Beginner:NooElec SDR Smart RTL AGC

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SCPD

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Feb 24, 2001
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FOR UHF WEAK SIGNAL!!

NooElec NESDR Smart 0.5 ppm TCXO Rafael Micro R820T/T2 Tuner chip.

Most of you know that usually the RTL-AGC gain is not very powerful but on UHF I have found it actually does increase considerably around 460mhz. I monitor a jail frequency that isn't very strong from a huge facility. Without auto gains it is around S5-S7 units at best.I am using the telescoping antenna full extended.

First Image RTL-AGC OFF with 40.2dbm manual gain.
Small amount of imaging from nearby DRM repeater Signal intelligible on 460.2375mhz
Small increase in signal strength.

Second Image RTL-AGC ON with 40.2dbm manual gain.
Some imaging from nearby DRM repeater. Signal stronger on 460.2375mhz
Considerable increase in signal strength

Third Image Both RTL-AGC and Tuner AGC ON
Considerable amount of imaging from nearby DRM repeater. Signal weaker than image two but stronger than image one. Not the best setting.


Out of this you can get a idea of how to use the RTL-AGC on weaker signals. It is not as effective on VHF. With these settings nearby imaging can "pull" down on the signal strength or what we call 'desensitizing' the front end. It's flexible enough to get a happy medium. Experiment with best possible reception. The dongle runs cooler with TUNER AGC OFF.

Recommendation:
Do not enable TUNER AGC. It can cause desensitization from imaging!!!! Best for VHF!!
Adjust tuner gain manually
Use RTL_AGC only if needed!!
 

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