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How does Britain know what time it is?

  • Publicado em 3 Abr 2022
  • Did I need to get a radio controlled clock and travel to Anthorn to film this video? Absolutely not. But for a few minutes, that clock was really, really accurate. • Thanks to the team at NPL! More about NPL Time: www.npl.co.uk/time-frequency/... - their Open Day is on 20th May! www.npl.co.uk/open-day
    I'm at tomscott.com
    on Twitter at tomscott
    on Facebook at tomscott
    and on Instagram as tomscottgo

Comentários • 2 254

  • Tom Scott
    Tom Scott  5 meses atrás +11394

    And if you're wondering why "coordinated universal time" abbreviates to "UTC": that's because it officially stands for "temps universel coordonné", and this way neither English or French speakers are happy. Compromise!

    • microcolonel
      microcolonel Mês atrás

      Splitting the baby.

    • Jesu Christo
      Jesu Christo 4 meses atrás

      @Lazar Aleksandrov No.

    • Adam Kirsopp
      Adam Kirsopp 4 meses atrás

      @David Kovalev we don’t that’s why we use GMT and BST as standard

    • The legend
      The legend 4 meses atrás +1

      I looked it up and he's not joking wtf

    • Keith
      Keith 5 meses atrás

      Only the French cared.

  • L N
    L N 5 meses atrás +772

    "How does Britain know what time it is?"
    Not by looking at where the sun is. I can tell you that much.

    • Arturo Brito
      Arturo Brito 5 meses atrás +6

      I like this joke

    • Matt Watkins
      Matt Watkins 5 meses atrás +30

      Funny :) Interesting tidbit: turns out the 13th century Vikings had a system for telling the direction of the sun even through cloud cover by using a polarizing crystal.

    • deelkar
      deelkar 5 meses atrás +4

      actually they do. Just not by eye ;)

  • The Engineering Mindset
    The Engineering Mindset 5 meses atrás +1373

    A cargo ship used to sail past my workshop, we knew it had passed because it changed the time on all our clocks and watches with whatever signal it was broadcasting. Had to switch to manual change devices.

    • Paris Luhv
      Paris Luhv 14 dias atrás

      @Deft Knight "brackets" ... again, diffinitive proof yall some idiots...
      it's called a quote my guy. Read about it.

    • Jeff Ross Fishing and Family Adventures
      Jeff Ross Fishing and Family Adventures Mês atrás

      @The Engineering Mindset 2.4 million subscribers can’t be wrong !!

    • Mutleyboy
      Mutleyboy 3 meses atrás

      @Elmojomo and probs some of their cargo

    • JmKrokY
      JmKrokY 4 meses atrás


    • Elmojomo
      Elmojomo 4 meses atrás +1

      @Deft Knight Very! Interesting, I mean. :)

  • manicminer
    manicminer 5 meses atrás +274

    For perspective on how little power you need to consume this signal: I once had a digital clock with a capacitor that could keep it running, accurately, for weeks after removing the single AA battery

  • Claudia Jade
    Claudia Jade 5 meses atrás +82

    This was...bonkers. Had no idea could have clocks that 'set themselves' via radio control.

    • Prayag Suthar
      Prayag Suthar 2 meses atrás +1

      Honestly! It's kinda cool to think about clocks setting themselves, that too by radio; I wish we had these in the U.S. tbh 😞

  • George H-W
    George H-W 5 meses atrás +4945

    Tom Scott: consistently answering questions I never thought I had

  • Charlie Dobbie
    Charlie Dobbie 5 meses atrás +479

    I bought some radio-controlled clocks at auction. They were quite cheap, which more than made up for the fact they're fixed to the DCF77 signal out of Germany not the MSF signal out of the UK so they're technically an hour out. I took them apart and adjusted the hour hand so when it thinks it's 12 o'clock the hand points at 11 o'clock - and nobody is any the wiser. Apart from daylight savings transitions when the clock adjusts itself an hour before you'd expect.

    • T P
      T P 5 meses atrás

      @Rufus Stone sure!

    • Rufus Stone
      Rufus Stone 5 meses atrás +3

      @T P At the same exact point in time, but not at the same time, BST/IST/WEST at 1:00, CEST at 2:00 and EEST at 3:00.

    • Charlie Dobbie
      Charlie Dobbie 5 meses atrás +1

      @T P How interesting! I see now that the clocks are supposed to change at 2am CST, 1am GMT - but that didn't match the behaviour I saw from my clocks this year. Will have to pay closer attention in October to see what's going on. Thank you!

    • T P
      T P 5 meses atrás +1

      FYI. Europe moves onto summer time at exactly the same time as the UK.

    • GodmanchesterGoblin
      GodmanchesterGoblin 5 meses atrás +3

      @eDoc2020 And that is exactly what some watches do. I have one that only acquires the DCF signal (it is a German watch, so that's reasonable) and I have another that handles multiple frequencies and standards. These days, the decoding is a trivial software exercise. Running a miniature low power consumption receiver of adequate sensitivity that also supports multiple frequencies is another thing altogether. I believe they use miniature quartz crystals to help achieve the required selectivity in the receiver.

  • ronkemperful
    ronkemperful 5 meses atrás +103

    I live 6 miles from the national atomic clock transmitter in the USA that does the same thing. However, the timezone and daylight savings settings must also be selected on the clock for it to be accurate for the region. The UK has a great advantage with just one time zone. Great video.

