Different gain settings used in NOAA script?

SatNOGS Software
1

Looks Like default settings rather than user configurable gain settings used in satnogs_noaa_apt_decoder.py

self.osmosdr_source_0.set_gain(satnogs.hw_rx_settings[rx_sdr_device]['rf_gain'], 0)
self.osmosdr_source_0.set_if_gain(satnogs.hw_rx_settings[rx_sdr_device]['if_gain'], 0)
self.osmosdr_source_0.set_bb_gain(satnogs.hw_rx_settings[rx_sdr_device]['bb_gain'], 0)
self.osmosdr_source_0.set_antenna(satnogs.hw_rx_settings[rx_sdr_device]['antenna'], 0)

EDIT:

self.osmosdr_source_0.set_gain(satnogs.handle_rx_rf_gain(rx_sdr_device, rf_gain), 0)
self.osmosdr_source_0.set_if_gain(satnogs.handle_rx_if_gain(rx_sdr_device, if_gain), 0)
self.osmosdr_source_0.set_bb_gain(satnogs.handle_rx_bb_gain(rx_sdr_device, bb_gain), 0)
self.osmosdr_source_0.set_antenna(satnogs.handle_rx_antenna(rx_sdr_device, antenna), 0)

Maybe I do not understand this code so well.

It could explain why I see different backgrounds in waterfalls between NOAA passes and Meteor at similar frequencies.

1 Like
2

NOAA 18

image.png577×834 715 KB

Meteor pass was next

image.png580×845 544 KB

Notice the difference in background noise.

3

@surligas any comments?

4

Sorry for being late,

which version of gr-satnogs do you use? v1.1.0 does not use only the hard-coded values. Custom gains etc can be passed through the available command line options.

satnogs_noaa_apt_decoder.py --help will give you the available parameters.

5

Difference in noise and signal levels can also be caused by different bandwidth used by two different receivers. As far as I know the FFT size is the same for each receiver, so if the bandwidth increases, so will the power level in each FFT bin.

6

I have been using the v1.1.0 version of gr-satnogs. Different bandwidth could explain the difference. This had been bugging me for a while.
Thanks.