Apache Labs Community Forum

Hello,

I am wondering if the Thetis AGC Gain control has the same behaviour as the AGC-T control described in the Flexradio Document (https://www.flexradio.com/documentation ... -controls/).

Thank you very much and 73'
Enzo, iw7dmh

Yes, that is correct. See also page 40 in this document for more detailed information in the implementation that exists in PowerSDR mRX and Thetis: https://github.com/TAPR/OpenHPSDR-wdsp/ ... 0Guide.pdf

It is also worth noting that before adjusting AGC Gain, change into step attenuator mode (S-ATT) by double clicking the "ATT" above the attenuator control spinner, and fine adjust the attenuation until you start to see a drop in SNR between the displayed average noise level and the largest signals on the band. This will optimize your ADC dynamic range for existing band conditions.

I just corresponded with the author of the code, Warren, NR0V. He said that the AGC implementation in the original PowerSDR was significantly flawed. It probably does not operate as described, although it is supposed to. This is not a problem in PowerSDR mRX or Thetis, where things do work as described.

Additional note: AGC slope factor defaults to 0dB for all built in presets. You can change this in Setup > DSP > AGC/ALC.

Hello Scott,
thank you very much for the hints and for pointing me up to the WDSP doc.

73' Enzo
iw7dmh