Can radio-controlled clocks work on electric railways?

[Dai Corner]

I built an MSF receiver once, 1970s. It used a short ferrite rod antenna. That was directional. Same as an old-style portable AM radio.

Fair comment. My RF theory is rather rusty

 

[josh-j]

A fascinating choice in this day and age - I struggle a bit* to read analog clocks and I think many people my age (early 20s) are the same.

(Presumably they do intend to provide both, but still, it seems like a lot of space for something fewer and fewer people will use.)

* I can do it! But it takes a few seconds to stop and think, whereas I can read a digital clock instantly. Certainly I wouldn’t be able to read one as I was rushing for a train!

There's a pretty interesting video about this:

Personally I think it'd be sad if analog clocks went away in public places. Although the competition doesn't strictly mandate anything - there are examples of digital clocks in the accompanying materials.

 

[Gaelan]

There's a pretty interesting video about this:

Personally I think it'd be sad if analog clocks went away in public places. Although the competition doesn't strictly mandate anything - there are examples of digital clocks in the accompanying materials.

Yeah, for sure. It does seem like a case of individual preferences going both ways, so public places should definitely have both. (I’m aware I sounded like I was arguing against that a moment ago! On further thought, both definitely makes sense.)

I do feel like analog clocks are particularly poorly suited to the railway, though, as everyone looking at the clock will be comparing it to a timetable (either mental or on a departure board), which is almost certainly in “digital” (ie xx:yy) form. So even someone who could get a better intuitive sense of “roughly what time it is” from an analog clock would have to go to more trouble to convert it into something they can use to know when the train comes. But I could be wrong, because I’m not one of those people!

 

[josh-j]

That's a good point to be honest! And lots of train times are like 8:38 etc. which isn't easily distinguished on an analog clock at a glance. Analog clocks (when you're used to them) are brilliant at telling the rough time very quickly (quicker than digital - you don't need to read numbers from them you just glance at the shape of the hands and you know the time) but for precision, especially comparing to a timetable or something, it does take longer for me too and I'm not quite in my 20s any more!

Still, I just like them They're like public art.

And the competition does seem a bit more about art than practicality (though I like that - why can't be have nicely designed things at our stations rather than everything being cost reduced to nothing.... rant over)

I'd hope information screens would still show a digital time though regardless of what they do with this competition.

 

[edwin_m]

Digital time is important because all the train times on information screens are in this format - I can't see it being either practicable or acceptable to show miniature clock faces alongside each departure! It's also easier to tell the time to the individual minute or second - important for railways but not possible with an analogue clock face unless you're pretty close to it. As mentioned, analogue helps people get a quick approximate impression of the time, and is useful to people who don't quite get the 24-hour clock, but I'd say it was secondary in a railway station.

 

[talldave]

Digital time is important because all the train times on information screens are in this format - I can't see it being either practicable or acceptable to show miniature clock faces alongside each departure! It's also easier to tell the time to the individual minute or second - important for railways but not possible with an analogue clock face unless you're pretty close to it. As mentioned, analogue helps people get a quick approximate impression of the time, and is useful to people who don't quite get the 24-hour clock, but I'd say it was secondary in a railway station.

Except stations managed by London Overground, where the scheduled departure time of the train is a closely guarded secret. Their screens are utterly useless.

 

[davews]

As an aside, I noticed that the clock showing on the platform PIS at Brixton underground yesterday was five minutes out...
If as usual your Anthorn radio controlled clock synchronises to the transmitter once a day or once hourly it matters not whether it can receive the signal inside a train. But since it moved from Rugby to Anthorn some years ago the signal strength down here in the south is now much less and you don't need much to block it - putting the clock next to a desk top computer or whatever usually kills them.

 

[Recessio]

As an aside, I noticed that the clock showing on the platform PIS at Brixton underground yesterday was five minutes out...
If as usual your Anthorn radio controlled clock synchronises to the transmitter once a day or once hourly it matters not whether it can receive the signal inside a train. But since it moved from Rugby to Anthorn some years ago the signal strength down here in the south is now much less and you don't need much to block it - putting the clock next to a desk top computer or whatever usually kills them.

Victoria line station clocks have been weird for ages. Vauxhall was consistently a few minutes out for the best part of a year.

As others have said, I think that surely in this day and age it makes far more sense to use Network Time Protocol, which is many times more accurate than radio frequency, and also allows for DST correction.

