SDR# Guide for version #1920 (Alpha 17 – 2023.09.25) – AM / DSB Mode

Radio Panel

The Radio panel has the main controls for setting up your demodulator.

Some of the options available are:

  • Types of demodulator. For an AM signal, DSB is best (LSB + USB).
  • Filter type (I leave this on default).
  • Order – This is how sharp the filters are. Higher = sharper.
  • Binaural – Psuedo-stereo based on atmospheric effects, can be fun.
  • Lock Carrier – This locks to an AM carrier, necessary when using DSB on an AM signal.
  • Correct IQ (Some SDRs require this setting if they aren’t performing correctly).
  • Anti-Fading (This splits either side of an AM signal into bands and chooses whichever side is strongest per band. This helps with multipath fading but damages digital data, especially EasyDRF!).
  • Sticky Lock (Designed to stick to and track a single AM carrier. Can work great with carrier sway!).
  • Invert Spectrum (If the spectrum is backwards, this should fix it by reversing it in SDR# back to correct way round).


The AGC or Automatic Gain Control is a system to automatically raise and lower your volume to make the audio sound more level. This is ideal for e.g. Shortwave where signals are endlessly changing strength!

  • Learn button (This button sets the threshold to the current signal strength. Pretty simple and easy way to adjust it)
  • Threshold (Manual adjustment. E.g. if you wanted to hear a signal as it gets weaker, lower it a little. Reverse for only listening to strong signals).
  • Decay (This is how many ms it takes for the levels to change. Too high and it’ll be very noticeable. Too low and they might not change fast enough!).
  • Use Hang (This is a system changes the AGC from gradual changes to sudden drops once the ms limit is hit).

IF Multi Notch

This notching system is perfect for removing single tones / birdies etc…

  • Asymmetric Filter (Enables a very high order filter to adjust each sideband separately. Personally I prefer the Asymmetric Filter in “IF Spectrum”).
  • Notch Tracking (This tick box turns on / of the notch tracking system).
  • Add new (Adds a new notch to track exactly where SDR# is tuned to).
  • Delete (Deletes the selected notch).
  • Width (Sets the notch’s width. Narrower is better for single tones and wider for things like FSK data but it’s best to go by eye).
  • Attenuation in dB (This is a clever system. You can choose to lower the notch by only a few dB, especially useful if using noise removal and interference to have the real audio survive or you cold raise it up by a certain amount which can be great on transmitters that have weird EQs!).
  • IF Spectrum (This opens the widget as seen in the middle and right image. I choose after processing which lets you see what your notches are doing in real time!).
  • The IF Spectrum Window (Once this is open, you can close the IF Multi-Notch window and control it entirely from a Spectrum Window. It’s as simple as clicking on the spectrum to make a notch, dragging the edges – the white arrows – to adjust width and dragging the notch – the black arrows – to move it. There are also buttons to toggle the before/after view and toggles for the Notch Filters and Asymmetric Filter).