I do a lot of work with DSP and I am looking for an inexpensive down converter so as to down convert from the FM band to some intermediate frequency. Not necessarily to standard FM 10.7MHz but something lower that I can choose. The reason that I want to do this is that I want to be able to "grab' up to 4 FM "stations" at a time and do the discriminators in DSP using something called a polyphase channelizer, after A/D conversion, which I have done in simulation. Yea, I know that there might not be 4 active FM stations within 200KHz of each other but I'll deal with that problem later.

I thought of using the RF front end to the venerable RTL-SDK, just taking the output of the E4000 RF IC bypassing the decoder but that part has a limited bandwidth. I am not sure if there is too much roll-off past the original FM station that it is tuned to.

The bottom line question is, is there a SDR that has an RF front end that I could use to down convert a group of FM stations? I did not want to go off half cocked before asking the experts. Perhaps there is a commercial unit available that has an IF out with a wide bandwidth? I suppose that I could get out my ARRL Radio Handbook and build one myself but I want to see what I can start with.

Thank You Tom

  • $\begingroup$ LimeSDR Mini can capture a bandwidth of over 10 MHz. SDRPlay can capture around 6 MHz of bandwidth. Both in the VHF range. Neither inexpensive. $\endgroup$
    – hotpaw2
    Apr 16, 2022 at 16:45

1 Answer 1


More or less any of them, I'd say. RTL-SDRs usually work with 2MHz of bandwidth, and that limitation has more to do with the ADC than the tuner. Many other SDR receivers are capable of 10MHz slices or more.

  • $\begingroup$ True, as long as the host computer can manage the sample rate. $\endgroup$
    – user21417
    Apr 15, 2022 at 16:05

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