 

[XAM2175]

As others have said, I think that surely in this day and age it makes far more sense to use Network Time Protocol, which is many times more accurate than radio frequency, and also allows for DST correction.

Even Solari (yes, that Solari) have got on board with NTP now

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[dcbwhaley]

I used to have a DCF-receiving watch and I could never get it to receive the signal from Frankfurt while on an electric (OLE) railway in London. I tried an MSF-receiving clock on Wednesday night at Waltham Cross station but no luck - even taking the clock a significant distance across the adjacent field wouldn't pick up the signal from Cumbria. Thinking that being practically at sea level might be part of the problem, I then tried reception on a station on the Hertford Loop with instant success, but since the trains were bustituted on Wednesday night, the OLE on the Hertford Loop might have been switched off.

The reason it matters is because there is currently a competition to design a clock for the railway, and the competition advice does not specify how the time will be received - if MSF is not receivable on electric railways and internet time sources are intrinsically laggy, how would one set the time on a railway clock?

Try the Harrison H4 chronometer ????

 

[Carlisle]

Victoria line station clocks have been weird for ages. Vauxhall was consistently a few minutes out for the best part of a year.

As others have said, I think that surely in this day and age it makes far more sense to use Network Time Protocol, which is many times more accurate than radio frequency, and also allows for DST correction.

Sound like a faulty master clock wherever it’s located rather than anything to do with the Anthorn signal etc

 

[Ediswan]

As others have said, I think that surely in this day and age it makes far more sense to use Network Time Protocol, which is many times more accurate than radio frequency

I agree that NTP is usually the better choice, but it is not always more accurate. MSF/DCF will always be slow by the time the radio signal takes to propagate. NTP can be better, it can be worse. It depends on the variability of propagtion delays within the network. Where NTP is especially good is over a carefully designed and managed private network. MSF/DCF are liable to be better than using NTP over the public internet.

In all cases, the error is milliseconds, which should be more than good enough for station clocks.

 

[Pigeon]

MSF/DCF will always be slow by the time the radio signal takes to propagate.

But for a fixed site you just need a fixed correction, and you can work it out from the map.

Of course having a carrier frequency of only 60kHz does limit your ultimate precision a bit

 

[edwin_m]

But for a fixed site you just need a fixed correction, and you can work it out from the map.

Of course having a carrier frequency of only 60kHz does limit your ultimate precision a bit

As the signal travels at 186,000 miles per second, it's not really significant.

If you want real accuracy, GPS time is derived from atomic clocks on board the satellites and correcting for the propagation delays to the receiver is an inherent part of the position calculation.

 

[gimmea50anyday]

Completely unrelated but coukd also be a "symptom" ....

Older iPhones when plugged in to 80x trains to charge batteries the touchscreen digitizer stops working and the phone slows down and becomes unresponsive. Something to do with the electrical fields generated by the train interferes with iPhones (but not android devices strangely)

There could be a connection with the OPs apparent issues with radio watches on electric trains....

 

[Ediswan]

But for a fixed site you just need a fixed correction, and you can work it out from the map.

True. I tried and failed to find an MSF/DCF receiver which offers this correction. That is not the same as saying none exist (or once existed).

If you want real accuracy, GPS time is derived from atomic clocks on board the satellites and correcting for the propagation delays to the receiver is an inherent part of the position calculation.

Exactly. MSF/DCF and NTP accuracy is usually quoted in milliseconds. The inherent accuracy of a GPS clock is usually quoted in tens of nanoseconds.

 

[DelW]

Still, I just like them They're like public art.

And the competition does seem a bit more about art than practicality (though I like that - why can't be have nicely designed things at our stations rather than everything being cost reduced to nothing.... rant over)

We could do worse than emulate the Swiss railway clock, which has become a design classic in its own right. I have a Mondaine watch with that face, and it's quite often recognised even by people who haven't travelled on Swiss trains. Presumably that actual design is copyrighted though.

 

[XAM2175]

Presumably that actual design is copyrighted though.

It's a trademark owned by SBB, which they protect with some vigour (as Apple found out to their cost in 2012).

 

[transportphoto]

My TOC watch is supposedly radio controlled but doesn’t change when the clocks go back/forward.

Just an FYI, TOCWatch usually has a toggle setting for DST on/off/auto