back to article Chicken Little report: Sat-nav dependency spells DISASTER!

A heavyweight UK tech body has just issued a report claiming that growing dependence on satellite navigation systems poses serious economic and safety risks to society. There's some truth in the report, but unfortunately it verges on scaremongering at times and appears to have been unduly influenced by organisations which can't …


This topic is closed for new posts.
  1. Anonymous Coward

    How on earth did we cope...

    ... With A to Z's and ordinance survey maps?

    1. Thomas 4

      We didn't

      I remember following an Ordinance Survey map and thinking "Gosh, I really wish I had a celebrity to tell me how to get to my destination instead of all these carefully laid out roads landmarks."

      1. Fr. Ted Crilly Bronze badge


        erm thats Ordnance as in things miltary (mapping) etc.

        Not Ordinance as in local authority bye-laws.

        Grammer Nazi 'cos sometime you just have too

        1. some vaguely opinionated bloke


          "Grammer [sic] Nazi 'cos sometime [sic] you just have too"

          Sometimes you just have as well?

          Did you mean: "Sometimes you just have one more than one"

          Or did you mean: "Sometimes performing the actions of a Grammar Nazi becomes a necessity"

          Or did you mean: "I'll choose the "pedantic grammar nazi alert" icon to point out a spelling mistake rather than any incorrect use of grammar"

          (Thankyou, yes, I'm ready now for other PGNs to pick my own response apart 8-) )

          1. Gilgamesh

            pretty sure you meant to say

            "thank you"

            "thankyou" is a noun

            And I'm posting the Grammer Nazi to!

            And using conjunctions to end sentences with.

          2. alwarming

            @some vaguely opinionated bloke && @Fr. Ted Crilly

            It's obvious that "@Fr. Ted Crilly" was deliberately spewing erroneous grammar. Or, maybe not that obvious to some. LOL.

    2. Anton Ivanov

      You are new here I guess

  2. JasonW

    Mark I eyeball (perhaps a pair of them) and appropriate charts/maps

    Oh and the ability to use both in conjunction with a compass & clock when necessary.

    Is it really so hard? If it is, then you probably shouldn't be driving/riding/sailing/flying in the first place.

    Mine's the one with a rolled up Admiralty chart & compass in the pocket.

    1. Liam Johnson

      Is it really so hard?

      Yes, unless you have someone sitting there as navigator. You definitely shouldn't be driving with an OS map on one hand and a compass in the other, while trying to read street names.

      1. James Hughes 1


        You could pull over and read the map. Just like you pull over and use your mobile phone perhaps.

        1. Liam Johnson

          pull over and read the map

          Depends. Driving through cities with one way systems, stopping restrictions, heavy traffic and inconsistent signage can be a pain in the ass even with sat nav or someone to map read. Unfortunately, the more complex the road system and consequently the more time you need to spend reading the map, then less chance you will have of being able to pull over and do so.

          It's probably a law of nature or something.

  3. Tim Greenwood

    Ah the good old days

    I remember being really impressed 20-25 years ago with the accuracy of Decca off Bridlington. It took us to within 100 metres of a mark in foggy conditions allowing us visibity of it.

    These days the GPS on my phone knows which room of the house I am in if I use the Sat view on Google maps as the marker switches around as I wander about the house.

    1. Anonymous Coward
      Anonymous Coward


      I happen to have a load of Decca station gear which I inherited: Lots of gold flashed single layer PCBs with nixie tubes and pre TTL ICs. Really ought to do something cool with it one day and alert the Internets.

  4. Mystic Megabyte

    Everybody down!

    I was steaming about the Pentland Firth last night at 20kts.

    Autopliot went tits-up, Gyrotrac gone wonky by 30 degrees but the Mark1 eyeball and radar is very good.

  5. Spider

    Use the bloody window

    As a fellow ex-OOW (and still a Hydro surveyor) more than one "old man" used to forever shout at the baby bridge teams to "look out the bloody window". People get sucked into staring at a computer screen when closest points of danger could clearly be seen, both in ships and cars.

    As for technical kit, AIS, GMDSS, radar, ad nauseum, all these need is a positional feed. Be it GPS, DGPS, Glonass or galileo. it's the lack if a resolved position that causes the alarm, not the fact that a positional feed is out of error budget. Redundancy in systems prevents this, adn you can always hit the alarm cancel button and use a paper chart and a compass...

    As for Loran - there's a reason it fell out of fashion. It isn't as good. otherwise we would still use the damn thing, and anyone trying to seriously wreck radio positioning just needs to add a frequency to crash that as well, however they try to enhance it.

    Besides, it's not the interference with signals that is the real disaster scenario, it's spoofing. being able to fool systems into calculating a wrong position. And despite Hollywoods (and pinewoods) best efforts, that is actually very difficlut to acheive.

    As with every report. Follow the cash. Who paid for it to be written and whats their agenda?

  6. shoesday

    Pre Sat Nav

    Want to get from one place to another but don't know the way? Theres a mapp for that

    1. Anonymous Coward
      Anonymous Coward

      Very good...

      Although I believe it's traditional to finish a comment like that with:

      "Thankya very much, I'll be here all week..."

  7. Britt Johnston

    Great name

    <Commissioner of Irish Lights>

    I'd work for them at 1$ a year, given a title like that.

