[LEAPSECS] LEAPSECS Digest, Vol 53, Issue 13

[Tom Van Baak]

> And in Japan, since the main transmitter for JJY is within the

> Fukushima evacuation zone, such watches have presumably been

> freerunning and accumulating errors without resets ever since the

> earthquake.


Fortunately (and uniquely) Japan has two time code transmitters;
the one in NE Japan at 40 kHz and one in SW Japan at 60 kHz.
Modern radio controlled clocks in Japan receive either frequency
automatically. Even some RC clocks sold here (usually with the
word "global" in them) are capable, if in range, of receiving either
JJY station as well as WWVB and MSF and DCF in Europe. As
they say, once you have receivers tuned for 40/60/77.5 kHz
decoding the time code(s) is just a matter of software...

Still, with one station down, I'm sure reception for many Japanese
isn't as favorable as it once was. I'm waiting for confirmation of
this or anecdotes by time nuts there. Right now they have bigger
problems. Ironically the 40 kHz JJY station is only 10 miles from
the power plant; no wonder they had to evacuate.

I've looked at the raw data from JJY40 and you can see when the
quake hit and a day later they had to shutdown and leave.

There's a very nice per-hour animated map of average JJY signal
strength here: http://jjy.nict.go.jp/fs/dis_contour_e.html
I think this pair of graphs would make Edward Tufte proud.

Anyway, thread is getting off-topic, so I'll leave it at that.

/tvb

http://www.cio.com.au/article/381374/nuclear_crisis_stopped_time_japan/
http://en.wikipedia.org/wiki/JJY
http://maps.google.com/maps?q=37.372500,140.848889+(JJY40)
http://maps.google.com/maps?q=37.316933,141.021713+(Daiichi)
http://maps.google.com/maps?q=33.465556,130.175556+(JJY60)
http://jjy.nict.go.jp/QandA/data/leapsec.pdf
http://jjy.nict.go.jp/QandA/data/leapsec.html
http://jjy.nict.go.jp/QandA/data/dut1.html