What's the problem when it is at 140MHz?

gasparka / spectrogram

80MHz bandwidth with LimeSDR-Mini and GQRX

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What's the problem when it is at 140MHz? #22

Closed juzhang74 closed 4 years ago

juzhang74 commented 4 years ago

Hi, I meet a strange problem with this program. When it running at 2.4GHz, all seems OK. If I set the central freq at 140MHz, with GNURadio and the official FPGA, all things seems OK, but at the same central freq, spectrogram's outputs has nothing except noise floor. Could anyone tell me why? Any advice will be appreciated.

gasparka commented 4 years ago

Hi You can press Control + j to open SDR configuration sidebar. Antenna selection should be already at "Auto", but maybe you need to increase the gain?

juzhang74 commented 4 years ago

Yes-ish!!! I can see signals at 140MHz with LNA gain set to 20. Thanks a lot!

gasparka commented 4 years ago

LNA should be by default set to 30. Did you mean VGA, or maybe we are dealing with some bug here?

juzhang74 commented 4 years ago

We use your usage_demo.ipynb demo. And in this demo, Default gains are set to "gains = {LNA: 0, TIA: 0, PGA: -12}". That's the problem. When I set LNA gain to 20, all seems Ok!

juzhang74 commented 4 years ago

Thank you very much!