    • Jules
      Jules Mês atrás

      ​@Steve Sether Cool Steve! It is really magical technology. my country doesn't have it, so it was wild to learn about it from the video.

    • Steve Sether
      Steve Sether Mês atrás

      @Jules I have one of these clocks, but it's not all that complicated. You just select which timezone you're on, and enable or disable DST. That's it. I think I paid $20 for it.
      The signal, WWV broadcast a shortwave signal out of Colorado has an audio component you can listen to, but also broadcasts a binary encoded signal once a minute with the time. The binary encoded signal has a component that says if DST is active or not.
      I've always been amazed you can get this signal thousands of miles away from a cheap $20 clock with no visible antenna, just sitting on my wall.

    • L T Mundy
      L T Mundy 4 meses atrás +1

      @VTX Bing

    • VTX Hobbies
      VTX Hobbies 5 meses atrás

      At the tone, 12 hours, one minute, coordinated universal time.

    • Jules
      Jules 5 meses atrás +6

      @T J America's problem is that different states have different timezones and rules for DST. For example some states have daylight saving time, but some do not. Britain has DST, but it has only one timezone and one rule for DST. Not so for the US, so the equipment must be much more complex.

  • Daniel Turner
    Daniel Turner 5 meses atrás +32

    I've had the privilege of being involved in conducting peer review of Australia's equivalent of NPL and visited the clocks held by the National Measurement Institute of Australia, which maintain that country's connection to UTC. Fascinating stuff!

  • Simon Eavery
    Simon Eavery 5 meses atrás +56

    I remember hearing one of the NTL time group members complain about their shiny new building. It was made of metal and was expanding and contracting by mm with the ambient temperature changes. Antennas on the building associated with time transfer were now seen to be moving in time during the day. Their previous brick building was less prone to this effect.

    • laskin riubn
      laskin riubn 5 meses atrás +2

      If I had a nickel for ever time I stood with a domestic appliance by an ocean, I would have two nickels. It’s not a lot, but it’s weird that it happened twice.

  • tsvk
    tsvk 5 meses atrás +25

    I would have been interested in the radio protocol for transmitting the time data. What exactly gets sent over the air and how often does it update? Is it time only or date also? How much is there error correction for improving resilience? What kind of chips do the clocks contain to decode the data? Etc.

    • cdl0
      cdl0 5 meses atrás +3

      Wikipedia has all the details. See also NPL's website.

  • Thomas Vlaskamp III
    Thomas Vlaskamp III 5 meses atrás +29

    The US has a similar system. NIST has the radio station in Colorado, WWV, transmitting at 2.5, 5, 10, 15, and 20 MHz. It's designed to cover most of the US. The site is shared by its longwave cousin, WWVB, transmitting at 60kHz. And in Hawaii, theres WWVH transmitting at 5, 10, and 15 MHz. All 3 stations use UTC for their time codes

    • denelson83
      denelson83 Mês atrás

      And of course, we in Canada have CHU on 3.33, 7.85 and 14.67 MHz.

    • J H
      J H 5 meses atrás +1

      The USA's similar system is the WWVB on 60 kHz.
      Shortwave time signals are different purpose and usage.
      Depends what's meant by "similar"...

    • autarchex
      autarchex 5 meses atrás +4

      @Thomas Vlaskamp III If you don't, knowing the current time might not be the highest priority.

    • Thomas Vlaskamp III
      Thomas Vlaskamp III 5 meses atrás +2

      @tvdan1043 Seems reasonable. As long as you know which way Colorado is from you

    • tvdan1043
      tvdan1043 5 meses atrás +9

      The instructions for my clock have a suggestion for when it has trouble receiving the signal inside a building: "Take the clock outside and point the back of the clock in the general direction of Fort Collins, Colorado."

  • MrMockingbird1313
    MrMockingbird1313 5 meses atrás +22

    Hey Tom, Years back I had a similar discussion with an USAF expert. The USA national standard is a clock in Denver Colorado. It is critical to know how far the sender radio is to the receiver clock. Then a range adjustment is made, so that satellites line up, bombs hit on target, and official top secret communication is made in real time. BTW, the adjustment from Denver to Scott AFB, just outside St. Louis where I live is a +4000/second.

    • MrMockingbird1313
      MrMockingbird1313 5 meses atrás

      @Quill Maurer Your information is more current and accurate. But, my information goes back 20 years. I just remember vividly that secure transfer of information depends on an accurate time standard and the transmitter was 4000/second west of here. Funny stuff? Thanks for your correction.

    • Quill Maurer
      Quill Maurer 5 meses atrás

      @MrMockingbird1313 The Air Force Academy is in Colorado Springs, about an hour south of Denver (Boulder is a half hour northwest). The time standard, at least currently, is in Boulder, I had an internship there a few years ago (the time-standard atomic clock itself is sort of anti-climactic, looks like a server farm). That time-standard sends a signal to an antenna array similar to the one in this video located north of Fort Collins.

    • MrMockingbird1313
      MrMockingbird1313 5 meses atrás +1

      @valkyrie_pilot Perhaps it is now. I believe I was told it was in Denver, years ago. But what you say makes sense because USAF has a large presence in Boulder. For instance, the Air Force Academy is in Boulder. Anyway your presentation was excellent. And my second point is that the EXACT time adjusted around the globe is critical for TOP SECRET communications. So, today, exact time is more critical than it was 20-30 years back when this plan was hatched.

