File Name format: ???_< YYYY> <MM> <DD> <HH>. Agl
Here is an example: STN_2010011022.Agl
1) The almanac is an ascii (8 bit characters) text file with lines separated by <CR> or <CR><LF>
2) The Almanac is a series of “entries”
3) Each “entry” represents almanac data for one space vehicle or satellite in the Glonass constellation at a particular time/date.
4) Each “entry” is three lines of the file and has 20 numbers plus an optional comment which could be non-numeric
5) Each line of an “entry” is some numeric values with one or more spaces between values, the first line could optionally have a comment at the end which could be non-numeric
6) Integers may have leading zeros “01” .vs. “1”
7) Non integers are in “E” format: “0.273825937E+05 “ is the number 27382.5937
8) There are no blank lines between “entries”, there are no optional comment lines
9) The file starts with line 1 of the first entry
10) There can be a large number of “entries” in an AGL file with almanac data valid at different times and for different satellites (space vehicles)
Here is an example of an “entry” – there are three lines of the text file.
01 01 2011 1800 COMMENT
1 1 1 01 01 2011 0.273825937E+05 0.000000000E+00 0.000000000E+00 0.179290771E-03
0.5286379E+00 0.9077072E-02 -0.1849365E-01 0.5264282E-03 -0.2655781E+04 -0.1586914E-02
Here are the descriptions of the data on the three lines. Data is separated by one or more spaces.
Line 1
1 – day of Almanac
2 - month of Almanac
3 - year of Almanac
4 - time of receipt of the Almanac from the beginning of the day, UTC
5 – optional comment (with which the receiver is received, SW version etc.)
Line 2
1 - number of spacecraft in the grouping (orbital slot number)
2 - number of frequency channel (-7 .. 6)
3 – SV health indicator (0 -> bad, 1 -> healthy, operational)
4 - day
5 - month
6 - year
7 - the reference time of the almanac
8 – Correction from GLONASS to UTC
9 – Correction to GPS time relative GLONASS
10 - Correction of time relative to GLONASS system time,
Line 3
1 – Lamda - longitude of first ascending node passage, angle in semi-cycles
2 - dI - correction to the mean value of inclination, in semi-cycles
3 - w - argument of perigee, in semi-cycles
4 - E - eccentricity
5 - dT - correction to the mean value of Draconian period, in second
6 - dTT - rate of change of Draconian period, in second / coil