  8. This post has been deleted by its author

  9. Red Bren

    Who is this "Chicken Little" you speak of

    Even when referring to children's stories Lewis, you still have to push your "US is better than UK" agenda!

    1. Paul Berry

      The "Chicken Little" you speak of... better known here by it's name of "Chicken Licken", which rhymes properly and everything.

  10. The Fuzzy Wotnot

    Never mind all that!

    Never mind all that rubbish, how about you educate ( in the sense of baseball bat to head ), these morons who follow their SatNav's advice to the letter and end up on train tracks and/or in lakes?!

    You know the ones, always in The Sun moaning about their Garmin/Tomtom, "Duh, da fing on da dashboard what tells me what place to go done told me to turny left and I done it and now my motor is busted and is all wetted! Duh!"

    1. DaveyDaveDave

      "on train tracks and/or in lakes"

      Are there many places where train tracks go through lakes? :D

  11. ShaggyDoggy

    Old tech

    We call it MapNav

    It involves sheets of printed paper (does anybody remember paper) usually in a book (that's a collection of printed sheets of paper) and you had to read it (that's right it doesn't talk to you - at the next roundabout take the third exit, etc)

    LORAN - because you're worth it (tm)

  12. The Nameless Mist
    Paris Hilton

    [Insert Deity of Choice] forbid

    ... that we should actually remember / learn how to read a map.

    I've seen people walking down streets in London, Blackberry in hand with the GPS doing the "you are X and moving in -> that direction" trick, and then wrap themselves round signposts.

    Actually its quite enjoyable watching them do that.

    {Paris - because she's got some flunky to GPS for her}

    1. Code Monkey

      That'll be fun

      ...when it makes it out to the provinces. Speaking for myself: if I'm lost it's usually somewhere where I don't want to pull out an Android, lest it get nicked.

  13. Ian Michael Gumby

    @Lewis are you confused?

    I'm sorry but the line:

    "These days a lot of hardware makes use of the GPS timing signals for purposes unrelated to navigation: for instance to synchronise the precise clocks often needed in digital communication systems, or to put exact time stamps on financial transactions. Using GPS is often cheaper than installing a highly accurate timepiece."

    I think you're confused.

    Large scale financial institutions as well as trading floors usually have their own 'atomic' clocks which they sync to a standard atomic clock, usually run by a university or a government organization. Now these stand alone clocks have a GPS antennae.

    The clocks get their timing signal as a radio signal from the known source which is at a relatively precise GPS coordinate. If you know your own coordinates you can calculate and account for the time it takes for the radio wave to travel to your location. (Yeah, even though the radio waves travel at the speed of light, it still takes time for them to travel thousands of miles from their source to your location...)

    Since we're talking about things traveling at the speed of light, if your coordinates are off by a couple of meters, it shouldn't matter too much, however, if you are a type A personality, I guess you could set up a base station, monitor your GPS position for 48 hours or so and get it accurate to within a couple of cm.

    With respect to using the clock in the GPS signal to set your cell phone's clock... that's possible but more than likely it will be set by the connection to the local cell tower.

    1. Liam Johnson



      And the smaller than "Large scale” financial institutions and communications companies might well use a GPS synchronised NTP system, which is cheaper than an atomic clock.

      Who is confused by this?

      1. Ian Michael Gumby


        Ok Liam,

        Lets look at this from least accurate to most accurate.

        1) You run an NTP client and point to a government/university controlled NTP server.

        (You don't care about network latency because its 'accurate enough and you don't have a highly accurate clock in your pc)

        2) You sync to a local NTP server which either is accurate enough, or it has its own 'atomic clock'.

        This NTP server is used to sync all of the local machines in your machine room/cluster/HPC environment. The NTP server can be a rack mountable appliance with a very accurate clock so that once you set it, you don't really have to worry about clock skew.

        3) You put in an 'atomic clock' in to your own server. This is usually a CS clock and you have connections so you can run a cable to an external set of antennae for radio and GPS signal. This is the most accurate and its not *that* expensive for a business where time matters. (Under 10K)

        Now most financial firms have their trading platforms housed in leased space near the exchange and these sites do one or more of the following:

        1) Offer an NTP server that is slaved off the exchange.

        2) Offer an NTP server that is slaved to a government controlled clock.

        It doesn't matter what time it is as long as it matches what the exchange says the time is.

        Now does that make sense?

        You don't sync with a clock that is sitting in orbit. Now why is that?

        Hint: Einstein could tell you but he's dead. Not to mention that its not as accurate as a radio signal from the standard clock sitting in Boulder, and for the same accuracy, you have other options. Like a radio receiver that gets the Boulder radio signal, and then you just plug in either your street address, or the geo-encoded x,y coordinates you got from going to the web...

        Bottom line, you don't pull the time from the clock signal off of GPS and again Lewis made the comment that financial shops rely on GPS signals for their clocks.


        You do realize that time is relative, right? :-)

        Mine's the coat that has a small card deck sized atomic clock I got from military surplus.

        1. Liam Johnson


          Wow I am impressed. You completely missed the point twice in a row.

          Your assertion that GPS is not used as a clock reference is just plain wrong. There are plenty of devices which do this. I can only assume that since they fall between 1) and 2) in your list that you don't consider them worth bothering with.

