[time-nuts] time-nuts Digest, Vol 104, Issue 37

Bob Camp lists at rtty.us
Mon Mar 11 12:19:55 EDT 2013


The other point that could be made is: 

In a contest situation, you have a lot of stations to net to. You really
aren't worried about the stability over 48 hours. You really are concerned
about drift since your last set of contacts. If it takes you an hour or less
to get to your next site, that's a *much* looser requirement than the 48
hour number.

It all depends on what you are doing....


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Jim Lux
Sent: Monday, March 11, 2013 10:13 AM
To: time-nuts at febo.com
Subject: Re: [time-nuts] time-nuts Digest, Vol 104, Issue 37

On 3/11/13 6:49 AM, James Peroulas wrote:
>> Date: Sun, 10 Mar 2013 17:37:13 -0700
>> From: gary <lists at lazygranch.com>
>> To: time-nuts at febo.com
>> Subject: Re: [time-nuts] frequency reference for portable operation
>> Message-ID: <513D2739.8030107 at lazygranch.com>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>> I haven't researched this yet, but the SDR crowd is using GSM and LTE
>> for tuning their sample clocks.
>>> https://github.com/steve-m/kalibrate-rtl
>>> https://github.com/Evrytania/LTE-Cell-Scanner
>> I have no idea what kind of accuracy you can get from a tower.
> GSM and LTE (and WCDMA and TD-SCDMA for that matter) are spec'd for 50 PPB
> accuracy. However, these networks are 'often' synchronized to an external
> reference which would presumably be GPS. This would give better long term
> accuracy, but the short term accuracy would depend on the actual
> implementation of the basestation.
> JP
> P.S. I'm the author of LTE-Cell-Scanner.

There might also be a problem getting a decent signal at some of the 
locations  (remote mountain tops for instance).  For several years, we 
did JPL Amateur Radio Club  Field Day up on top of Mt Gleason, and it 
was notorious for no cell coverage.   (I suspect it's better today.. 
that was at least 6-7 years ago)

But a battery powered OCXO seems to be a "good enough" and self 
contained as well.

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