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vhf sig gen?

Discussion in 'd.i.y.' started by Jim Audiomisc, Jan 26, 2019.

  1. MJS

    MJS Trade: Consultant at WH Audio

    My output was distorted. But that's because I probably haven't tweaked the SDR settings yet. I'll test further.

    I had a play at decoding the mpx wav in gnuradio yesterday. I got a valid signal out of that and it also works with a cheap rtl dongle for off-air reception. I was using a 38kHz carrier re-insertion oscillator to get the baseband stereo difference back. That was made from a notch filtered 19kHz pilot tone driving a PLL and then multiplied by itself to get 38k.
  2. MJS

    MJS Trade: Consultant at WH Audio

  3. MJS

    MJS Trade: Consultant at WH Audio

    I got the LimeSDR transmitting the MPX signal acceptably. I was able to receive it through another dongle in stereo. Good so far. I was then able to recreate a multiplexer from scratch and feed it stereo audio and receive in stereo. I'm happy so far but it doesn't fulfil Jim's brief, rather I've been seeing what's possible.

    Looking for cheap and cheerful VHF generators have a look at the following:
    BA1404, BH1415/6/7 and modules from ebay are complete FM stereo transmitters but can run with separate MPX in and out.
    MAX2606 VHF VCO can be turned into an FM Tx, e.g. https://www.ebay.co.uk/itm/MAX2606-...h=item4d82152bac:g:CsgAAOSwWSlb9TRj:rk:6:pf:0
  4. Jim Audiomisc

    Jim Audiomisc pfm Member

    My problem is that I avoid eBay and Amazon! So I'd try to use someone like CPC or contact the vendor bypassing eBay.

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