          Their quoted specs however, are not usually any worse than systems synched to the various long range transmitters which you also mention. Although those reference systems like NIST and DSF are they best clocks we have, sticking the signal through a huge transmitter and bouncing it off the ionosphere does degrade the accuracy a little. The ionosphere moves during the day and hence so does the phase of your supposedly accurate clock.

          Sure if time is really your thing, then you need to get yourself a top of the range clock. But none of this discussion has anything to do with the fact that GPS provides a reasonably accurate reference signal, and some people use it because it is of a similar standard to the long range transmitters (in the real world). Often better by virtue of being able to get a decent signal at all.

          I assume by your comments on relativity that you haven’t realised that this is built into the calculations for the GPS system. It wouldn’t work very well otherwise.

          1. Charles Manning

            No low-tech alternative for timing

            GPS is near ubiquitous use in high precision timing is far more worrysome than anything loss of navigation.

            GPS provides accurate timing down to tens of nanoseconds. Nothing else comes close (except for Galeleo and GLONAS).

            Radio time signals, NTP etc are orders of magnitude away and are not good enough for high precision timing.

            No more cell phones. No more broadband. That's where the real dark ages will come from.

  14. Aristotles slow and dimwitted horse Silver badge

    Maybe for commercial vessels...

    It may be cheaper to employ a monkey who is only capable of watching a computer screen. But as far as I know all commercial vessels over a certain size have to be staffed by a competent bridge officer, or a trained officer of the watch. So this begs the question of what exactly is it that these monkeys are being taught in their deck officer courses if they cannot revert to manual navigation methods and techniques.

    Regardless, ALL vessels on the high seas - and that includes you holidaymakers over there on your pedalos and jet skis are required by law (i.e. the IMO) to maintain a watch at all times to prevent collisions at sea.

    Being a yachtie myself, I find GPS an invaluable aid to navigation in fog and bad weather - but have never relied on it as I find it much more satisfying to work with paper charts, pilotage and my trusty Freiberger - but mostly my eyeballs.

    1. Lionel Baden


      My family taught me to navigate by stopping at every pub on the port side. till you either get where you going or moor up for the night pending pub availability.

  15. BristolBachelor Gold badge

    Sat naving

    I guess then that they are saying that money should be put into Gallileo, the Euro sat nav system to be a backup to GPS ? :)

    Also Gallileo has a "signal integrity" function that can let receivers know to not trust the signal from a sat because there is something wrong with it.

    Differential GPS is very good. The system set up for the new tunnel from Germany to Denmark ( gets an acceracy of a few millimetres over the entire work area.

    As for comms networks, I understand that the fully sychronous ATM network backbone that BT runs (used to run) was very timing critical, but I thought that the new packet-switched-based network didn't really care about timing?

    1. Anton Ivanov
      Thumb Down

      More and more of the current GPS use is aGPS

      If you are "a"-ing on GPS via the cellular network in the first place you can detect if the GPS is giving you stupid results. Similarly, if GPS is totally dead you can still use the "a" bit to navigate.

      As far as networks using GPS for timing - it does so in the USA. In Europe it does not. It may be one of the sources, but nearly all cellular networks make extensive use of network side clock where once again GPS is only one of the sources. Ditto for financial transactions - there is a GPS input to a very high precision NTP stratum 1 source and that in turn is used to provide timing.

      As far as failure of people, cars, etc to navigate that is even less likely to happen tomorrow than today. "Pure" GPS devices are disappearing and more and more people rely on their phones which once again have the "a"-bit in place and can provide a position even if there is no GPS signal available.

      In any case, ensuring that cellular networks have proper timing so that they can supply positioning and timing information (they can do both) provides _BETTER_ overall national infrastructure resilence than sticking yet another set of easily jammable low power transmitters.

  16. Fr Barry

    Oh yes they do

    " the "MSF" (nobody really knows what this stands for) radio station ..."

    MSF is the callsign allocated to the transmitting station. The "M" being one of the ITU allocated callsign prefixes (we also have 2 and G) and its original callsign was GBR.

    Those who used to watch Zcars will probably remember "BD to zvictor1" coming over their police radios - the BD being short for M2BD, the Lancashire police callsign I believe. All radio amateurs in the UK have callsigns starting with 2, G or M.

    More info at

    73 from G4HDU

    1. This post has been deleted by its author

      1. Pigeon

        Er.. @Sculptor

        I didn't know that MSF had moved from Rugby. Not that I bother to put the propagation delay in my NTP config. I used to live in Anthorn, so the guys that still live in the three cottages probably get good time now.

        I'm sure that our famous Mr. L Page knows about callsigns from his time as a Foreign legion radio operator.

      2. Fr Barry


        Another standard frequency I used to use was BBC Radio 4 Long Wave on 200 Kc/s. This was picked up on a long wave receiver, the audio filtered out, squared off and passed through assorted TTL dividers (divide by 200) to give a very accurate frequency source (and hence timing source). I believe it was (and still is?) accurate to 1 second in 3000 years and monitored by the National Physical Laboratory. My frequency source is no longer used as Radio 4 moved to 198 KHz and I didn't bother building a new one with new dividers.

        1. This post has been deleted by its author

    2. peter_dtm

      tks om

      saved me writing that up

      As an ex Sparky (RE/O- Radio Electronics Officer) I am horrified that the Grey Funnel Line (Royal Navy) had an OOW who doesn't know what callsigns are - how did he get his bridge ticket with out his R/T ticket ? No R/T (radio telephone) ticket no talky on bridge vhf set. No talk on Bridge VHF set - no watch keeping officer certificate; so no standing as OOW (Officer of the Watch).

