Location of Time Transmitters
Edited by David Barth, 7 December 2008 and 17 November 2011.
Courtesy Wikipedia, The Free Encyclopedia
Several national physics laboratories operate radio transmitters that broadcast a time code signal. The following transmitters operate in the 40-80 kHz range and are used to synchronize
radio clocks over areas several hundred to some thousand kilometers across:
Japan
- JJY: The first transmitter has 40 kHz, 50 kW and is located on the summit of the Otakadoya-yama mountain near Miyakoji-mura/Fukushima/Japan (37 degrees 22 minutes North,
140 degrees 51 minutes East).
- The second transmitter uses 60 kHz, 50 kW, is located on the summit of the Hagane-yama mountain, near the border of the Saga and Fukuoka prefectures of Japan
(33 degrees 28 minutes North, 130 degrees 11 minutes East), and was put into service in October 2001.
Czechoslovakia (decommissioned in the Spring of 1995)
- OMA: 50 kHz, 50 kW, Prague/Czechoslovakia. Was in operation from April 1958 to Spring 1995.
Russia
- RTZ: 50 kHz, 10 kW ERP, Irkutsk/Russia (52 degrees 26 minutes North, 103 degrees 41 minutes East).
- RBU: 66.66 kHz, 10 kW, Moscow/Russia (55 degrees 44 minutes North, 38 degrees 12 minutes East).
United Kingdom
- MSF: 60 kHz, 15 kW ERP, Britain (currently: Rugby, 52 degrees 22 minutes North, 01 degrees 11 minutes West; to be replaced by: Anthorn, 54 degrees 55 minutes North,
03 degrees 15 minutes West), received throughout much of Northern and Western Europe.
United States
- WWVB, 60 kHz, 50 kW ERP, Ft. Collins/Colorado/USA (40 degrees 40 minutes North, 105 degrees 03 minutes West), received throughout most of mainland USA.
Switzerland
- HBG: 75 kHz, 20 kW, Prangins/Switzerland (46 degrees 24 minutes North, 06 degrees 15 minutes East), DCF77 compatible code.
Germany
- DCF77: 77.5 kHz, 50 kW (30 kW ERP), Mainflingen/Germany (50 degrees 01 minutes North, 09 degrees 00 minutes East), receivable up to around 2000 km from Frankfurt/Main (Germany).
Advantages of LF time-signal broadcast:
Compared to other time-signal transmissions in higher bands (WWV, GPS, etc.) long-wave (low frequency) signals have a number of advantages. They can go around obstacles such as
mountains or buildings.
Since no line-of-sight (LOS) is necessary between the transmitter and receiver, a single very powerful station can cover a huge geographic area. Long-wave signals even penetrate the walls of
most buildings quite well. Propagation happens mostly in the form of a ground wave, such that transmission delay is less affected by the variability of the ionosphere.
Robust receivers can be constructed very easily for as little as 20-30 USD/EUR and are found today in many radio clocks. Low-cost components can be used to build a receiver.
A receiver consists of the following:
- a tuned ferrite core antenna from HKW Elektronik; a 60 kHz version sold by Maplin, order number MK72P; a 77.5 kHz version sold by Conrad, order number 641138-62.
- a receiver IC for amplification, selection, AM detection, and automatic gain control (e.g. AtmelT422740-120 kHz or U4223B40-80 kHz, HKW UE6010/UE6011, GSG Semicon AK2124,
AK2125 or AK2127, MASMAS1016 or MAS1017).
- a microcontroller with ADC input for decoding the time signal and phase-locking a software-controlled local clock to it.
Low-cost time-code receiver integrated circuits (ICs), prebuilt modules and units, antennas, and test equipment for DCF77/MSF/WWVB are available from HKW Elektronik and other vendors.
Complete WWVB receivers are also available from Ultralink. MSF and DCF77 wrist watches are distributed in the UK by watch-heaven.com and other vendors.