[time-nuts] ublox NEO-M8T improved by insulated chamber?

Leo Bodnar leo at leobodnar.com
Tue Nov 7 17:07:43 EST 2017


Coincidentally, I have been testing relative phase difference of two GPS clocks http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=107&products_id=301 since Friday. 
They are completely independent, including separate antennas and positioned a few yards away from each other so ionospheric disturbances would affect both units equally.  Devices use Ublox chipset.

Average phase difference did not change in four days since Friday but there is phase wander within around 10ns.
Here is a video of 4 hours worth of data.  One horizontal division is 20ns:

http://leobodnar.com/balloons/NTP/twoGPSclocks.mp4

Cheers
Leo 

> From: Lars Walenius <lars.walenius at hotmail.com>
> If I look on the NIST database for the last days it seems to be a daily variation of about 8-10ns. Could this be for the same reason as Ole’s variation? Is the daily variations due to not perfect ionosphere correction? Can you get much better than the data in the NIST database for an ordinary timing receiver like the LEA-6T?




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