[ntp:questions] Re: radioclk DCF doubling

Serge Bets serge.bets at NOSPAM.laposte.invalid
Sat Jul 9 10:04:23 UTC 2005


Hello David,

 On Wednesday, July 6, 2005 at 7:32:47 AM +0100, David Woolley wrote:

    [fudge time1 0.020]
> Serge Bets <serge.bets at NOSPAM.laposte.invalid> wrote:
>> The LW propagation delay at 430 km given by propdelay is between
>> 2.219 and 2.762 ms. I wonder what are the 17.xxx remaining ms...
> Receiver filter group delay, or more simply described, half the filter
> rise time, in this case.

Thanks for your reply. I'm not sure to have enough background knowledge
to understand it fully. You mean the filter removing 77.5 kHz carrier to
keep 1 Hz pulses needs 17 ms to recognise the lower amplitude during the
pulse? Does it need the same time to recognise the end of the pulse,
when carrier comes back to full power?

There is something strange: These pulses that should be in theory 100 ms
(or 200 ms), when seen by "radioclk -t" are always shorter, around
92.9 ms (or 190 ms). What could explain that?

Quick awk stats over some 22 minutes -t testing pulse duration gave
(values are in µs microseconds):

| 0 count=972, min= 87088, max= 96876, mean= 92852.1
| 1 count=399, min=186026, max=193427, mean=190024


Serge.
-- 
Serge point Bets arobase laposte point net




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