back to article Register Lecture: Can portable atomic clocks end UK dependence on GNSS?

The US-based GPS, a network of more than 30 satellites, is used by millions of phones, handsets and other devices in this country, for satellite mapping, navigation and communications technology. Then there's the European Union's Galileo system, which the UK had – until Brexit – contributed to building. Galileo, of course – …

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  1. PermissionToSpeakPlease

    first lecture of the decade

    Will surely be in 2021, not 2020...

    1. Totally not a Cylon
      Boffin

      Re: first lecture of the decade

      IT people count from zero, though.

      So is 1 or 0 actually the first number?

      1. Dan 55 Silver badge
        Headmaster

        Re: first lecture of the decade

        Centuries and millennia start at year 1 but when we talk about "the 1900s" most people think of 1900 as the first year.

        Presumably decades should also start at year 1 but that ship already sailed centuries ago.

        1. John Robson Silver badge

          Re: first lecture of the decade

          Technically the 1900's is a different time period to the 20th century... but with the recent demise of the apostrophe protection society I suspect we're just going to have to accept that idiocracy was a documentary.

      2. katrinab Silver badge

        Re: first lecture of the decade

        Sure, but there was no year zero, because we hadn't invented the number zero back then. We went from 1 BCE (/BC) to 1 CE (/AD).

        1. Quantum Leaper

          Re: first lecture of the decade

          The first use of Zero was in 3 BCE. The only problem was they used a different Calendar back then.

        2. Anonymous Coward
          Anonymous Coward

          Re: first lecture of the decade

          We? Speak for yourself. It was in fact about 3761, no - sign needed.

          By the time BC and AD were common in Europe, zero was in use.

      3. Erebus_77

        Re: first lecture of the decade

        We work with computers, 1 and 0 are the ONLY numbers!

      4. Flywheel

        Re: first lecture of the decade

        Just a sec .. I'll consult my clock .. oh, wait...

    2. umacf24

      Re: first lecture of the decade

      You went there. They went there. Oh God, NOBODY HAD TO GO THERE BUT YOU WENT THERE ANYWAY.

    3. John Savard

      Re: first lecture of the decade

      While it's true the first lecture of the century was in 2001 and not 2000, since we're in the twenty-first century and not the "two thousands", since decades are described by their leading digits - i.e. we had the "nineteen-sixties", and not the "197th Decade", 2020 will be the first year of the twenty-twenties. 2021 will be the first year of the Two-Hundred and Third Decade, but no one will pay attention to that.

    4. jake Silver badge

      Re: first lecture of the decade

      "Will surely be in 2021, not 2020..."

      You can say that until you are blue in the face, and even implement it personally. However, the vernacular says otherwise. Unless you are willing, able and capable of convincing the GreatUnwashed of the wisdom of your words, all people will do is look at you funny and try to find someone else to sit next to at lunch.

      A wise man doesn't fight unwinnable battles, Grasshopper ... and stop calling me Shirley.

      1. Anonymous Coward
        Anonymous Coward

        Re: first lecture of the decade

        I believe the Pope sides with the great unwashed. There's a story in which someone sells his soul to the Devil to be collected on the 1st day of the 20th century - the Devil being a mathematician duly turns up at midnight on 31st December 2000 only to be told that he is a year too late by Papal reckoning, and therefore the deal has lapsed.

    5. cwl

      Re: first lecture of the decade

      A decade is a period of 10 years, it is not tied to any start or end year. Similarly, century and millennium are periods of time with no fixed start and end years.

  2. Chairman of the Bored

    Interesting

    From what little I know about atomic clocks, the typical caesium and rubidium clocks work off the microwave lines from hyperfine transitions. Electronics transitions allow use of light wavelengths and correspondingly higher precision. For higher precision yet one needs to cool the atoms. All this is established art.

    What I'd like to know more about are what specific claims are made for these clocks and how they differ from the chip-scale rubidium references NIST is publishing on. Specifically, what's the root Allan variance? Settling time? Time transfer methodology?

    The real neat trick is time transfer from device to device and handling the bookkeeping appropriately as one transfers time from stationary devices to moving devices such as aircraft. At caesium stability, relativity becomes apparent even for modest accelerations.

    Mines the one with the 100 gram atomic clock in the pocket: https://www.orolia.com/products/atomic-clocks-oscillators

    1. Brewster's Angle Grinder Silver badge

      Re: Interesting

      "At caesium stability, relativity becomes apparent even for modest accelerations."

      This. Plus changes in altitude.

    2. smudge

      Re: Interesting

      The real neat trick is time transfer from device to device and handling the bookkeeping appropriately as one transfers time from stationary devices to moving devices such as aircraft.

      Not just moving devices - altitude too, so your aircraft was a good example. Time passes more slowly the closer you are to a centre of gravity. There was a TV programme a couple of years ago where they synchronised two portable atomic clocks, then took one up to the top of Snowdon and back. That one was then found to be ahead of the other because it had run faster when at altitude.

      So if you really need the precision of atomic clocks, then you are going to have to allow for altitude.

      1. alain williams Silver badge

        Re: Interesting

        So if you really need the precision of atomic clocks

        This is the key -- how much precision does your application really need ? I doubt that many need more precise than 1 ms.

        1. theblackhand

          Re: Interesting

          "This is the key -- how much precision does your application really need ? I doubt that many need more precise than 1 ms."