      And of course the new site for MSF doesn't even cover the UK.

      So MSF on 16KHz - GBR on 5MHz and 10MHz along with WWV (Colorado US) and WWVH (Honolulu)

      Callsigns don't stand for anything - though occasionally the licensing authority will assign a sequence of letters that 'make sense' - GBR was at Rugby (GB R - Great Britain Rugby)

  17. Paul Johnston

    Trinity House

    I went to school there, wonder if they still teach O-Level Navigation?

  18. Anonymous Coward

    Bring back Consol

    A Long Wave radio and a chart was all you needed. Oh, and the ability to count. Oh, and the ability to assume you weren't 1000 miles away from whwre you thought you were. Oh, and the nouse to know that your position was pretty good but still approximate, so don't assume it's infallible and therefore end up piling up the coastline next to the harbour, blaming your GPS-connected auotpilot.

    AND it could be used with just one station, though two or three were better.

  19. Kevin Reilly
    Black Helicopters

    Good for bombs tho'

    It may help with the nukes but GPS has changed the definition of close air support. When Stormin Norman was on stage showing the world how to do shock & awe it was with expensive bombs dropped by even more expensive aircraft. Now geriatric museum pieces (more reliable than the B1s & 2s) drop dumb iron bombs with satnav (JDAMS kit fitted) from 48000ft & 10Km away then land them within a couple of metres of the designated target. in the 1940s a mile was as good as a hit. the yanks are raiding aviation museums to keep the B52s flying. If we still had a few Vulcans the Us would be begging for the RAF to use them to take som of the pressure off their pensioners. After all they did once defeat Norad & pretend bomb the land of the free.

  20. Anonymous Coward

    Disruption to Rail Networks?

    "In 500 metres, at the next railway bridge, turn sharp left".

    "At the next railway station, for no reason, stop the train for 15 minutes".

    "At the next railway crossing, turn right, and follow signs for Guildford".

  21. Anonymous Coward
    Anonymous Coward

    Excellent article

    But, "AIS is nowadays mandatory for ships of any size" versus "...small vessels don't carry AIS"?

    1. Intractable Potsherd Silver badge
      Thumb Up

      I noticed the same ...

      ... but put it down to that arcane difference between "ships" and "boats" that no-one ever seems to explain, but which allows those in the know to sneer at you.

  22. JeffyPooh

    What ever happened to the GPS Pseudolite concept?

    Basically take a GPS satellite (much, much, MUCH cheaper version) and bolt it to a pole. The ephemeris location is obviously surveyed and hard-coded. Each pseudolite would broadcast the exact same sort of signal as does a GPS satellite, but would obviously provide a much higher signal strength in the local area (vastly increasing reliability in the local area). These gadgets would be scattered around airports and major waterways.

  23. Ian 35

    What on earth are they on about?

    "The RAE's Ploszek suggested to the Reg that the MSF signal isn't good enough to stand in for GPS, saying "at 60Hz, I'd suspect that it isn't going to offer enough precision"."

    A man who can't tell the difference between 60Hz and 60kHz isn't to be trusted with sharp objects. The MSF time signal simply gates a 60kHz carrier, so the precision you can recover the edges to depends on the precision to which you can spot the carrier going away. That's of the order of a microsecond if you're keen enough.

    1. Bob H

      kHz! = Hz

      I saw that as well! I am suddenly much more concerned for the state if engineering skill in the UK! My thesis, many years ago, used MSF and as a result I was required to study timing systems quite extensively.

      MSF is transmitted at 60kHz with an accuracy of 2 in 10^12. As was implied above, with clean detection and a correctly designed PLL you could easily depend on MSF. When I was at the BBC a standard reference for both time and frequency was an agreement between multiple GPS and MSF receivers. But that kind of kit cost more than a COTS 1pps GPS receiver.


      1. Bob2011

        Shudder to think...

        ..that you might consider the "Hz" to be a typo!

      2. Robert E A Harvey


        And, of course, the stability of both th MSF and 198KHz Droitwich carriers is well-known, and monitored by the NPL. It should be possible to 'dead reckon' timing between GPS fixes several weeks apart. Droitwich is controlled to ±1 part in 10^11

    2. alwarming

      Like Calories

      and KiloCalories! ;)

  24. Frederic Bloggs

    GSM / mobile phone timing

    It seems to be a lesser known fact (nobody on El Reg seems to have mentioned it so far specifically) that many mobile comms systems rely on a cheap gps receiver in every base station to provide a common understanding of time. This includes, but is not limited to, GSM (or mobile phone systems in the EU) and TETRA (what the emergency services use).

    The reason a common understanding of time is important is that these systems are Time Division Multiplexed (TDM) systems. And the timing is rather critical, for GSM base stations have to know their "time" within a few nano-seconds. TETRA isn't as bad, it only requires accuracy to within a few micro-seconds, but it still matters.

    Sticking a GPS jamming device near one (or preferably a group of) base station(s) won't knock it over immediately, but over a hour or three it will go unreliable as its clocks lose their synchronisation with nearby base stations. Base stations rely on accurate phase relationships between neighbours as part of the cellular arrangements, losing "time" means these break down and so a portion of that network gets flaky. It won't necessarily stop it working completely, one just gets increasing dropped or unanswered calls, even with 5 bars of signal strength.

