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If you can help us with additions, corrections, new links, please
contact us.
The address is on the NZ&A Time home page.
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SUPPORTING 'SELF-CORRECTING' CLOCKS |
Available in Europe, USA, Japan - but at present NOT normally usable in New Zealand or
Australia, although in 'some' circumstances these clocks may 'perhaps'
'just' manage to operate (see reported examples below).
In many regions of the world, Governments provide a low frequency (LF) Standard Time signal at below the old "Long Wave" band. These transmissions are in the range of 40 kHz to 162 kHz, with 60 and 77.5 kHz being the most common. A typical example is WWVB on 60 kHz in the USA; others are in Japan JJY on 40 kHz and 60 kHz, the United Kingdom MSF on 60 kHz , Germany DCF77 on 77.5 kHz (information in German), and others in Switzerland HBG on 75 kHz (in English, German, French and Italian!) and France TDF on 162 kHz (in French). Some other, unusual stations are listed in the Station Lists Compiled by William Hepburn, LWCA .
From information on the web sites of some of these stations their
nominal useful range is of the order of 2000 to 3000 km so that WWVB
covers all of
North America, DCF77 covers all of western Europe, etc. Also
refer to David
Mills' excellent site with information on
Time and Frequency Services
These signals are provided because there is a world wide mass market
for low cost "Radio Controlled Clocks" and watches, often
termed "Atomic (accuracy) Clocks/Watches", which automatically
synchronise themselves to these LF signals. Such self-correcting
clocks are extremely useful in schools, offices, etc. because they also
adjust to daylight saving switches,
leap seconds, and recover nicely after power outages. Typically,
a
'radio controlled clock' will synchronise itself a few times each day
(e.g.
every 6 or 12 hours), or upon user request, and at other times keep
running
as a normal quartz clock. The LF band has the advantage that its
waves
penetrate deep into buildings, making for almost "universal" coverage
in
those regions where transmitters exist. In practice, clocks
working at 60 kHz and 77.5 kHz are widely used.
If you were to purchase one of these clocks please consider whether it will receive the most common frequency in your Region. Some clocks (e.g. SEIKO Global Wave) can automatically search at both 60 kHz and 77.5 kHz to serve all their world markets. However, other brands produce different models for 60, 75 or 77.5 kHz. For example, Oregon Scientific and Sangean produce clocks for 60 kHz for the US and British market, and different models (with different model numbers) receiving 77.5 kHz for continental Europe. A number of Swiss companies produce models for 75 kHz which is used only in Switzerland. A strange situation because Switzerland is well within the range of German DCF77, and HBG and DCF use the same time code. France, too, is following its own course.........
We see these "atomic clocks" advertised in international
publications, even in Australia (see lower on this page) and may be tempted to buy
them in Duty Free shops in overseas Airports, but because
there are no transmitters in New Zealand or Australia these clocks
should not be expected to automatically adjust in our region.
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However, in July 2005 we received a report on a 'Seiko World
Global Radio Wave Control Radio' from Perth, Western Australia: Subject: JJY 60 KHz SURPRISE
- SOMETIMES THEY DO WORK HERE......
