[time-nuts] GPS: ADEV or MDEV?

Hal Murray hmurray at megapathdsl.net
Sun Apr 22 04:10:40 EDT 2007


> 12) provision for measuring OCXO case temperature and power supply
> current to allow compensation for variable internal wiring voltage
> drops  for those OXCOs that do not allow Kelvin sensing of the EFC
> varactor  voltage.

> Some OCXO's (FTS1200 etc) do not have independent sensing of the EFC
> varactor differential voltage, so the temperature dependent voltage in
>  the internal "ground" wiring drop due to the variable oven current
> will  modulate the OCXO output frequency when the DAC ouput voltage is
> fixed.   If this effect is modelled sufficiently accurately then the
> DAC output  can be adjusted to compensate. 

Does anybody have a list of OCXOs with a separate ground pin for the oven?


Some of the OCXO data sheets I've looked at have a Vref output.  Seems like a 
good idea.  They already have good temperature control and that's most of the 
trouble with getting a stable reverence voltage.

Do any OCXOs also include the DAC internally?  Isn't that the obvious next 
step?




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