[hpsdr] AGC

[FRANCIS CARCIA]

I really like an accurate AGC. (I drive a R&S ESIB40 at work) The step attenuator is the way I would go. My TCI 8174 uses analog switches with resistors in the IF to switch in fixed attenuators also an attenuator near the front end if i remember. Pin performance changes with frequency so relays might be better in the front end. The RA6830 DF receivers used pin diodes in the IF to select pads and fixed gain amplifiers to make an accurate AGC. Analog AGCs drive me crazy because the S meter is never accurate throughout the range.
  I've found the better the roofing filter the better the SDR performance. Wideband dynamic range is improved over the A/D performance with the right front end. 
  Frank, WA1GFZ   
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