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  1. Thread: Fft256

    by Bazz
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    4,538

    KPC I've checked with my 'scope that data is...

    KPC

    I've checked with my 'scope that data is present on the line-in pins of the audio board and have tried varying the amplitude but kept it below 1v. I've tried simply connecting the audio board...
  2. Thread: Fft256

    by Bazz
    Replies
    22
    Views
    4,538

    FFT256 with IQ input data

    Paul, kpc

    I have been trying to get the FFT256IQ code running with the 2.8" TFT and real data coming into the line-in stereo pins.

    kpc's code runs properly with synthetic data generated inside...
  3. Thread: Fft256

    by Bazz
    Replies
    22
    Views
    4,538

    Paul, KPC Many thanks for all your help. The...

    Paul, KPC

    Many thanks for all your help. The code now compiles and gives sensible looking answers.
    My next step is to add the Teensy 2.8" TFT display.

    Bazz
  4. Thread: Fft256

    by Bazz
    Replies
    22
    Views
    4,538

    FFT256 with IQ input data

    kpc

    I've tried running your sketch but hit two problems.

    Firstly, I had to make a slight change to the .h file to include a reference to prevblock_i and prevblock_q



    class...
  5. Thread: Fft256

    by Bazz
    Replies
    22
    Views
    4,538

    FFT256 with IQ input data

    kpc

    Just checked my bit-wise boolean algebra again and realised that the spectrum swapping can be done in one statement, as you suggested! Well at least I'm learning!




    // swap spectrum...
  6. Thread: Fft256

    by Bazz
    Replies
    22
    Views
    4,538

    FFT256 with IQ input data

    kpc

    I've now modified the .cpp file to swap the positive and negative halves of the frequency spectrum.



    /* Audio Library for Teensy 3.X
    * Copyright (c) 2014, Paul Stoffregen,...
  7. Thread: Fft256

    by Bazz
    Replies
    22
    Views
    4,538

    kpc Once again, many thanks for your really...

    kpc

    Once again, many thanks for your really helpful reply. Hopefully, I'll try this tonight and report back

    Bazz
  8. Thread: Fft256

    by Bazz
    Replies
    22
    Views
    4,538

    FFT256 with IQ input data

    kpc

    Many thanks for your comments. I've had a go at changing the code as you suggest but I'm sure there are many mistakes/omissions in my efforts!

    .h code is below


    /* Audio Library for...
  9. Thread: Fft256

    by Bazz
    Replies
    22
    Views
    4,538

    Many thanks for the revised code snippets. I've...

    Many thanks for the revised code snippets. I've put these into the .h and .cpp files and will try this out later this evening.

    The I and Q data from the radio receiver front end already has the...
  10. Thread: Fft256

    by Bazz
    Replies
    22
    Views
    4,538

    Fft256

    Paul

    Many thanks for the quick reply.

    For a SDR application, the two input signals from the receiver (I and Q) have a phase difference of 90 degs. Hence it's essential that the input data to...
  11. Thread: Fft256

    by Bazz
    Replies
    22
    Views
    4,538

    Fft256

    I'm wanting to use the FFT256 (or FFT1024) code to display the spectrum of a waveform which has been sampled by the Teensy audio board. Am I correct in thinking that FFT256 only accepts data from a...
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