[time-nuts] UBlox GPSDO

Keith Loiselle keith.loiselle at gmail.com
Fri Apr 17 19:53:40 EDT 2015

We put together this comparative analysis between the LTE-Lite and LEA-M8F
based on our measurements and observations.  We have also noted that the
LEA-M8F seems to use the digital power supply for its TCXO. This results in
poor phase noise and spur performance and high sensitivity to external
supply voltage noise and fluctuations. The LTE Lite uses two internal LDOs
for much higher performance. Also the LEA-M8F's ADEV under the same ambient
conditions is not as good. Lastly, the recovery from holdover results in
frequency jumps that are more than 10x larger than on the LTE Lite.



On Fri, Apr 17, 2015 at 9:45 AM, Alan Ambrose <alan.ambrose at anagram.net>

> Re LEA-M8F
> >>> The main thing is that there is a lot of jitter at 10MHz (much less at
> 8MHz) so you need to phase lock another oscillator to it.
> Yes, as they've got most of the guts of a basic GPSDO in there with a
> VCTCXO - but it seems they missed the boat in making the divisor for 10MHz
> produce a jittery result.
> It does have the ability to control an external OCXO as well, although
> that may not actually help much.
> The application note is here btw:
> https://www.u-blox.com/images/downloads/Product_Docs/Timing_AppNote_%28GPS.G6-X-11007%29.pdf
> Alan
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