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Re: DSP software on Sunsat SO-35



Bob.....back off !  You have forgotten what it takes to make a satellite
in ham service viable!  Renew the fundamentals again.  Cliff K7RR

On Sun, 13 Feb 2000, Bob Bruninga wrote:

> On Sun, 13 Feb 2000, Johann Lochner wrote:
> 
> > Sunsat is equipped with a high resolution imager capable of filling 
> > the 64 MB ramtray in a matter of seconds.  However, because of the 
> > failed 40 Mbit/s S-band downlink, we are forced to download data at 
> > only 9.6 kbit/s.  With about 40 minutes of useful download time per 
> > day this is getting extremely boring (not to mention the frustration 
> > for not being able to capture such wonderful images more often).
> 
> Why be limited to just 40 minutes a day?  When you could have 6 hours
> or more?  With just four  people in the USA, one in the UK,
> one in Australia, one in Hawaii, one in Japan  and a few other places with
> simple Kenwood THD7 walkie-talkies and their build-in 9600 baud TNC's 
> we can provide as much as 6 hours a day or more of downlink
> connectivity to our amateur satellites.... Its trivial to 
> couple the output of the walkietalkie to the internet so that any
> satellite operator can get live feeds from other hams anywhere on earth
> that the internet goes.
> 
> Our site is live and feeding a TELNET port 24 hours a day of every 9600
> baud amateur satellite that comes over the East coast of the USA.  I can
> privately give you the TELNET address (since it is a single user IP
> address).  And my total investment is an HT and and old dos PC running
> APRStk for auto doppler tuning.  Anyone with the Kenwood or other
> 9600 baud receive set up can do the same thing (with the right software).
> 
> This is how we feed all the worldwide APRS data "live" everywhere.  We
> tried to get others to join us and in 1996 through 1998, we had 3
> stations, ours, and one in Madrid and one in Taiwan providing such
> continuous feeds for the MIR downlink.
> 
> The only thing the satelite needs to do is stream the data in UI frames
> instead of a connected protocol.  Then just collect it and munge it back
> together as it dribbles in from all over.
> 
> Similarly, we could VASTLY improve the downlinks of bulk files from our
> existing pacsats if we didnt try to download the same files to every
> ground station, but just let everyone pool their captures together.  This
> would permit a 10 fold improvement in data throughput or more... (unless
> someone is already doing this)...
> 
> Yes, the PACSAT PROTOCOL is very effecient, but it still is delivering
> identical copies of every single byte in every different footprint
> worldwide.  Yes this IS REQUIRED for isolated stations without internet
> connectivity.  But if we only had 4 stations in the USA "pooling" their
> downlink captures, then you would have a 99.99% chance of getting every
> file in only ONE transmission (assuming they get 90% each normally)
> 
> Linking ground stations by the internet is a trememdous bandwidth
> multiplier which we need to take advantage of in the Amateur Satellite
> Service.. 
> 
> de WB4APR, Bob   (US Naval Academy Satellite Lab)
> 
> All the pieces are there (sort of)...
> 
> Kenwood plug-n-play 9600 baud data radios with built in TNC's
> WinAPRS and APRS+SA and others automatically feed all UI packets to IP
> Tracking programs abound...
> 
> (Sorry, my configuration is probbly NOT reproducible because I am using
> a BASIC program on a DOS machine feeding a single RS-232 hardware Remote
> Terminal LAN which just happens to give an IP address to each
> dumb-terminal...
> 
> Anyway, just a thought... (and of course, I could have completely
> missunderstood your posting, and if so, ignore this..<grin>)
> 
> 
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