          Light travels at about 1 foot per nanosecond/1 meter per 3.34 ns, so if you wish to compute your location to the nearest foot/meter, that's how accurate your time needs to be.

          Traditional GPS gives you your location to within 10m at a resolution of 40ns but I believe gains a little from multiple sources. 1ms gives you your location to the nearest 250 meters if my math is correct (probably not...)

          1. elkster88
            Boffin

            Re: Interesting

            "1ms gives you your location to the nearest 250 meters if my math is correct (probably not...)"

            300 000 000 m/s * 1/1000 s = 300 km.

            1. Anonymous Coward
              Alien

              Re: Interesting

              So you can travel 300 km in 1ms at the speed of light. That is not the same as the accuracy of a location fix if your clock has a 1 ms skew.

              My phone often has a skew of rather more than that on its clock and yet can get a decent satellite only location fix via GPS. Using ntp with say five reasonable sources will generally settle down to about 1 ms without its own stratum 0 source.

              1. rcxb Silver badge

                Re: Interesting

                My phone often has a skew of rather more than that on its clock and yet can get a decent satellite only location fix via GPS.

                Your phone doesn't need accurate time to use GPS (though it helps). But the GPS satellites, themselves need to have incredibly accurate time. So too, any time signal used for location calculation.

                Welcome back GEE / LORAN-C

                1. Anonymous Coward
                  Anonymous Coward

                  Re: Interesting

                  yes that was one of the designs of GPS you don't need an accurate clock on the receiver as the satellites hold an accurate time source

                  1. John Savard

                    Re: Interesting

                    Given that, instead of putting portable atomic clocks in our smartphones at great expense, why not just put atomic clocks in our cell towers or something? In fact, once one gets an accurate position for every cell tower, it's quite possible that some old-fashioned method of radio navigation, not needing atomic clocks at all, could be used to find one's position without the help of satellites. Although maybe the atomic clocks would still help in rural areas.

                    1. Emir Al Weeq

                      Re: Interesting

                      Using atomic clocks in cell towers wouldn't work in locations where two or less cells (from different towers) are available. I suspect that's most of the Earth's surface and everywhere at altitude.

                      1. Emir Al Weeq

                        Re: Interesting

                        Ok, just re-read the headline: this is about UK dependedence. Ignore me.

                2. Grinning Bandicoot

                  Re: Interesting

                  If its only a a pulse that to be used in the determination then we go further back in time were at LORAN-A. LORAN-C used multi pulses to provide transmitter identification in each burst with phase comparison to complete the fix.

                  Now if the clocks are used to provide an ultra precise frequency, DECCA is back with lane counting.

                  Having worked at and on a Differential GPS site all I will honestly say is that the Velocity Factor varies in both the micro term and the long and any radio derived fix must receive the signals from several sources not local and with different frequencies. Omega was good but highly vulnerable to hostile intent.

              2. Bill Gray

                Re: Interesting

                "...My phone often has a skew of rather more than that on its clock and yet can get a decent satellite only location fix via GPS"

                Light moves at about 300000 km/s. One millisecond corresponds to about 300 km, so I can guarantee you that the GPS circuitry in your phone has the time nailed down to better than a microsecond (300 meters). But I do know what you mean. I've seen devices where the time displayed clearly wasn't coming from the GPS.

                On at least one older, stand-alone GPS unit, you could turn it on and watch the clock as it searched around for satellites. When it got a position fix, the clock would jump by a few seconds. It had a somewhat crummy quartz clock, just good enough to figure out which satellites might be visible. Once it could "see" four satellites, it had four equations and could solve for four parameters (x, y, z spatial coordinates and delta-T clock error). Then it would adjust the clock accordingly. (Four satellites are enough -- or three, plus a clock so you can set delta-T=0 -- but additional satellites do help you to reduce errors and give you some redundancy when you lose a satellite or two behind a building.)

                1. gnasher729 Silver badge

                  Re: Interesting

                  Actually, with a single satellite you know that you can't be more than 15,000 km away from a satellite that you can connect to (satellites on the other side of the earth could be further away but they are invisible), so you know your time within 50ms. Don't think any GPS implements it :-)

          2. alain williams Silver badge

            Re: Interesting

            Yes: but they are not talking about a replacement positioning system, just the accurate time part of GPS.

          3. katrinab Silver badge

            Re: Interesting

            Most people use GPS to find out what the time is, not to find out where they are.

            If you are a bank and need to know what time someone withdrew some money, and whether it was before or after some other transaction; I don't think you need nanosecond accuracy, given that the process takes a few seconds to complete.

            1. John Sager

              Re: Interesting

              For bank transfers, stock trades, etc you need event ordering, not necessarily absolute time. Time works for that when trades aren't local that need to be compared.

            2. TRT Silver badge

              Re: Interesting

              Banks need nanosecond accuracy to make sure they capture events for which they can charge a whole month's overdraft fee. The money-grabbing bastards.

              1. A.P. Veening Silver badge

                Re: Interesting

                But they don't get better than microsecond accuracy and mostly do with millisecond accuracy. And some older systems still use whole seconds as most accurate level. And yes, I used to work as a programmer for a large, international bank and one of my jobs was to improve accuracy of timestamps to the microsecond level.

        2. Cynic_999

          Re: Interesting

          "

          I doubt that many need more precise than 1 ms.

