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Radio controlled clocks

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Tony Jeffree12/06/2021 17:30:58
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I have 3 wall clocks dotted around the house which used to contain "standard" Quartz clock movements, but a couple of weeks ago I remembered that I had three MSF radio controlled clock movements squirreled away doing nothing, and have replaced the "vanilla" Quartz movements with them. For the benefit of those that are not familiar, these movements use the radio time signal from Anthorn in the Lakes (broadcast at 60 KHz) to keep the clock accurate, and they revert to a conventional Quartz movement if they lose radio signal for any reason. The great advantage of these movements is that they are always accurate and automatically compensate for GMT and British Summer Time changes, so you fit and forget.

So far, so dull. However, given my recent experiments with a free pendulum clock where I used a gutted Quartz movement as a cheap means of providing motion work (see https://www.model-engineer.co.uk/forums/postings.asp?th=171748 ), it occurred to me that these movements could be useful in other projects, given that it should be possible to extract useful pulses from the drive system. The movements I have here seem to have separate drives for the minute/hour hands (pulsed every 15 seconds) and the second hand (pulsed every second), and these could be used to drive other things, for example:

- Use the 1-second pulse in place of a pendulum to drive more conventional and visually interesting motion work;

- Use the 1-second pulse to drive a hit-and-miss synchroniser to accurately synchronise a mechanical pendulum & associated motion work;

- etc.

There are also receivers/decoders around that can extract the whole of the data stream transmitted by Anthorn, which includes year, month, day of the month, day of the week as well as time of day, so potentially one could produce a mechanical clock with perpetual calendar, taking the data from the radio signal.

Anyone ventured down these (or similar) paths?

John Haine12/06/2021 17:34:59
4279 forum posts
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I was wondering about doing the opposite, having an Arduino controlled clock that broadcasts a replica time signal on a slightly different frequency round the house to re-tuned RC clock movements...

Tony Jeffree12/06/2021 17:39:36
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That would work! Actually, the BBC Micro:bit processor that I am using in my current clock is capable of broadcasting to other Micro:bit processors so that might be a simple thing to achieve - not sure about range though, I suspect it is similar to the range of Bluetooth so may not be good for the whole house.

Tony Jeffree13/06/2021 11:35:51
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Apparently the Micro:bit radio is good for around 300 feet in clear air, so it might just be workable to distribute time signals in a house.

Douglas Johnston13/06/2021 11:55:11
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I have one of those radio controlled clocks that refuses to lock on to the signal and slowly gains a few seconds a month. When the clocks change in October and April I have to take my clock to a high point in the back porch and leave it there for a day or two and it finally does the conversion. When it was new it worked fine for a number of years, then decided to annoy me for some reason.

Doug

SillyOldDuffer13/06/2021 11:56:27
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Last time I dabbled with MSF I couldn't find anyone selling a suitable receiver. No problem, I thought - cannibalise a clock. That failed too, all the radio clocks on sale at the time used DCF77 in Germany. So I built a simple TRF receiver and had awful trouble with it. Investigating with an SDR receiver, I found the MSF signal in my part of Somerset is weak and the noise level high. I put it down to mains bourne interference - overhead power lines all round the village, and my hobby room's fluorescent light wipes MSF out completely.

I decided building a better receiver and improved antenna were too much trouble. I see this module is available today and will have another go!

Ta,

Dave

Tony Jeffree13/06/2021 12:02:51
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Posted by SillyOldDuffer on 13/06/2021 11:56:27:

Last time I dabbled with MSF I couldn't find anyone selling a suitable receiver. No problem, I thought - cannibalise a clock. That failed too, all the radio clocks on sale at the time used DCF77 in Germany. So I built a simple TRF receiver and had awful trouble with it. Investigating with an SDR receiver, I found the MSF signal in my part of Somerset is weak and the noise level high. I put it down to mains bourne interference - overhead power lines all round the village, and my hobby room's fluorescent light wipes MSF out completely.

I decided building a better receiver and improved antenna were too much trouble. I see this module is available today and will have another go!

Ta,

Dave

There seem to be plenty of radio clocks on Ebay these days that claim to be MSF - I've ordered one up to take apart & see if I can extract usable pulses from it.

Yes, I had spotted that module on Amazon too - looks very interesting!