    • valkyrie_pilot
      valkyrie_pilot 5 meses atrás +3

      isn't it in Boulder, at NIST?

  • TastyBusiness
    TastyBusiness 5 meses atrás +23

    I'm betting we're being shown one of the engineering labs in the facility rather than a production time source, because that lack of cable management screams "test bench" and not "permanent infrastructure"

  • Hadinos Sanosam
    Hadinos Sanosam 5 meses atrás +2703

    4:45 "Standing by the ocean with a domestic appliance" is just normal Tom Scott behaviour at this point xD

    • Martin Paulsen
      Martin Paulsen Mês atrás +1

      @Jaded Cynic Or, as Auric Goldfinger put it, "Once is happenstance, twice is coincidence, three times is enemy action."

    • WyvernYT
      WyvernYT 5 meses atrás +1

      Hopefully Tom will have an excuse to hold a toaster while standing near Towchester.

    • johno4521
      johno4521 5 meses atrás

      Technically just a River estuary, but OK

    • Isaiah P
      Isaiah P 5 meses atrás +2

      “This is a Teasmade.” Interestingly that video was also about keeping accurate time in the Uk.

    • criggie
      criggie 5 meses atrás +2

      Not the last time either...

  • Brad Griffin
    Brad Griffin 5 meses atrás +7

    I've been a mild timezone/time-keeping geek since childhood when I learned about Greenwich Mean Time and Time Zones as a five-year-old. These very British timekeeping quirks bring me much joy.

  • Papa Bad Dad 2
    Papa Bad Dad 2 5 meses atrás +7

    I'd love to hear about how this process is handled in other countries, even if just briefly

  • Backroad Junkie
    Backroad Junkie 5 meses atrás +12

    40 years ago when I used to TSD Rally (Time-Speed-Distance, you can calculate any one of them if you know the other two), we used to synchronize all out clocks/watches to WWV.
    WWV (the shortwave station that broadcasts time in the US) has been in operation since 1919, 103 years...

  • IJR
    IJR 5 meses atrás +4

    I’ve asked myself this question many times before, but never thought to seek out the answer. Thanks for giving it to us!

  • laskin riubn
    laskin riubn 5 meses atrás +1

    I'd love to hear about how this process is handled in other countries, even if just briefly

  • The Next Outing
    The Next Outing 5 meses atrás +2

    Tom Scott is 100% one of our favourite BRclip. The quality of his videos with the level of research etc…
    Answering questions no one thought they needed to know!

  • Neall McLaren
    Neall McLaren 5 meses atrás

    Great video Tom, We tend to take the time signal for granted and forget how lucky we are to have a free service which offers such highly accurate timing. Can you maybe do a followup video about leap seconds and why, when and were they are used. Atomic timekeeping is a big subject without such accurate timekeeping, satellites would be out of position and could literally fall back to earth.

  • Peter H
    Peter H 5 meses atrás +1

    In a previous job, when the UK signal was moved from Rugby up to Anthorn i was task with moving our receive antenna slightly to compensate for the different location. The antenna was a ferrite rod in a white plastic box so it was directional. Being located on the south coast of the UK, we could pick up the DCF77 signal much stronger than Anthorn.

  • dzarko55
    dzarko55 5 meses atrás +1207

    My workplace got one of those! Too bad they forgot the control room is 20 meters from a 20MW induction furnace. It constantly tried setting itself to random times of day.

    • TriGGeRosT
      TriGGeRosT 5 meses atrás +4

      you could shield the clock under the a faraday cage

    • Vigilant Cosmic Penguin
      Vigilant Cosmic Penguin 5 meses atrás +8

      This must be that time dilation those fancy science fellers are talkin' about.

    • Mr. Marc G.
      Mr. Marc G. 5 meses atrás +17

      @jackiwi Could have fixed the problem by putting up a sign for the correct city for each clock. London, Chicago, Tokyo, Sydney, hahahaha

    • Adam Holmes
      Adam Holmes 5 meses atrás +4

      @jackiwi Possibly the hour hand fell off, or was jokingly taken off and put in the wrong place.

    • Owen Smith
      Owen Smith 5 meses atrás +19

      @type17 German signal is perfectly receivable at my house and my parents (Cambridge and Holmfirth)

  • psprog
    psprog 5 meses atrás

    These transmitters always fascinated me when I was younger (having been born and raised in Carlisle, a few miles away). They only recently became the time signal source after Rugby shut down. Was originally a low frequency transmitter for submarines I believe.

  • Benjamin G
    Benjamin G 5 meses atrás

    The importance of security to timekeeping is astounding and spans many RFC docs on best practices.

  • Joop Plankman
    Joop Plankman 5 meses atrás

    Hallo Tom, great topic for a watch enthusiast like me. I receive my radio signal from the Mainflingen complex in Germany. Never had a problem receiving a good signal here in the Netherlands (for my Casio Waveceptor watches) . There are great videos about the way the signal itself works. Thanks!

  • WistrelChianti
    WistrelChianti 5 meses atrás

    Would be interesting to know more about the signal and how to use/decode it. Especially if it's simply enough to work with that cheap domestic clocks do it. (although appreciating that cheap electronics can do some complex stuff these days)

  • Odditorium Leviathan
    Odditorium Leviathan 5 meses atrás +1369

    If I had a nickel for ever time I stood with a domestic appliance by an ocean, I would have two nickels. It’s not a lot, but it’s weird that it happened twice.