    Of course, whether anyone would actually notice any difference from normal is moot.

    PS this requirement for nano-second timing is the reason why there are speed limits for GSM comms. This is because of the variable doppler shift as you move past a base station. The shift gets worse with increasing frequency and speed. 1800Mhz operators have it significantly worse than 900Mhz ones. which may explain one or two other things going in the GSM world.

  25. Bassey


    It's funny how many people extol the virtues of map and compass whilst criticising "folk today" for walking into stuff whilst following their GPS.

    As a mountain Rescue navigator, I've walked into far more things (rocks, bogs, sheep shit etc) following a map and compass that I ever have with a GPS unit. A map and compass (along with counting your paces) requires far MORE concentration than a sat nav.

    And just telling people they "should learn" is rediculous. Sat Nav is wonderful. It's cheap, easy and accurate and requires little training. You can pick one up, having not used it for months, and you are right back where you left off.

    Learning to use a map and compass to a good level of accuracy (<10m in thick fog) can take a couple of years and requires you to practice monthly or so to maintain that level of skill.

    I suspect most of the "it's about time people learnt" brigade probably last used a map and compass back in the boy scouts and assume it is a skill they still have. As someone who pulls people like you (usually dead) from the bottom of cliffs and mountains on a regular basis, I can assure you that you forgot those skills many years ago.

    Even people who are good with a map and compass and use them regularly still make mistakes and it is just bloody hard work. SatNav really is the dogs bollox.

    1. Pierson


      Most of those suggesting that people learn to use maps for navigation, do not have high precision dead reckoning on the top of a mountain in adverse conditions in mind.

      They are suggesting, for example, that people in cars learn to read a combination of road signs and an AA atlas, rather than blindly following the silky voice telling them to turn left into the next available swamp.

      Your points are well made, but largely irrelevant to the bulk of the situations in which people will find themselves. The post to which you were replying, for instance, referred to people on their Blackberrys in an urban setting, not half-way up Snowdon on a foggy November night.

      As an experienced Mountain Rescue volunteer, the reference to walking into lamp posts might have alerted you to the intent of the original poster - the damn things are pretty thin on the ground up most non-Narnian mountains that I'm familiar with.

      You are confusing a requirement for expert, specialist knowledge of a subject with a call for a more people to take the trouble to acquire some basic skills that will be of use to them in many circumstances other than the demanding situations in which you have chosen to work.

  26. Tim Parker

    Another article doing the rounds currently..

    1. Intractable Potsherd Silver badge

      If it's in the "New Scientist" ...

      ... it can safely be ignored (unless they have got a decent editorial staff again). It is the Daily Fail of science tabloids.

  27. Anonymous Coward

    Ceci n'est pas un title

    It's interesting how many people see GPS solely as "sat nav". The important point being made is how pervasive GPS has become in lots of unexpected nooks and corners, and the assumption that it'll always just keep on working.

    Someone needs to be asking the question, 'well, what if GPS did just pack up?' It's a theoretical possibility with the increasing sunspot activity, and, however important it is to the DoD, they can't exactly just pop up there to fix their kit.

    AFAIK GSM cell sites use the 1 pulse per second signal from GPS as a method to set highly accurate frequency refs, not absolute time. They could use MSF or something similar, but then would need to have lots of different national variants.

    Interestingly, I think UK govt networks are supposed to derive their accurate time from NPL and no-one else, which means NPL's NTP servers or MSF, and not GPS. Draw your own conclusions.

    Oh, and GPS can be spoofed, but the kit is expensive and bulky. If you had a van you could follow someone about and make their life miserable, but, on the other hand, you'd keep getting lost too :-)

  28. Stevie


    <<your correspondent, as a Royal Navy navigating officer at sea in the early 1990s, was furnished with GPS only occasionally and thus had to make occasional reluctant use of Decca>>

    I am appalled to discover that the proud ships of Her Majesty's Royal Navy couldn't not provide you with proper navigation equipment, especially as such equipment has been standard on ships since the days of sail.

    An enquiry must be instigated immediately as to what had happened to the charts, the sextant and the chronometer on your ship.

  29. pete23

    No content, but...

    <3 Lewis Page's defence coverage.

  30. Anonymous Coward

    Compass. Stopwatch. Accurate map. Sextant. A thumb. Sun.

    " Give me a stopwatch and a map, and I'll fly the Alps in a plane with no windows."

    God, I love that Red October movie so much.

    Remember that jamming a GPS device was the whole plot of a James Bond movie FFS. Come on.

    Oh yes, another movie where the guy was lost flying a crop duster plane (modified to carry extra gas instead of fertilizer) and used his FREAKING THUMB AGAINST THE SUN to get his bearings, with the help of a passenger plane and a radio beacon. (And the only reason he got lost in the first place was gyro drift and shear wind???) In that case, he wasn't close to anything remotely capable of jamming a GPS.

  31. Malcolm Weir Silver badge

    Time -- the reality!

    A coupe of points:

    @Ian Michael Gumby references a clock in Boulder, Colorado - presumably NIST-F1. He is a little confused: there is a transmitter in Fort Collins, Co. (WWVB) that broadcasts a time signal derived from a (bunch of) cesium clock(s) at the transmitter site, although those clocks are synchronized from NIST-F1 in Boulder. In NTP terms, NIST-F1 is the highest stratum, WWVB's clocks are a stratum lower than NIST-F1.

