TimeDelay

class baseband_tasks.sampling.TimeDelay(ih, delay, *, lo, frequency=None, sideband=None)

Bases: TaskBase

Delay a stream by a given amount, taking care of phase rotations.

The delay is added to the sample times (by adding to the start_time of the stream), and the sample phases are rotated as needed if the signal was recorded after mixing with a local oscillator. For an upper sideband, the phases are rotated by

\[\phi = - \tau f_{lo}.\]

For the lower sideband, the rotation is in the opposite direction.

Note that the input data stream must be complex. For real-valued streams, use ShiftAndResample with shift as the delay, no offset, and pad=0 (this works for complex data as well, but is slower as it involves fourier transforms).

Parameters:

ihtask or baseband stream reader

Input data stream, with time as the first axis.

delayfloat, Quantity

Delay to apply to all times. Can be (float) samples, or a quantity with units of time.

loQuantity, or None

Local oscillator frequency. For raw data, this can just be if.frequency. But for channelized data, the actual frequency needs to be passed in. If data were recorded without mixing (like for CHIME), pass in None.

frequencyQuantity, optional

Frequencies for each channel. Should be broadcastable to the sample shape. By default, taken from the underlying stream. (Note that these frequencies are not used in the calculations here.)

sidebandarray, optional

Whether frequencies are upper (+1) or lower (-1) sideband. Should be broadcastable to the sample shape. By default, taken from the underlying stream. Assumed to be correct for the lo.

See also

ShiftAndResample

also resample a stream, or delay a real-valued stream

baseband_tasks.base.SetAttribute

change start time without phase delay

Methods Summary

task(data)

Methods Documentation

task(data)