[time-nuts] DATUM 9390 Info wanted
magnus at rubidium.dyndns.org
Wed Sep 12 10:36:56 EDT 2007
From: "Rob Kimberley" <rk at timing-consultants.com>
Subject: Re: [time-nuts] DATUM 9390 Info wanted
Date: Wed, 12 Sep 2007 15:10:28 +0100
> The 3 digit days shown are because the 9390 units evolved from their IRIG
> time code units. IRIG time code use the format SS:MM:HH:DDD (or more
> usually displayed DDD:HH:MM:SS) They kept the same format for the GPS units
> as most had IRIG outputs also. Other manufacturers adopted a more user
> friendly time display giving day/date info.
> As you say not really a problem!
> The 2 seconds between your cell phone and your GPS is however interesting.
> Keen to know what you find out.
There are most probably several uncompensated delays in various paths of that
one-way time transfer system relating to the time-of-day.
Message propagation in the cell phone system as such, number of jumps from the
BSC to the BS, maybe also the delay down to the BSC may be uncompensated, not
to speak of the delay within the phone itself.
The traceability of some operators clocks can be highly questioned by itself.
Some operators have fairly good knowledge in these things where as others may
be content with having more or less the same time throughout their network, but
don't see it necessary to coincide with civil time (whatever that is).
I still wonder how Danish operators is supposed to follow UTC (as implied by a
new rule) when it is not acknowledged in Denmark. But then again, it would not
be the first time requirements and actual law does not coincide.
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