Re: [gpsd-users] Time precision of gpsd with u-blox GPS receiver

[Benedikt Kleinmeier]

Hi Rob,

thank you very much for your detailed explanations. Now, it is easier for me to 
understand the complete accuracy/PPS topic.

One more note:

> Almost everybody leaves their GPS at the default one pulse per second,
> on the second, so the fractional part is zero.

According to u-blox Receiver description [1] page 129:

  The u-blox positioning technology supports navigation update rates higher or 
lower than 1
  update per second. The calculation of the navigation solution will always be 
aligned to the
  top of a second.

I guess because of this aligning, the fractional part of the reported time (in 
seconds) is always zero. Changing the update rate via a "CFG-RATE" message to 
250 ms for example would reveal a fractional part unequal zero.

Thanks,
Benedikt

  [1] 
http://www.u-blox.com/images/downloads/Product_Docs/u-blox7-V14_ReceiverDescriptionProtocolSpec_Public_%28GPS.G7-SW-12001%29.pdf