Issue with AGC operation
Posted: Fri Mar 13, 2015 8:44 pm
Using the latest HDSDR plug-in I've noticed some strange behaviour with the LNA GR threshold in relation to the Overall gain reduction. Basically with the gain reduction threshold reduced to turn off the LNA the (Total) Gain reduction figure increases. Examples in 5 MHz B/W in different parts of the band:
LNA Gain threshold (LNA on/off) Total gain reduction
1. 59 on 51
40 off 54 new total GR
2. 50 on 34
30 off 38 new total GR
Now I would have thought that the total GR would go down with the LNA turned off as a 24dB gain reduction has been manually induced. Unfortunately the HDSDR EXtIO doesn't show the GR figures for each stage like the SDR# one does so can't see what if happening to the Mixer and IF gains.
Can the SDRPlay team replicate this and comment please. It seems to me to be affecting the performance.
Thanks
David
LNA Gain threshold (LNA on/off) Total gain reduction
1. 59 on 51
40 off 54 new total GR
2. 50 on 34
30 off 38 new total GR
Now I would have thought that the total GR would go down with the LNA turned off as a 24dB gain reduction has been manually induced. Unfortunately the HDSDR EXtIO doesn't show the GR figures for each stage like the SDR# one does so can't see what if happening to the Mixer and IF gains.
Can the SDRPlay team replicate this and comment please. It seems to me to be affecting the performance.
Thanks
David