[time-nuts] u-blox NEO-M8T GPS initial tracking test

David Witten wittend at wwrinc.com
Sun Feb 12 18:49:09 EST 2017


This behavior is described in the document:

u-blox 8/M8 Firmware v 3.01 for Standard Precision GNSS, Release Notes
<https://www.u-blox.com/sites/default/files/GNSS-FW3.01_ReleaseNotes_%28UBX-16000319%29_Public.pdf>

This document says, among other things,:

"New multi-GNSS messages use UTC as time reference. In some cases unknown
parameters (leap seconds, interGNSS time offsets) may lead to a reduced
accuracy of the output time. This inaccuracy can be as high as 20 s
(unknown leap seconds), which overflows the accuracy fields of some
messages, resulting in maximum accuracy figures (e.g., the UTC time
accuracy in UBX-NAV-PVT is capped at 4294967295ns when deriving UTC from
GPS time with unknown leap seconds)."

Is this perhaps the reason this firmware is marked "Not for Timing Use"?
The 2.01 Release at this location is similarly marked.

Dave


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