[time-nuts] LTE-Lite module

SAIDJACK at aol.com SAIDJACK at aol.com
Mon Oct 20 19:07:07 EDT 2014


Thanks much Charles,
 
just to remind everyone that the main idea of making the boards  available 
was to get folks a good disciplined TCXO, not to work as a  development 
platform to discipline external OCXOs.. Also as mentioned in the  FAQ, the 
typical performance plots I have been sending and are also in the  user-manual 
are gathered under optimal conditions of course: a roof-top antenna,  units 
shielded from airflow, and units running for a couple of days before  testing.
 
Please also note that I tried an OCXO with only +/-2Hz EFC range and  it 
did not lock due to the ~10Ks resulting time-constant and the loop being way  
to slow to capture the OCXO..
 
External oscillators should have between 9Hz per Volt to 100Hz+ per  Volt 
EFC sensitivity from what I can tell, otherwise an OPAMP circuit would be  
needed to bring the EFC into that range. Sorry, I cannot propose such a 
circuit,  but such a circuit had been sent as a schematic to the time nuts some  
years ago by someone if I remember correctly.
 
Bye,
Said
 
 
In a message dated 10/20/2014 15:55:45 Pacific Daylight Time,  
csteinmetz at yandex.com writes:


>here is the ADEV plot from my overnight test with the  DOCXO.  *  *  *
>
>This was done without any loop  adjustment whatsoever, same board and
>software that drives the on-board  TCXO. I will let the result speak 
>for  itself,
>save to say  the loop, the DAC, the DAC reference, and the GPS with a   
proper
>OCXO can achieve performance at a level approaching two orders  of
>magnitude better than our spec which is 1ppb for this   particular product.

Thanks for the ADEV plot, Said -- more pertinent  for most time nuts 
purposes than PN.  Of course, the typical  performance of the LTE-Lite 
with the TCXO is significantly better than the  spec (according to the 
user manual, about 5e-11 at 1 second and 1e-10 at  10 seconds, already 
1 to 1.5 OOM better than spec), so the typical  improvement with the 
OCXO wouldn't be a full two orders of  magnitude.  Still, very 
noteworthy performance that *surely*  justifies time nuts in buying 
one of the good, cheap OCXOs flooding the  surplus market to go along 
with their LTE-Lite.  Good  show.

Best  regards,

Charles



_______________________________________________
time-nuts  mailing list -- time-nuts at febo.com
To unsubscribe, go to  
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the  instructions there.




More information about the time-nuts mailing list