Satgen353 Going Digital by GM4IHJ 30th Dec 95 For most Radio Amateurs, the step up from terrestrial radio communications via the ionosphere, to satellite communications via ordinary analog SSB or CW , is a step too far. Those who do make this move successfully are few in number, and being the more adventurous members of the amateur radio community, they want to take their new found ability as far as it will go. Which these days means, that they will eventually want to try their luck with the digital satellites. It has to be said right from the start, that this is no easy step , even for the amateur who can afford to purchase all the latest black boxes and computers. For those who have to " Home Brew ", it can appear an almost impossible task, but, there are ways in which steady progress can be made , one step at a time. , rather than in a giant leap straight onto the highly complex Pacsats and Uosats. Now back on line , and coming down on 145.820 FM, with AX.25 telemetry is the ever useful Dove. If you have never tried to copy digital signals from space, Dove is the place to start. With a standard AX.25 terrestrial station and an omni directional 2m antenna you can copy Dove simply by leaving your receiver tuned to 145.820 FM , and feeding your receiver audio into your station terminal node controller (TNC). Please be careful that you dont mix up Dove with Uosat 11 which uses the same frequency. You will find your TNC decodes Dove and passes its telemetry to your computer as ASCII, whereas, Uosat 11 which sounds much the same as Dove is not AX.25, and produces nothing from your TNC. During 1996 Dove may be joined by the Stanford University satellite Sapphire which may eventually provide two way 2m AX.25 communications, though actual dates when this might be available are not yet finalised. There is also Spacestation MIR, operating AX.25 digital communications on 2m down links , and up links. But MIR is not recommended as a test vehicle for digital newcomers. Its transmissions are less frequent than Doves, and it is regularly targeted by high powered stations who make it impossible for normally operated stations to get access , or , break up normal station traffic once it has started. Once some experience has been achieved on simple 2m AX.25 links, the next step is up to Phase Shift Keying, the mode employed by Pacsat AO16 and Lusat AO19, and until recently used by Fo20 mode JD, all on 70 cm down links. The Fuji (Fo12 and Fo20) series of Japanese satellites were a much simpler step up than Pacsat or Lusat, as both these latter require powerful computer support, whereas the Fuji protocol is much simpler and does not require a complex computation protocol. Unfortunately the present Fuji Fo20 cannot now operate digitally, because of that modes heavy demands on its now aging and depleted power supplies , but JAS-2 the next Fuji satellite should be in space by late summer 96. So anyone building a PSK modem onto G3RUHs excellent modem PCB, should have it ready when JAS-2 becomes operational, if building of the modem starts now.