John Haine13/06/2021 13:25:10
4279 forum posts
252 photos
Posted by Douglas Johnston on 13/06/2021 11:55:11:

I have one of those radio controlled clocks that refuses to lock on to the signal and slowly gains a few seconds a month. When the clocks change in October and April I have to take my clock to a high point in the back porch and leave it there for a day or two and it finally does the conversion. When it was new it worked fine for a number of years, then decided to annoy me for some reason.

Doug

If it's an MSF clock it may have stopped working when they moved the transmitter from Rugby (nearly in the centre of the UK) to Anthorn in Cumbria, so your signal level may have dropped.

old mart13/06/2021 15:05:43
3418 forum posts
210 photos

The thing to remember is that any deficiencies in the quartz crystal is corrected when the time signal is picked up. The average accuracy over a year might be within a 1/10 th of a second, but a graph made with a sensitivity of 1/100 of a second might show plus or minus reading throughout the year.

I used to work in aircraft parts manufacture, and all the timepieces used for any process were checked and recertified every year. By far the greatest errors in timing a process which might be over one minute would be the operator, not the clock.

Georgineer13/06/2021 16:58:14
525 forum posts
32 photos

A while back I was given an MSF radio-controlled clock because one of its hands had dropped off. I opened it up and replaced the hand, then failed utterly in my quest to find instructions for setting it up.

I managed to get it running correctly, and since then it has run ... erratically. The minute hand always seems correct, but the hour hand, at random intervals, is out by a random number of hours then when I look again later it has corrected itself.

The designer of the case was very optimistic, since the movement is inside a metal case and behind a metal face, so the signal can only sneak in round the back. I shall probably convert it to a standard movement since it shows no sign of settling down.

Off topic a bit, I visited the Anthorn transmitting station during the 1960s. It was fascinating, huge and all very hush-hush, and it had its own nuclear shelter still very much in commission. One cause of amusement was that when transmitting morse code, the lights in the village dimmed in time with it. It must have been infuriating for anybody who could read morse to have a stream of encrypted gibberish appearing in their living room.

George B.

Tony Jeffree13/06/2021 17:08:42
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Posted by old mart on 13/06/2021 15:05:43:

The thing to remember is that any deficiencies in the quartz crystal is corrected when the time signal is picked up. The average accuracy over a year might be within a 1/10 th of a second, but a graph made with a sensitivity of 1/100 of a second might show plus or minus reading throughout the year.

When they are working correctly, with a god signal, they update the time hourly or thereabouts, so the deviation is likely to be very small. I have a Casio radio controlled watch that only updates once a night.

Tony Jeffree13/06/2021 17:11:07
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Posted by Georgineer on 13/06/2021 16:58:14:

Off topic a bit, I visited the Anthorn transmitting station during the 1960s. It was fascinating, huge and all very hush-hush, and it had its own nuclear shelter still very much in commission. One cause of amusement was that when transmitting morse code, the lights in the village dimmed in time with it. It must have been infuriating for anybody who could read morse to have a stream of encrypted gibberish appearing in their living room.

A colleague of mine used to work at Rugby before al the ULF stuff was moved. Apparently, the amount of radiated RF in the control room was such that the fluorescent lights continued to fluoresce after you switched off the power!

John Haine13/06/2021 18:31:57
4279 forum posts
252 photos

My father worked for Metrovick in Manchester before WW2 and was visiting a colleague who worked for BTH in Rugby, who had been a ships radio operator. They were walking along to the pub in the town one evening and suddenly the colleague said "oh, the Australians have just won the test!". Reading morse was second nature to him and they had just transmitted the news on the big 16 kHz transmitter so he read it off the street lights. I was always fascinated by the huge towers of the big GBR transmitter when I was a teenager in Rugby but never managed to blag a visit there. All replaced by a commercial park now...

Douglas Johnston14/06/2021 11:45:58
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762 forum posts
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Posted by John Haine on 13/06/2021 13:25:10:
Posted by Douglas Johnston on 13/06/2021 11:55:11:

I have one of those radio controlled clocks that refuses to lock on to the signal and slowly gains a few seconds a month. When the clocks change in October and April I have to take my clock to a high point in the back porch and leave it there for a day or two and it finally does the conversion. When it was new it worked fine for a number of years, then decided to annoy me for some reason.

