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Bought a german radiocontrolled clock...


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Jan 29, 2004
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Hi all.
Will it work/receive the time signal in USA ? So far 4 hours on with no signs of acting... What is the typical range of the european frequency, with, without RF skip ?
Thanks. Understood; as the manual has zero specifications on receiving frequency. Just mentions 'RCC' Unknown if built for the US market and its WWV or for european 77.5KHz.

The German time signal is called DCF77 and operates with 77.500kHz AM / ASK.
It´s easy find detailed informations in the internet.

The transmitter is located near Frankfurt/Main in Germany. As a rule of thumb it works 1000 km around the transmitter.
And obviously it transmits German time zone MEZ / MESZ (CET / CEST) information which is GMT+1h / GMT+2h.

My thoughts:
* obviously the USA is more than 1000km away from Frankfurt. Are there other compatible 77.5kHz time signal transmitters in the USA?
* For sure it may be possible to receive long wave in the USA - depending on whether conditions. With a suitable antenna and receiver .. it could work. But then still: Then you get CET/CEST informations.

WWVB and the UK-MSF use 60 KHz signals but WWVB uses bits 04-07 for year but bits 17-24 for UK-MSF.
Germany uses 77.5 KHz.
Japan uses 40 and 60 KHz
China uses 68.5 KHz.

We used to have WWVB cards for our portable programmable Seismic recorders in 1974 designed by someone in the physics dept. Two summers before this we had to use 24 channel recorders and a Timex watch to sync. with the very distant blasting crew.

This for U of M seismic research as we as students worked near the DEW line in Manitoba to record the ground reflections and the Seismologist graduate then digitized the data and FFT processed the result to map surface and ground waves and create 3D model of the earth's crust down to 30 miles where precious minerals were later found. I spent my last year fixing the automated 1974 CMOS design (with a few bugs) like race conditions from different CMOS speed devices.

That WWVB card was reliable but our SW voice radios were not for some reason due to the rock structure , freq. and long distance. The blasting crew dropped a hundred kg of C4 down an old mine shaft which was submerged under a small lake, near Flin Flon, using a raft. We rarely saw traffic except the miner's bus between Lynn Lake and Thompson (two mining towns) in Manitoba in different sector every day. We had to rely on old Timex watches to sync our recording operation using 24 channel optical recorders and 24 channel mag tape recorder. Not a sound was heard as the lake rose 12" and dropped, but we got nice clean seismic signals. Except for a deer a few hundred yards away that caused some interference. These were so sensitive I could flex my knees on the Earth Sciences basement and peg the VU needle a couple meters away on full gain. One day the bus driver was not going to stop as I stood in the middle of the highway with a STOP sign wearing a white hard hat. WTF he said. I replied if he didn't mind waiting while we were doing some blasting. 15 minutes later with road silence and all the signals recorded, not a peep , a deer or even a bear and he looked bewildered when I said, "Ok you may go now."


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I have two 'atomic' radio-controlled clocks (brands: Skyscan & LaCrosse technologies). They receive US based time signals from the transmitter in Fort Collins, Colorado. Frequency 60 kHz. There are places in my dwelling where they don't pick up the signal. I've had to carry them to different spots and leave them until a little antenna with rings around it pops up onscreen. It takes several minutes for them to tell me time/day/month/year/lunar phase. Usually I have to press buttons to change the time zone or allow for Daylight saving time.

At night you might have luck receiving European 77.5 kHz time signals. That's when radio waves often carry around the world thanks to atmospheric skip (especially long wavelengths).

The antenna inside the clock is small. Perhaps you can build a larger antenna, and tune it to 77.5 kHz, then place it to influence the clock somehow. Like a DIY of a store-bought gizmo which listeners placed near their AM radio to boost reception.

Select-A-tenna AM radio.jpg
My 1st design project out of school was in aerospace with a Doppler VLF Nav. radio for a floating weather station in the Beaufort Sea using all the time sync US Navy channels from around the world on 5 channels using a Polar Bear proof whip antenna on a moving ice flow near Tuk and off shore oil rigs. It was world's first ocean weather station and we Tx's all the weather data sensors to GOES 1 (one and only at that time).. After I left the company for more pay 5 yrs later, I heard it rotated around the pole and ended up in Siberia or somewhere in the USSR. It had an egg-beater 1 Hp wind-turbine (Sevonius-Darrus) to charge the pile batteries , so maybe someone found that interesting. I used 2 stage 5 degree X cut crystals for each of the 5 channels and the whole design had a budget of 5 mA @ 12V to send phase shift on a serial port.
To be honest, unless you want a lot of work, I would give up.
I have a friend here in the UK that bought a clock in Germany and is probably just inside the 1000Km radius of DCF77. It occasionally locked but then showed the time one hour out because of the different time zone. There are so many problems trying to isolate a very, very, very weak signal from the background interference that it really isn't worth the bother. Even if you can receive a local time code, the arrangement of bits in the data stream is different from DCF77 so it will probably fail parity checking and refuse to set itself anyway.

Cheap alternative if you need to use that clock is to use a small Wifi module (ESP8266 for example), then have it log in and retrieve NTP signals. You can fake a local but time zone corrected DCF77 signal quite easily.

There is more to it than just the receiver. The time code is a series of single or double pulses sent by turning a radio carrier on and off at one second rate. The pulses advance the seconds count and the length of the first pulse and presence of the second pulse carry a binary code to set the minutes, hours and date. A special pulse (or absence of one) is used to indicate second 59 so it can synchronize the seconds count. In the binary code there are also parity bits and some special ones to indicate DST is about to start and finish. The position of the bits within each minute is different from one time system (WWV, DCF77, MSF etc) so if the controller that drives the LCD display expects one format but gets another, it will at best show the wrong time and date. More likely, it will see the parity checking fail and assume the signal has been corrupted by interference and continuously try reading the code over and over again before it can set the time.

Sad but true. Parity bits are added to some of the time/date data so it is also possible that if the stream of bits is split incorrectly because the actual and expected formats are different, the parity check will fail and under normal circumstances the time would not update at all. It would assume there were added or missing bits caused by interference and sit in a loop forever re-trying to read valid data. Bear in mind that at low frequencies there is a huge amount of background noise from SMPS and low energy lighting so it is essential that the data integrity is confirmed before the clock is set. The time codes are not normally displayed 'live', that would be too prone to interference, once a valid set of data is received, it is used to set a hardware or software clock then checked again after some period has elapsed.


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