    BUT none of that has any relevance to the GPS constellation: NIST-F1 provides civilian time. Military timekeeping centers around the US Naval Opservatory in Washington, which provides the top-level time reference for GPS, and LORAN-C using "dozens of cesium clocks" and a dozen of Hydrogen Maser clocks. GPS time signal correction is relayed vie Schriever Air Force Base in Colorado Springs, Co.

    Ironically, GPS may actually provide better timekeeping than a single source time signal like WWVB or MSF, because the propagation delay of the terrestrial signals depends on the distance one happens to be from the transmitter, whereas a GPS time reference *can* (but usually isn't) be derived from the aggregate signals from 12 or more satellites, even more so if you already know your precise location.

    Oh, and has been implied earlier, the 60Hz reference in the article is just dumb, and not just because of the missing "k": in the time biz we distinguish between time interval and time reference. The time reference can show up at whatever interval you like ("At the third stroke, the time will be..."), the time interval is the duration between successive reference "hacks" ("Beeeep!"). So if you get a time interval reference at, say, 0.0166 recurring Hz (i.e. once a minute), and you know that the time reference is accurate to within 2 or 3ns of the USNO's equivalent datum point, then your problem becomes creating a clock that is sufficiently accurate to run freely for that one minute.

    In short, if someone gives you a 60Hz signal whose time hack (rising edge, beep, whatever) is accurate to within 2ns of the One True Time (whatever that is), making a clock that won't drift far between ticks is generally a solved problem (it's not easy, but there's not a lot of point in getting too good because the reference is going to waffle around by up to 2ns).

    Oh, and PTP (IEEE1588) will distribute network time far more accurately than NTP, for what it's worth.

    1. peter_dtm


      just bumped into PTP this week - it is rather impressive - but the assumption here (Industrial Automation and Control) was that the source would be ...

      GPS - special module designed to fit in the PLC rack (if I said 1756 I'd give away who I work for ....).

      Complete with switches to PTP standard that know how long it takes a PTP packet to route through it !

      Impressed - oh yes...

  32. Primus Secundus Tertius

    Mr Page's career

    Lewis Page seems to have had an interesting career, including bomb disposal duties and navy watchman.

    I am puzzled.

  33. Christopher Blackmore

    Another alternative...

    Another alternative would have been the Securicor Datatrak unit, that worked off ground based radio signals. When I was one of the people working on it, there was some concern that this new-fangled GPS thing was much more accurate, and would corner the market. A quick Google search appears to show that they cleverly gave up that technology and adopted GPS instead.

  34. Andrew Moore


    I'm pretty sure GLONASS already has decent coverage.

  35. Barry Lane 1

    Tom Tom hopeless

    Tried to set the sat-nav early this morning to get my wife from home to a meeting at an address in Chertsey, Surrey. The Tom Tom route planner website not only failed to recognise a perfectly ordinary address including the postcode and the magic letters "UK", but it moved Chertsey to, variously, Ireland, Germany, somewhere in California and, finally, Ottershaw, which is a mile or more away from the desired destination. Odder still, when it couldn't track down the desired address, it simply came up with one of its own, somewhere near Stuttgart, if memory serves. Google Maps nailed it immediately, mind you, so one up to them. It wasn't so long ago that both Google and Tom Tom tried to send travellers across a non-existent bridge across the railway near Polegate, East Sussex.

    Anyway, my wife will be fine, because she'll stop and ask directions if she gets lost. Me, I'd just drive around the M25 until I fainted from exhaustion and lack of food, or I'd try to locate the UK head office of Tom Tom and beat their CEO to death with his crappy sat nav.

    1. Anonymous Coward

      re: Tom tom hopeless

      I relate to your pain, except I was using a Mio GPS using a 3rd party map. It was based on a printed version of a pretty recommended city guide published around here. The GPS itself worked fine, except the guide numbered a 10km street BACKWARDS. So did the GPS.

      Since the street began on the city center and ended in a crossroad outside town, guess where I ended up. I looked at the printed version (outdated, but still inside my car) and noticed the mistake was there too, except it's been wrong for 10 years. Nobody even took a once-over review of the thing before cramming it inside the GPS.

      Curiously, for known addresses, the numbering was correctly marked. So, if the number belonged to a known address in the city guide (like a gas station or a Police Department), it would be placed correctly. I was amused to see the 1000m mark of the road to be set 8,8km apart from the 200m mark.

    2. Anonymous Coward
      Anonymous Coward


      I must say I think that TomTom is a long way from the top of the satnav pile although I've never known it to fail to find a postcode that is at least a couple of years older than the mapping on the device.

      I have known it misplace a postcode by about half a mile. I have also known it try to plan routes on roads that don't exist. But never to totally fail to find a postcode altogether. Putting addresses into a sat nav that works on full seven digit postcodes seems to be a waste of time anyway.

      However my current IGO doesn't do postcodes and I prefer it. Yes it takes longer to put in address, but I've never known it to be fooled yet. I did get a bit annoyed a while back when I tried a street name that it couldn't find. However a quick check on the Royal Mail website for the postcode showed the street name to be entirely different. Google and Multimap both agreed with the Royal Mail. When I got to the site I found that the organisation concerned had given their own driveway a street name and included it in their address.