          "

          It's the *drift* that's more important. If the clock runs slow or fast by 1mS per day, it will be 1 second out in less than 3 years. Whether than is important depends on the application - especially how frequently it can be corrected from an accutate source.

          1. Anonymous Coward
            Anonymous Coward

            Re: Interesting

            I think (if memory serves me correctly as I haven't done this kind of thing since uni in 1990) the GPS ground stations can update the satellites to allow for drift

      2. tip pc Silver badge
        Thumb Up

        Re: Interesting

        "There was a TV programme a couple of years ago where they synchronised two portable atomic clocks, then took one up to the top of Snowdon and back"

        i remember that tv show, was Jim Al-Khalili on beeb 4.

        lots of different students took time devices to different places, up mountains, further north, south etc, was interesting.

        not the beeb but think this might be it.

        https://www.youtube.com/watch?v=QQRj78jOxWo

      3. Alan Brown Silver badge

        Re: Interesting

        "if you really need the precision of atomic clocks, then you are going to have to allow for altitude."

        and frame dragging - which is a very real thing.

    3. Red Ted
      Thumb Up

      Re: Interesting

      Microsemi (now part of Microchip) make chip scale atomic clocks in little modules you can mount on a circuit board:

      https://www.microsemi.com/product-directory/clocks-frequency-references/3824-chip-scale-atomic-clock-csac

      1. Phil O'Sophical Silver badge

        Re: Interesting

        Is that actually a clock, which gives time of day, or just a very stable/accurate oscillator?

        1. Cynic_999

          Re: Interesting

          "

          Is that actually a clock, which gives time of day, or just a very stable/accurate oscillator?

          "

          It's a stable oscillator (0.5ppb) Which equates to 1 second drift over about 100 years.

          1. TRT Silver badge

            Re: Interesting

            Hm. It derives its clock by exciting caesium molecules using a pair of lasers, though. Some sort of clever feedback system which keeps the laser excitation frequencies tuned very tightly to just either side of the critical resonance frequency of the molecules. So it is a genuine atomic clock.

            I'm not explaining it well. Hang on...

            It says "The SA.45s CSAC employs coherent population trapping (CPT) to interrogate an atomic frequency. A laser illuminates atoms in a resonance cell with polarized radiation at two sidebands separated by the atomic resonance frequency. The atoms are excited to a non-scattering coherent superposition state from which further scattering is suppressed. The small size and low power of the CSAC is enabled by a novel electronic architecture, in which much of the functionality of conventional atomic clocks has been implemented in firmware rather than hardware.

            The SA.45s electronic hardware consists of a low-power digital-signal processor, a high-resolution microwave synthesizer, and analog signal processing. The microwave output is derived from a tunable crystal oscillator and is applied to the laser within the physics package to generate the two sidebands necessary for CPT interrogation. A photodetector detects light transmitted from the laser after it passes through the cesium vapor resonance cell. Based on the measured response of the atoms, the microprocessor adjusts the frequency of the crystal oscillator."

            And then there's a whole lot of other stuff about how stable it is and why that is. It's all bloody clever, mind you. Still not accurate enough to calibrate the timing circuit of a Type 40 TARDIS though. For that you need beryllium.

            1. jake Silver badge

              Re: Interesting

              It is possible that the substrate the thing is built on is beryllium. Sadly, it is probably a more modern engineered ceramic, though.

            2. A.P. Veening Silver badge

              Re: Interesting

              For that you need beryllium.

              Unfortunately, beryllium is quite toxic, so take care when using that Tardis.

        2. ThadiasVonBasterd

          Re: Interesting

          Surely a clock is just a measure of an oscilator?

    4. Uffish

      Re: 100 gram atomic clock

      How much does the battery weigh ?

  3. TRT Silver badge

    Doors open at 18:30:00.00000000000000000000000 UK time for a 19:00:00.00000000000000000000000 start.

    1. Wellyboot Silver badge
      Coat

      Going to be a little late?, you won't miss a thing if you get there before the sound waves make their merry way to the back of the hall.

      1. jake Silver badge
        Pint

        "you won't miss a thing if you get there before the sound waves eventually make their merry way to the back of the hall."

        FTFY. Beer while we wait.

  4. Chairman of the Bored

    Wonder if I will have to send it for calibration?

    I worked in a firm that became ISO-9000. A worthy cause, but some bureaucrats become a little too aggressive.

    I had a caesium primary time reference in my electronics lab, adorned with a good half dozen ISO-compliant inventory tracking stickers, but no Cal Lab sticker.

    Cal lab: "You have a piece of equipment we need to cal! And you refuse to send it to us! Waahhh!"

    Me: "It's ... A primary standard. You, uh, should know already that by definition we Cal other crap off it IT! Given that you don't grasp that, I'm ... concerned."

    Cal lab: "Bad boy! It has stickers on it. That means it can be cal'ed! You're just being a poopyhead!"

    Me: "!..!"

    1. Anonymous Coward
      Anonymous Coward

      Re: Wonder if I will have to send it for calibration?

      A "local" primary standard should still be calibrated against national/international standards.

      1. Chairman of the Bored

        Re: Wonder if I will have to send it for calibration?

        Agreed, but for that If just ship it to NIST in Gaithersburg. My guys just did not have any reasonable explanation for what they were going to do with it.