    • Jivan Pal
      Jivan Pal 5 meses atrás

      Y'all good, Doofenshmirtz?

    • David Roddini
      David Roddini 5 meses atrás +1

      What? Doesn’t everyone who lives near an ocean bring domestic appliances there regularly?

    • Space Waldo
      Space Waldo 5 meses atrás +2

      came here for this exact joke.

    • Backroad Junkie
      Backroad Junkie 5 meses atrás +3

      @Sam Reid Actually, it's a US law passed in 2007 that specifically prohibits the melting of cents and nickels.
      It's in 2007 that the worth of the copper and nickel in the coins exceed the value of the coin. They were afraid the coins would be melted down creating a shortage of those coins.
      The law is E7-7088 in the Federal Register...

    • Sam Reid
      Sam Reid 5 meses atrás +3

      @Contagious Gloom yes. In most countries defacing or destroying currency is against the law. The US has some of the more harsher sentences for it because there was a period in our history where gold and silver coins were melted down either because the metal itself was more valuable or because people would coat baser metals in it and stamp it to create counterfeit coins.

  • AwesomeBoysJPTV
    AwesomeBoysJPTV 5 meses atrás

    The more I watch Tom Scott videos, the more I learn about weird real-life jobs that exist

  • annando
    annando 5 meses atrás +3

    Tom should visit the DLR in Braunschweig in Germany. That's where the German time is measured. The room itself looks fantastic (I once visited it). It is a room with copper walls to avoid any electromagnetic influence from the outside. The time signal is then transferred to Frankfurt from where it is transmitted via longwave at 77.5 KHz.

    • aliceif
      aliceif 5 meses atrás

      Funny enough the transmission towers are very close to the 50°N 9°E point - which is in a nearby forest, maybe about a kilometer away.

  • James Corrall
    James Corrall 5 meses atrás

    We need to make a playlist of every time Tom has been standing somewhere random with an appliance.

  • RichXKU
    RichXKU 5 meses atrás

    Great info! No reason to ever buy a manually set clock when these are so widely available. I have 5 at this point, one is 20 years old and the batteries last well over a year.

  • ben
    ben 5 meses atrás +2729

    I always find it amazing when I hear about these lesser known organisations which perform such vital work for the UK and the world. Great video, Tom!

    • PandaCake978
      PandaCake978 5 meses atrás

      @Erik Uden you need someone telling everyone else, "right this is the correct time" otherwise as time goes on (no pun intended) different organisations using slightly different internal systems for clocks will drift.
      You could leave your work which thinks it's 10.00 but get to the bus station 5 mintues which thinks it's 10.15 and you've missed your bus. A simple example but add the world+timezones and it gets very messy

    • Nahsor
      Nahsor 5 meses atrás

      one take!

    • Clive M
      Clive M 5 meses atrás

      @Vigilant Cosmic Penguin they prefer to be called time lords actually

    • ben
      ben 5 meses atrás +1

      @Keshuel thanks for that astute observation, I would never have noticed!

    • Chris
      Chris 5 meses atrás +1

      @g76agi I'm fine, thanks

  • Seb Gibbs
    Seb Gibbs 5 meses atrás

    I've been looking at weird wave like patterns that keep appearing in clouds a few weeks ago. We have had some very unusual weather which prompted me to regularly look at weather satellites images. These wave like patters keeps appearing almost daily, usually in the morning over hundreds of miles, at a very specific distance of 5km between wave peaks. It turns out that radio clock signals are some of highest powered transmitters in the country and the only possible source of a 5km long wavelength.
    However, I'm not looking at the UK, I'm looking at the East side of Australia, which apparently, doesnt have these radio clock transmitters. Just wondered if anyone else here has done any similar diligent work in to this.

  • Michael Bauers
    Michael Bauers 5 meses atrás

    great video. I love this topic. TAI is interesting. It's a weighted combined scale of atomic clocks over the world. But it's not until after the fact TAI tells you what time it is. It's like the tell you what time it was, sometime in the past. Ultimately though, UTC is a set offset from TAI. The offset is the number of accumulated leap seconds.

  • ke6gwf - Ben Blackburn
    ke6gwf - Ben Blackburn 5 meses atrás

    The US has a similar system in place.
    And I loved your practical demonstration of how to introduce time errors!

  • Povilaz
    Povilaz 5 meses atrás

    Absolutely love this kind of technology. I sometimes can pick up (I think) this time signal on my shortwave radio.

  • iissaacc
    iissaacc 5 meses atrás +1074

    I appreciate that this video was done in "real-time" with the physical clock still ticking during the interview

    • James Orpin
      James Orpin 5 meses atrás +10

      @Stephen Wood didn’t look in that much detail. Just the general idea that the OP was getting at

    • eekee
      eekee 5 meses atrás +14

      @jasonrubik 2 seconds isn't bad at all. :)

    • jasonrubik
      jasonrubik 5 meses atrás +24

      @James Orpin It seems to be off by 2 seconds. At the beginning, the clock was behind by 5 seconds ( video timestamp was 0:09 and clock said 10:40:04 ) At the end of the video, the timestamp was 4:49 and the clock said 10:44:46 , approximately.

