pulsarbat.DualPolarizationSignal#

class pulsarbat.DualPolarizationSignal(z, /, *, sample_rate, start_time=None, center_freq, freq_align='center', pol_type, meta=None)[source]#

Class for dual-polarization complex baseband signals.

See the documentation for RadioSignal and BasebandSignal for more details.

Parameters:

zarray-like: The signal data. Must be at least 3-dimensional with shape (nsample, nchan, npol, ...) where npol = 2.
sample_rateQuantity: The number of samples per second. Must be in units of frequency.
start_timeTime, optional: The start time of the signal (that is, the time at the first sample of the signal). Default is None.
center_freqQuantity: The frequency at the center of the signal’s band. Must be in units of frequency.
freq_align{‘bottom’, ‘center’, ‘top’}, default: ‘center’: The alignment of channels relative to the center_freq. Default is ‘center’ (as with odd-length complex DFTs). ‘bottom’ and ‘top’ only have an effect when nchan is even.
pol_type{‘linear’, ‘circular’}: The polarization type of the signal. ‘linear’ for linearly polarized signals (with basis [X, Y]) or ‘circular’ for circularly polarized signals (with basis [L, R]).
metadict, optional: Any metadata that the user might want to attach to the signal.

See also

Signal
RadioSignal
BasebandSignal

Notes

Linear polarization is assumed to have basis [X, Y] and circular polarization is assumed to have basis [L, R]. For example, with pol_type='circular', z[:, :, 0] refers to the right-handed circular polarization component.

We use the PSR/IEEE convention. The circular and linear bases are related by:

L = X - i Y
R = X + i Y

The linear basis is converted to Stokes representation by:

I = X X* + Y Y*
Q = X X* - Y Y*
U = 2 Re(X* Y)
V = 2 Im(X* Y)

where * denotes a complex conjugate.

Attributes

`axes_labels`	Dictionary of axes labels.
`bandwidth`	Total bandwidth.
`center_freq`	Center frequency.
`chan_bw`	Channel bandwidth.
`channel_freqs`	Center frequencies of all channels.
`data`	The signal data.
`dt`	Sample spacing of the signal (`1 / sample_rate`).
`dtype`	Data type of the signal.
`freq_align`	Alignment of channel frequencies.
`max_freq`	Frequency at top of the band.
`meta`	Signal metadata.
`min_freq`	Frequency at bottom of the band.
`nchan`	Number of frequency channels.
`ndim`	Number of dimensions in data.
`pol_type`	Polarization type (linear or circular).
`sample_rate`	Sample rate of the signal.
`sample_shape`	Shape of a sample.
`shape`	Shape of the signal.
`start_time`	Start time of the signal (Time at first sample).
`stop_time`	Stop time of the signal (Time at sample after the last sample).
`time_length`	Length of signal in time units.

Methods

`compute`(**kwargs)	Returns signal with computed data.
`contains`(t, /)	Whether time(s) are within the bounds of the signal.
`get_axis`(axis)	Axis number from an integer or axis label.
`like`(obj[, z])	Returns a signal object "like" given signal object.
`persist`(**kwargs)	Returns signal with data persisted in memory.
`rechunk`([chunks])	Rechunks signal data if stored as a Dask array.
`to_circular`()	Converts the dual-polarization signal to circular basis.
`to_dask_array`()	Returns signal with data as a Dask array.
`to_intensity`()	Absolute square of signal.
`to_linear`()	Converts the dual-polarization signal to linear basis.
`to_stokes`()	Converts signal to IQUV Stokes representation.

compute(**kwargs)#

Returns signal with computed data.

Has no effect unless data is stored as a Dask Array. kwargs are passed on to the dask.compute() function.

contains(t, /)#: Whether time(s) are within the bounds of the signal.

get_axis(axis)#: Axis number from an integer or axis label.

classmethod like(obj, z=None, /, **kwargs)#

Returns a signal object “like” given signal object.

This classmethod inspects the class signature and creates a signal object like the given reference object. The signal data (as an array) must always be provided as well as any other arguments that are intended to be different than the reference object. All arguments required by the class signature that are not provided are acquired from attributes of the same name in the reference object.

Parameters:

objSignal: The reference signal object.
zarray-like: The signal data.
**kwargs: Additional keyword arguments to pass on to the target class.

persist(**kwargs)#

Returns signal with data persisted in memory.

Has no effect unless data is stored as a Dask Array. kwargs are passed on to the dask.persist() function.

rechunk(chunks=None, **kwargs)#

Rechunks signal data if stored as a Dask array.

If the underlying data is not a Dask array, it is converted to one first. By default, there is no chunking along the first dimension and other dimensions are automatically chunked based on the default chunk size set in Dask’s configuration. kwargs are passed along to dask.array.rechunk().

to_circular()[source]#

Converts the dual-polarization signal to circular basis.

If polarization basis is already circular, simply returns a copy of the signal object.

Returns:

DualPolarizationSignal

to_dask_array()#

Returns signal with data as a Dask array.

Uses dask.array.asanyarray() to convert signal data to a Dask array.

to_intensity()#

Absolute square of signal.

Returns:

IntensitySignal

to_linear()[source]#

Converts the dual-polarization signal to linear basis.

If polarization basis is already linear, simply returns a copy of the signal object.

Returns:

DualPolarizationSignal

to_stokes()[source]#

Converts signal to IQUV Stokes representation.

Returns:

FullStokesSignal