Last updated: June 23, 2019.Let's Get Lost is the title of a 1940s jazz song,famously recorded by singer and trumpeter Chet Baker. Back then, gettinglost was not just a romantic idea but still a realistic one. Today, it'salmost impossible to get lost, no matter how hard you try.Whether you're haring down the freeway or scrabbling up Mount Everest,you're always in sight of satellites spinning through spacethat can tell you exactly where you are.Walking round with a smartphone in your pocket, you'llhave ready access to a GPS (Global Positioning System) receiver thatcan pinpoint your position, on a good day, to just a few meters.
Take a wrongturn in your car, and a determined voice—also powered byGPS—will insist you 'Take the next left,'Turn right,' or 'Go straight ahead' until you're confidently back ontrack. Even riding on a bus or train, it's barely possible to get offin the wrong place. Handy display boards scroll the name of thestop you want long before you need to rise from your seat. Apart fromhelping us reach our destination, satellite navigation can doall kinds of other things, from tracking parcels and growing crops tofinding lost children and guiding the blind. But how exactly does itwork? Let's take a closer look!Photo: Getting lost is a thing of the past thanks to mobile devices like this with built-in GPS receivers and mapping apps. What is satellite navigation?Satellite navigation ('satnav') means using a portablereceiver to pick up speed-of-light signals from orbiting(sometimes technically referred to as space vehicles or SVs) so youcan figure out your position, speed, and local time.It's generally much more accurate than other forms of navigation, whichhave to contend with pesky problems like accurate timekeepingand bad weather.
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Because it's a broadcast system based on radio signalsthat reach all parts of our planet, any number of people can use it at once, anywhere they happen to be.The best-known satnav system, the Navstar GlobalPositioning System (GPS), uses about 24 active satellites (including backups). Day and night, 365 days a year,they whiz round Earth once every 12 hours on orbital planes inclined at 55 degrees to the equator.Wherever you are, you're usually in sight of at least half a dozen of them, butyou need signals from only three or four to determine your positionto an.Photo: A NAVSTAR GPS satellite pictured during construction on Earth in 1981.You can get an idea how big the satellite is from the engineer pictured some distance beneath it.
Picture courtesy ofUS Department of Defense.GPS was kick-started by the US military in 1973 and its original satellites were designed to last about 7.5 years, but the latest generation are expected to survive twice as long. In total, around 60 Navstar satellites have been launched altogether, in three distinct generations and several separate groups called blocks, though many of them have now retired. How GPS worksPhoto: An artist's impression of the 24 NAVSTAR satellites in orbit around Earth.Picture courtesy of US Department of Defense.Satellite navigation systems all work in broadly the same way. Thereare three parts: the network of satellites, a control station somewhereon Earth that manages the satellites, and the receiving device youcarry with you.Each satellite is constantly beaming out a radio-wavesignal toward Earth. The receiver 'listens out' for these signals and,if it can pick up signals from three or four different satellites, itcan figure out your precise location (including your altitude).How does that work? The satellites stay in known positions and thesignals travel at the speed of light.
Each signal includes informationabout the satellite it came from and a time-stamp that says when itleft the satellite. Since the signals are radio waves, they must travelat the speed of light. By noting when each signal arrives, the receivercan figure out how long it took to travel and how far it has come—inother words, how far it is from the sending satellite. With three orfour signals, the receiver can figure out exactly where it is on Earth.Where in the world are you?. If your satellite receiver picks up a signal from the yellow satellite, you must be somewhere on the yellow sphere. If you're also picking up signals from the blue and red satellites, you must be at the black dot where the signals from thethree satellites meet.
You need a signal from a minimum of three satellites to fix your position this way(and four satellites if you want to find your altitude as well). Since there are many more GPS satellites, there's more chance you'll be able to locate yourself wherever on Earth you happen to be. How do satnavs calculate distance from time?Suppose you're carrying a GPS-enabled or satnavin your car. How does it know the exact distance to the threeor four satellites it uses to compute your position? Every satelliteconstantly beams out signals that are, in effect,time-stamped records of its position at that time.Since they're carried by radio waves, the signals must be traveling at the speed of light (300,000km or 186,000 miles per second).
