Hi On Jun 1, 2013, at 3:34 PM, Magnus Danielson <[email protected]> wrote:
> On 06/01/2013 09:02 PM, Scott McGrath wrote: >> True >> >> However with LORAN and to a lesser extent WWVB traceability process was >> well/known and documented and had been in place for decades and was easy to >> implement correctly With GPS not so much especially with S/A. Supposedly >> the new satellites don't have S/A but since the GPS satellites are primarily >> military in nature how will precise positioning be denied in emergency >> situations. Shut down L1?, dither the signal ???? Or is S/A still there >> and how does a T/F user respond to GPS not running normally??? >> >> A colleague of mine runs a cal lab. Guy is a wizard with physical and >> electrical standards >> >> I run some of my gear there in exchange for calibration of my instruments as >> lab has temp / pressure / humidity controls for physical standards so we >> both benefit. >> >> Since the demise of LORAN and WWVB (although d-PSKer may allow us to bring >> spectracoms and 117a's back. >> >> To achieve traceability we have been shipping our CS and some Rb standards >> under power to labs who have achieved traceability >> >> This is is a pain to say the least. The procedures currently are not well >> documented on achieving traceability in the age of GPS only. >> >> And it's also true that most people confuse traceability with adjustment. >> In reality it's more of a chain of data with documented values all the way >> back to NIST or other national standards lab > > NIST offers a calibration service which gives time and frequency calibration > to NIST using common view GPS. Essentially that's a box being placed at the > location you feed with your local signals and the box will communicate back > to NIST and create the calibration records. > > The pieces in this, isn't all that magic and esoteric, but put together in > good way and with routines to put it all together. > > How to do it properly when getting the NIST service is much more fuzzier. I > have not seen a description of how it should be done, but it should be > possible to achieve in principle. You do the same thing they do. You both watch the same sat(s) and compare to it / them. If you are in the US, you can do common view. There are LOTS of papers on how to do all that. Bob > > Cheers, > Magnus > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