    • Stephen Wood
      Stephen Wood 5 meses atrás +16

      @James Orpin If you look carefully, its not in synch with the time on the video. It jumps forwards and backwards

    • James Orpin
      James Orpin 5 meses atrás +172

      @Vigilant Cosmic Penguin they mean that at the begging the clock shows 10:40, by the end of the 5 min video it shows 10:45. Tom has done his segments with specific gaps for the interviews so the clock keeps time with the video

  • bobandveganlover
    bobandveganlover 5 meses atrás

    Having noticed my radio controlled clock changing and wondering how it worked, this was a fantastic video.

  • HotelPapa100
    HotelPapa100 5 meses atrás

    What I find interesting is that the low-tech, low bandwidth telegram of the radio clock signal takes about a minute to transmit. So when you switch it on, it takes a few minutes to actually synchronise.

  • Rowana Hedley
    Rowana Hedley 5 meses atrás

    Living not far from here, I was always curious whenever I saw them of what they did, but never enough to look it up, so this was cool to watch. And it's always exciting whenever you see a place nearby/that you know being featured in a video.

  • Beirtí Ó Nunáin
    Beirtí Ó Nunáin 5 meses atrás

    I love that you're holding a clock showing BST that is perfectly aligned to the UTC digital clocks that you briefly cut to at NPL. Nice touch:)

  • Adam Kuecker
    Adam Kuecker 5 meses atrás +890

    I used to work tech support for a radio controlled clock company. The amount of people that called in worried about the device being labeled with "atomic time" and having concerns about being irradiated was slightly concerning.

    • Jonathan Odude
      Jonathan Odude 5 meses atrás

      @Anankin12 I thought the point was everyday unavoidable exposure?

    • Anankin12
      Anankin12 5 meses atrás

      @Jonathan Odude not getting through the magnetosphere, but that's besides the point

    • Jonathan Odude
      Jonathan Odude 5 meses atrás

      @Anankin12 α radiation showering the earth? from the sun?? getting through the magnetosphere???

    • Dónal O'Flynn
      Dónal O'Flynn 5 meses atrás

      @kuebbisch You're made of atoms too bro.

    • Dónal O'Flynn
      Dónal O'Flynn 5 meses atrás

      @Dem Pilafian You think that people who are afraid of radiation wash themselves every day? Have you ever had the misfortune to stand downwind of a hippie?

  • Andrew John Gwilt
    Andrew John Gwilt 5 meses atrás

    Amazing how time can be so correct all the time. Mobile phones, computers, consoles and other gadgets have time and always keep on updating. Whilst microwaves, ovens, washing machines, watches and many more stuff don’t need WiFi to tell the time because we always change the times on the clocks.

  • Anthony Francis-Jones
    Anthony Francis-Jones 5 meses atrás

    It is interesting to note that if you buy your clock in a different time zone it still syncs with that time zone in the UK if it can pick up a transmission. We have a radio clock from Germany that is always out by one hour but still picks up daylight saving etc. changes.

  • logan holmberg
    logan holmberg 2 meses atrás

    Many of the solar watches in my watch collection use this technology. Its highly prevalent in Citizen and Casio watches. Some of the more advanced ones use gps signals or less expensive ones use Bluetooth to get the time from your phone (only use if your phone corrects itself to an atomic clock. not all do). These 2 options are handy for countries that do not have the signals. I believe the only places that use atomic radio are North America, Japan and Western Europe? Frankly I wish more countries did this. Its a highly valuable time correction device that can be very cheaply put into electronics. Even Quartz devices can lose up to a few seconds a month, which might not sound like much, but cumulatively over time lead to high inaccuracies in time. Also you ever notice when you ask most people what time it is most of them have different answers by a few minutes. This kind of tech would fix that problem.

  • Noahsart
    Noahsart 5 meses atrás

    I love the way you keep finding random yet interesting stuff to talk about!

  • TheNewGreenIsBlue
    TheNewGreenIsBlue 5 meses atrás

    I was hoping you'd get into how it actually works. It's fascinating and it takes about an hour to broadcast the time. My Sony Radio-controlled digital alarm clock never has never had to have the time set, despite being on the West Coast of Canada. It reads the Signals from a tower in the US.

  • Eri
    Eri 5 meses atrás

    When I moved abroad I took my radio controled clock with me, it still worked precisely at about 1000 miles away from UK

  • zzx
    zzx 5 meses atrás

    Great video Tom, I prefer your more technical based videos like this, over the 'historical' based ones, but thats just me.

  • Sirius
    Sirius 3 meses atrás

    In America, every part of the country except Hawaii receives time signals from one station in Denver. It's truly a robust signal. The time station also operates a shortwave station that you can listen to to get precise time.

  • ThePixel1983
    ThePixel1983 5 meses atrás +688

    The German version of this (DCF77) used to have a few bits just for the engineers to receive a few error codes. Today those bits transmit encrypted weather data and there's just one error bit. I built a receiver that shows those 60 bits on LEDs, and you could listen to the bips (100 or 200 ms each second) and decipher them on a piece of paper if you needed to.

    • Britonbear
      Britonbear 5 meses atrás +3

      The one I got from Lidl stopped working after Brexit; I don't know if that's coincidental or not.

    • denelson83
      denelson83 5 meses atrás

      @Roland Endersby And Japan does not use DST, but neither do WA, NT or QLD.

    • Roland Endersby
      Roland Endersby 5 meses atrás +2

      Japan has one and the car I have uses it to set its time and there's no way to adjust it, so in Australia my car clock is forever wrong.

    • micha c
      micha c 5 meses atrás +1

      @Moatl Greed, the universal hoooman fallacy.

