Re: I like internet/satelite idea!!!

["Curtis D. Levin" <kd4zkw@xxxxxxxxx>]

Most sats that use high speed digital access don't have to compensate for
doppler shift, as they are in geosynchronous orbit. So, they are
stationary over one point at all times. Thus, no doppler shift. 
Aside from that, most of the high speed packet goes over land, or under
water. Fax might be one exception, but it only moves at 9600 baud, 
and 9600 baud isn't unthinkable. 

Maybe we should be thinking more in terms of duplexing the signal. 
Besides, most packet traffic, aside from mails, etc, are simple
keyboarding. Java might be able to supplement this, if the applications
are local. Aside from that, most of the graphical stuff you see on the
Inet isn't practical for radio, and wastes alot of bandwidth.  Also,
for spacecraft, power consumption is a problem. Some amateur sats have
to be shut down on occasion, as their usage causes mucho current drain.

My thinking on the subject is to do our best to eliminate redundant
transmissions. redundancy occurs in packet radio when a sat has to 
transmit data to each individual station, even if all stations in range 
pick up every transmission. This is due to the fact that packet requires 
an ack from every station it's linked to. This is what causes the problems
on the Mir digipeater and mailbox. My thinking is the ideal setup would be 
to eliminate ack transmissions, as in unproto mode. But it's hard to
keyboard in unproto, as the monitor sees every transmissions going to and
from the platform. Two ways to eliminate this.

1) Go duplex. Transmitted sigs would go to the uplink without the need for 
an ack, as the ack would be whatever was retransmitted down. If you didn't
receive it, then it wasn't sent. Software that is written for this
specific purpose is plausible, but technologically speaking, a system
would have to be devised so that the tnc would listen on the tr freq, and
delay would have to be set so that other stations could also transmit, and
not interfere. The other possibility is to devise a scheme that uses a
mixer to accomplish this, so that all stations could transmit on slightly
different freqs and be received simultaneously. SS is another possibility.

2) Give the platform a dedicated link to an Earth station, and give the
radios a link to a station that is linked to the earth station. Or a
network of earth stations. APRS has been doing this, and it is functional,
but it's not a direct connection to space. it is a connection to the space
vehicle tho, and if that is the goal, then the problem is solved. 

With a little ingenuity, both might be accomplished, serving different
purposes. Packet isn't outdated tho. All things considered, it's pretty
efficient, at least for keyboarding. Beats rtty, and alot of other modes
right out of the water, and the first phone modems were only 300 baud, so
this is much faster. 9600 would be even better. eventually, someone might
even make a data radio that works the way it should.

Face it, most of the bulk transmissions received over the net is
redundant. Headers, etc are a waste of space, and so is most of
the info we transmit to each other. The best way to avoid this is to
develop applications, like java, that only transmit the necessary info
to update an already running application. A dual link, like one into
space, and one onto the inet would work, if people adhered to the original
scheme, and started cacheing information locally. There are other
applications that allow for this, for group projects, etc. Think about
what is being sent to and fro, and eliminate the unnecessary, and you will
find 1200 baud to be pretty adequate. Loosen up a bit, and you'll get more
fo your bit than ever before.
73

Curtis - kd4zkw