Mark5BStreamWriter

class baseband.mark5b.base.Mark5BStreamWriter(fh_raw, header0=None, sample_rate=None, nchan=1, bps=2, squeeze=True, **kwargs)

Bases: baseband.mark5b.base.Mark5BStreamBase, baseband.vlbi_base.base.VLBIStreamWriterBase

VLBI Mark 5B format writer.

Encodes and writes sequences of samples to file.

Parameters:

fh_raw : filehandle

For writing filled sets of frames to storage.

header0 : Mark5BHeader

Header for the first frame, holding time information, etc. Can instead give keyword arguments to construct a header (see **kwargs).

sample_rate : Quantity

Number of complete samples per second, i.e. the rate at which each channel is sampled. Needed to calculate header timestamps.

nchan : int, optional

Number of channels. Default: 1.

bps : int, optional

Bits per elementary sample. Default: 2.

squeeze : bool, optional

If True (default), write accepts squeezed arrays as input, and adds any dimensions of length unity.

**kwargs

If no header is given, an attempt is made to construct one from these. For a standard header, the following suffices.

— Header kwargs : (see fromvalues())

time : Time

Start time of the file. Sets bcd-encoded unit day, hour, minute, second, and fraction, as well as the frame number, in the header.

Attributes Summary

bps	Bits per elementary sample.
complex_data	Whether the data are complex.
header0	First header of the file.
sample_rate	Number of complete samples per second.
sample_shape	Shape of a complete sample (possibly subset or squeezed).
samples_per_frame	Number of complete samples per frame.
squeeze	Whether data arrays have dimensions with length unity removed.
start_time	Start time of the file.
subset	Specific components of the complete sample to decode.
time	Time of the sample pointer’s current offset in file.
verify	Whether to do consistency checks on frames being read.

Methods Summary

close()
tell([unit])	Current offset in the file.
write(data[, valid])	Write data, buffering by frames as needed.

Attributes Documentation

bps

Bits per elementary sample.

complex_data

Whether the data are complex.

header0

First header of the file.

sample_rate

Number of complete samples per second.

sample_shape

Shape of a complete sample (possibly subset or squeezed).

samples_per_frame

Number of complete samples per frame.

squeeze

Whether data arrays have dimensions with length unity removed.

If True, data read out has such dimensions removed, and data passed in for writing has them inserted.

start_time

Start time of the file.

See also time for the time of the sample pointer’s current offset, and (if available) stop_time for the time at the end of the file.

subset

Specific components of the complete sample to decode.

The order of dimensions is the same as for sample_shape. Set by the class initializer.

time

Time of the sample pointer’s current offset in file.

See also start_time for the start time, and (if available) stop_time for the end time, of the file.

verify

Whether to do consistency checks on frames being read.

Methods Documentation

close()

tell(unit=None)

Current offset in the file.

Parameters:

unit : Unit or str, optional

Time unit the offset should be returned in. By default, no unit is used, i.e., an integer enumerating samples is returned. For the special string ‘time’, the absolute time is calculated.

Returns:

offset : int, Quantity, or Time

Offset in current file (or time at current position).

write(data, valid=True)

Write data, buffering by frames as needed.

Parameters:

data : ndarray

Piece of data to be written, with sample dimensions as given by sample_shape. This should be properly scaled to make best use of the dynamic range delivered by the encoding.

valid : bool, optional

Whether the current data are valid. Default: True.