    2. jake Silver badge

      Re: Wonder if I will have to send it for calibration?

      ISO 9000? You mean you fully documented that your documentation was documented?

      1. Chairman of the Bored

        Re: Wonder if I will have to send it for calibration?

        Yeah! Turtles, er I mean documents, all the way down! When your team starts stamping each other's foreheads with property management stamps before the inspectors come in, and labelled every toilet in the men's room "This container is not authorized for the storage of sensitive information" ... and "report any information spillage to your security officer!" on the floors under the urinals ... you're approaching compliance.

  5. CAPS LOCK

    Not gonna happen. Other countries have satellites, the UK must have satellites...

    ... even if there is ALREADY a land based alternative. (eLoRaN fact fans)

    1. Anonymous Coward
      Anonymous Coward

      Re: Not gonna happen. Other countries have satellites, the UK must have satellites...

      ...or even WAAS & LAAS for GPS I suppose.

    2. Alan Brown Silver badge

      Re: Not gonna happen. Other countries have satellites, the UK must have satellites...

      One of the more "interesting" parts about using Loran for nav is that you need to know what KIND of geography is around the area.

      Radio diffracts/refracts quite differently around a pointy peninsula than a round-ended one and differently still along a smoothish coastline - this would frequently result in Loran-derived positions that were several miles from where you actually were - not good if the area in question has rocky reefs in it (or if you're giving Loran positions for SAR purposes - it wasn't uncommon for them to be 20 miles out and a small boat in open ocean in bad conditions is remarkably hard to spot even when only 5 miles away in the air)

      There's a very good reason it fell out of favour quickly when civilian GPS got into high-accuracy mode.

      1. Anonymous Coward
        Anonymous Coward

        Re: Not gonna happen. Other countries have satellites, the UK must have satellites...

        pah Loran American rubbish bring back DECCA!

        1. Toastan Buttar
          Facepalm

          Re: bring back DECCA

          But guitar groups are on the way out, Mr Epstein.

          1. jake Silver badge

            Re: bring back DECCA

            But The Deccas are a guitar group, Mr. Rowe.

      2. CAPS LOCK

        Radio diffracts/refracts quite differently around a pointy peninsula...

        Fortunately landscape changes slowly so a 3d correction map is a complete solution.

  6. Anonymous Coward
    Anonymous Coward

    end UK dependance on GPS?

    A very small atomic clock will be a significant technical achievement but I can't see how it provides a means of navigation or removes the need for GPS.

    It could be part of a navigation system as atomic clocks already ready are in satellite navigation systems. On the face of it this is just hype based on the first thing that has any connection to precision time keeping, or I am being very stupid and there is someway that a really accurate time source provides position without the need for signals from satellites, measuring the position of astronomical objects etc.

    The hype seems to originate from the University of Sussex or the researchers as it is not just in the register.

    1. Natalie Gritpants Jr

      Re: end UK dependance on GPS?

      I'm guessing you stick one on each mobile phone mast and then you can get position anywhere that you can get a mobile signal from three masts - oh,wait...

      1. Rich 2 Silver badge

        Re: end UK dependance on GPS?

        Mobile phone signals are synchronised to GPS anyway

    2. TRT Silver badge

      Re: end UK dependance on GPS?

      An accurate time piece is very much able to provide a positional reference, thank you very much.

      The real question is, have they managed to miniaturise the sextant that goes with it?

    3. Stumpy

      Re: end UK dependance on GPS?

      I was just about to ask the same question.

      I always thought that the whole purpose of having the signals beamed from satellites was that you could triangulate from the three known coordinates, and the only reason for the clock signals was to measure the tiny variances in the time taken for the signals to reach the receiver.

      So how does having your own portable clock absolve the need for the satellite signals? How doe the unit triangulate?

      1. Anonymous Coward
        Anonymous Coward

        Re: end UK dependance on GPS?

        But how does your device know the distance to each satellite?

        If only there was something that could be measured that when combined with an initial location (i.e. latitude/longitude/altitude) and a known speed (close enough to the speed of light plus some adjustments for atmospheric effects) that would allow you to work out distance.

        1. Cynic_999

          Re: end UK dependance on GPS?

          "

          But how does your device know the distance to each satellite?

          "

          It doesn't (initially). The calculation is very much chicken-and-egg. Initially you only know the approximate *difference* in distance between you and each satellite being received - this being calculated from the difference in the time-stamps each satellite sends from its on-board atomic clock. (It is approxiate because the amount of refraction of each signal is at that point unknown). The latest time stamp being from the satellite closest to you, and the earliest time-stamp from the most distant satellite. As you do not know the absolute distance between you and any satellite, you also do not know the real time to any great accuracy, and hence the exact position of each satellite in its orbit.

          But so long as the geometary (relative positions) of the satellites are favourable, then there will only be one place on the surface of the Earth where any particular combination of distance differences between 3 or more satellites can occur. So if you are receiving 3 or more suitably placed satellites you can calculate your approximate position. Then you can reverse calculate the distance to any satellite, also its elevation to get a more accurate figure for the amount of refraction of its signal as it passes through the ionosphere, and from that calculate the time its signal took to reach you, and hence get a more accurate real-time as given by the satellite's atomic clock.

          So the whole thing is re-calculated with the more accurate information. Do this several times (iterations) and the position will (should) converge until it stops changing between iterations or reaches the desired accuracy.