And in July 2006 we received the following report from a travelling user in Scotland and New Zealand: <>I have been visiting your website because I was hoping to get some clarification of a rather strange phenomenon. I own a watch which synchronises with the DCF77 signal from Mainflingen in Germany. Being based in Scotland it never fails to obtain the signal at 1 am in the morning. If the watch cannot obtain a signal, as was the case when I went to southern Africa, it starts counting the days from when it obtained the signal last. On my recent trip to Christchurch, NZ, I did not expect to receive any synchronisation signal - not only because of the distance but also because all other international time signal broadcasts are done on a different frequency. I was very surprised to note that my watch seemed to obtain a signal but always with a one-day delay. Throughout our 6-week stay it showed 1 day (instead of the normal 0), during our flight back home it went up to 2 and finally went back to 0 after it re-synchronised back home. I was wondering if there might be a logical explanation for this behaviour of my watch in NZ. The above report raises the questions: was this particular watch able to receive 60 kHz, as used by JJY and WWVB (in addition to its "listed" DCF77? If it was using WWVB, would that explain the one day offset? Or is there another explanation?> SURPRISE - SOMETIMES THEY DO WORK HERE...... Report of a 'Casio Ceptor' working in Melbourne in mid
2007: When I asked him why my Casio Ceptor
watch was functioning perfectly, he told me what you say in your website; Australia does not have a
60 kHz WWVB format signal. On
Friday the 22nd of June 2007 I received my new Casio Ceptor in the
mail. I turned it on at 6:30 pm. The watch was able to figure out the date
straight away. Then the analogue hands started swirling around and stopped at the wrong time (but the
minutes were correct). In timekeeping mode I held down button A for four seconds to get GMT differential value. I
adjusted this from GMT+4 to GMT +10. The analogue hands started swirling around again, stopping at the
right time and started ticking away happily. The
closest signal to Melbourne is Japan. As the two Japanese radio
stations coverage is small enough that they need two stations to cover
their archipelago, Melbourne seems like an awfully long way. I would certainly like to hear your thoughts on
this. Much as would love to own a Suunto with GPS that can pick up signals from satellites, money
prohibits. How far is it from Melbourne to Japan? I look forward to
your reply. SURPRISE - SOMETIMES THEY DO WORK HERE...... Report on a 'Citizen Skyhawk'
from Brisbane in March 2008: > YOUR
NZ - AUS USER FEEDBACK IS WELCOME
For example, is it possible that these clocks may in fact work in the North Island of New Zealand or the State of Queensland in Australia??? And - if so - is there a way to work out whether the device is using a "fringe" signal from JJY Japan? or from WWVB, US??? - please advise YOUR NZ - AUS USER FEEDBACK IS WELCOME |
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There is some well-informed discussion in the USA and Japan of
these Low Frequency ("Atomic") clocks in the IOTA Occultations email
group: http://groups.yahoo.com/group/IOTAoccultations/
For example, please note this paragraph from a post (No. 3864) on this Group by Mitsuru Soma on 6 February 2003: "I examined such cheap clocks sold here in Japan, that are set with the Japanese JJY longwave time signal broadcasts of 40 kHz and 60 kHz, and found that they have delays of about 0.1 sec to 0.3 sec with respect to the time signals even just after the automatic adjustment, as noted in Occultation Newsletter (August 2000, Vol. 8, No. 2, p.4). An engineer of clock maker Casio also admitted that their radio clocks and watches have delays of about 0.2 sec when the automatic adjustment is made. So check the accuracy of your 'atomic time clocks' before using them for your observations." These delays may (?) or may not (?) be present in clocks manufactured by other companies in other countries, but it is essential that their accuracy be checked. |
Despite the above, these clock are often sold in
Australia. The wise buyer beware....
In Australia, the National Time Committee has in the past
considered establishing such an LF standard time station, but to date
this has always been rejected on the grounds of cost. Despite
this, occasionally such LF clocks are sold in Australia by over-zealous
marketers. For example, in early 2002 this occurred in the
"Australian Geographic" chain of shops, when they advertised such
"Radio Controlled Clocks" for sale, which were subsequently withdrawn
from the catalogue when it was found that there is no suitable signal
available in Australia. Again in May
2003, "Australian Geographic" included in their Winter Catalogue the
"Oregon
Scientific Projection Barometer", with the product description:
"A
multifunction, RF- controlled projection calendar clock that
automatically synchronises current time and date." Upon
contacting "Australian Geographic" we were advised that: "the
clock will work within 1,500 kilometres of the DCF transmitter".
Because the DCF transmitter is in Germany, this too far from any users
in Australia or NZ. While it
is probable that such a clock module could also use the LF signal from
e.g.
the Japanese equivalent transmitter, this is unlikely to be of
sufficient strength in the south Pacific. In 2006 it was found
that both Dick Smith
and David Jones sold a range of Oregon Scientific clock suitable for
DCF77,
but their packaging correctly advises the purchaser that the radio
control
function will not operate in Australia.
Since then such clocks keep popping up in shops in Australia.
Sometimes with a small sticker on the box advising that the automatic
setting will not work here, but more often without any advice. It
seems most people buy such clocks because they like the 'style' or
'design' and don't worry about whether they keep time.
Until the standards organisations in
our region can make governments decide to build suitable transmitters,
these LF synchronised clocks can generally not be expected to work
reliably in New Zealand or Australia,
although you may just be (very) lucky.......
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