  36. Anonymous Coward
    Anonymous Coward

    Oh My!

    "Erroneous GPS signals in an urban area could cause road accidents"

    How? Really, how could an erroneous signal cause a road accident?

    Despite what the authors seem to think automotice sat nav systems are a hell of a long way from fool proof. Of all the systems I've tried I've never ever come across one that doesn't try to make you go the wrong way up a one way street, make an illegal turn, make an impossible turn or some similar error. They do it mostly because their mapping is wrong, nothing to do with the reliability of GPS signals. In the vast majority of cases (like five nines) this doesn't cause accidents. And when an accident does happen in this situation it's not the fault of the sat nav but the idiot driver who would be the type to have an accident anyway.

    We hear stories of idiots blaming their GPS when they drive into a pedestrian precinct or the wrong way up a motorway slip road. I have two problems with these stories. One is that there is never any investigation. Did the sat nav really send them the wrong way or is it just a convenient scapegoat? The other is that it takes a special kind of idiot to drive against all the signs whether their sat nav tells them to do it or not.

    Actually I think most drivers would be shocked at how innacurate GPS location can be in the first place. Ten metres is reasonable accuracy in an urban setting where you can't get too many satellites. Your sat nav is clever enough to try to work out where you are from the signal it has, where you've come from and what direction you were heading in and by combining that with it's mapping. Sometimes however you can catch it out. This is why you see occasional glitches like when you take a slip road and just for a moment the sat nav has you following the main road.

    I know plenty of people who think GPS will always locate you to within centimetres of your real position. This is partly because they have an implicit trust in technology (technology is the new God) and partly, I think, because they watch and believe too much shit like Spooks on TV.

  37. Mok

    Navigational Abilities

    I think the report quoted here is not very far off as to what would happen to shipping if GPS were to fail. Due to satellite positioning navigation has become such a trivial task, that indeed quite a number of watch officers are not all that familiar with alternate means of navigation anymore.

    I am not talking about the use of sextants, but of taking radar and optical bearings! It is simply not done anymore. Look at any random logbook, you will just find GPS positions, no position fixes by other means.

    The usage of sextants, by the way, is at MOST a hobby for some enthusiasts. I have never used it myself and seen it used to get a position (only for checking the gyro and that only very rarely as a pelorus is the tool of choice here). In terms of accuracy it can at most be a tool to get a rough idea where the vessel is, give or take a couple of degrees. A position fix with an accuracy of a dozen miles or so is fairly difficult to obtain even with some training, which is why nobody uses it...

    1. SleepyJohn

      "Take off your hat, Midshipman"

      So goes the apocryphal, but in my experience true to reality, response of the Royal Navy Captain when he inspected a young Midshipman's sextant fix in the middle of the ocean. "According to your fix, Mid, we are currently steaming up the nave of Canterbury Cathedral".

      Speaking as an ex-Naval Officer and professional yacht skipper from the days when a landfall accuracy of ten terrifying, nail-biting miles was sometimes considered quite good, I can only agree with the commenter who described GPS as 'the dog's bollocks'. Protect it from dangerous interference certainly, but 'switch to traditional methods'? I don't think so.

      Few people seem to grasp how much skill, and continual practice, is required to get anything like half-reasonable position fixes from traditional methods. What is that saying about knowing enough to get into trouble, but not enough to get out of it?

      In the early days of GPS in yachting circles there was much alarmist discussion about what to do if your GPS fails. A well-known magazine editor put this to rest with the simple statement that GPS is so cheap now that you should just carry three of them.

  38. Chris 58


    Anyone ever read the book Able One? Pretty much covers, in a fictional work, what really would happen. Stone Ages it be.

  39. peter_dtm

    Decca run by who ?


    In the beginning there was OBOE - a WWII German hyperbolic navigation system - you followed the phase interference pattern between two radio transmitters - each transmitting on a different multiple of a base frequency . The Time Difference patterns that the Phase patterns represent form hyperbole around the two transmitter masts. OBOE was set to 'read' a TD and output a warble when you were on it - with distinctive tones for being to the left or right - easy navigation until the Britts (DECCA Company) started interfering with it & 'bending' it so they missed. Over target was indicated by another 'beam' which crossed the navigation beam over the target. (See Arthur C Clarke's 'Glide Path')

    Post war the DECCA Navigation Company was set up which LEASED Decca Navigators to end users (ships/aircraft/surveyors). The Decca Navigator Company used the lease money to make a profit and maintain all the Decca Transmitter chains around the world. Decca works with THREE frequencies (all multiples of some base frequency - 3f; 5f; 7f ). The base frequency gives the base accuracy. If I remember correctly it was some 100 metres or better at extreme range and approached 10 metres or better in the area between the three transmitters.

    They also had HiFix Decca - which was accurate to better than 0.5m with in the coverage area (pilotage from Euro1 buoy to Europort first time I saw it used I was amazed as the Pilot wanted to know the mid point of the Decca Aerial - he then stood 'under' that point for the run in to Europort).

    The Yanks refused to allow Decca to operate in the US as Decca's leasing model apparently broke some US law. However the Washington Chain (in Canada) was used by non US airlines going to Washington; and the East Canadian Chain was used for trans-Atlantic flights.

    DECCA was a commercial organisation that built and maintained its transmitters and leased out its receivers. You could quite easily train OOWs in its accurate use.

