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

On 12/02/2017 6:49 PM, David Witten wrote: > Is this perhaps the reason this firmware is marked "Not for Timing Use"? > The 2.01 Release at this location is similarly marked. > > Dave According to posts in the ublox forum, there are specific issues regarding timing specific features in the timing products that are not in the SPG releases. Load it with an SPG release, and timing features/functions disappear. One example given was a timing solution from a fixed location from a single satellite. Others were concerned that some messages in the stock M8T weren't present in the SPG 3.01 release, but some have confirmed that some timing specific messages are in the 3.01 SPG release. You'd have to check their forum to see if the messages you need are/aren't in the SPG release. I'm seeing the caution that once you flash a timing product with SPG 3.01, you can't go back (I presume because you don't have the bin of the timing firmware to put back on it). I have managed to find the release note UBX-16004908 (.pdf) from 24 February 2016 for FW3.01 TIM1.10, which includes "The default configuration is optimized for timing applications and is compatible with the previous release FW2.30 TIMRAW1.02. The following table summarizes the significant differences between GNSS firmware 3.01 and the TIM1.x firmware." The release also: lists new protocol messages and modified protocol messages; cautions that the mechanism for firmware update has changed; and, "The ranges of tracking channels that can be assigned to each constellation is more restrictive than in previous releases." The release is only 120 kb, but I don't think I should be sending that out to everyone. Anyone who wants it and can't find it by the name above, email me for a copy. Michael