Observation 147405: ISS (25544)

Satellites & Observations Observations
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Regarding Observation 147405 …
My first one … I used a vertical antenna. I don’t have my LNA and turnstile up yet.
It demonstrates that my RTL-SDR, Raspberry Pi and network connection is working.

–Konrad, WA4OSH

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Indeed your setup seems to work fine! Maybe you need to reduce a little sdr’s rf gain.

Just have in mind that currently ISS APRS doesn’t work due to technical problems on the equipment.

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Fredy,
Thanks … I was going to ask how to adjust the gain because it looks like my LNA is a little “hot” into the RTL-SDR.

Is there a way to run my GS live? On a terrestrial signal, or reference source?

–Konrad

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If you have something like gqrx installed you can do a sweep of the 2m band to find persistent emitters. For example, there’s some sort of pager system active near 169MHz for my station, which I sometimes use to check gain settings using a script like the one below which records about a minute of data for various gain settings. You can generate waterfall plots from the dat files with: gnuplot -e "inputfile='waterfall.dat'" -e "outfile='waterfall.png'" -e "height=1600" /usr/share/satnogs/scripts/satnogs_waterfall.gp.

#!/bin/bash

for gain in 49.6 44.5 43.4 40.2 37.2 33.8 29.7 25.4 20.7 16.6 14.4 08.7 03.7 01.4 00.0; do
    satnogs_fm_demod.py --rx-sdr-device=rtlsdr --rx-freq=137500000 --file-path=./audio-out.ogg --waterfall-file-path=./waterfall-${gain}.dat --iq-file-path=./iq.dat --rf-gain=$gain &

    sleep 63
    killall satnogs_fm_demod.py
    sleep 1
done

As for changing the gain settings; run sudo satnogs-setup and you’ll find the rf-gain paramater under the advanced settings.

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since you are in the US… find the freq of your closest NOAA radio transmitter to use as a reference

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In addition to the above check also this adjustment guide

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What do I have to install in order to get the GUI I normally get on Debian for RPi? (Startx does not work) I definitely will install gqrx.

49.6 44.5 43.4 40.2 37.2 33.8 29.7 25.4 20.7 16.6 14.4 08.7 03.7 01.4 00.0

Are these gain or attenuation values? Is there some reasoning behind these values?

@cshields
NOAA Weather Radio on 162.400, 162.425, 162.450, 162.475, 162.500, 162.525, and 162.550 MHz. Is a pretty strong (Full quieting ++). Is that about the strongest signal you expect? S9+40 dBm is -53 dBm S9 full quieting is -93 dBm

–Konrad, WA4OSH

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If you’ve got another Linux machine already set up with a GUI, you might find it easiest to just do the adjustment with the RTL-SDR hooked up to it. But if you need to get the GUI installed on your Pi, this article might help. Keep in mind that leaving the GUI on permanently might tax your Pi when it’s doing observations…depending on how familiar you are with Linux, the very simplest way to ensure the GUI is turned off might just be to reinstall the SatNOGS image afterward

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quote=“saintaardvark, post:8, topic:2139”]
If you’ve got another Linux machine already set up with a GUI, you might find it easiest to just do the adjustment with the RTL-SDR hooked up to it…
[/quote]
Sure. It certainly makes sense not to put GUI code onto the RPi. I already have gqrx installed on my Linux Mint laptop. And executing the various Bash scripts is also easy for me. So that’s a plan. Thanks.

–Konrad

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Those are the gain values. If you run rtl_test it’ll show you which discrete values it will use (accept?).

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