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8 Using Network Audio from SDRPlusPlus

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Mark Jessop edited this page May 6, 2023 · 8 revisions

Last updated: 2022-02-18

SDR++ is a new cross-platform Software-Defined-Radio receiver software package which is completely open source, and supports a large range of SDR models. It is under constant development to improve performance and add new features, so this guide may become out-of-date.

Getting SDR++

You can get the latest SDR++ release from here: https://github.com/AlexandreRouma/SDRPlusPlus/releases I recommend using the latest 'nightly' build, as there hasn't been a proper release of SDR++ for far too long. Look for the 'SDR++ Nightly Build' section at the top of the releases page, and click the 'Assets' button to get a list of release downloads.

There is further information on compiling SDR++ from source and getting the latest 'nightly' builds here: https://github.com/AlexandreRouma/SDRPlusPlus#installing

Making an RTLSDR work under Windows

If you want to use an RTLSDR, you will probably need to use the 'Zadig' utility to install the WinUSB driver. There is a short guide available here: https://www.rtl-sdr.com/getting-the-rtl-sdr-to-work-on-windows-10/

Receiving using an RTLSDR (or other SDRs)

The following figure presents an overview of the SDR++ window, showing a Horus Binary signal being received (outlined in red).

SDR++ Overview

To configure SDR++ to receive the Horus Binary signal, you will need to:

  • Select your SDR type in the 'source' selection.
  • Set your RF gain settings. If using a RTLSDR, the 'RTL AGC' setting is often OK to use. If using a preamplifier, you will probably want to turn this off and set the gain to around 25-30 dB.
  • Set the modulation type (modulation settings) to 'USB' (Upper SideBand)
  • Set the frequency (click on the top/bottom of the numbers to adjust them up/down). Set it 1 kHz below the expected frequency of the signal, e.g. 434.199.000 for a 434.200 MHz signal.
  • Click the 'Start' button to start receiving.
  • Confirm the signal appears within the receiver passband area. You will probably need to adjust the waterfall zoom to be able to see this properly.
  • Once you have confirmed the presence of the signal, you can setup UDP audio output.

Demodulated Audio output via UDP

  • In the pane on the left of the SDR++ window, scroll down to find the 'Sink' (output) settings. These should be set as follows: SDR++ UDP Audio Output Settings

  • In Horus-GUI, select "UDP Audio" from the audio device selection, and click 'Start'. You should now be seeing signals in the Spectrum display on Horus-GUI.

  • You may need to adjust the audio level coming out of SDR++ such that it is around -12 dBFS. The SDR++ volume control is available near the top-left of the window.

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