[time-nuts] oscillators

Bob Camp lists at rtty.us
Thu Aug 30 06:31:32 EDT 2012


Hi

An OCXO crystal needs to be "good" only at one temperature. The crystal in an MCXO needs to do well over a wide range of temperatures. That complicates things quite a bit.

Bob

On Aug 30, 2012, at 12:22 AM, Hal Murray <hmurray at megapathdsl.net> wrote:

> 
> richard at karlquist.com said:
>> No it doesn't use a cheap crystal.  It uses a *special* SC cut crystal. This
>> crystal could very easily cost more than an OCXO crystal. 
> 
> What's special about it?
> 
> I assume the cost-more aspect would be to allow an overall goodness factor competitive with an OCXO in the low power corner of the marketplace.  It might be cheaper overall to use a good crystal and a uP to correct for temperature than provide the power to run the oven.
> 
> --------
> 
> The other area where a uP is useful is in an environment with high vibration.  It can correct for acceleration as well as temperature.  There were several good URLs mention on this list in the past year or two.  The context was radar on helicopters.  Helicopters are full of vibrations/accelerations.  The numbers work out such that the frequency broadening due to vibration is interesting if your radar is looking for slowly moving things like people.
> 
> ----------
> 
> Crazy question dept:
> 
> What do low cost rubidium oscillators do when vibrating?  Is it dominated by the cleanup crystal?
> 
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> 
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