    • WFMG
      WFMG 5 meses atrás +4

      Ah, the good old blinkenlichts!

  • J.B. Dazen
    J.B. Dazen 5 meses atrás

    What's so great is that the time change on the clock is just as long as the video itself, so you did that presentation without any (significant) breaks.

  • Walter White
    Walter White 5 meses atrás

    Such an informational video, I love it! It would be really good if they showed how do they synchronize the time when the daylight saving kicks in

    • deelkar
      deelkar 5 meses atrás +1

      most broadcast formats I'm aware of either send an offset to UTC or normal time when DS is in effect, or send the DS time, with an "awareness" bit to indicate that the transmitter is, in fact, transmitting DST so Clocks that need to run on UTC can get that back from that.

  • beautifulsmall
    beautifulsmall 5 meses atrás

    Interesting, time by fibre to the us. I bought a MSF module for arduino to log against a pendulum .Great insight.

  • Jonas C
    Jonas C 5 meses atrás

    A timespan, that is so small, that you can visualise the travel distance of light with your hands is incredible.

  • James England
    James England 5 meses atrás +181

    Ah, yes. My kids' elementary school had these in every classroom. They were usually waaaay off, or exactly right, or forever spinning to recalibrate, or whatever whimsical thing they wished to be doing. Mostly being wrong.

    • Uncle Stephen
      Uncle Stephen 5 meses atrás

      @ParticuLarry We have a saying in England. Only Germans have the same sayings as us. :-)

    • Laurence Fraser
      Laurence Fraser 5 meses atrás +4

      @ParticuLarry In English there is the saying "Even a stopped clock is right twice a day" (meaning that even the most incompetent person will occasionally be correct purely by chance). It's specifically a stopped clock rather than a broken one, as a broken clock could, depending on precisely how it was broken, do just about anything, with stopping (and thus having the metaphor work) being just one possibility (and a clock can stop without being broken, too.)
      Amusingly, all of these sayings only make sense if you're using a twelve hour (probably analogue) clock. Stopped 24 hour clocks are only right Once a day.

    • Vigilant Cosmic Penguin
      Vigilant Cosmic Penguin 5 meses atrás +4

      When the clocks recalibrated, that was the highlight of the day.

    • Clive M
      Clive M 5 meses atrás +2

      we had the slow kid who spent most of the day counting bricks but sometimes would also start spinning round and round uncontrollably and put three teachers in hospital

    • Bruno Lopes
      Bruno Lopes 5 meses atrás +5

      @ParticuLarry we have a similar saying here in Brazil, but it goes like: even a broken clock is correct twice a day

  • A Day as a Breese
    A Day as a Breese 5 meses atrás

    I have been wondering this since I was in elementary school and saw a clock spin forward an hour by itself after daylight savings! I took the clock off the wall and it looked totally normal.

  • Eric Hakanson
    Eric Hakanson 5 meses atrás

    I'd love to see you do a video on how those "atomic" clocks work.

  • RWallace514
    RWallace514 5 meses atrás +13

    The Canadian version of this, CHU, is even more interesting; in addition to putting out a time signal on a low frequency, its 3330 KHz signal carries Bell 330 modem tones as well as the speaking clock.

    • denelson83
      denelson83 Mês atrás

      It's actually Bell 103-compatible time code.

    • J H
      J H 5 meses atrás

      Actually, the Canadian version of "this" is the USA's WWVB, which covers much of Canada. The shortwave signals (CHU, WWV) are sufficiently different purpose and usage that they should not be conflated with the VLF time signals topic here.
      Nitpick. :-)

  • Alex Fritch
    Alex Fritch 5 meses atrás

    My school uses these same clocks. I didn’t realize they were synchronized until the battery in my physics teacher’s clock died. It was sort of eerie watching the clock set itself to the correct time after we put a fresh battery in.

  • LR S3
    LR S3 5 meses atrás

    I love how complicated this is just to know the time

  • Niel Malan
    Niel Malan 5 meses atrás +1

    A fascinating story about the importance of time is the restarting of the New York electrical grid, after 9/11, when the legacy synchronisation infrastructure was destroyed. A GPS solution was used, but I think that if the UK was in the same position, their LF system would be much simpler. (If it's not already used for that purpose.)

  • Sakher Sawan
    Sakher Sawan 5 meses atrás

    Hey @tom, I have a few of these clocks and have always been amazed with accuracy (although every blue moon the would drift by an exact hour for some reason) but always wonder, how are they secured?? And how vulnerable is the infrastructure for attacks that alter the time?!

    • eDoc2020
      eDoc2020 5 meses atrás

      If you're talking digital security of the transmitted signal, none at all. It's fairly easy to make your own pirate transmitter which will fool nearby clocks.

    • memes
      memes 5 meses atrás +1

      No need to ask tom when my friends dad is the indian guy in the video 💀 im not kidding!!

  • John Gardner
    John Gardner 5 meses atrás +3

    When this video popped up, I was actually retro-fitting radio controlled clock mechanisms into all of my wall clocks!

  • JustWasted3HoursHere
    JustWasted3HoursHere 5 meses atrás +521

    I remember seeing a demonstration of Einstein's Theory of Relativity where they had two synchronized Cesium clocks and they took one of them on an airplane and flew for an hour at about 600mph and, sure enough, when those clocks were re-compared the one that flew in the airplane was a few billions of a second behind the one that stayed on the ground, proving that time actually does slow down as you move faster.