Theoretically, then, if a receiver picks up the signals some time later, and has a clock of its own, it knows how long the signals have taken to get from the satellite, and how far they've traveled (because distance = speed × time). That sounds like a nice, simple solution, but it introduces two further problems.First, how long does the signal take to travel? Haven'twe just swapped one problem for another (time for distance)? Thesolution to this involves a hi-tech version of 'synchronizingwatches': each satellite carries four extremely precise(two cesium and two rubidium, typically accurate to something like one second in 100,000 years), while thereceivers (which have less accurate clocks of their own) receive their signals and compensate for the time it takesfor them to travel down from space. GPS satellite signalsNavstar satellites constantly broadcast the two different flavors of GPS, PPS and SPS,on two different radio frequencies (carrier waves) known as L1 (1575.42MHz) and L2 (1227.6MHz).L1 carries the civilian SPS code signal (also known as the C/A code or Coarse Acquisition code), which is relatively short and broadcast about 1000 times a second, and what's known as the navigation data message, which includes the date and time, satellite orbit details, and other essential data. L2 carries the military PPS code, also known as P-code (Precision code), which is very long and precise and takes an entire week to transmit.
It's to form what's known as the Y-code, partly so that only authorized users can access it, and partly (because encryption is a form of signing things to confirm they're authentic) to help prevent things like 'spoofing' (where third parties broadcast fake, disruptive signals purporting to be from GPS satellites). Military-grade GPS receivers pick up both frequencies, and compare them to correct for the effects of the ionosphere. Civilian receivers pick up only one frequency and have to use mathematical models to correct for the ionosphere instead. Applications of satellite navigationMost of us use satellite navigation for driving to places we'venever been before—but that's a relatively trivial application.
Onceyou can pinpoint your precise position on Earth, much moreinteresting things become possible. Roll time forward a fewdecades to the point where all cars have onboard satnav and can drivethemselves automatically. Theoretically, if a car knows where itis at all times, and can transmit that information to some sort ofcentralized monitoring system, we could solve problems like urbancongestion, finding parking places, and even auto theft at a stroke.If every car knows its location, and knows where nearby cars are too,highway driving could become both faster and safer; it will nolonger rely on the vigilance of error-prone human drivers, too easilyconfused by tiredness and bad weather, so cars will be able to travelat much higher densities. The same goes for, where GPS isfinally set to become an integral part of air trafficcontrol—gradually reducing our historic overdependence onradar—over the next decade.Photo: Many tractors, combine harvesters, and crop dusters are now equipped with GPS.And it's not just cars and planes that will benefit from pinpointprecision. For emergency services and search and rescue workers,navigating to remote, sometimes uncharted locations, in a hurry,makes all the difference between life and death. Farmers have beenusing GPS systems in, and crop-dusters to map,plant, manage, and harvest their crops with efficiency and precision.According to an industry body called the GPS Alliance, high-precision satellite navigationboosted US crop yields by almost $20 billion from 2007 to 2010 andis now used in 95 percent of crop dusting.
Meanwhile, farm animals,pets, and rare wildlife are easier than ever to track usingGPS-enabled collars and backpacks. Blind people, traditionally guidedby seeing-eye dogs or the elbows of friends and family, can finallygain true independence equipped with talking handheld GPS systems,such as Trekker Breeze, that can announce street names or read spokendirections from A to B. Needless to say, a system conceived by themilitary still enjoys many military applications, from guidingso-called 'smart bombs' to their targets with pinpoint accuracyto helping troops navigate through unfamiliar terrain. GPS is asstandard a part of modern military equipment as maps andwere 100 years ago.Photo: GPS satellite IIR-12 is fired into orbit by athree-stage Boeing Delta II space rocket on June 23, 2004. Photo by Carleton Bailie courtesy of. Rival satellite navigation systemsIn the United States, GPS is universally used as a synonym forany and every kind of satellite navigation; in other countries, suchas the UK, 'satnav' is a more familiar generic term. In fact, GPSis only one of several global satnav systems.
