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| TECHNICAL DESCRIPTION |
negative when entering from the front panel. This only applies to the LMO data field.
NORAD data | The NORAD ephemeris data consists of a string of 166 | |||
| characters. The first 160 characters are split into two “Card | |||
| Element Sets” of 80 characters each. The next two characters | |||
| (161 & 162) comprise the Minutes Interval and characters 163 | |||
| & 164 comprise the Period of Validity of the ephemeris. The | |||
| final two characters (165 & 166) are the check sum. | |||
| There are ten blocks of orbital element parameters contained | |||
| in the NORAD ephemeris character string :- | |||
| Charas. | Data | Description | |
| 19 | - 32 | EPOCH | format - YYDDD.DDDDDDDD |
| 34 | - 43 | XNDT20 | 1st rate of change (rev/day/day) |
| 45 | - 52 | XNDD60 | 2nd rate of change (rev/day/day/day) |
| 54 | - 61 | BSTAR | damping factor |
| 89 | - 96 | XINCL | inclination (deg) |
| 98 | - 105 | XNODEO | ascending node (deg) |
| 107 - 113 | EO | eccentricity | |
| 115 - 122 | OMEGAO argument of perigee (deg) | ||
| 124 - 131 | XMO | mean anomaly (deg) | |
| 133 - 143 | XNO | mean motion (rev/day) | |
RAPID MODEL GENERATION The
The
For the NORAD data there are five choices of NORAD algorithm. These are SGP, SGP4, SGP8, SDP4 & SDP8 and each gives a slightly different Az/El pointing for the same NORAD data.
⎯ | SGP | the original NORAD algorithm |
⎯ | SGP4 | applies to Near Earth Orbits |
⎯ | SGP8 | applies to Near Earth Orbits |
⎯ | SDP4 | applies to Deep Space Orbits |
⎯ | SDP8 | applies to Deep Space Orbits |
Orbits are differentiated by their period. Those of less than 225 minutes are Near Earth Orbits and those of more then 225 minutes are Deep Space Orbits. Geostationary satellites are in Deep Space Orbit.
It is assumed that the user know which algorithm applies to the data to be used. However INTRAC will not allow a Near Earth Orbit algorithm to be used with Deep Space Orbit data and
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