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TODO.md

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Simulation Results

  • Comparison of runtime vs num channels with the folllowing three things:
    • cyclo and OS (without combined FFT)
    • cyclo and OS (with combined FFT)
    • cyclo and polyphase
    • Note that I need to decide how to compare - should the WB sample rate always be the same? Probably
    • Modify so SCD estimate is computed for the entire spectrum
  • Allow analysis channelizer to operate at a higher rate so there are no disallowed frequencies
  • Runtime analysis
    • Function for running with arbitrary number of radnomly placed channels
    • Function for monte carlo test of channelizers
    • Use MATLAB profiler on channelizers
      • Polyphase
      • Overlap-save
    • Run tests on a range of numbers of signals
      • generate plots of runtime vs number of channels
      • generate plots for various output baud rates, choose sample rate so that decimation is not a nice FFT size (not multiple of 2 or 5) for comparison
    • Run in parallel on server
    • Make cyclo/overlap-save FFT size a config parameter
  • NMDFB
    • Get it working!!
    • Match input/outputs for synthesis/analysis for any size
    • Get entire polyphase channelizer working end-to-end
    • Figure out magnitude difference

Core Goals

  • Try to use cyclo detect FFT for channelizer
  • Figure out simple channelizer
    • Figure out why channels are offset by half channel spacing
      • Because thats how the channelizer works - valid frequencies are integer multiples of the output sample rate (since we rely on aliasing for tuning)
    • Fix channelized output first and second halves being switched
  • Create simple synthesis channelizer for recombining adjacent channels
    • Create synthesis channelizer test
    • Perfect reconstruction filter?
  • Try to do cyclo detect with only one FFT (by aligning baud and fft spacing)
  • Average cyclo detects over time
  • Rolloff filter faster? Why are we getting aliasing from neighboring channels
    • Seems like filter is sharp enough... tried just filtering a single channel and downsampling and everything was fine
    • Definitely related to the goofy sidebands we get in "test_synthesis_chan"... If I can figure that out I think we're golden
    • Problem was caused by synthesis channelizer input commutator running in the wrong direction - resolved now
  • Polish cyclo
    • Compute multiple cyclic spectra to search for frequencies with specific baud rates
    • Use a single FFT for each baud
  • Create function for generating WB file given a list of freqs/bauds/modulations
    • List of freqs
    • List of modulations
    • Allow empty channels
  • Fix noise power calculation
  • Move parameters to a configuration file
    • List of freqs/bauds/modulations for WB
    • List of bauds for cyclo detect
    • Sample rate/upsample
    • RC rolloff
  • direct analysis/synthesis channelizer with cyclo detects
  • Create overlap-save filter bank
    • Make os filter bank work for N channels
    • allow frequency shifting in EITHER time or frequency
      • When we do shifting in time we can relax the requirement for ldf(P, fft_size)
  • Polyphase todo
    • Get channel input/output straight for synthesis/analysis channelizers (output from one should be able to go directly to the other)
    • Return a cell array
    • Create combination synthesis/analysis channelizer
    • Get scaling consistent for various size of synthesis
    • Allow analysis channelizer to operate at a higher rate so there are no disallowed frequencies
  • Combine OS and cyclo_detect
  • README and document critical code

Figures To Generate

  • Full SCD plot
  • SCD estimates at specific baud rates for WB signal
  • Output channels for OS filter bank
  • Output channels for polyphase channelizer

Extras

  • Speed up packetization if I still need it
  • Cache generated filters so we dont have to regenerate
  • Compute graphs of Pd vs Pfa vs SNR empirically
  • Experiment with morphological filter for peak extraction