Observation 4523347: NOAA 15 (25338)

Satellites & Observations Observations
#1

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.

Observation 6083835: RAAF M2 A (99950)
#2

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

My guess would be a faulty cable connection or something.

#3

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

1 Like
#4

Hi,

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.

#5

Hi,

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.

#6

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.