> On May 5, 2016, at 8:07 PM, Gary E. Miller <g...@rellim.com> wrote:
>
> Yo Frank!
>
> On Thu, 5 May 2016 19:49:28 -0400
> Frank Nicholas <fr...@nicholasfamilycentral.com> 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
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