          Note that the refraction amount is not an accurate variable even if you know your time & position 100% because the ionosphere is constantly changing in strength, height and thickness in a way that cannot be accurately determined, and so the amount of refraction cannot be known with absolute accuracy. This puts a limit on the best positional accuracy possible with the system, especially if all the satellites used are low to the horizon.

          If you have an accurate real-time clock, then you could calculate position with only 2 satellites rather than 3 (Add one satellite if you are not on the surface of the Earth).

          1. Colintd

            Re: end UK dependance on GPS?

            I'm afraid you explanation is incorrect. A 3d fix needs 4 satellites as you need to solve for time and 3 spacial variables, which is why GPS receivers can typically provide very accurate time output, as they already solve for that.

            The time/frequency references used for static telecoms start with a survey mode which removes 3 variables, and then allows you to get pretty accurate time with just one satellite (the ephemerides and an L2 receiver can give you a lot of ionospheric compensation).

            Portable atomic clocks are great tech, but won't really help with GPS as even if you ignore relativistic drifts, you'd still need 3 sats for a 3d fix.

      2. Cynic_999

        Re: end UK dependance on GPS?

        The reason you need an accurate clock is so that you know exactly where the satellites are in their orbit. The difference in the times reported by the satellites gives you their relative distance from each other to you (the signal takes longer to travel from the furthest satellite). As this only gives you relative distance compared to all other satellites being received, you need at least 3 satellites to compute a position (so long as you know your altitude). If you had an accurate local clock, you would only need 2 satellites.

        The old "transit" satellite navigation system used the change in doppler shift of 1 satellite as it orbitted to find a position, but that depended on knowing the distance and direction you had moved while taking the readings (which took about 20 minutes to complete). A transit satellite would pass within range about every 2 hours on average (more frequently the closer you are to the poles). So you could only obtain a position about 12 times per day. So no good for precision real-time navigation.

        1. Paul Crawford Silver badge

          Re: end UK dependance on GPS?

          You don't need a local accurate clock: with 3 satellites you do, but with 4 you can solve for position and time. All that this would do is eliminate the need for one degree of the solution, but you really want more than the minimum anyway because (a) some might close together leading to the "geometric dilution of precision" and poorer fix accuracy and (b) with N+1 you can tell if one satellite is flaky, and with N+2 you can tell which one it is.

          So really all that you get from an accurate local clock is a benefit if you are using GPS for time sync (important for mobile phones, DTV, etc) as you can run for longer between synchronisation times. What you don't get is navigation without some form of triangulation (even if star tracking...)

    4. mutt13y

      Re: end UK dependance on GPS?

      If you also have accurate accelerometers you could dead reckon.

      You would still need the occasional* reference, perhaps from land based systems

      *how occasional depends on the accuracy of your clock and accelerometers.

      I believe inertial navigation is still one input to commercial aircraft navigation systems

      1. A.P. Veening Silver badge

        Re: end UK dependance on GPS?

        If you also have accurate accelerometers you could dead reckon.

        The problem with dead reckoning is that if you don't reckon correctly, you end up dead.

    5. LeahroyNake

      Re: end UK dependance on GPS?

      I'm quite sure I have previously read about ship navigation beacons similar to how a lighthouse works. The beacon ( lighthouse would be a good place to situate it) sends a very accurate time signal along with a location ID, some clever maths and a lookup to the location database would be able to give a very accurate distance from the known location of the beacon. If you have 2 or more beacons in range you can calculate your position, the more beacons in range more accurate you can be. Virtually the same as GPS and other space based versions but obviously needs more beacons due to the curvature of the earth etc (if its flat.. I'm not going there).

      Anyway the ground based version should be massively cheaper for local navigation / busy shipping lanes where line of sight is not such an issue.

      I think the main problem would be putting up these beacons in enemy territory so bombs could be dropped where you intend.... And that's why GPS etc can be turned off and has encrypted channels, just in case you know.. Oceana are allies with Eastasia today...

      1. Cynic_999

        Re: end UK dependance on GPS?

        Google "Decca" and "Loran" These were land radio based systems that could provide a position fix to within 300m or so. They were pretty ingeneous long-wave systems and so could operate way beyond line-of-sight.

        1. Alan Brown Silver badge

          Re: end UK dependance on GPS?

          "These were land radio based systems that could provide a position fix to within 300m or so"

          Supposedly. Under ideal conditions. Close to the transmitters

          Reality, earth curvature, ionospheric waveguide effects, time of day and the shape of the land/sea interface always degraded that somewhere between slightly and "you won't believe how far out it is"

      2. Anonymous Coward
        Anonymous Coward

        Re: end UK dependance on GPS?

        basically this is what differential GPS does, a fix point with a known location also broadcasts out this along with the GPS signals from the sat's gives you a more accurate location, down to cm's

    6. katrinab Silver badge

      Re: end UK dependance on GPS?

      As an example, bank ATMs have GPS receivers in them.

      One use of that probably will be to make sure that the ATM is still positioned in the wall of the bank, and to do something if it detects movements; however, the most important use of it is simply to get a precise time signal, because it needs to know exactly what time things happen.

      This is actually the most common use of GPS - to get the time rather than to get location.

      1. A.P. Veening Silver badge

        Re: end UK dependance on GPS?

