Feature request: LOWER FFT resolution options in SDR#

Bob Dengler

I'm using the SNR logger to log peak power of NBFM stations using an Airspy Mini. However, the peak power is derived from the FFT spectrum, not the total channel power. This is fine for CW signals, but when there is modulation on the NBFM signals the peak power drops because the width of emission exceeds the FFT bin size. I have the FFT resolution set to 512, which is the lowest it can be set to. The only way to get the FFT bin size large enough to adequately capture a NBFM signal is to disable decimation, which leaves me with only 12 bits of dynamic range. In the crowded SoCal VHF/UHF RF environment I often find that I need a couple more bits of resolution to maintain decent sensitivity without occasional overloading, so I prefer to use a decimation of 16 or 32. I could still effectively log NBFM channel power if I could further reduce the FFT resolution to, say 16. At a decimation of 32, the bin size would be then 150 kHz / 16 = 9.38 kHz, just enough. The FFT display would be kind of useless, but it would allow using the SNR logger to record channel power of wider emissions like NBFM, & my guess is that this would be very easy to implement since fewer resources would be needed to implement a smaller FFT.


Bob NO6B

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