    • JmKrokY
      JmKrokY 4 meses atrás


    • Anu Jiba
      Anu Jiba 5 meses atrás +2

      Movement itself is relativ

    • Iam Sagittare
      Iam Sagittare 5 meses atrás +22

      @C. H.
      No. Relativity makes it so that it's impossible to measure the absence of time dilation and distance contraction effects. To any observer it always seems as if they are entirely stationary, no matter their velocity or the gravitational warping of their local spacetime.
      You should look into it, it's very interesting stuff!

    • chrthiel
      chrthiel 5 meses atrás +1

      @Jackson Larson They're also constantly updated via ground stations

    • Paul Haynes
      Paul Haynes 5 meses atrás +6

      I think they did something similar with the Apollo flights - onboard clocks were behind the earthbound ones when they got home.

  • Paul Wheeler
    Paul Wheeler 5 meses atrás

    We have three of these in my church. One in each of the vestries and one in the tower. Yes the one in the tower is used to set the time on the Victorian tower clock. I’m very impressed at the single take and that Tom must have waited for exactly the right amount of time for each segment from NPL to be edited in. The elapsed time in the video and the clock match to the second, very impressed indeed.

  • GreenSteve
    GreenSteve 5 meses atrás

    Cool! I'd never heard of radio-controlled time correction. I don't think we have that in Australia!

  • Matthew Bester
    Matthew Bester 5 meses atrás

    We have those radio clocks at work. Always puzzled me how it works. Thanks Tom!

  • Rob Whitmore
    Rob Whitmore 5 meses atrás

    Hey Tom, have you seen Veritasium's video about measuring light speed? This video reminded me of it.
    Also, I'd really like to know how they initially worked out exactly what the time is.

    • deelkar
      deelkar 5 meses atrás

      UTC was, and still is, synchronised to Astronomical Time, hence the need for leap seconds.

  • Melisha 👉 𝐹**СК МЕ - СНЕ𝒞𝒦 𝑀𝒴 Р𝑅𝟢𝐹𝐼𝐿Е

    Tom Scott: consistently answering questions I never thought I had

  • Jomir
    Jomir 5 meses atrás +7

    Tom Scott has all the answers!

  • urkerab
    urkerab 3 meses atrás

    That clock might not actually have been "really really" accurate for a few minutes. It probably saves power by only listening for the time at intervals, so you would need to have been lucky to be there at a time when it decided to listen, although in that case it would then stay "accurate" until it next listened.

  • John Beauvais
    John Beauvais 5 meses atrás

    My favorite wristwatch has this feature, the Citizen Radio Controlled series update every night and have a little dial to show whether or not it got reception last night. It’s really cool during spring forward when it stops, twitches, then the hour hand springs forward on its own.

  • Sam
    Sam 5 meses atrás +208

    It’s never really occurred to me how radio controlled clocks work beyond “probably some kind of radio signal somehow” but they’re fun to watch when the hour changes

    • Vigilant Cosmic Penguin
      Vigilant Cosmic Penguin 5 meses atrás +2

      The only good thing about daylight savings is the way the clock goes 'round.

    • Charlie Dobbie
      Charlie Dobbie 5 meses atrás +20

      @notsostrong They're not usually digital clocks - they're analogue. So they tick away as normal but then daylight savings changes and the hands spring into action and whirl around until they settle on the new correct time. It's something quite unexpected to see from something that's usually just a crystal oscillator and and bunch of plastic cogs.

    • Sam
      Sam 5 meses atrás +27

      @notsostrong At least the ones I’ve seen and from what I remember (it’s been a while) the hands whizz round and round for a bit until they settle on the new time

    • Nick's Repository
      Nick's Repository 5 meses atrás +10

      @notsostrong I'm assuming he's talking about when DST either starts or ends

    • notsostrong
      notsostrong 5 meses atrás +6

      As a dumbass American, could you please elaborate on why it's fun to watch when the hour changes? Is that when it syncs up or something?

  • d00mfish
    d00mfish 5 meses atrás +9

    Looking at how certain countries are able to destroy or push sattelites out of orbit this is very important. Especially with a conflict like ru/ukr going on.

  • mikemetaled
    mikemetaled 5 meses atrás

    I was hoping you'd get the closing shot of your clock spinning a full 12 hour rotation as it syncs like the radio clocks at school used to, but we can't have everything.

  • Lots Of Lattes
    Lots Of Lattes 5 meses atrás

    I live very close to NPL so this was very surprising to me that they also broadcast the time frequencies, you never really hear about what they do around here so i am not surprised i didn't know

  • Evan Hildreth
    Evan Hildreth 5 meses atrás

    But I want to know how the clock mechanism works? Does it transmit the time as ASCII text, so some rudimentary number of ticks on the hour? Does the clock just tick extra fast to catch up to the correct time, or does it have separate motors for the second and minute hands?

  • MeFreeBee
    MeFreeBee 5 meses atrás +200

    The best thing about those radio controlled clocks is my 88 year old mum doesn't have to get a neighbour in to reset the one high up on her kitchen wall when the clocks go forward/backward.

    • MeFreeBee
      MeFreeBee 5 meses atrás +23

      @TheQuark6789 I have changed it when visiting, just to be on the safe side.

    • TheQuark6789
      TheQuark6789 5 meses atrás +5

      Do you still have to change the battery, or is it wired or solar?

    • MonkeyJedi99
      MonkeyJedi99 5 meses atrás +9

      That is a GREAT feature! A fall for an older person can be very dangerous.

