Re: LRPT Laboratory Bandwidth testing

Patrick Lindecker

Hello Fred,


TKS for the LRPT pictures.


>I was using the Sawbird but kept the signal levels low (which may help, or hurt, I don't know yet). 

If you can avoid it, better is to avoid. In my opinion, even if of good quality, it brings a small signal degradation.

>Anyway, beautiful snow pictures, but plenty of lines. 

I looked at these lines. In fact, they are 8 pixels width. A line must be composed of elementary small pictures of 8x8 pixels, transported by one or several bad received frames.





De : [] De la part de Fred Albertson
Envoyé : lundi 21 décembre 2020 15:06
À :
Objet : [multipsk] LRPT Laboratory Bandwidth testing


Hi Patrick, Andrea, Josef, et al,

Using the I/Q output from my RSPduo into MultiPSK (still refining the procedure), I decoded an almost perfect
pass this morning at 1318Z.  M2 was 88 degrees overhead and 826kM away.  The NORAD altitude information shows:

Perigee: 825.3 km
Apogee: 835.1 km

So it was about as close as it is going to get until it falls out of the sky!

The only problem was that NOAA19 came wandering in at about 1328Z, which halted the decode.  By that time
I had about 3700 synchros, and some pretty good pictures:

64                                                                              65                                                                             68                                                                             R-G-IR

I was using the Sawbird but kept the signal levels low (which may help, or hurt, I don't know yet). 

My theory was that narrowing the bandwidth, by using the 120kHz filter in the RSP, vice the full 192kHz,
would keep the VDL2 signals (136.975kHz), which I receive loud and clear, out of the signal that AMIGOS,
was seeing.  I believe that I did that effectively. I can not tell for sure that other VHF signals are not in
the bandwidth, but continuous manual monitoring with no satellite in view does not show interference.

Anyway, beautiful snow pictures, but plenty of lines. 

This is an Alpha level report, so I am not drawing any conclusions.


Great Day,


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