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Thread: Teensy 4 to make an aid to tune 455 khz if's at work?

  1. #1
    Senior Member
    Join Date
    May 2015

    Teensy 4 to make an aid to tune 455 khz if's at work?

    Would it be practical to try to use a Teensy 4 fft to display +/- 50khz and 20khz around a center of 455 khz as an aid to peak and center if? I could really use that at work. They are too cheap to buy a spectrum analyzer. Heck the scope I have to use is an old tube one with 20mhz bandwidth. I know I would have to amplify the signal. I think its only about 10 mv peak to peak but could be 100. I can't remember which right now.

  2. #2
    Senior Member DD4WH's Avatar
    Join Date
    Oct 2015
    Central Europe
    How would you sample the IF? With a 1MSPS ADC? Does the Teensy 4.0 ADC support a sample rate of 1 MHz ? I do not know. If yes, how would you proceed? You would have to decimate the signal (perhaps with CIC decimation filters) and process the samples at a much lower internal sample rate. Otherwise even the T4 (which is not SO much faster than the T3.6!) would not be able to process your samples in time.

    Alternatively you could use an analog local oscillator with 445kHz and an analog mixer and sample the (455kHz - 445kHz) = 10kHz signal with audio sample rate (44.1 or 48kHz), that would be more feasible. But that would be a really huge effort with analog circuitry . . .

    So, all depends on your goals.

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