  • John Graham
    John Graham 5 meses atrás

    I literally live 5 miles from these radio towers and never knew any of this! Thanks Tom!

  • vapofusion
    vapofusion 5 meses atrás

    Very cool and had no idea how important such a institute is 👍
    Long may they keep time 😁

  • Chris
    Chris 5 meses atrás

    I love seeing these old school technologies keeping the world running. If it ain't broke, no need to fix it.

  • robert o
    robert o 5 meses atrás

    I worked at a cinema once where they had 2 of those clocks. One either end of the projection room. They both showed different times.

  • Yuval Talya Nehemia
    Yuval Talya Nehemia 5 meses atrás +708

    Never heard about radio controlled clocks. Are these even a thing outside the UK?
    Cool nonetheless.
    edit: outside Europe?

    • Not a Name
      Not a Name 5 meses atrás

      @HailHydra27 Australia used to have it, they shut down the Radio VNG transmitters in 2002

    • autarchex
      autarchex 5 meses atrás

      @Chris Rutledge I have several of their clocks and love them. It is very efficient; I have changed the battery in the alarm clock by my bed only three times in about fifteen years (rarely using the alarm, just running the clock.) I'm also maybe a little biased by living very near their headquarters in Portland...
      I assume your clock is made for the UK market? It isn't listening to the US signal, is it? That would really impress.

    • juslitor
      juslitor 5 meses atrás

      @Dggxx Fhhfxc The german one also works fine for radio controlled clocks in southern Finland

    • stephhugnis
      stephhugnis 5 meses atrás

      Yes. In the US NIST transmits WWVB our radio clock signal from Fort Collins, Colorado.

    • RathØX
      RathØX 5 meses atrás

      @tomtalk24 lmao i have quite a few watches. God tier casio as a daily :P

  • Mark Finlay
    Mark Finlay 5 meses atrás

    I've seen these radio masts as I live fairly near and had no idea they were for radio clocks. Excellent Tom!

  • Thomas Scott
    Thomas Scott 2 meses atrás

    I worked there briefly in the 70s, back then it was a VLF station using 8ft glass valves for communicating with submarines.

  • speno80
    speno80 5 meses atrás

    I've been to Anthorn a couple of times to do maintenance on some of the masts. Great views of the Lake District and Dumfries. Usually quite windy though, you were lucky to get your drone up!

  • Matheus Jahnke
    Matheus Jahnke 5 meses atrás

    Could the clocks use the energy of the radio signals to power themselves(Like the crystal radios)?

  • T Code
    T Code 5 meses atrás +210

    Here in Germany we actually have a similar institute in Frankfurt. It is called DCF77 and broadcasts at 77khz. Apparently the signal of DCF77 can still be received in Spain and Britain. I know that because I am currently doing my final exam as an it clerk here in Germany. My topic is actually about NTP, Wich is a protocol used to distribute time across a network. So this is a somewhat scary coincidence.

    • Jul W
      Jul W Mês atrás

      @Pixel Okay

    • denelson83
      denelson83 Mês atrás

      @Sirius That station is called WWVB, near Fort Collins.

    • Sirius
      Sirius 3 meses atrás

      @Dave Walker here in America the entire country except Hawaii receives time signals from one station in Denver so it isn't like that's too far away.

    • pcread
      pcread 5 meses atrás

      I bought a Citizen watch in Holland that uses DCF77. It can just about pick up the signal in West Finland and North Wales (mountains are a problem). It also charges by light, so the ultimate lazy person's timepiece.

    • GodmanchesterGoblin
      GodmanchesterGoblin 5 meses atrás +2

      Pedant here... it's actually 77.5kHz, but no-one cares... ;)

  • Si Blacklock Hughes
    Si Blacklock Hughes 5 meses atrás

    Thanks Tom, I see these regularly and always wondered what they were!

  • R Fletcher
    R Fletcher 5 meses atrás

    I've had many radio clocks (it makes changing from GMT to BST and back so much less hassle).... even my wristwatch updates nightly by receiving a radio signal.

  • Russell Whitbread
    Russell Whitbread 5 meses atrás +1

    I recently changed a battery in one of these (digital) clocks and weirdly the time is the correct UK time but the day of the week is spelt in Germany. Waking up on a Tuesday and being told DIE isn't overly nice

  • Sander A.
    Sander A. 5 meses atrás

    As someone who hasn't ever seen or heard of such clocks, would have been cool to see how it auto-sets the time.

  • Kerpinos
    Kerpinos 5 meses atrás +248

    Tom is really good about finding stuff that interests me but that I would otherwise have no clue existed.

  • Typical Nerds
    Typical Nerds 5 meses atrás

    The best thing about those radio controlled clocks is that if they lost signal, they would sometimes infinitely fast forward

  • Chris C
    Chris C 5 meses atrás

    I knew about the US radios that transmit the time - maintained by the US Naval Observatory atomic clocks (same as their website and phone line) - but didn't know how many other nations had their own!

  • BA Elevators & More
    BA Elevators & More 5 meses atrás

    Radio controlled clocks can be that simple? I’ve only seen digital clocks with radio control. Not analog. That’s cool!

  • brunoais
    brunoais 5 meses atrás +1

    One thing I'd like to see is the clock behaves.
    If you remove the battery, it stops. How fast it recovers? Does it move backwards, if it's too much forwards? Does it just speed up by a lot?