        All bank ATMs have a direct connection (secured internet) with a server of that bank and can use the time server of that bank that way. The time server of the bank just polls one or more NTP servers, no need whatsoever to complicate things with GPS, which signal may not even be available inside a building.

    7. Cynic_999

      Re: end UK dependance on GPS?

      "

      ... someway that a really accurate time source provides position without the need for signals from satellites, measuring the position of astronomical objects etc.

      "

      Yes. It's called "celestial navigation," discovered (invented?) in 1837 by Thomas Hubbard Sumner. The big problem at the time was that there was no way to determine the time with sufficient accuracy when you did not know your position - thus prompting the race to invent a super-accurate clock that was impervious to both a ship's movement and temperature changes.

  7. Threlkeld

    " It's a system that employs portable, optical atomic clocks as a means of extremely accurate time-keeping that theoretically completely ends the need for navigation systems here on Earth to talk to an orbiting network of satellites."

    My phone TALKS to an orbiting network of satellites? And there was me thinking it just listened.

    1. Anonymous Coward
      Anonymous Coward

      Do you think its easy just listening all day? Modern phones tell satellites about their day to ensure they keep their sanity.

      I'm not saying satellites listen, but as long as the phones are happy...

    2. IGotOut Silver badge
      Joke

      No I think you'll find they do indeed transmit to the satellite, Stephen Fry told me so.

  8. Anonymous Coward
    Anonymous Coward

    "Synchronise watches... I make it 12:23:57... NOW!!" "Sorry sir, I make it only 12:23:56.999999999999999999999999999999999999"

    When we all have our personal atomic clocks, who sets the standard?

    Hey, why not have a cluster of master clocks that we could all synchronise our pocket atomic clocks to..

    And even better/easier/cheaper, we could do away with having our own portable atomic clocks and just synchronise all our devices to it, just like, erm...

    1. Chloe Cresswell Silver badge

      Who sets the standard? Why it'll be a British Standard... and like most standards, therefore there will be at least 2 competing times to set yours to...

      1. KittenHuffer Silver badge

        Imperial time? Metric time? Whitworth time?

        I'll stop there cos it's just gonna get silly!

        1. TRT Silver badge

          Hammer time.

          1. Admiral Grace Hopper

            Sadly Hammer Time won't be much use. You can't touch this.

          2. KittenHuffer Silver badge

            And Hammer Time clocks will Stop!

            1. TRT Silver badge

              Breakit down.

            2. IGotOut Silver badge

              Do someone say Stop? I better reset my Atari.

        2. Alan J. Wylie

          Imperial time? Metric time? Whitworth time?

          British Association, of course!

          1. KittenHuffer Silver badge

            If we're having BA time then we have to have Face time and Murdock time as well!

            But if we add Hannibal time we could group them all together! I wonder what we could call them?!?

            1. TRT Silver badge

              The Time Team.

        3. katrinab Silver badge

          GMT and UTC. There is a small difference of up to a second between them.

      2. jake Silver badge

        Standards? We can do that.

        "The nice thing about standards is that there are so many of them to choose from." —Andrew S. Tanenbaum

        1. KittenHuffer Silver badge

          Re: Standards? We can do that.

          The best thing about being me... There are so many "me"s - Ageny Smith

  9. Anonymous Coward
    Anonymous Coward

    The European Commission and Galileo

    > the European Union's Galileo system, which the UK had – until Brexit – contributed to building .. remains accessible to the UK after Brexit, although the country will cut itself off from access to its encrypted channel after the country's departure from the union.

    I don't understand the logic of rescinding full GB access to Galileo after Brexit, as long as they continued to provide finance and technical support, after all a lot of the technology was provided by private contractors and it's not as if the Island is going to disappear into orbit.

    > The EU says the agreement struck over the terms of the 21-month transition period after Brexit gives it the freedom to do so ..

    https://www.theguardian.com/politics/2018/may/25/what-is-galileo-and-why-are-the-uk-and-eu-arguing-about-it

    Why would GB agree to be blocked from Galileo post Brexit, unless this is yet another example of Brussels making up the rules as they go along.

    "The commission has suggested" you turn over your Laundry Service to our friend Whispers :]

    1. Alister
      Facepalm

      Re: The European Commission and Galileo

      Why would GB agree to be blocked from Galileo post Brexit, unless this is yet another example of Brussels making up the rules as they go along.

      As I recall, it was the UK who insisted that that particular bit of regulation was included.

      1. Yet Another Anonymous coward Silver badge

        Re: The European Commission and Galileo

        >As I recall, it was the UK who insisted that that particular bit of regulation was included.

        Regulations can be changed,

        That surely is the whole point of working within a sensible, democratic, efficient and technocratic organisation such as the Eu.

        Neither side would retreat to childish blocking of cooperation for public point scoring or to further political gains in other areas

        1. Dan 55 Silver badge

          Re: The European Commission and Galileo

          If the other countries in the EU change the rules to suit us whenever we want then they surely must make up a sensible, democratic, efficient, and technocratic organisation and they are good.

          Otherwise if they don't change the rules to suit us whenever we want then they are crazy, antidemocratic, burocratic, inefficient, and, er, technocratic and they are therefore evil.

          Got it.

        2. Doctor Syntax Silver badge

          Re: The European Commission and Galileo

          "Neither side would retreat to childish blocking of cooperation for public point scoring or to further political gains in other areas"

          I take it you haven't been in the UK for the last few years.