The Soviet Unionlaunched a rival system called GLONASS in 1982 (also using 24satellites) and Russia continues to operate it today. Europe has beenslowly building its own, more accurate 30-satellite system calledGalileo, which is expected to be completed around 2020, and China isdeveloping a global system known as Compass. The preferred umbrellaterm for world-spanning satnav systems is GNSS (Global NavigationSatellite Systems). Apart from the four big global systems, there arealso a few smaller regional rivals, including China's BeiDou andIndia's IRNSS.Although a given satellite receiver is typically designed to useonly one of the global systems, there's no reason why itcan't use signals from two or more at once. Theoretically,combining signals from GPS, GLONASS, and Galileo could give satnavdevices something like a 10-fold increase in precision, especially inurban areas where tall buildings can block or distort signals,reducing the accuracy of any one system used alone.
Using multiplesystems also promises to make satellite navigation much faster: ifmore satellites are 'in view,' the so-called —the initial delay before your satnav locks onto satellites,downloads the data it needs, and is ready to start calculating yourposition—is reduced. Since TTFF typically varies from about 30seconds to several minutes, it makes a big difference to casual GPSusers (and is one of the first features people compare when theylook at buying a new satnav receiver).
Challenges and issuesKnowing the absolute position of anything, anytime, anywherebrings obvious benefits in a globalized world that relies on swift,safe, and reliable transportation. But it raises issues too.
Ifcivilian transportation systems are designed to rely onsatellite systems provided by the US or Russian military, doesn'tthat make us too vulnerable to the sudden twists of internationalpolitics, especially in times of war? Although the US military nolonger routinely degrades the quality of GPS signals, and announcedin September 2007 that it would be removing Selective Availabilityaltogether from future versions of GPS satellites, currently it can still nobblethe system anytime it pleases. Could a future world of driverlesscars, hyper-efficient parcel shipping, and automated air-trafficcontrol be plunged into chaos purely at the whim of the superpowers?The European Galileo project is entirely a civilian system, whichshould eliminate possible military interference in time. But for themoment, it remains a concern.Fast-disappearing privacy is the flipside of the same coin. Ifyour car and your cellphone are both equipped with satnav, and you'realways using one or the other (or both), your movements can betracked at all times.
That raises obvious privacy issues, especiallyin repressive states. But every new technology brings its pros and cons, from internal combustion engines tosubmachine guns, and nuclear power plants to antibiotics.Progress involves making a tradeoff between benefits and costs, in the hope ofdoing things better than we ever could before. Satellite navigation isno different, swapping safe and unreliable navigation forefficient and effective transportation, albeit at a cost in privacyand (for the time being) continued dependence on military infrastructure. Find out more On other sites.: The official US Government site all about GPS and its applications.: A trade coalition furthering greater use and new applications of GPS.: A variety of useful GPS data from the US Naval Observatory.Articles.: Lockheed Martin Press Release, December 23, 2018. A quick look at the latest generation of GPS satellites. by Tekla S. IEEE Spectrum, April 19, 2018.
An interview with Bradford W. Parkinson, one of the pioneers of GPS technology. by Samuel K. IEEE Spectrum, October 23, 2017. The next generation of smartphone GPS will be accurate to about 30cm (1ft).
by Mark L. Psiaki and Todd E. IEEE Spectrum, July 29, 2016. It's difficult but not impossible to spoof GPS signals, potentially sending ships and boats on course to disaster. What technical methods are there to protect against spoofers?. by Eric A. The New York Times, July 15, 2015.
There are still good reasons to own a standalone GPS device, although now smartphones have bigger screens the gap between the two kinds of devices is closing fast. by James Oberg, IEEE Spectrum, February 1, 2008. Can Russia's alternative ever hope to compete with GPS?.
Gps Voice Navigation Not Working
by Barbara S. Peterson, Popular Mechanics, July 19, 2007. An introduction to the use of GPS in air traffic control.Books. by Aeronautics and Space Engineering Board, National Research Council. National Academies Press, 1995. A technical report evaluating the success of GPS and making recommendations for its future development as a joint civilian and military system.Technical references.: The official SPS and PPS specifications, downloadable in PDF format.: Technical details about Navstar from the US Air Force.Patents. by Norman F.
