Advantech INTRAC-305 user manual Epoch, XNDT20, XNDD60, Bstar, Xincl, Xnodeo, Xmo

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INTRAC-305 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 (er**-1)
	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 INTRAC-305 can use the IESS-412 or NORAD data to build the satellite’s orbit model instead of having to learn the orbit over a 24hr period.

The IESS-412 data is selected for the Rapid Model Generation in the Models menu and ENTER pressed. The orbit model is calculated and the INTRAC enters Tracking Mode.

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 vice-versa.

© 2011 Advantech Wireless INTRAC-305 MANUAL - Issue 3.2 Page 61