Trimble Outdoors Part Number 45005-00-ENG manual Tracking Modes, Self-Survey Mode

System Operation 5

5.2.2Tracking Modes

The Acutime 2000 operates in one of two main fix modes:

•Self-Survey (Position fix mode)

•Overdetermined Clock mode

After establishing a reference position in Self-Survey mode, the Acutime 2000 automatically switches to Overdetermined (OD) Clock mode.

Self-Survey Mode

At power-on, the Acutime 2000 performs a self-survey by averaging 2000 position fixes. The number of position fixes until survey completion is configurable using the 8E-4B or 8E-A9 command.

The default mode during self-survey is 3-D manual, where the receiver must obtain a 3-D solution with a PDOP below both the PDOP mask and PDOP switch. The PDOP mask and switch criteria can be set and queried using a TSIP packet. If fewer than four conforming satellites are visible, the Acutime 2000 suspends data output.

The highest accuracy fix mode is 3-D manual, where altitude is always calculated along with the latitude, longitude, and time. Obtaining a position requires four satellites with a PDOP below the PDOP mask. Depending on how the PDOP mask is set, 3-D mode can be restrictive when the receiver is subjected to frequent obscuration or when the geometry is poor due to an incomplete constellation.

If only a 2-D solution is desired, or if the exact altitude is known, 2-D manual should be requested. In this case, the receiver uses either the last altitude obtained in a 3-D fix, or the altitude supplied by the user. Any error in the assumed altitude affects the accuracy of the latitude and longitude solution. Use packet BB to set the desired position fix mode.

!Note – Altitude and the fix mode are stored in non-volatile memory.

5-4 Acutime 2000 Synchronization Kit User Guide