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Chapter 5 - I/O Commands
NMEA GPGGA MESSAGE
This command enables the NMEA GPGGA GPS Fix Data message and determines the rate at
which the information is transmitted. The periodic rate field (yyyy) instructs the receiver either to
output this message once (polled), or to output this message at the indicated update rate
(continuously). Once the receiver is set to continuous output, the continuous flow can be stopped
by sending a one-time (polled) output request. The receiver will output the response one final
time, and then terminate any further message outputs. The value of the periodic rate is retained
through a power cycle only if battery backup power is applied.
If the receiver has just powered up and has yet to compute a position fix (GPS status field is '0'),
then the time (hhmmss.ss) and HDOP (y.y) fields will be nulled. If the receiver is not currently
computing a position fix sometime after the first fix, the time field (hhmmss.ss) will be frozen and
the HDOP field (y.y) will be nulled. If the receiver is not currently receiving differential GPS
corrections (GPS status field (q) is not '2'), then the age of differential data (t.t) and differential
reference station ID (iiii) fields will also be nulled.
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NOTE: Height reported in the GPGGA message is GPS height, and the geoidal separation field
(g.g) will always be nulled since the M12 Oncore does not calculate this information.
Legacy Code Compatibility: The GPGGA message was output in a similar fashion by Motorola
VP, GT+, and M12 Oncore receivers.
Note: United States export laws prohibit commercial GPS receivers from outputting valid data if
the calculated GPS height is greater than 18,000 meters (11 miles) and the calculated 3D
velocity is greater than 514 meters/second (1135 miles/hour). If the receiver is used
above both of these limits concurrently, the height and velocity outputs are clamped to
the maximum values. In addition, the latitude and longitude information will be incorrect.
Motorola GPS Products - M12+ User's Guide Revision 6.X 09FEB05
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