Hi Said,
On 12/01/2012 06:28 PM, Said Jackson wrote:
Hello Azelio,
We added a user adjustable jam-sync threshold some time ago for European
DVB-T applications for that reason. The customer can now decide the phase
window in which the frequency is drifted slowly without a phase jump.
Interesting to hear that others have done the same thing. It seemed like
a decent way of dealing with it.
But I think your math may be off, with default settings we typically do
phase adjustments with about 2E-011 (0.02ppb, 0.0002Hz at 10MHz,
0.02Hz at 1GHz carrier) frequency offsets. To correct 1000ns offset from
your example, it would take about 50K seconds, or a bit more than a half
a day with those settings.
One can also wonder if the limit is relevant, as you are about to
resolve a rather catastrophic situation where you already cause
interference, so moving out of it quickly should be first priority and
only when back to reasonable time-error would it be relevant to obey
frequency error limits.
The transmitters and the recievers would be able to follow, as they have
large enough bandwidth for it.
But if you set the loop parameters more aggressively to 1ns/s as in your
example, it would take less than 20 minutes to correct 1us.. Not 12hrs.
Unless you meant to say ms?
What's a off by one prefix among friends?
But still, one has to be careful.
Cheers,
Magnus
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