[time-nuts] GPS: ADEV or MDEV?
Hal Murray
hmurray at megapathdsl.net
Sun Apr 22 08:10:40 UTC 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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