Problem with reception


I’ve just mound my 137MHz Turnstile antenna to my Raspberry Pi 3+ setup (together with RTL-SDR v3 dongle and the suggested FM notch/LNA module).

I am scheduling some observations but the waterfall I’m getting is like this one here:

It seems that you can find something like singal on the middle but its like I am having too much gain or something. I haven’t changed anything from the software and currently I am running the with the default values.

A little bit of help?

PS: My station look like that:

The blue LED on the FM notch/LNA is not ON just because I haven’t plug the power on my POE. Outside the enclosure I’m using a lightning protector N to N connector.

Hey @john_kedros,

for changing gain you will need to run satnogs-setup, change the RF_GAIN in advanced options and apply the changes. Then hit back and schedule new observation to test it.

For RF_GAIN values check also this

EDIT: the default value is 32.8 for rtl-sdr

Thank you fredy!

I’ve just made the changes I hopefully it will be a lot better now!

I’m guesing that with lower gain number I will reduce the “red” part in the waterfall. Is this correct or the satnogs software it interprets those values the other way around?

Using the 32.8 gain value on the SATNOGS_RF_GAIN (previously this field it was empty) I have almost the same results (maybe just a little bit better).

It seems that those are some possible values:
0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6

I will use a lower number like 14.4 for my next try…

Do you have any LNA connected and somehow powered up?

lower number, lower gain which will reduce “red” parts in the waterfall :slight_smile:

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Yes, I have the suggested LNA with the FM notch. You can see it on my first post

Please try to observe some of the sats with a lower transmitter bandwidth - e.g. NOAA or in the 2m satellite band e.g. FOX sats or FUNCUBE-1 and NAYIF-1.

Perfect! I will… and then post the results

With 14.4 RF Gain it look a lot better. But I think I have to increase the value a little bit now.

Soon I will have and a waterfall of a NOAA observation.

Is this ok? Do you think I have to increase or decrease the gain? Is this waterfall ok?

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And… here are the first results! What do you think? Do I need to increase or decrease the gain?

The waterfall:

and here is the image:

By the way, if I schedule an observation, lets say in 6 hours from now (with a gain of 30 for example) and before this observation I change the gain to 5 on my RaspberryPi… do the observation will use the latest gain of 5 - or it will use the gain that I had when I’ve original scheduled the observation?


The gain will be the current one, so in your example 5.

You gain looks good but maybe it will need some fine tuning… this would be done with doing more observations and see the results. For example you can try to observe FSK9k6 satellites and check how many packets are demodulated, just make sure that the passes are similar (elevation/azimuth) and from the same satellite.

Also check this page too:


I’ve put it out of Testing Mode. It looks good so far.

Is it possible to watch my previous observations and make comments? It thinks that I’ve mark as good and bad the correct way…

Follow this link which is the obaservation page with a filter to show observations from your station

You can open a discussion here in by going to the observation page and hit the blue button “Discuss” at the top right corner.

For marking/vetting an observation check this guide at our wiki:

EDIT: if you find that you have vetted wrong some of the observations, make a list with them and send them to me and I’ll fix them :wink: