Atul Sowani wrote:
> When I use tles downloaded from mmccant's site with SatTrack,
> I am getting "checksum error in line[2]" for all satellites.
Can't help with the error you are getting, but I can answer your question...
> What is "checksum" and how it is calculated?
The checksum digit is the last digit on the TLE.
Example:
TRMM
1 25063U 97074A 02073.54250259 .00066661 00000-0 92646-3 0 5707
2 25063 34.9757 236.9292 0000682 267.5731 92.5406 15.55953514246813
The checksum for the first line is "7", and "3" for the second line.
It is calculated by adding the digits of the first 68 characters, modulo 10
(the checksum digit is in column 69). For non-numbers: Blanks, letters,
decimal points and "+" each equal zero, the minus sign ("-") equals one. In
the first line above, adding the digits (don't add the 7 on the end), and
remembering to add one for each "-", you get 157 (157 modulo 10 = 7). For
the second line you get 223 (223 modulo 10 = 3).
Ralph McConahy
34.8829N 117.0064 670m
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This archive was generated by hypermail 2b29 : Fri Mar 15 2002 - 00:55:06 EST