        3. gnasher729 Silver badge

          Re: The European Commission and Galileo

          Thanks to the likes of Farage and the current bunch of EMPs, any sympathy for the UK has long disappeared in the EU. The UK insisted that things would be only available to EU members. And the UK insisted on leaving the EU. Not giving anything to the UK isn't for public point scoring or political gains, but just to tell them to feck off.

        4. A.P. Veening Silver badge

          Re: The European Commission and Galileo

          Regulations can be changed,

          Sure, but in that case there would still remain a tie to the EU after Brexit which was deemed unacceptable. Talking about having your cake and eating it ...

      2. Anonymous Coward
        Anonymous Coward

        Re: The European Commission and Galileo

        > As I recall, it was the UK who insisted that that particular bit of regulation was included.

        Do you have a link to the actual text where GB agreed to be excluded from Galileo post Brexit? According to that Guardian quote, the EU assumed the freedom to do so, but that is a curious phrase to use in relation to a legal agreement. Under that criteria, if you sold me your furniture, I could assume the rest of the house came with it. If you objected I could merely say but you gave me the freedom.

      3. Alan Brown Silver badge

        Re: The European Commission and Galileo

        "As I recall, it was the UK who insisted that that particular bit of regulation was included."

        Yup.

        At the absolute insistence of the USA

        Who wanted to ensure China was locked out of Galilleo

        Against the objections of every other member.

        So when Britain announced it was leaving, there was ZERO thought of changing the rules so the UK could stay.

        You know that saying about being careful what you wish for?

        (this isn't the only example of the UK forcing rules on the rest of the EU which are now being used against it as it's leaving, whilst the rest of the EU smirks and says "sorry, we can't change the rules")

    2. Len
      Coat

      Re: The European Commission and Galileo

      Considering the UK Government is now run from the Kremlin it's just a standard precaution.

      1. Yet Another Anonymous coward Silver badge

        Re: The European Commission and Galileo

        >Considering the UK Government is now run from the Kremlin

        The current occupant of No 10 is an Eton and Oxford educated classicist with no obvious skills but who has mysteriously risen to power - hardly the traditional profile of a Russian spy within the British establishment

        1. jake Silver badge

          Re: The European Commission and Galileo

          "hardly the traditional profile of a Russian spy within the British establishment"

          That's what they want you to think. (Whoever "they" is.)

        2. John Savard

          Re: The European Commission and Galileo

          True, for that he should have gone to Cambridge instead.

    3. Anonymous Coward
      Anonymous Coward

      Re: The European Commission and Galileo

      The whole point of Galileo is that it's an EU system, it exists for political reasons rather than technical ones. As such it's completely unnecessary.

      I'm no fan of Brexit, but this particular concern is just stupid.

      1. Anonymous Coward
        Anonymous Coward

        Re: The European Commission and Galileo

        One problem with GPS, GLONASS and Beidou is that they are all primarily military systems, under the control of the military leadership in their respective countries and their commercial services can be turned off at will, for military reasons, in part or all of their operating areas. Galileo is not a military system and one of the primary intended uses is for transport, in conjunction with EGNOS. In particular, EGNOS and Galileo will allow aircraft full CAT1 Autloand in a few years time, without the need for ILS infrastructure at airports.

        Barring non-EU countries from PRS use was a British idea but the EC has acted somewhat vindictively where it comes to the UK. Last spring, the EC sent a memo to all EU27 national governments, telling them that "the UK is not to be trusted on matters of security". This was at the same time as the EC were insisting that they have access to UK intelligence information, as part of the withdrawal agreement and when UK forces have been protecting eastern Europe from the big bad Russians, under the auspices of NATO. The EC's attitude and complications as regards non-NATO EU members maybe encouraging an increase in the importance/use of 5 Eyes.

        1. Robert Grant

          Re: The European Commission and Galileo

          The EC's attitude and complications as regards non-NATO EU members maybe encouraging an increase in the importance/use of 5 Eyes.

          This is pretty normal, though. Complications about who helps whom at the national / territory / treaty / bloc / etc level are always going to be a thing. Military types are used to it, and very good at it.

    4. Anonymous Coward
      Anonymous Coward

      Re: The European Commission and Galileo

      The tricky thing is that the EC has taken this a bit further: They have offered that the UK could use Galileo PRS - but only in activities that were coordinated with the EC or in activities that were inline with the EU's policies/interests. The implication of the EC's offer is that they would reserve the right to deny the use of PRS to the UK at any time, if they felt it was not in their interest or simply that they did not approve.

  10. Anonymous Coward
    Anonymous Coward

    First for a Reg lecture...

    A female attending

    1. Anonymous Coward
      Anonymous Coward

      Re: First for a Reg lecture...

      Every time something like this is said, it devalues the lecturer in question. They have a good contribution to make, can communicate well and are very smart; those are the criteria.

      Monitoring (and praise) of any other attributes will always start to imply (or in the worst case, create) a culture where people have been picked for said other attributes, because if there aren't enough good people who just happen to have those attributes, then less good people will be picked just because of those attributes.

  11. jake Silver badge

    Why does the UK need GPS anyway?

    Seems to me people have been navigating around that little pile of rock and mud for several dozen centuries without any electronic gizmos at all.

    1. Imhotep

      Re: Why does the UK need GPS anyway?

