[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: DSP software on Sunsat SO-35



On Sun, 13 Feb 2000, Clifford Buttschardt wrote:

> 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:
> > Why be limited to just 40 minutes a day?  When you could have 6 hrs or
> > more?  With just [..lots of individuals worldwide listening... and...
> > combining downlinks via the internet for spatial diversity reception... 

Not sure of your point.  I agree that looking at a picture someone "else"
donwloaded holds little thrill, but if *my* station contributed to the
packets that went into building that file in only 10% of the time or with
10%  of the bandwidth than it currently takes, then I would be proud of my
station's contribution and would look forward to each pass...

Or, if your point is that PACSATS are for delivering traffic to isolated
individuals and not to gateways, then you are overlooking the tremendous
contributions over the past many years of the 31 or so UO-22 SATGATES that
moved the bulk of the international amateur BBS traffic worldwide...

Or if your point was... being on an island in the middle of the pacific
where ther is no internet....  Even still,  I could improve
my downlink effeciency *many fold* if I simply operated two receiver
systems, and then sorted and merged the PACSAT downlink packets into
complete files.  Whether you combine receivers with twisted pair over a
few feet, or hundreds of miles via the ubiquitous internet, the
improvements in downlink effeciency are still great.

That was my only point.  That if we looked on downlinks as being a "group"
effort, instead of an individual one, we could move a lot more data.,
especially for the large image files... on some of the birds.

50 years ago "diversity reception"  was the most powerful technique
for improving HF reception.  No reason why we shouldnt be doing it on the
satellites for those large image files that we dont care how they get
down, as long as we get every pixel from someone somewhere...

I don't see the internet as a threat to the "fundamentals" of amateur
radio at all.  I think of it as a great un-tapped opportunity to
explore new benefits to amateur radio...

Another example is the dozens of HF receivers all feedin APRS traffic on
10.151 LSB.  Although 300 baud HF packet is a terrible way to send HF
data, the fact that there are many DOZENS of simultaneouse HF receviers
all over the USA combining their outputs into a single APRServe feed,
(199.227.86.221) makes it work very well in deed.  Even if the chance of a
packet getting through is 5%, the fact that 20 stations are listening
spread out over millions of square miles gives you an almost certainty
that at least ONE of them receives it.

de WB4APR, Bob


----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home