[time-nuts] UBlox GPSDO

Keith Loiselle keith.loiselle at gmail.com
Sat Apr 18 19:44:17 EDT 2015


We put together this comparative analysis between the LTE-Lite and LEA-M8F
based on our measurements and observations.

http://www.jackson-labs.com/assets/uploads/main/Comparative_analysis.pdf

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.

Keith


Keith

On Fri, Apr 17, 2015 at 5:00 PM, Wayne Holder <wayne.holder at gmail.com>
wrote:

> Thanks to everyone for all the great replies.  I figured that the 10 MHz
> output would have a fair bit of jitter/phase noise, but I figured I could
> use something like a SiLabs Si5317 to clean it up, as per this app note:
>
>   https://www.silabs.com/Support%20Documents/TechnicalDocs/AN513.pdf
>
> Page 4 of the app note says it "*can accept a noisy reference clock at any
> frequency from 1 to 710 MHz and provide two ultra-low jitter (0.3 ps rms,
> 12 kHz to 20 MHz) output clocks at the same frequency.*"  Thats seems
> decent to me, but I'm a novice at this.  Anyone have any thoughts, or
> caveats on this plan?
>
> Wayne
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