[LEAPSECS] Bulletin C and all that

Tom Van Baak tvb at LeapSecond.com
Tue Jan 27 12:28:37 EST 2015


> The truncated week numbers are a good source for potential errors

I agree, but...

> If the current week number is off by more than +-127 then this is ambiguous.

No, it's not ambiguous, it was just a Motorola bug. The wrap is in the spec and there's no problem with that. In fact, in 2003 everyone got it right except for one(?) model of Motorola GPS timing receiver. So the spec is fine, GPS is fine, wrapping is fine. But yes, it is a source for errors, and one engineer at Motorola fell for it.

The only limitation of using an 7- or 8-bit WN field like this is that it prevents GPS from announcing a leap second more than 2.5 or 5 years in advance. That's not much of a limitation.

/tvb


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