offset for contiguous SEARCH-mode files.

property nchans#: int: Number of frequency channels for each polarisation in the DATA table.

property chan_bw#: float: Channel bandwidth in MHz.

property channel_offset#: int: Channel offset for contiguous SEARCH-mode files.

property subint_samples#: int: Number of samples per subint or table row.

property nsamples#: int: Total number of valid samples in a search-mode file.

property subint_shape#

property sub_hdr#

property tsubint#: float: Time per subint or table row (seconds).

property offs_sub#: float: Time since the observation start at the centre of first subint (s).

property azimuth#: astropy.coordinates.Angle: Azimuth (degrees).

property zenith#: astropy.coordinates.Angle: Zenith (degrees).

property freqs#: sigpyproc.utils.FrequencyChannels: Frequency channels for first subint.

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