Nooelec NESDR Smart XDR and IF gain settings in SatNOGS

SatNOGS Hardware
1

Hi all,

In attempts to tweak the IF Gain (6 total) on a Nooelec NESDR Smart XTR, I’ve read the SatNOGS SDR setup guide and associated manufacturer data sheet.

The SatNOGS SDR setup guide offers this starting point for a E4000-based SDR such as the Nooelec:

  • SATNOGS_GAIN_MODE="Settings Field"*
  • SATNOGS_OTHER_SETTINGS=“IF1=6,IF2=3,IF2=2,IF3=0,IF4=0,IF5=2,IF6=3,TUNER=30”`*

This works without any modifications and yields decent observation results in terms of both the waterfall and generation of data frames for most satellites when compared to a RTL-SDR v3 blog that was in place for months prior to the Nooelec SMArt.

Why are there two IF2 parameters listed in the SatNOGS example, is it a typo? The Nooelec spec sheet show the possible setting for IF2 as 0,3,6,9 (not 2)
IF2

I’ve also tried changing the parameters to all 6 IF settings but do not see any difference but will keep messing with these.

I have noticed some satellites signals are now very weak and I can barely decode any frames from them any longer (FALCONSAT-3, BOBCAT-1 and RAMSAT-1 for example) when compared to using a RTL-SDR v3 blog for months with the same system and decoding tons of frames in single passes. Hence why I am trying to tweak the Nooelec IF gain settings.

Any insights would be greatly appreciated. Thanks.

satcolintel5

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I think I wrote that, and it’s possibly a typo on my part.
Look into the SoapyRTLSDR code, it looks like it’ll just pick the nearest valid gain setting to the user-provided setting: https://github.com/pothosware/SoapyRTLSDR/blob/master/Settings.cpp#L715

As for optimizing the E4000 gains… that’s a complex problem. I suspect you would be best off radiating a weak signal somewhere in the vicinity of your receive system, and tweaking the gains to adjust for best SNR, while also avoiding IMD products.

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Great, thank you for this, much appreciated. That helps a lot.

Cheers

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my satnogs station error when using this setting, the device used is nesdr smart-xtr. maybe you can show a screenshot of the settings for the gain. very grateful for the help

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Here are the relevant setting used on my satnogs-client for a nooelec xdr

        "satnogs_gain_mode": "Settings Field",
        "satnogs_other_settings": "IF1=6,IF2=3,IF3=3,IF4=2,IF5=9,IF6=12,TUNER=42",
        "satnogs_rf_gain": "42.0",
        "satnogs_rx_samp_rate": "2.048e6",
        "satnogs_soapy_rx_device": "driver=rtlsdr,serial=00000001",

Seems to work okay for me but I really have not spent much time adjusting the settings to much. More details on the possible settings for each IF stage here on pages 36-37.

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