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FFT Operator

Overview

A thin wrapper over the MatX fft() executor.

Description

The FFT operator takes in a tensor of complex float data, performs an FFT, and emits the resultant tensor.

Requirements

Example Usage

For an example of how to use this operator, see the psd_pipeline application.

Multiple Channels

The zero-indexed channel_number key will be looked up in metadata() on each compute() run. If no value is found, the default channel number is 0.

Configuration

The FFT operator takes in a few parameters:

fft:
  burst_size: 1280
  num_bursts: 625
  num_channels: 1
  spectrum_type: 1
  averaging_type: 1
  window_time: 0
  window_type: 0
  transform_points: 1280
  window_points: 1280
  resolution: 6250
  span: 8000000
  weighting_factor: 0
  f1_index: -640
  f2_index: 639
  window_time_delta: 0

The only parameters that actually impacts FFT computation at this point are the burst_size and num_bursts params. The rest of the parameters are simply passed along in the metadata.

  • burst_size: Number of samples to process in each burst
  • num_bursts: Number of bursts to process at once
  • num_channels: Number of channels for which to allocate memory
  • spectrum_type: VITA 49.2 spectrum type to pass along in metadata
  • spectrum_type: VITA 49.2 spectrum type to pass along in metadata
  • averaging_type: VITA 49.2 averaging type to pass along in metadata
  • window_time: VITA 49.2 window time to pass along in metadata
  • window_type: VITA 49.2 window type to pass along in metadata
  • transform_points: Number of FFT points to take and VITA 49.2 transform points to pass along in metadata
  • window_points: VITA 49.2 window points to pass along in metadata
  • resolution: VITA 49.2 resolution to pass along in metadata
  • span: VITA 49.2 span to pass along in metadata
  • weighting_factor: VITA 49.2 weighting factor to pass along in metadata
  • f1_index: VITA 49.2 F1 index to pass along in metadata
  • f2_index: VITA 49.2 F2 index to pass along in metadata
  • window_time_delta: VITA 49.2 window time delta to pass along in metadata