    Loran is/was moderately rubbish - its base frequency is around 100KHz- 400KHz range I think - pretty low so inherently inaccurate. But then it was designed to cover the mid ocean gaps between Decca Chains - so it didn't NEED to be accurate. Then there was OMEGA the benighted US attempt to use hyperbolic navigation on a global basis (f around 16KHz) and was a farce of Monty Python proportions

    I had the pleasure of sailing with a Magnovox Sat Nav - the first commercial Sat Navs - serial number 00001 ! In the days before the 'cage' was established and you could wait 6 hours to get 'lock'

    1. Rich 3

      That would have been Transit

      The forerunner to GPS was Transit. It used far less satellites and took a fix off a single satellite at a time. It was setup in the early 60's to enable accurate navigation of Polaris submarines (I believe they used the Transit fix to correct drift in their inertial navigation platform). With a Transit set, you typically got a fix every few hours as described. When GPS was in it's early stages, you got continuous fixing, but only for part of the day - which was fine for some applications like surveying, as you could schedule ops for GPS uptime.

  40. alwarming

    So using GPS's time service is bad.

    Why should that logic result in people should avoid satnav??

  41. Anonymous Coward

    Why the fuss?

    Bring out the sextants, I say.....

  42. Mephistro

    The biggest problem with GPS...

    ... is that it makes people lazy. I've been told by someone in the know - an ex-merchant sailor - that the ability to navigate using sextants, compass and maps is rapidly becoming a forgotten art. If a solar flare, a NMP or an anti-satellite weapon affects the GPS satellites -a possibility that has been already discussed- we would be in serious trouble regarding sea transport. And that would happen on top of other consequences from the flares or the war.

    Considering this, keeping one of these relics - LORAN, Decca or whatever- as a backup system doesn´t seem such a bad idea.

    My 0,02 €

  43. paulc

    Unskilled Monkeys?

    "A bridge watchkeeping officer who can't cope on passage without an electronic chart and automated collision warning is an unskilled monkey hardly worth paying:"

    but that's what the ship owning corporations WANT... unskilled monkeys... they already get their bridge crews from the cheapest nations on earth, now they want to take advantage of as much automation as possible to completely deskill the job so that unskilled monkeys can do it...

  44. John 61

    I use NPL's

    time server to set the clock on the pile of junk in front of me as doesn't work any more. or or if they pack up you can go across the pond with (no punctuation so they work) Just key/paste the lot in to the drop down box and have all three. If eLORAN is adopted it will have to be backward compatible with MSF as me (and no doubt others) radio controlled clock will pack up. People should remember the old GIGO principle of computing as that applies to maps too. Use of eyes and brains should get you where you want to go. I read elsewhere on the interweb that the Olympic "village" and surrounding streets are in the current A to Z of London, despite not being built yet. Ancient types used the stars, but that's only good at night if you ain't got the Hubble telescope.

  45. Anonymous Coward

    Gotta hate Quangos

    Yes, GPS signals can be blocked very easily due to the fact the signal strength that your TomTom (for instance) needs is miniscule. Or the signal received was miniscule, so TomTom's was devised as such. Whatever... A device the size of something that fits very easily inside a cig pack (including the antenna) can block the GPS signal over a good couple of hundred metres - the Royal Engineers Geo people have lots of fun with this to show it can be done. And recently got told off and had their wrists slapped for doing it...

    But for these money grabbing Quango cnuts to come along and say another system is required, to have loads of money thrown at it to make it reliable, as a backup should be seen as treason. Is the back up system safe from sabotage? At the minute perhaps, but if it was launched as a viable system would that be the case? I'd suggest the Geo blokes could very easily change the freq on their device to block that at the same time. Quango cnuts - hence the Stop sign.

    FYI a couple of people have mentioned the DoD, but due to the fact that it's an international cash-cow GPS is actually now run by the Department of Transport, and the US Gov make a lot of money out of it.

    Galileo and the Russian one are a useless waste of cash, that's completely ego-driven. "The American's have a system, that we're able to use cheaply, but lets create one of our own at a huge expence just so that people will think we're as important as the US"

    And I'm not really sure nuclear missiles need to be very worried about an accuracy of plus or minus 10m.

  46. Anonymous Coward
    Anonymous Coward


    It's interesting that people seem to think that aircraft will all crash if GPS were to fail. Yes it's quite possible for a modern airliner to take off, navigate to it's destination and land without any real intervention from the pilots. That does not mean however that this is the only way they can fly. Take a look at how many different ways a pilot has to navigate. There are more instruments and navigational aids in the average cockpit than you could shake a joystick at. And pilots have to be trained and keep up their training on all of them, right down to good old fashioned VFR.

    The odds of all these systems failing AND visibility being appalling are slimmer than Victoria Beckham.

  47. Matt 33


    The RAE owes me a new keyboard: eLORAN??? Really?

    Next they'll be saying "These DVD thingies are unproven Yank-technology, what we need is eBetamax"

    As Lewis states, the US gubmint has absolutely no interest in letting the GPS system degrade or otherwise fall out of the sky...if watch leaders are incapable of using the MK1 eyeball, dead reckoning and chart plotting, and RADAR then they're f-useless and should be re-assigned to bilge painting duty.


This topic is closed for new posts.

Biting the hand that feeds IT © 1998–2022