[time-nuts] Is it Hz or MHz ?
Kit Scally
kitscally at iprimus.com.au
Mon Jun 2 03:28:48 EDT 2014
Team Nutters,
GPSDO's are often specified for stability as so many parts per x. Using a
Symmetricom 8040C as an example, this has a quoted accuracy of typically
5E^-11 at shipment. Ageing (monthly and yearly) and ADEV stability rates
for 1, 10 & 100 seconds are also given. This particular device as 1, 5 and
10 MHz outputs.
The question - is this "accuracy" with respect to 1Hz - or 10MHz ? If the
latter, then the accuracy figures quoted needs to be modified by 10^6 (Hz to
MHz) to get a feel for the actual frequency changes at 10MHz.
Glossies of many GPSDO manufacturers seem deathly silent on this point, so
clearly, "something is assumed". I have seen an oscillator comparison chart
by Meinberg (a German company) that in their comparison chart, the accuracy
references need scaling to relate to 1Hz.
Appreciate some advice and/or direction on this before madness overtakes me
!
Kit
Canberra
Australia
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