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Copernicus GPS Receiver     1 6 5

TRIMBLE STANDARD INTERFACE PROTOCOL (TSIP)     A

Several packets have been added to the core TSIP protocol to provide additional 
capability for OEM receivers. In OEM Packets 

0x

8E and their 

0x

8F responses, the 

first data byte is a sub-code which indicates the superpacket type. For example, in 
Packet 

0x

8E-15, 15 is the sub-code that indicates the superpacket type. Therefore the 

ID code for OEM packets is 2 bytes long followed by the data. Command packet 
0x35 is used to enable superpackets.

This packet allows the user to change the default datum from WGS-84 to one of 180 
selected datums. The datum is a set of 5 parameters which describe an ellipsoid to 
convert the GPS receiver’s internal coordinate system of XYZ ECEF into Latitude, 
Longitude, and Altitude (LLA). This affects all calculations of LLA in packets 0x4A 
and 0x84.

The datum can be changed to match coordinates with another system such as a map. 
Most maps are marked with the datum used. In the US, the most popular datum for 
maps is NAD-27. You may choose a datum optimized for the local shape of the earth, 
however optimized datums are truly local and provide very different results when 
used outside of the area for which they are intended. WGS-84 is an excellent general 
ellipsoid valid around the world. To request the current datum setting, one data byte is 
sent. Report Packet 0x8F is returned.

Table A.56

Command Packet 8E-15

To change to one of the internally held datums, the packet must contain exactly 2 
bytes representing the integer value of the index of the desired datum.

Table A.57

Command Packet 8E-15

Byte

Type

Meaning

0

Superpacket

0x15

Byte

Type

Meaning

0

Superpacket ID

0x15

1-2

INT16

Datum index