Random Optimization Algorithm on GNSS Monitoring Stations Selection for Ultra-Rapid Orbit Determination and Real-Time Satellite Clock Offset Estimation

Table 1

Calculation strategy of the ultra-rapid orbit determination and real-time clock offset estimation.

	Parameter	Ultra-rapid orbit handing strategy	Real-time clock offset handing strategy
Observation information	Observation	Undifferenced ionosphere-free	Undifferenced ionosphere-free
		phase and code combination:	phase and code combination:
		L1 and L2(GPS)	L1 and L2(GPS)
	Elevation mask angle	7°; height angle	7°; height angle
		weight determination	weight determination
	Observation arc	24h arc	- -
Error correction	Phase winding	Model correction	Model correction
	PCO/PCV	IGS08 Model	IGS08 Model
	Gravity field	EGM96 model (8×8)	- -
	Ocean, solid earth and pole tide	IERS conventions 2010	IERS conventions 2010
	Relativistic effect	IERS conventions 2010	IERS conventions 2010
	Solar light pressure model	ECOM9 Model	- -
Parameter estimation	Satellite orbit	Estimation	Fixed as ultra-rapid predicted
			orbit of CUM
	Site coordinates	Estimation	Fixed as IGS week solution
	ERP	IERS prior constraint +	Fixed as IERS result
		parameter estimation
	Troposphere	SAAS model / GMF projection	SAAS model / GMF projection
		+ random walk estimation	+ random walk estimation
	Clock offset of satellite	Estimation (white noise)	SRIF estimation
	Clock error of receiver	Estimation (white noise)	Estimation (white noise)
	Ambiguity	Estimation	Estimation