n00b question about 1.5Ghz signals

batdude

Member
Premium Subscriber
Joined
Jul 29, 2002
Messages
216
I need some help trying to identify exactly what type of signals I am seeing - and what modulation scheme is being used for each.

This first image shows what I see @ 1.536 GHz. these are all fairly consistent 200ish-khz signals.

77447

Second picture shows much more narrow spikes than above but more of the 200khz signals to the right of the spectrum.

77448

Third picture: more similar to the first image.

77449

anyone care to weigh in?

I'm curious as to... what signals I am seeing (and perhaps even from where they are coming from) and the modulation scheme that may be in use (USB?) and .... again, being really basic here - what decoder program will work.

For reference, the antenna is pointed south / south-west from central florida.

I am currently using Skytale-C with the SDR# plugin. The only channel I have reliably decoded so far is the NSC channel on INMARSAT F4 @ 1.537.7xx



TIA


doug
 

prcguy

Member
Joined
Jun 30, 2006
Messages
8,307
Location
So Cal - Richardson, TX - Tewksbury, MA
I would guess QPSK or a QAM modulation. The pure CW carrier you see could be a satellite beacon for pointing or uplink power control purposes. CW beacons are usually at the very lower or upper edge of the spectrum.
 
Top