Doug

If it's an MSF clock it may have stopped working when they moved the transmitter from Rugby (nearly in the centre of the UK) to Anthorn in Cumbria, so your signal level may have dropped.

That is interesting but since I live on the east coast of Scotland I am nearer the new transmitter, although there may be geographical considerations at work. I nearly threw the radio out when it first started to misbehave but tried placing it in a number of locations until I found one that worked.

Doug

John Haine14/06/2021 11:53:02
4279 forum posts
252 photos

Another good theory bites the dust!

Tony Jeffree14/06/2021 12:10:04
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Posted by Douglas Johnston on 14/06/2021 11:45:58:
Posted by John Haine on 13/06/2021 13:25:10:
Posted by Douglas Johnston on 13/06/2021 11:55:11:

I have one of those radio controlled clocks that refuses to lock on to the signal and slowly gains a few seconds a month. When the clocks change in October and April I have to take my clock to a high point in the back porch and leave it there for a day or two and it finally does the conversion. When it was new it worked fine for a number of years, then decided to annoy me for some reason.

Doug

If it's an MSF clock it may have stopped working when they moved the transmitter from Rugby (nearly in the centre of the UK) to Anthorn in Cumbria, so your signal level may have dropped.

That is interesting but since I live on the east coast of Scotland I am nearer the new transmitter, although there may be geographical considerations at work. I nearly threw the radio out when it first started to misbehave but tried placing it in a number of locations until I found one that worked.

Doug

Sounds like the module is misbehaving. The 3 radio clocks I have are all on the "wrong" side of the house for the signal (I am in Mull and they are on the North of the house) and one is mounted on an aluminium clock face, which is less than ideal, but all three function perfectly.

SillyOldDuffer14/06/2021 13:29:18
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Noise!

The receivers in MSF modules are very simple, which makes them vulnerable to noise. Selectivity is provided almost entirely by the antenna's tuned circuit, which is relatively broad, and allows nearby muck in.

MSF transmits on 60kHZ, and that part of the radio spectrum is full of natural and man-made impulse noise which the detector used to decode MSF is sensitive too. Homes are particularly bad; full of motors, wall-warts, and maybe unfiltered VFDs! Also ignition noise from passing cars, electric fences (in the country), and noise on the mains and telephone wires. Pulses from lightning strikes travel thousands of miles is this band.

This waterfall display was captured from the online SDR Receiver at Twente in Holland a few minutes ago. This is a good receiver with an antenna high above domestic noise, which tends to be short-range at ground-level:

msftwente.jpg

The vertical lines are signals and the horizontal lines are mostly noise, or receiver artefacts. DCF77 is the bright (ie strong) signal on the right, MSF is the second labelled signal from the left at scale 60.

MSF is significantly weaker in Holland than DCF77 and there are two other strong signals nearby, GXH Thurso, and an unidentified teletype at 61.8kHz. There are also about 15 other weak signals just below MSF, possibly interference from switch mode power supplies.

Set to 600Hz bandwidth the Twente receiver has no trouble filtering out the racket, but set to 6000Hz, decoding MSF is like picking out a softly spoken friend across a noisy pub. When MSF clocks don't work, could be low signal, but more likely it's being deafened by high local noise due to the simple receiver's wide bandwidth.

Dave

Jon Lawes14/06/2021 15:05:39
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700 forum posts

I used a Rubidium Frequency standard to make my own "atomic clock" (yes, I know, I know) at home, and what I noticed was that even though my standard was in calibration there was a lot of drift from my anthorn synchronised clock. I guess they don't worry too much about the quality of the movement when they know its going to get constantly corrected.

Neil Wyatt15/06/2021 11:13:14
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The biggest challenge is remembering how to tell digital ones that use the Frankfurt signal to subtract an hour after you have changed the battery or dropped them on the floor!

Solved with an 'analogue' one, years ago, by repositioning the hour hand.

I do wonder what will happen if we get rid of daylight saving and Germany doesn't, or vice versa, Has anyone worked out the environmental cost of all those redundant clocks going in the skip?

Neil

Peter Greene15/06/2021 16:12:34
320 forum posts
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Posted by Neil Wyatt on 15/06/2021 11:13:14:

Has anyone worked out the environmental cost of all those redundant clocks going in the skip?

.... waste of time wink

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