clockace, now I'm getting a bit confused which transmitters and Megas you mean
The Mega 1000 can receive the 60kHz
WWVB signal from Fort Collins, Colorado, the 77.5kHz
DCF77 signal from Mainflingen (near Frankfurt), Germany, plus both Japanese Transmitters
JJY40 and
JJY60 (40 resp. 60kHz). It uses whatever is strongest.
To achieve this, a multi-frequency receiver is necessary (the Mega 1000 has one quartz for each frequency), and because the time codes are also different, for each transmitter the watch needs individual decoding software (or hardware if the decoding is hardwired).
At the beginning of RC watches, it was not yet possible to integrate a multi-frequency antenna plus receiver circuitry into a watch case, so the watches were made for specific areas. Junghans is in Germany, so they started with the European signal. The first RC watch (
Mega 1) could only receive DCF-77 in Europa - but did this very well, about 1500~2000km around Frankfurt
I'm not aware of a USA (WWVB) version of this Mega 1 (026/001x), but later there were many more "Mega 1s" that looked totally different (analogue etc.). Which Mega do you have?
WWV (same location as WWVB) and
WWVH (Hawaii) transmit audible signals for shortwave receivers. They are not used for radio-controlled watches and clocks (maybe for some very special applications, but not for consumer goods).
As for WWVB, there is only one radio station (which has two antennas, about half a mile apart).
Quote from
http://tf.nist.gov/timefreq/general/pdf/1976.pdf:
11.C. Coverage Area of the WWVB Signal
During the nighttime hours, the WWVB signal is strong enough to
synchronize clocks in the 48 states of the CONUS, in parts of Alaska
and Hawaii, in all of Mexico, in most of the populated areas of Canada,
and in some regions of Central and South America. (For coverage
maps and signal strength information recorded at various sites, see
http://tf.nist.gov/stations/wwvb.htm.)
The size of the coverage area is estimated using a field strength
figure of 100 μV/m, which in theory is more than enough signal for a
well-designed RCC to synchronize (Section 8.A). However, in practice,
simply having a large signal doesn’t mean that a RCC will be able to
work. What really matters is the signal-to-noise ratio, or the size of
the signal compared to the size of the electrical noise near the same
frequency. Raising the noise level is just as harmful as reducing the
signal level. For example, if the RCC clock is near a source of
interference, the noise level increases, and the clock might not be able
to synchronize even if the local field strength of the time signal is high.
Potential sources of interference are discussed in Section 11.D.1.
Problem is, the Mega 1000 apparently can NOT be considered a "
well-designed RCC"
We have several reports of people whose Casio etc. RC watches work without any problems, but their Mega 1000 doesn't - a bit frustrating as the Mega 1000 isn't actually a cheap watch...
@caviar: Good to see you finally managed to sync in a suburb - but you can't always travel to set your watch. It should sync ANYWHERE in Paris, at least at night.
Did you also try to sync on the Eiffel Tower
?
I'd ask for a replacement, maybe yours is exceptionally weak.