Yo Frank! On Thu, 5 May 2016 19:49:28 -0400 Frank Nicholas < address@hidden> wrote: We want to use PGGA sentence because it appears first, closest to
the start of the second in each cycle.
You have mode set to 17, using message GPRMC. Can someone who knows
more than me, explain to me if it really matters?
NMEA sentences are vaiable length. So you want to use the first one to cut jitter on the NMEA time. In practice you have the PPS, 10,000 times more accurate, so never a problem unless you lose PPS.
And on the Adafruit HAT & Ultimate GPS breakout board, the first NMEA sentence at the start of a cycle is “GPGGA”. So are you saying that with PPS, it really doesn’t matter? Your second sentence makes me think it matters. The last sentence makes me think it **doesn’t** matter... Some GPS can barely get all their sentences out every second at 9600.
If you have a lot of sats in view, or optional NMEA turned on, your
buffers may overflow.
On the above GPS, there are periodic (not every second) sentences that will cause a cycle to extend beyond one (1) second at 9600.
Thanks, Frank |