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AD9361 RSSI/AGC strange behavior

Question asked by hight77 on Apr 4, 2017
Latest reply on Apr 7, 2017 by hight77

Hello.  We are seeing strange AGC/RSSI behavior with an adjacent channel interferer.   Our sample rate is 16MHz and we have a 14MHz bandwidth.  If we inject a large interferer (using CW for now) close to our intended signal (with 70MHz) we see that the RSSI increases as expected (interferer adds to our signal and AGC tracks with less gain).

 

However, when the interefer is farther away from Fc, we see the RSSI drop around 20dB and the AGC is reporting adding more gain.  The interferer is now causing our intended signal to look weaker that what is actually coming in.

 

Has anyone else seen this?  Any ideas of what may be causing it?  Seems like it could be some kind of mixing artifact that could be overflowing one of the AGC calc points.

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