On Mon, May 7, 2012 at 1:48 PM, Gary E. Miller <address@hidden>
On Mon, 07 May 2012 16:44:36 +0100
Ed W <address@hidden
> Hi, Could Eric or similar give me a confirmation on the current gpsd
> nmea time calculation?
Nope, nothing anywhere near so fancy. And since the start of gps
> My understanding is that you take the final GPZDA sentence, then work
> *back* the timestamp of the initial $ by counting the number of
> characters divided by baud rate?
sentences is so jittery there is no point to trying except for a
few special case GPS.
His is one of the special case GPS that has a solid PPS synced start bit.
> Granted NMEA time is not traditionally considered incrediblyRight now the NMEA uncertainly is 70 milliSec or much worse. 1 milliSec
> accurate, but *if* the calculation is as I describe above, then we
> could potentially increase measurement accuracy by 0.5-1ms?
On ONE of the more jittery chipsets
> The reason for asking is that my Venus6 + CP210x has NMEA time thatUntil the CP210x kernel driver is fixed there is no point thinking about
> appears to measure almost as accurately as a theoretical PPS over
any usage of CP210x for timing.
Not if the USB latency in the CP210x is constant