Trimble Standard Interface Protocol

A

0x2B

!

0x2D

Command Packet 2B

Initial Position (Latitude, Longitude, Altitude) Command

This packet provides the GPS receiver with an approximate initial position in latitude and longitude coordinates (WGS-84). This packet is useful if the user has moved more than about 1,000 miles since the previous fix.

Note – The GPS receiver can initialize itself without any data from the user; this packet merely reduces the time required for initialization.

This packet is ignored if the receiver is already calculating positions. The cold-start default LLA position is 0, 0, 0.

The data format is shown below.

Table A-20 Command Packet 2B

Byte

Item

Type

Units

 

 

 

 

0-3

Latitude

Single

radians, north

 

 

 

 

4-7

Longitude

Single

radians, east

 

 

 

 

8-11

Altitude

Single

meters

 

 

 

 

The GPS receiver returns packet 4C.

Command Packet 2D

Oscillator Offset Request

This packet requests the calculated offset of the GPS receiver master oscillator. This packet contains no data. The GPS receiver returns packet 4D hex. This packet is used mainly for service.

A-26

Acutime 2000 Synchronization Kit User Guide

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Trimble Outdoors Part Number 45005-00-ENG manual 0x2B 0x2D, Initial Position Latitude, Longitude, Altitude Command