Krasner, Precision Tracking, Inc. September 2, 1997. A detailed technical description of how a typical GPS receiver works. by Norman F. Krasner, Snaptrack, Inc. Another of Krasner's patents, covering assisted GPS. by Charles L.
Karr, Tracbeam LLC. Another patent describing 'assisted GPS' that combines GPS and wireless networks.
Hello there,For just about the past year (since about iOS 9 release), my phone's GPS has not been working. When I would try to use Apple Maps, it would say my car was off the road somewhere in the grass, and sometimes many roads over. It could never keep up with me while driving.
This also occurred while using Google Maps, so I knew it wasn't just a problem with the Apple Maps app.I tried to restart the phone several times, delete GPS apps and reinstall them, fully wipe the phone and start it from scratch, etc. The problem still exists. So for a while I just dealt with it. I just used my car's GPS if I needed one. Though it always bothered me that my 128GB iPhone 6's GPS was not working. However, with the release of the game 'Pokemon GO' which relies on GPS, I am quite disappointed as I keep getting an error message that my GPS signal is not detected (yes, I enabled location services for the app).Is there some app or something I can use to diagnose my GPS antennae within the phone? I have full 5-bar (dot?) signal, and my phone is in developer/debug mode, so I can also see the detailed signal strength is -81.
I have AT&T as my carrier. There must be some way to determine if something in my phone is damaged. I would go to the Apple Store, but the closest one is about an hour and a half away, so I would like to avoid that if possible. I have the exact same problem. When I am using Maps or Google Maps, it can originally locate me and give me he directions to a certain location.
However, when I start moving or driving, the GPS function just seems to fail and does not follow me. I have tried to fix this by resetting my phone and checking the location services. I even went to the Apple Store and they factory resetted my phone, but still no fix. I then went to a cell repair shop and said they did not know how to fix it as well.I have also attempted to play the new app Pokemon Go and I am highly disappointed that my GPS issues do not allow me to play because it never follows allng with me or it just tracks me in completely inaccurate locations.My warranty has expired for my phone as I got it in September 2014. Are there any other options possible to fix my GPS? I have the same problem as well. I noticed it over a year ago when I tried using the WAZE app for the first time and it didn't pinpoint my location accurately enough.
I never really cared since I rarely travel too far and my GPS worked well enough for me to navigate when I did have to rely on a map. Now that Pokemon GO is out which relies on very accurate positioning since certain Pokemon can only be captured in certain areas, it is really annoying that my phone takes a long time to put me in a general location or fails to find me at all.
I know this is just a game but it is really annoying since this is the first week of release and all of my friends play it. My GPS seems to only work well enough to play when I am more urban areas in my city (maybe the buildings help concentrate the signals to my phone) compared to parks and more suburban areas. The phone would make my in-game location off by tens of meters and sometimes would teleport me around to another whole BLOCK!I think it may be a hardware problem since I also noticed my phone started to become worse at picking up WIFI signals as well. I use to be able to walk around my business and maintain a good WIFI signal and now it seems that I can barely connect to my router unless I am within 10 feet of it. I've read around that this could be a short from either a bad charging cable, heat damage that damage the WIFI and GPS modules, or an update which fried partial systems.edit: I checked my router with another person's newer iPhone and they had really good WIFI signal reception like what I had at first so that's why I think it's a hardware issue.
I have had the same issue for about a year. Then, just like @FunnyAsianBoy, my wifi card started failing. Then my Bluetooth. I've lived with that for about a year, when last week my. cell service started failing! NO SIGNAL or SEARCHING in areas where there is typically -60db signal strength (very good).
Just an FYI, I own a fairly large IT consulting firm; troubleshooting is second nature. That said, I tried every 'fix' I could find for this issue, still. Nothing.Apple has been useless so far. Year ago at the Genius Bar, they asked if I did the factory reset, the network settings reset, etc. I had done all that prior to coming in, and they said, 'well, just use the Maps app from Apple, we can't ensure that Waze or Google Maps always work.'
