Observation 11536564: NOAA 15 (25338)

Satellites & Observations Observations
1

Regarding Observation 11536564 …

Hello guys! I am sorry if this question is repeated but I am really new on this and I have close to 0 knowledge in radio (maybe I started building the house by the roof lol). The thing is that I have configured a RPi 3B with a RTLSDR as written in the official documentation of this project and even I followed all the steps there seems to be a problem with my readings.

All the audio is static noise and the waterfalls appears to be empty. I have tried the antena by just trying to get some FM radio to see if there was a problem with it, and the terrestrial signal I can read it correctly.

So I bet there is a problem between my configuration adn SatNogs to know exactly what to read from. I don’t really know from where starting to dig into this problem. Any one can recommend something?

I would be really appreciated!

Thanks!

2

Congratulations Joaquin.
I have the same problem, and no solution found yet.

Daniel

3

Looking at the meta data of your observation, I see there is no gain: null value, it is still null

Without any details on the RF path, I need to assume a situation where you have no LNA I would suggest to start with a value of 42.1

This are all the supported gain values when using a rtl-sdr, the higher the more gain, but also more noise.

Supported gain values (29): 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

Jan | PE0SAT

1 Like
4

This was a low pass for me but once you have the gain setup it should look like this.

https://network.satnogs.org/observations/11537724/

1 Like
5

Thank you so much for your reply! It was really useful. I set value of 42.1 as suggested and see data already! SatNOGS Network - Observation 11542556

However the data doesn’t seem to be very clear. I am sorry for this newbie question, but what is the difference between a lower gain value and a higher gain value? Is there any documentation you can refeer for me to learn about this?

Thank you in advance!

6

Have you checked @PE0SAT answer? Really helped me :slight_smile:

7

This page will help explain the setting up of the gain, you have to find the sweet spot. to much gain and potentially you will get a lot of noise/interference to little and you will receive poor signal on none.
Omnidirectional Station How To - SatNOGS Wiki

8

Yes, I’ve played around with these values but no success.

9

Thanks for the reply, looking at the obs, it seems you are picking up some local interference.

Can you share more information on your setup and especially the RF path.

Antenna (type/surroundings) → LNA (yes/no) → coax (type/length) → SDR (type/connection)

Jan | PE0SAT

10

Looks like basics is working just fine now.
The interference seen in 11542960 looks a bit like wide FM (88-108MHz) broadcast.
Installing a FM bandstop filter should alleviate this. It can be connected directly to the sdr (not sure about using biasing to a lna through it).

11

I had the same issue and the bandstop filter made a big difference.