Satgen 342 Satellite Software Pt9 by GM4IHJ 14 Oct 95 HIDDEN EXTRAS - KEPS etc. For many newcomers to Amateur satellites, there is sometimes a shock when they discover that the most expensive of satellite tracking software will not work accurately unless it is fed regular inputs of data by the user. Tracking software is the second step in the complex process of orbit prediction. The first , and much more difficult step, is the regular calculation of the Keplerian orbital elements from radar observations of the satellites orbital behaviour. Fortunately this step is done for us by North American Air Defence ,NORAD and distributed by NASA. Users get these Keplerian elements and enter them into their tracking program software. Keplerian elements are available to Radio Amateurs in two formats , one from NASA, the other via Amsat sources. These formats have slightly different layouts and the user has to know which he is getting. For the above and other reasons there is no absolutely hands off automatic way to update your tracking software. Normally the software is obtained from NASA via Internet or direct, or in the other form from Amsat packet bulletin boards and Amsat publications. But be warned the BBS sometimes carry the NASA format. The user can download to disc from one of these sources using the ordinary internet/packet protocol software " Capture to Disc". But this raw download usually needs editing in a word processor to remove surplus satellite names etc . Care being taken during this process to ensure that the copy does not acquire extra spaces between data items which would upset the Checksum count.The file thus edited is titled as say KEP1.DAT and converted to ASCII format. The tracking program can now be loaded, and run , selecting if available the AUTOUPDATE menu choice. This choice is usually followed by a menu question " NASA or AMSAT " asking the user to identify the format being loaded. Then the file which may contain one or several sets of Keplerian elements for different satellites is transfered. If your software lacks autoupdate, it may have a menu option allowing manual editing of each satellites Kep data from the keyboard. If this option is not present the user is forced to find the data in a program listing and edit the required section again via the keyboard but this time using the operating system edit facility. Always check any entry by running the program after uploading Keps. It is good form to run the program before uploading new Keps and take a print copy of a short tracking sequence, which after uploading can be compared with the revised track show by the new Keplerian elements. Some small changes should be evident but be suspicious of any large changes. Indeed it pays to remember to check and save the new program with its new Keps only when you are happy with the changes. Some years ago, one Keps source corrupted and issued a copy of orbital elements for the Mir space station just as an English cosmonaut was due to operate from the station. IHJ was lucky he happened to spot that the new set were markedly different so he did not use them . Other UK stations were not so lucky.