Nice.Now I've called support for the cellular issue and they said reset the network settings, do a reinstall. Still not working.TOTALLY HARDWARE RELATED.I now have a $500 iPod. I FIXED the problem. Before I give you the answer read on and make sure this is what is happening to you. I was having GPS issues where the both Apple and Google Maps were incorrectly mapping my location so directions would just cease. I would drive on a freeway and the Maps program would show me off the freeway in a field a little distance away and the Maps would not provide any direction other than the message 'Proceed to the starting point'.
This issue happened after a recent iOS update and I assumed it must be an iOS bug. Turns out that it was not an iOS update bug.Instead, it is the antenna inside of iPhone6 that was malfunctioning. The malfunction probably was made more apparent by the iOS update but the GPS issues were a result of antenna malfunction. I called around 6-7 iPhone repair places and 2 of them said they can replace the antenna for 60 bucks. I believe that the part is called 'iPhone6 Logic Board Antenna Flex Cable'.
Once replaced my iPhone GPS issues went away and all is back to normal. I have the same problem as well. I noticed it over a year ago when I tried using the WAZE app for the first time and it didn't pinpoint my location accurately enough. I never really cared since I rarely travel too far and my GPS worked well enough for me to navigate when I did have to rely on a map.
Now that Pokemon GO is out which relies on very accurate positioning since certain Pokemon can only be captured in certain areas, it is really annoying that my phone takes a long time to put me in a general location or fails to find me at all. I know this is just a game but it is really annoying since this is the first week of release and all of my friends play it. My GPS seems to only work well enough to play when I am more urban areas in my city (maybe the buildings help concentrate the signals to my phone) compared to parks and more suburban areas. The phone would make my in-game location off by tens of meters and sometimes would teleport me around to another whole BLOCK!I think it may be a hardware problem since I also noticed my phone started to become worse at picking up WIFI signals as well. I use to be able to walk around my business and maintain a good WIFI signal and now it seems that I can barely connect to my router unless I am within 10 feet of it. I've read around that this could be a short from either a bad charging cable, heat damage that damage the WIFI and GPS modules, or an update which fried partial systems.edit: I checked my router with another person's newer iPhone and they had really good WIFI signal reception like what I had at first so that's why I think it's a hardware issue.
I have the exact same problem. When I am using Maps or Google Maps, it can originally locate me and give me he directions to a certain location. However, when I start moving or driving, the GPS function just seems to fail and does not follow me.
I have tried to fix this by resetting my phone and checking the location services. I even went to the Apple Store and they factory resetted my phone, but still no fix. I then went to a cell repair shop and said they did not know how to fix it as well.I have also attempted to play the new app Pokemon Go and I am highly disappointed that my GPS issues do not allow me to play because it never follows allng with me or it just tracks me in completely inaccurate locations.My warranty has expired for my phone as I got it in September 2014. Are there any other options possible to fix my GPS? I have had the same issue for about a year. Then, just like @FunnyAsianBoy, my wifi card started failing. Then my Bluetooth.
I've lived with that for about a year, when last week my. cell service started failing! NO SIGNAL or SEARCHING in areas where there is typically -60db signal strength (very good). Just an FYI, I own a fairly large IT consulting firm; troubleshooting is second nature. That said, I tried every 'fix' I could find for this issue, still. Nothing.Apple has been useless so far.
Year ago at the Genius Bar, they asked if I did the factory reset, the network settings reset, etc. I had done all that prior to coming in, and they said, 'well, just use the Maps app from Apple, we can't ensure that Waze or Google Maps always work.'
Nice.Now I've called support for the cellular issue and they said reset the network settings, do a reinstall. Still not working.TOTALLY HARDWARE RELATED.I now have a $500 iPod. Apple Footer.This site contains user submitted content, comments and opinions and is for informational purposes only. Apple may provide or recommend responses as a possible solution based on the information provided; every potential issue may involve several factors not detailed in the conversations captured in an electronic forum and Apple can therefore provide no guarantee as to the efficacy of any proposed solutions on the community forums. Apple disclaims any and all liability for the acts, omissions and conduct of any third parties in connection with or related to your use of the site. All postings and use of the content on this site are subject to the.