Trimble Outdoors Part Number 45005-00-ENG Automatic Operation, Satellite Masks, Elevation Mask

System Operation 5

5.2Automatic Operation

When the Acutime 2000 has acquired and locked onto a set of satellites that pass the mask criteria listed below, and has obtained a valid ephemeris for each satellite, it performs a self-survey. After a number of position fixes, lasting approximately 40 minutes, the self- survey is complete. At that time, the Acutime 2000 automatically switches to a time-only mode and periodic outputs of navigation information cease.

5.2.1	Satellite Masks
	The Acutime 2000 continuously tracks and uses up to eight satellites
	in an overdetermined clock solution. The satellites must pass the
	mask criteria to be included in the solution.
	Table 5-1 lists the default satellite masks used by the Acutime 2000.
	These masks serve as the screening criteria for satellites used in fix
	computations and ensure that solutions meet a minimum level of
	accuracy. The satellite masks can be adjusted using the TSIP protocol
	described in Appendix A, Trimble Standard Interface Protocol.
	Table 5-1	Default Satellite Mask Settings
	Mask	Setting	Notes
	Elevation	10°	SV elevation above horizon
	SNR	4	Signal strength
	DOP	8	Self-survey only

Elevation Mask

Satellites below 10° elevation are not used in the solution. Generally, signals from low-elevation satellites are of poorer quality than signals from higher elevation satellites. These signals travel farther through the ionospheric and tropospheric layers and undergo distortion due to these atmospheric conditions.

5-2 Acutime 2000 Synchronization Kit User Guide