Trimble Standard Interface Protocol

A

0x47

0x48

Report Packet 47

Signal Levels for all Satellites Report

This packet provides received signal levels for all satellites currently being tracked or on which tracking is being attempted (that is, above the elevation mask and healthy according to the almanac). The receiver sends this packet only in response to packet 27. Table A-37 shows the data format.

Table A-37 Report Packet 47

Byte

Item

Type

 

 

 

0

Count

BYTE

 

 

 

1

Satellite number 1

BYTE

 

 

 

2-5

Signal level 1

SINGLE

 

 

 

6

Satellite number 2

BYTE

 

 

 

7-10

Signal level 2

SINGLE

 

 

 

(etc.)

(etc.)

(etc.)

 

 

 

Up to 12 satellite number/signal level pairs may be sent, indicated by the count field. Signal level is normally positive. If it is zero then that satellite has not yet been acquired. If it is negative then that satellite is not currently in lock. The absolute value of signal level field is the last known signal level of that satellite.

The signal level provided in this packet is a linear measure of the signal strength after correlation or de-spreading.

Report Packet 48

GPS System Message Report

This packet provides the 22-byte ASCII message carried in the GPS satellite navigation message. The receiver sends this packet in response to packet 28 and when this data is received from a satellite.

The message is effectively a bulletin board from the Air Force to GPS users. The format is free-form ASCII. The message may be blank.

A-48

Acutime 2000 Synchronization Kit User Guide

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Trimble Outdoors Part Number 45005-00-ENG 0x47 0x48, Signal Levels for all Satellites Report, GPS System Message Report