[time-nuts] Beginner's time reference
Bob Camp
lists at cq.nu
Fri Dec 11 12:54:51 UTC 2009
Hi
Simple answers:
Will you have fun - yes indeed.
Will a $100 rubidium deliver more accurate time long term than a GPS - no.
To get close to what the GPS delivers you will need to go at least to a Cesium standard. Getting one with a working tube is not going to be cheap. Once you do, the tube has a finite lifetime. They are an expensive thing to replace when they wear out. Most manufacturers rate the tube life in the 5 to 10 year range.
The rubidium also has wear out mechanisms. Most people seem to get 10+ years out of them in continuos use.
Lots to play with.
Bob
On Dec 11, 2009, at 7:00 AM, Charl wrote:
> Dear Hal and others,
>
> Thank you for your suggestions. I suppose I should have emphasised that I
> was looking to have my own reference, i.e. something not dependent on GPS,
> LORAN, or other signals from the aether. Indeed I might get better accuracy
> for less money by tapping the GPS time signal, but to me that's not as much
> fun as building my own atomic reference.
> Hal, is there much difference in quality for these rubidium tubes? Will I
> get what I pay for? In any case, you make a good point about measuring the
> accuracy. I'm a university student, so perhaps I can pay the physics
> department a visit. Otherwise, maybe I could compare it to the GPS signal?
>
> Kind regards,
> Charl
>
>
>
> On Fri, Dec 11, 2009 at 9:30 AM, Hal Murray <hmurray at megapathdsl.net> wrote:
>
>>
>>> I'm hoping to build my own circuit around the device, which might cut
>>> down the costs somewhat. Some rubidium sources on eBay go for less
>>> than $100, but I'm not sure what quality to expect. Any advice or
>>> suggestions are appreciated!
>>
>> Short answer: Sure, get one of the $100 rubidium boxes and see what you
>> can
>> do with it.
>>
>> Long answer: You just stuck you toe into a huge tar pit. Pick a corner
>> that
>> seems like fun and dive in.
>>
>> How are you planning to measure if whatever you build is any good?
>>
>>
>>
>> --
>> These are my opinions, not necessarily my employer's. I hate spam.
>>
>>
>>
>>
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