Satgen 135      Some Satellite Problems   by GM4IHJ           27th Oct 91

Uosat3 and Uosat5.  Have just spent two weeks using the Amsat PBG version
5/09/91 ground station client software on Uo3 and Uo5. The authors are to
be congratulated. It really works. But there are still lots of pitfalls
for the newcomer with what some regard as a Catch 22 situation still
applying. Whereby - To get on Uosat3 you need to know all about it - But
to know all about it, you need to be on Uosat3.
The recent publication of the Pacsat Beginners Guide , does not help much.
It contains no information on the Uosats, and it has many gaps when it
tackles Pacsat. So what are these difficult features ?
Firstly as the Amsat NA software is only configured for Pacsat AO16. If
you want to use Lusat or Uosat you must build your own configuration
files. Easy if you are a DOS wiz but difficult if you are not. Also
because it concerns itself strictly with Pacsat it gives no hint that when
running the faster Uosat at 9600bps you must run your TNC to micro link at
19200bps to allow for data expansion in the TNC, and , your TNC to micro
cable must be wired 6 way not the usual packet 3 way ( see Uosat3
Operating Manual revised edition , for details ). Less obvious are the
implications that the Pacsat protocol uses  8 bit No parity. By contrast
European terrestrial packet uses 7 bit even parity. So the would be user
has to accept that his satellite and his terrestrial systems are
incompatible, and he can either accept a time wasting plug busting,
mistake inducing change of BAUD, AWLEN, Parity plus cable changes to or
from a modem disconnect situation, every time he switches from terrestrial
to sat operation, or, he must do as many have already done and devote a
dedicated TNC and micro computer to Uosat. Noting that at least the latter
takes care of the multiple software he must run ( Tracking, Doppler and
Protocol ) if he is to use Uosat comfortably.
Please note that in addition to the above Uosat3 needs direct Tx audio to
the Tx varactor, direct Rx audio from the Rx discriminator, and while Tiny
2 and Micropower2 TNCs seem to work well. The two TNC 320s Ive seen cannot
be used because they jump PORTs when transmitting up to the sat, and I
have not heard of anyone getting a PK232 to work at 9600bps full duplex.
Despite the above all is not lost. G3RUHs 9600 modem notes are excellent
and the Paccom instruction book with their NB 96 version of the RUH modem
is also very useful. Whilst on the home front GM4IHJ has tried to help
with a full update of his Uosat Op Manual. So do not despair, Uosat is
streets ahead of the other Pacsats and it is well worth the effort.

RS12. This being my week for admitting that not everything in the
satellite garden is perfect, I must now correct a misunderstanding in
regard to RS12. This sat is on mode K 21MHz up 29MHz down to take
advantage of the very high levels of solar activity. Which means that
while it may give the specially equiped stations some excellent sub
horizon ionosphere assisted contacts from the other end of the world, it
is not performing at all well as a normal sat link when above your
horizon. The fact is that given the present very disturbed Sun, none of
RS12s modes of operation is much use for ordinary sat work. So I apologise
if I have misled newcomers into thinking RS12 was marvelous at the moment,
when in fact it is only going to produce any sort of half decent results
at night. 73 de GM4IHJ @ GB7SAN