[time-nuts] UBlox as a reference clock source - accuracy ??

Thu Jun 20 11:20:07 UTC 2019

That is probably good enough for my needs and certainly better than the cheap XOs in the instruments.

BTW I just came across a document "GPS-based Timing Considerations with u-blox 6 GPS receivers - Application Note" that makes interesting reading.

Many thanks
Dave

On 20/06/2019 00:19, Bob kb8tq wrote:

Hi

On a second to second basis, the 10 MHz will be off by < +/- 0.02 ppm.
Averaged over 24 hours ( = your frequency counter is set to a > 80,0000 second
gate time) you will be much closer. +/- 0.0000001 ppm is a good guess.

The important point is that the first number is more often the one you bump into.
The second one only “counts” if you have some sort of flywheel that does the

80,000 second averaging for you.

Bob

On Jun 19, 2019, at 4:31 PM, David Slipper <softfoot at hotmail.com><mailto:softfoot at hotmail.com> wrote:

Hi, I am running a UBlox Neo-6M and have configured it with LadyHeather
to produce a 10MHz output for use as a better reference for a couple of
instruments.

Is there any way with LH to determine the accuracy of the 10MHz output
in ppm??

I am aware that the 10MHz output is jittery on my scope (is that phase
noise??) due to the fact that the internal clock is divided by a
non-integral value to reach 10 (I believe the internal oscillator is
16MHz).  If I set it to produce 8MHz it is rock solid.

I am really interested in the long term accuracy of the 10MHz signal -
say over 24 hours.

I'm a bit of a newbie at this so any clarification would be welcome.

TIA Dave

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