GGA - GPS Fix Data

GGA - GPS Fix Data

This command enables the 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 quality indicator field (q) is zero), 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, (GPS quality indicator field (q) is zero), the time field (hhmmss.ss) will be frozen and the HDOP field (y.y) will be nulled. If the receiver is not using differential GPS (GPS quality indicator field (q) is not two), then the age of differential data (t.t) and differential reference station ID (iiii) fields will be nulled.

Input Command

• Set response message rate:

  $PMOTG,GGA,yyyyCC

  yyyy	update rate	0 .. 9999 seconds
  CC	optional checksum

Response Message

• Response to above command at selected rate:

  $GPGGA,hhmmss.ss,ddmm.mmmm,n,dddmm.mmmm,e,q,ss,y.y,a.a,z,g.g,z,t.t,iiii*CC

  hhmmss.ss	UTC of position fix
  hh	hours	00 .. 24
  mm	minutes	00 .. 59
  ss.ss	seconds	00.000 .. 59.99
  ddmm.mmmm,n	latitude
  dd	degrees	00 .. 90
  mm.mmm	minutes	00.000 .. 59.999
  n	direction	N = north, S = south
  dddmm.mmmm,e	longitude
  ddd	degrees	000 .. 180
  mm.mmm	minutes	00.00 .. 59.9999
  e	direction	E = east, W = west
  q	GPS status indicator	0 = GPS not available
  		1 = GPS available
  		2 = GPS differential fix
  ss	number of sats being used	0 .. 12
  y.y	HDOP
  a.a,z	antenna height
  a.a	height
  z	units	M = meters
  g.g,z	geoidal separation
  g.g	height
  z	units	M = meters
  t.t	age of differential data
  iiii	differential reference	0000 . . 1023 station ID
  CC	checksum