      But chronometers were a big help when they came along. I believe the UK gets the credit for that.

      1. Yet Another Anonymous coward Silver badge

        Re: Why does the UK need GPS anyway?

        If you need to take sun and star sightings it limits you to invading places with clement weather

        1. jake Silver badge

          Re: Why does the UK need GPS anyway?

          The Vikings didn't seem to have any problems. (The real ones, not the blather on DearOldTelly.)

      2. jake Silver badge

        Re: Why does the UK need GPS anyway?

        "I believe the UK gets the credit for that."

        I believe the followers of Huygens dispute that claim.

        1. Imhotep

          Re: Why does the UK need GPS anyway?

          Certainly Mr Huygens was a pioneer in the field, but I believe John Harrison's were the first chronometers accurate enough for the royal navy.

    2. Francis Boyle Silver badge

      Re: Why does the UK need GPS anyway?

      The ghosts of a multitude of dead sailors now residing in Davy Jones' locker might beg to differ.

      1. jake Silver badge

        Re: Why does the UK need GPS anyway?

        That was the weather, not lack of ability to navigate.

    3. Alan Brown Silver badge

      Re: Why does the UK need GPS anyway?

      "Seems to me people have been navigating around that little pile of rock and mud for several dozen centuries"

      Not always successfully. The electronic gizmos have vastly increased the chances of staying in the wet bits over running into the unforgiving bits.

  12. eldakka
    Coat

    Can portable atomic clocks end UK dependence on GNSS?

    I wouldn't think the post-apocalyptic wasteland full of roving Mad Max-style gangs the UK will become after Brexit would need that sort of accurate positioning, would it?

    1. Yet Another Anonymous coward Silver badge

      Proper observance of teatime will still be important

      1. A.P. Veening Silver badge

        Even if tea itself has become unobtainable due to import tariffs.

        1. Anonymous Coward
          Anonymous Coward

          I thought tea came from Yorkshire?

          1. jake Silver badge

            It did. And apropos of the original topic, Time itself came from Greenwich ... that's why Dr.Who's adversaries are always trying to take over the British Isles. innit.

  13. jms222

    Decca chains

    We had Decca chains how long ago ?

    Come to think of it planes do pretty well with radio beacons and with a bit of software attached produce useful coordinates and speed.

    Accurate clock not needed.

    1. Yet Another Anonymous coward Silver badge

      Re: Decca chains

      For navigating in your home waters they are rather excellent, although a trifle heavy for carrying while mountaineering.

      For dropping precision guided munitions on the fuzzy-wuzzys they are are bit limiting.

      Once you have successfully negotiated with the recalcitrant natives to install your navigation beacons it seems rater bad form to then bomb them.

    2. Anonymous Coward
      Anonymous Coward

      Re: Decca chains

      my degree is in navigation and I covered decca back in the early 90's I think the Europe chain was turned off in 2000

  14. arctic_haze
    Mushroom

    Will portable nuclear reacotors solve aor energy problem?

    And other fairy tales.

  15. Jamie Jones Silver badge

    The future is here already...

    By Gavin Clarke 23 Jan 2020 at 19:00 119 Reg comments SHARE ▼

    The US-based GPS....

  16. Anonymous Coward
    Anonymous Coward

    Thought they used

    A whispering gallery to get the exact location for slide windows?

    I suppose any sufficiently accurate independent time source would work though.

    Incidentally I finally managed to source an FE-5680 but need to find out if using an SDR directly would avoid the need for all that bulky and heavy circuitry from the early Netscape era. This is possible as the actual core which gets to about 100 celsius when in use comparable to a laptop CPU will fit into a far smaller case assuming its not needed all the time ie just for calibration purposes.

    For calibration it does not need to output 10 MHz as long as I know what the correct frequency is and add external filters accordingly.

  17. Conundrum1885

    Also useful

    The nice folks at some 'Uni invented an optical and electrostatic trap that "locks" Sr ions.

    In principle this system would be ideal for something like this.

    I looked into DIYing a Rb clock which is possible thanks to advances in SDR and lasers: the LNBs from a few years back will with some modification tune into the Rb hyperfine transition at 6.8 GHz so a bit of RbCl2 off eBay and some argon eg from a new fluorescent tube starter with the SRD made from a modified tunnel diode or used GaAs based Gunn out of a broken door scanner should work.

    You could literally DIY an atomic clock this way but it would be a lot of work comparable with a doctoral thesis and making a double oven OCXO using parts from a broken 8088 MB is possible.

    Cs is harder but the transition is closer to the range on LNB so you could do the same here however it will never be as good as a proper CSAC or used module with regenerated lamp.

    1. Conundrum1885

      Re: Also useful

      Why the thumb down? Also my double oven OCXO showed up.

      The mini £30 Rb lamps are actually quite easy to use but do have issues: seems that some have off centre pinches and other manufacturing glitches so might need some creative engineering.

      This is still a good idea even if it takes more signal processing than I first thought.

      Note: Making a SRD from a broken Gunn oscillator is literally nearly impossible but you might luck out. Negative resistance diodes do often run at strange harmonics and the mixer diode is even wider range.

      https://pic-microcontroller.com/rubidium-atomic-clock/ (Not mine!)

      The argon gas actually increases the frequency slightly but as its a known effect it can be compensated for, also 3D printed silver cavity is feasible with some post printing fine etching to get the exact shape.

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