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SOLVED: AM/FM Demodulator with decimation -> defunct / crashes


when using the AM/FM demod and you enable decimation to get a lower I/Q rate, the demod
cannot properly decode the audio anymore.
On top of that the session gets instable and tends to crash when e.g. saving or editing the node graph.

Please find the logs and the example config attached.

I already reported it using the feedback reporting tool, but it didn't give me feedback that the upload was successful.
It has shown me the same dialog again where I again could upload or cancel.
Did you receive the report that way already?


Uploaded files:

Please connect the AM/FM demod to the IQ output as shown below. Don't be confused about the label "Spectra" on the demod block port. Will be fixed in upcoming version:

g3gg0 has reacted to this post.

Great, didn't expect that.

But thats even more reasonable than demod from spectrum, thanks.

Folow-Up Question: Adding LSB, USB and narrower filters isn't on your schedule, is it?


It is for sure but if you want to push it add it to the 🙂

g3gg0 and CorNic East have reacted to this post.
g3gg0CorNic East


Thank you for sharing this:

I already reported it using the feedback reporting tool, but it didn't give me feedback that the upload was successful.

We've implemented a messagebox which reports the result of the submit action.

Submit success

Great, thanks a lot 🙂

DasGuteG has reacted to this post.

I am currently running Aaronia_RTSA_Suite_PRO_2.1.1.10245_Setup_64bit with SpectranV6 A3-x-02000032 xxaaxaa.  I am having a few interesting issues with the AM/FM block:

  1. When I try to connect the SpectranV6 IQ Stream 1 output directly to the AM/FM Demodulator block, I cannot get any audio to the Audio Monitor.  In order to hear audio, I need to insert the IQ Power Spectrum block.
  2. When tuning to a local (strong) FM station (99.1MHz), I need to tune slightly higher (99.15MHz) to get good/clear audio.  Is this possibly due to calibration?
  3. This has been difficult to replicate, but when I construct a new AM/FM demodulator mission, I don't always get the audio output.  It seems as if I need to configure the Monitor setting from Selected to another setting, then back to Selected.

Additionally, I would like to request in the AM/FM Demodulator block the ability to:

  1. Change the spectrum graph to NOT have persistence/color, just simple line (this would make it easier to perform manual tuning).
  2. Completely turn off the waterfall and audio spectrum.
  3. Even though the analysis/demod BW is easily adjusted (i.e. Channel Width), it would be nice to have some standard entries in the Modulation pull-down for FM-N, FM-W, (optimally CW, USB, LSB).

Works fine with direct IQ but indeed you need to play with the settings till it starts. That's indeed a bug and now on the TODO list.

Concerning wanted features please post them to the Wishlist threads and ONE wish per posting otherwise this forum will end in a total mess.

Direct IQ AM/FM Decoder


Sofon has reacted to this post.