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Audio-DSP-Lab 1.6 — the receiver as a backend only

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@andiepp andiepp released this 11 Nov 11:29
· 6 commits to main since this release
v1.6
6243d73

Audio-DSP-Lab 1.6 makes the receiver a pure SDR receiver backend from the IF on. Your front end delivers a real IF or I and Q to the line input K2; the application no longer drives a front end of its own. The dial is now called IF and starts at 12 kHz, and what a front end should deliver comes down to one simple rule: about 1 mV amplitude at K2.

Downloads

  • Audio-DSP-Lab-1.6-windows-x64.zip: the Windows application (self-contained, no .NET needed), the board and panel firmware with the flash tool, the manual and the installation guide.
  • Audio-DSP-Lab-firmware-1.6.zip: the firmware alone.

Flash the board with Flash-Firmware.cmd, the front panel with Flash-Panel.cmd (see the installation guide). The protocol is unchanged (version 1); the other applications are unchanged.

What's new

Firmware 1.6, protocol 1 (unchanged), application 1.6, panel firmware 1.6.

  • Receiver, backend only: the application's Front end on card (the author's test front end: an Arduino Uno driving an Si5351A), the RF dial and its tuning, the 20 m band warning and app/tools/RxTuneCheck are removed; the front end is entirely yours. Null image and the I/Q correction stay, for any I/Q front end.
  • The IF dial: the dial is called IF in the application and on the front panel, and it starts at 12 kHz instead of 10 kHz. The protocol's parameter keeps its name offset, so scripts and stored settings still work.
  • Docs: what a front end should deliver is one simple rule: about 1 mV amplitude at K2 (2 mVpp; the S-meter reads about −63.5 dBFS), 42 to 46 dB above the receiver's noise in 2.4 kHz and about 63 dB below full scale. The specification at K2 (full scale, noise, sensitivity, band-limiting, frequencies) stays. The manual's sections on the test front end, its card, the Uno's commands and its measurements are removed; the installation guide has a short section on connecting a front end. Screenshots of the application and the panel at 1.6.

With an I/Q front end, an IF of exactly 12 kHz is a quarter of the sample rate, where a front end's third-order products fold onto the image: for the deepest image rejection put the station near 10 kHz (see the manual).

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