User`s guide

Chapter 5 - I/O Commands
Motorola GPS Products - M12+ User's Guide Revision 6.X 09FEB05
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GPRMC (NMEA RECOMMENDED MINIMUM SPECIFIC GPS/TRANSIT DATA)
This command enables the GPRMC Recommended Minimum Specific GPS/Transit 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 (a) is
'V'), then the time (hhmmss.ss) and date (ddmmyy) fields will be nulled. If the receiver is not
computing a position fix sometime after the first fix, the time (hhmmss.ss) and date (ddmmyy)
fields will be frozen. If the receiver is not computing a position fix (status field is 'V'), then the
speed over ground (z.z) and track made good (y.y) fields will be nulled.
Note 1: The Magnetic Variation field (d.d) will always be nulled since the M12 Oncore does not
have this information.
Note 2: 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.