Observation 4523347: NOAA 15 (25338)

Regarding Observation 4523347
Can anyone please tell me what the blue horizontal lines are likely to be? There are no known sources of local interference that could cause this.

Just curious @m0roj did you find out what was the source of these lines?

My guess would be a faulty cable connection or something.

Hi @fredy, I still did occasionally get these horizontal lines. I checked and even changed the cabling - just in case - but they did still occur. Possibly local interference, although nothing discernible in this location.
However, my SatNOGS station is offline at present and I’m concentrating on weather sats’ as I was just not getting much out of SatNOGS and became somewhat bored. I need to explore more about using the mode demodulators and Grafana. In other words learn more about interpretations and decodes and putting them to interesting use.
Cheers, Roj

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my guess is a strong interferer outside the observation bandwitdh which causes the AGC of your receiver (RTL Dongle?) to kick-in or otherwise desense your receiver. I have similar effect caused by a near-by APRS Repeater. Using an RTL-Dongle disable AGCs and set the Manual Gain at 25-30 dB, this should give you some margin for such effect and still provides enough sensitivity.


I further lookef at your NOAA observation
I really think that you have too much gain in your system. Try to reduce to the minimum. Do you really need a LNA for the NOAAs on VHF. If yes, reduce the gain setting in the Dongle…My NOAA observations with a similar set-up look better - but I have to use a LNA as my station is in the baseband, 25 m coaxial cable meters (H-100 cable) away from the antenna The gain of the LNA on VHF is 10 dB and the Dongle has 25 dB. Hope this points in the right direction.

Hi @DL5FAB - many thanks for your comments and suggestions. They’re very much appreciated.
At present my SatNOGS station is down as I’m using the equipment for RaspberryNOAA. When I return to SatNOGS I’ll carry out further investigations and also try your suggestions.
Thanks again.