Help Required Possible c-band beacon at around 61.5° west.

John

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Can anybody throw any light on this beacon type signal 3994.5 H which is from the 61.5° W area. There is nothing else Hor across the band and nothing Vert, LHC or RHC.

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Possible 61.5°West - 3994.5 H - possible beacon .. full band .. reduced image...jpgPossible 61.5°West - 3994.5 H - possible beacon ..... reduced...jpg
 
John

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Can anybody throw any light on this beacon type signal 3994.5 H which is from the 61.5° W area. There is nothing else Hor across the band and nothing Vert, LHC or RHC.

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View attachment 122697View attachment 122698



... The nearest satellite i can find that last used that freq was Amazonas3 @ 61° West and was for 'LFG' feeds but was on the Americas beam. ( info courtesy of SatBeams )
 
frank-sinatra

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I don't found this signal from 61w, only 65w

See:

Screenshot_20190206-214610.jpeg
Screenshot_20190206-214644.jpeg
Screenshot_20190206-214545.jpeg

This is my tp list (61w): don't appear 3994

Screenshot_20190206-214724.jpeg
Screenshot_20190206-214737.jpeg
 
John

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frank-sinatra

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Maybe feed 61w? Test again please, then I'll check here too.

Tell me about this spectrum... Very interesting.
 
Feedsat_DXer

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Can anybody throw any light on this beacon type signal 3994.5 H which is from the 61.5° W area. There is nothing else Hor across the band and nothing Vert, LHC or RHC.

........................................................................................................................................................................................................................................................................................................................................................

View attachment 122697View attachment 122698
OK John, just checked and unfortunately, flat spectrum from 58W to 65W from my QTH

regards
 
John

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OK John, just checked and unfortunately, flat spectrum from 58W to 65W from my QTH

regards



Thanks for checking - can confirm that the activity that was seen has been absent over the last two days. When the first narrow signal of 3994.5 H was spotted on the 2nd Feb 19, three other low level signal spikes were spotted at later times and day at 3942 H, 3984 H & 4060 H. The signals were not from an inclined sat as they remained at the same elevation for many hours. The signals also looked to be from a satellite source and not a local ground interference source as they were directly on the arc and could be eliminated in a normal manner by raising reflector slightly above or below the arc and also a couple of degrees East or West nudging. Signals were only seen in the Horizontal, nothing at all in Vertical, LHC or RHC. I managed to take a quick grab of when there were two spikes up and running. I'm wondering if it was something off Amazonas-3 from the America beam that was getting across to us due to freak conditions ?? ... don't know. I'm keeping obs on it anyway.
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mystery - Cband 61° west area .... reduced..jpg
 
hvdh

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I was thinking you might have IF leaking into your system. The first peak is at about 1575 MHz if I read correctly, which is the L1 carrier 1575.42 MHz of the GPS system. Inmarsat-3 F5 at 54.0°W has GNSS payload, that may be active on that frequency. Maybe with the offset from the observed 61°W, signals are focussing somewhere on the coax cable?

Edit: sorry, now I'm not sure if I read the IF frequencies correctly! Anyway, IF leaking could be an issue.
Or a sidelobe grazing towards earth (the horizon).
 
Last edited:
John

John

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I was thinking you might have IF leaking into your system. The first peak is at about 1575 MHz if I read correctly, which is the L1 carrier 1575.42 MHz of the GPS system. Inmarsat-3 F5 at 54.0°W has GNSS payload, that may be active on that frequency. Maybe with the offset from the observed 61°W, signals are focussing somewhere on the coax cable?


Thanks for the suggestion, i'll give that some thought. The signals when present, were up for a fair amount of time as well, not random quick short burst etc. I'll monitor the position for further activity, thanks again.
 
Terryl

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It could be a harmonic off one of the transponders on EchoStar 16 at 61.5, too many to do the math right now, but a spur or a harmonic could be what your seeing, as 3994.5 is not a standard "C" band transponder freq.
 
beavs2112

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Tell me about this spectrum... Very interesting.
Without hearing from @John directly @frank-sinatra I think that is a screenshot from his Promax field strength meter.
 
John

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Without hearing from @John directly @frank-sinatra I think that is a screenshot from his Promax field strength meter.

Thanks beavs, i wasn't too sure what Frank was asking previously.
It is indeed a Promax HD RANGER +. It's a very very useful bit of kit. :Y
 
John

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... one last report on this mystery as iv'e reached my limit with it on a 2.2 PF.
Tonight at the mystery location i am seeing after having a chat with s-band what looks to be like narrow data signals but very low in level for me.
Again- only seen sigs on Hor polarity across the band, nothing on V / L or R. Signals seen were - 3640-H. 3641-H. 3705-H. 3711-H. 3713-H. It would appear from the Promax that there are others present across the band but even lower in amplitude.
Here's a quick Youtube vid showing these low level sigs. The clicking on the video audio is me throwing a switch on the polarity/skew controller next to the Promax to emphasize the presence of these low level sigs.
Link:-
 
Terryl

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Another funny thing is that there are no "C" band satellites at 61.5, the closest one is at 61.0W, Amazonas 3.
 
John

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... yes that's right, initially when the thread title was started it seemed to be Quote: > "from the 61.5° W area." < only after digging a bit more into the mystery that it becomes possible it is somewhere between 61° to 61.5° West position. The beamwidth on my 2.2 PF and the pulse count on the Venture actuator are not narrow enough to give a more precise arc position fix.
 
Terryl

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How low to the horizon is this satellite to your dish??
 
John

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