SDR bandwidth change gain and SNR

  • As no one else has replied I will have a guess it is down to the level of noise power that the input has to deal with the wider the more noise the narrower the less noise, well I am probably thinking of analogue receivers but I can not believe that SDR would be any better.

    When you are reducing the sample rate you are reducing the bandwidth the A to D converter deals with.

    Have a read of this:-



    Before I forget and you reduce the sample rate to 250 KHz and leave it there you may notice that signals can disappearoff one end and wrap around come back in view as though traversing in the wrong direction or come back in at the other end of the view screen. I believe that can be down to something called aliasing. Some thing I barley understand as I am still old school, but have come across it several times when playing, something about sampling at at east twice the rate of bandwidth you wish to see.

    I am sure there will be more brainier people along soon.

  • G8UGD Thanks Adrian, but the surprise is that, I got better resulst with a wider bandwidth. Achim DH2VA has probably right that it depends how Simon calculates noise.

    I have tried:

    • 250 kHz bad results
    • 1MHz good results
    • 1,5MHz the same as 1MHz
    • 2MHz the same as 1MHz

    I have not tried 500 kHz yet.

    It's good to know for somebody that the reception with SDR could vary with the bandwith differently that in analog world. Thanks!