Reading up on how to establish traceability of GPS for audit purposes. Wondering if anyone else is usgin the method I'll describe below:
Reading a NIST white paper: "The Use of GPS Disciplined Oscillators as Primary Frequency Standards for Calibration and Metrology
Laboratories" it looks like to establish traceability using a GPS with GPSDO (disciplined oscillator - which my Symmetricom has), it looks like I need to develop a procedure which assigns an uncertainty - in my case, there is a 1 day uncertainty or shorter periods with a little lower accuracy (I'll have to decide which we want to use - the best accuracy requires a full day of integration, I think). Then I have to have a method to regularly monitor satellite lock. Ours has a time clock I think showing how many hours since last loss of lock. And on the NIST website they have plots of error that can be pulled. I think its a little late in the day... anyone have a similar process they could share, or detailed thoughts about how to tackle this (to be added to scope of accreditation).
For A2LA purposes,. you can get all the data required from the following website:http://www.nist.gov/pml/div688/grp40/gpsarchive.cfm.
We use a Fluke 910R and this website info is all we need to show every quarter. Typically our 910R is at 0.1-12 parts and is self correcting.