In article , Don Pearce
wrote:
As for R4, are you finding that the offset is consistent, or does it
change during the day as they change bit rate?
Not determined as yet, but I suspect that the DAB/FM time offset *does*
vary with bitrates, etc. The problem is that it is quite difficult to
determine this accurately with 'normal' speech and music. Ideally, I'd like
to determine the time alignment to the order of 1 sample interval at
44.1ks/sec, but so far I've only got close to this for R4 using the pips.
With R3 it becomes hard to determine this closer than a few milliseconds.
My 'best estimates' so far are 1.368 sec for R3 and 1.344 sec for R3, (R4
at 128kb/s and R3 at 192kb/s - although of course the rates of all the
other stations on the MUX may affect this.) For the data I have so far the
R4 value seems more reliable.
Alas, my main interest is in R3, not R4...
I suspect it may also vary across the UK due to differences in distribution
deplays. Also probably from one DAB tuner to another due to different
decoding process timings... :-)
The values I have at the moment are OK for some purposes, but not accurate
enough for some of the analysis I'd like to try.
Slainte,
Jim
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