Satgen60 Satellite Operation - The Software Questions 22 May 90 Even before the advent of the Pacsats, the number of satellite tasks requiring software support was multiplying rapidly, and the problem was intensified by the requirement, to run all these different software tasks at the same time. Today , the operator who wishes to utilize satellites needs some or all of the following :- a. Satellite tracking software . Recently this has included interactive software providing autotracking via computer control of antenna servos. This software is only as good as its Keplerian elements. Modern methods of direct input of NASA/NORAD Keps are coming into use, and, packet radio BBS systems mean anyone can have up to date Keps every 14 days. But many sets of Kep Elements are inaccurate, and different authorities may be using the same names to talk about different methods of producing Kep elements. b. It is at this point that good tracking software with accurate Doppler shift calculation can partly overcome the short comings of the Keplerian elements. Eg.You should not be aiming at the horizon when measured satellite doppler at your Rx indicates the satellite is near overhead. Few Amateurs have used this up to now , but pacsats demand this use of any feature that increases accuracy and reduces operator workload. c. If you track a pacsat or read a comsats telemetry, you need more software for the packet protocol and yet more for the downlink decoding. The hidden implication behind all this, is that you must be able to run ,several programs simultaneously .Something very few Radio Amateurs have done up to now. This demands special software and special computers. The software is known in the trade as " Terminate and Stay Resident". This means you can load the software and it stays in the background working away whilst you pay more direct attention to other programs all running simultaneously on the same computer. In practice this implies that your micro computer must permit these background programs to be attached to its disc operating system , and to be available working all the time unseen, except when you call for a pull down window to make a routine adjustment, before returning the program back to its hidden task. When you buy software look for these features, and when you buy a microcomputer check that it supports these features. The IBM PC , PS2 and direct clones will do this . Ataris may do it with IBM emulators albeit slowly. Amigas are unlikely to have this type of software or features. This does not mean however that stations without IBMs are unable to use Pacsat. You can get by , without autotrack or doppler software on Uosat3's 9600 bps signal , and, you can receive Pacsat and Lusats BPSK if your receiver has Up Down Tuning, capable of being attached to the G3RUH Fuji modem. But it helps particularly on BPSK to have these software aids, and, you should be aware of this trend to simultaneous use of software and all its hardware implications. 73 de John GM4IHJ@GB7MAC 22 May 90