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Lassen-SK8 Embedded GPS Module A-33
Trimble Standard Interface Protocol
the almanac). The receiver sends this packet only in response to Packet 0x27. The data
format is shown below.
Up to 8 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. Units, either AMU
or dBHz, are controlled by Packet 0x35.
A.17.28 Report Packet 0x48
This packet provides the most recent 22-byte ASCII message broadcast in the GPS
satellite navigation message. The receiver sends this packet in response to Packet 0x28.
The message effectively is a bulletin board from the Air Force to GPS users. The format is
free-form ASCII and is often enabled or encrypted. The message may be blank.
A.17.29 Report Packet 0x4A
This packet provides current GPS position fix in LLA (latitude, longitude, and altitude)
coordinates. If the I/O “position” option is set to “LLA” and the I/O “precision-of-position
output” is set to single-precision, then the receiver sends this packet each time a fix is
computed.
Table A-32. Report Packet 0x47 Data Formats
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.)