5 gps operations, 1 introduction, 2 gm862-gps serial ports – Rainbow Electronics GM862-GPS User Manual
Page 97: 3 wgs 84, 1 gps serial port b (nmea)
GM862-GPS Software User Guide
1vv0300729 Rev. 5 - 05/07/07
Reproduction forbidden w ithout Telit Communications S.p.A. w ritten authorization - All Rights Reserved
page 97 of 120
5 GPS operations
5.1 Introduction
The GM862-GPS module is equipped with a SiRFStar III GPS receiver that is controllable by the GSM
modem using a setof AT commands or dedicated NMEA sentences.
5.2 GM862-GPS Serial Ports
2 serial ports are available on the module:
•
MODEM SERIAL PORT
•
GPS SERIAL PORT B (NMEA)
5.2.1 GPS SERIAL PORT B (NMEA)
This port is carrying out the GPS navigation data in NMEA 0183 format.
The default configuration is 4800 bps, 8, n, 1
It is available on the following pins:
PIN #
NAME
DESCRIPTION
TYPE
35
TX_GPS
GPS TX Data (N MEA)
CMOS 2.8 V
41
RX_GPS
GPS RX Data (NMEA)
CMOS 2.8 V
5.3 WGS 84
GPS receivers perform initial position and velocity calculations using an earth-centered earth-fixed
(ECEF) coordinate system. Results may be converted to an earth model (geoid) defined by the
selected datum. For GM862-GPS the default datum is WGS 84 (World Geodetic System 1984) which
provides a worldwide common grid system that may be translated into local coordinate systems or
map datums. (Local map datums are a best fit to the local shape of the earth and not valid worldwide).