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[aprssig] high altitude balloon / Raspberry Pi SSTV/ RTTYtracking

Charles Blackburn ai4ri at cfl.rr.com
Fri Jul 20 22:16:49 UTC 2012


using VSB (vestigal side band) you have fast scan TV, but that's not 
packetised data, that's a constant stream. normal ntsc style VSB video is 6 
meg wide.

It definitely wont work on vhf at 1200 bps.

-----Original Message----- 
From: Lynn W. Deffenbaugh (Mr)
Sent: Friday, July 20, 2012 5:57 PM
To: TAPR APRS Mailing List
Subject: Re: [aprssig] high altitude balloon / Raspberry Pi SSTV/ 
RTTYtracking

Read http://wa8lmf.net/bruninga/vision.html

AFAIK, never been truly implemented, but has some discussion about
packet counts required to assemble even a small grayscale image. I
really couldn't see any way that video frames could come in over 1200
baud, or maybe even 9600 baud, and have any chance at actually getting
enough frames per second for motion.

It's not the APRS-IS that's the major consideration, but the RF channel
first.  But don't get me wrong, the APRS-IS isn't really made for
transmitting that kind of packet rate either.

Lynn (D) -KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

On 7/20/2012 5:38 PM, Thomas Krahn wrote:
> Keith,
>
> In principle SSDV frames could be transmitted through APRS just as fine 
> (imagine live pictures popping up at various places on the APRS map).
> However we already have extremely high APRS packet collision rates at some 
> regions and hot running aprs.is servers so that I hesitate to encourage 
> it. The solution is probably to shift to higher frequencies and baud rates 
> for this. I wonder if the aprs.is backbone could handle that. Maybe the 
> backbone specialists could give us some idea what is realistic.
>
> Thomas
> KT5TK
>
>
>
> On 07/20/2012 02:16 PM, Keith VE7GDH wrote:
>> Thomas KT5TK wrote...
>>
>>> The balloon with the Raspberry Pi was actually transmitting
>>> the webcam pictures with SSDV rather than SSTV...
>>> http://ukhas.org.uk/guides:ssdv
>>
>> Thanks for the clarification. I hadn't heard of SSDV before.
>> It was an interesting project even if APRS wasn't involved.
>>
>
>
>
> _______________________________________________
> aprssig mailing list
> aprssig at tapr.org
> https://www.tapr.org/cgi-bin/mailman/listinfo/aprssig
>



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