E X T R A C T W.P. Koorts wpk@saao.ac.za ~~~~~~~~~~~~~ ~~~~~~~~~~~ http://www.saao.ac.za/~wpk/ This program builds smaller element files for selected satellites by extracting a subset of elements from a bigger source NORAD element file containing fresh elements. The names and numbers of the satellites to be extracted are contained in intermediate user defined text files. To minimise input typing, default filenames and extensions are intelligently prompted according to your preferences and can be saved for future defaults. THE FILES. ~~~~~~~~~ After unzipping, the following files should be present : * EXTRACT EXE --- The program EXTRACT DOC --- This file EXTRACT PAS --- The Turbo Pascal 4 source file * SETUP DAT --- The startup default filenames and extensions # ALL SAT --- The "all satellites" extraction file EXAMPLE SAT --- An example satellite extraction file NISSEN SAT --- Most of W.Nissen's selected sats (SeeSat list 1 Jul 1996) NEW_MOLC --- An example NORAD element file CRLF EXE --- Program to fix CR/LF problems in element files The files marked '*' are essential for the program to run. The file marked '#' (ALL.SAT) is a special case when you want to extract all the valid satellite elements from a text file. For the above files, the contents of SETUP.DAT will look as follows : new_molc *.sat .tle The first line in SETUP.DAT contains the name of the source NORAD element file from which the elements would be extracted. The second line in SETUP.DAT refers to the default extension of the files containing the list of satellite names or/and numbers you want to extract. The third line in SETUP.DAT refers to the default extension of the output file that is going to be created by the program. Although the user can change the contents of this file by editing, it is normally done by the program itself. On exiting from the program you would be prompted if you want to save the file names & extensions you used, for future defaults. If you answer yes, SETUP.DAT would be saved as such. EXAMPLE.SAT looks as follows : Mir Complex HST 5 KH 11 COBE 5557 Lacrosse 999 TiPS NOSS 10144 MOS Junk This is a list of satellite names and numbers which would be extracted from the source NORAD element file. As can be seen, any mix of names and numbers is allowed. Names are case sensitive, but a subset of a name is allowed eg. the "NOSS" entry will extract all the satellites who's names contain the phrase "NOSS". Numbers smaller than 5 digits are allowed and leading zero's will be added automatically. In practice, you would build a number of these files, containing the names and/or numbers of specific satellites, grouped together under meaningful filename, eg. bright.sat, flashers.sat, zenits.sat, gps.sat, etc. NEW_MOLC, the sample source NORAD file, may contain extra text lines as the program first checks for the signature of valid three line satellite elements to perform the search on. It assumes one line containing the satellite name / description, followed by the standard two line element for each satellite. This file would need to be constantly updated with fresh elements. The filename can be anything since you can input and save it through the program. NISSEN.SAT contains all but the 15.52 EORSATs and the 14.13 Zenit-2's of Walter Nissen's favourite satellites - see his message on the SeeSat mailing list of 1 Jun 1996 and Jim Cook's message on 6 Sep 1996. AN EXAMPLE RUN OF THE PROGRAM. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ To run the program, type "EXTRACT" from the dos prompt. A brief help screen will appear followed by a prompt for the input (source) NORAD filename. Inside "< >" brackets a default filename will appear which is selected by pressing Enter. If you want to change this filename, type it in and enter, including the extension. This now becomes the default for subsequent entries during the current session. Next, a disk directory of all the files with the default extension for extraction files is listed and you are prompted for your entry. Inside "< >" brackets again are the default extension for your input. If you are happy with this extension, only the filename needs to be entered. If you want to change the extension for these files, type the full filename including the extension. This extension now becomes the default for subsequent entries. If you cannot remember what the file with this different extension was called and you want to first see a listing of all these files, enter "*.ext" for a directory listing of all ".ext" files. A special case is "ALL.SAT" which will extract all valid elements from a source file containing other redundant text effectively stripping this text and leave you with just the valid elements. Next, you are prompted for the output filename. Inside "< >" brackets again the default becomes the same filename as the above with the default extension for output files. If you are happy with this selection, simply press Enter. If you want to change the name and/or extension, retype the whole thing. Again, the entered extension becomes the default for subsequent entries. The screen now clears and a summary of your selection is given. If any filename was invalid, the program flags an appropriate error. A running report of which satellite is being processed is given and any unknown one's are reported, together with a beep. When done, you are asked if you are finished extracting and pressing Enter will default to "No". If you are finished, you are asked if you want to save the current filenames as future defaults and pressing Enter selects "No" .... The program exits. The output file(s) created, contains the elements of the satellites extracted from the source file as selected by the extraction file(s). Sometimes you may find that the program cannot find any of the satellites you want, even though you are sure they are contained in the source NORAD file. When this happens, look at the source file to see if the format is correct. When down-loading on some computer setups it can happen that all the lines in the source file become separated by an extra blank line. To fix this, use the program CRLF.EXE on the source file by typing "CRLF sourcefilename" from the DOS prompt in the directory where these two files are. Willie Koorts 24 January 1998