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NB before AGC
Posted: Thu Jul 23, 2020 5:42 pm
by Tony EI7BMB
A friend of mine who uses Expert SDR2 has told me that he is having great results with NB engaged before AGC . I have had a good look in Thetis but just in case i am missing something is there any way to do this presently ?
Re: NB before AGC
Posted: Thu Jul 23, 2020 7:03 pm
by laurencebarker
The noise blankers (NB, NB2, SNB) are always before the AGC in Thetis. NB and NB2 are right at the front; SNB a little further through. There is a simplified version of the RX flow graph in the Thetis manual section 2.4.1, and a more detailed one in the WDSP guide.
You can download the Thetis manual from the front page of the Apache-labs website; you can get the wdsp guide at
https://github.com/TAPR/OpenHPSDR-wdsp
Re: NB before AGC
Posted: Thu Jul 23, 2020 7:41 pm
by Tony EI7BMB
Thanks for the info Laurence , most helpful
Re: NB before AGC
Posted: Thu Jul 23, 2020 7:43 pm
by w-u-2-o
It's also worth noting that NB and NB2 are wideband modes that act on the entire 1st IF, i.e. the 192 or 384KHz, etc. that you see on the spectral display. SNB is a narrowband mode that only processes the 2nd IF (the selected RX passband), in much the same manner as NR and NR2.