Satgen355  Going Digital Pt3   by GM4IHJ                      13 Jan 96

Dove Ao17 has come back on the air again this last week. So notes in
Satgen353 apply regarding using Dove as the simple first entry to the
world of digital satellites. When you get more ambitious , you will need,
as explained in satgen354, a PSK Phase Shift Keying modem in order to be
ready to operate through the JD digital mode of satellite JAS-2 which is
scheduled for launch in September 96.    Once you master the rudiments of
PSK digital operation on JAS-2, you can then think about moving up to the
more complex Ao16 Pacsat, and Ao19 Lusat, which also use PSK downlinking.
Frequencies for these digital satellites are :-

Satellite        Uplink Mhz                    Downlink Mhz
JAS-2        145.85 145.87 145.89 145.91         435.910
callsign      NRZ-I biphase FM 1200 bps        NRZ-I PSK 1200 bps
posibly                or                              or
8J1JCS ?      NRZ-L FSK 9600 bps               NRZ-L FSK 9600 bps

Pacsat Ao16  145.9 145.92 145.94 145.96          437.051
 Pacsat              Biphase FM 1200 bps       PSK 1200 bps

Lusat Ao19   145.84 145.86 145.88 145.9          437.1258
 Lusat               Biphase FM 1200 bps       PSK 1200 bps

You will require a computer ( PC, Amiga, Atari ) with tracking software to
manually or automatically aim your antennas. The G3RUH modem has automatic
frequency control hardware to tune your receiver, to correct the large
doppler shift ( Tx tuning is not necessary ).In addition you will require
communications protocol software. In the case of JAS-2 operation, this can
be a standard packet radio protocol which you use for terrestrial packet ,
but please note that if you wish to track and communicate on the same
computer, it must be capable of using "Terminate and stay resident"
programmes sequentially, or have "Multi tasking capability ".

JAS-2 will be accessed using a simple command ( probably)  c 8J1JCS
When the satellite confirms access , single letter commands tell it what
you want (A,B,F,H,K,M,R,U,W,Y,Q). Some are the same as terrestrial packet
commands, but B= Bulletins , not Bye , and Q = quit. In Jas-1 Fo20 the
operator had to make a hard disconnect ( Control C followed by D )

A016 and Ao19 use a much more complex communications software protocol
referred to as PG for uploading and, PB for some downloading. Recently an
excellent Windows program WiSP has appeared. WiSP is much easier to set up
in your computer and to use on the air. PG PB require a PhD in Microsoft
DOS to figure out how to set them up. 

Note... JAS-2 will have both 1200 bps PSK and, 9600 bps FSK operation .
These will not be available simultaneously. So it is to be hoped that
Jamsat will schedule at least one day a week of PSK 1200 bps operation in
order to continue the availability of this simplest of all PSK formats ,
to help provide a good starting platform for digisat newcomers.