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Why The US Military Made GPS Free-To-Use

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  • Dipublikasikan tanggal 18 Jun 2017
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  • Sains & TeknologiSains & Teknologi

Komentar • 5 412

  • Andrew Maksimovich
    Andrew Maksimovich 2 tahun yang lalu +682

    I never thought a satelite would have to consider time dilation, props to the engineers..

    • Jeff Spaulding
      Jeff Spaulding Bulan Yang lalu

      Another interesting place you wouldn't expect time dilation: the electron orbitals of large atoms.
      Atoms form compounds (molecules) because of how their electrons behave. The electrons hang out in "orbitals," each of which can contain an exact number of electrons. An atom achieves its lowest energy state when all its orbitals are either completely full or completely empty, so it will share or steal electrons from other atoms to achieve this. When this happens, the two atoms will form a bond.
      The really large atoms at the bottom of the periodic table have electrons that move so fast in their orbitals that they experience time dilation. Theoretically, this could alter their chemical properties and change they way they form bonds. Unfortunately, it's really hard to study the effect since the atoms are so short-lived.

    • Awesome Panda
      Awesome Panda 8 bulan yang lalu

      hey we have the same profile picture

    • Dr. Irina Luminesk
      Dr. Irina Luminesk 9 bulan yang lalu +4

      I want to read pyropulse's comment too. But it's deleted.

    • GravySauce171
      GravySauce171 2 tahun yang lalu

      Dont be like @pyropulse

    • xXYannuschXx
      xXYannuschXx 2 tahun yang lalu

      @pyropulse So you only realized that when you were told that acceleration causes time dilation? And that's why you are not an engineer or a smart person in general.

  • Kabloosh
    Kabloosh 2 tahun yang lalu +964

    A lot of innovation came out of military necessity.

    • I'm Going Supersonic
      I'm Going Supersonic 6 bulan yang lalu

      Damn near all. So many things we have today are the result of war.

    • Alfonso Siagian
      Alfonso Siagian 6 bulan yang lalu

      @faizul ICOM jet engine, modern rocket technology, Internet, radar, and even duct tape

    • Alfonso Siagian
      Alfonso Siagian 6 bulan yang lalu

      @Cheesy Goodness missiles or ICBM uses the same technology as of commercial rocket launch, in fact there are some retired ICBMs converted into commercial rocket, basically the current rocket technology was come out of military

    • Rocketboi channel
      Rocketboi channel 8 bulan yang lalu

      @Necro that isn’t what racist means? But you get the message across

    • EffectHunter
      EffectHunter 10 bulan yang lalu

      @Saar Ron very true as well

  • 김도운
    김도운 4 tahun yang lalu +388

    Some intersting technical notes here.
    1. Trilateration technically requires 3 satellite in 3 dimensional space. However, 4 satellite required to pinpoint the user location because of receiver clock error. Actually rx clock error is 'solved' by some complicated computation. Therefore, in theory, synchronizing rx clock to reference time is not necessary. In reality, rx clock is steered so that approximately synchronized to reference time, but not exactly.(ns accuracy is impossible withoit atomic clock)
    2. The intended scrambling known as 'selective availability' was theoretically eliminated by Differential GPS. It was one of the reason why the selective availability was removed.
    3. There are a lot of considerations in order to make GPS correct. Relativity is just one of example. Speed of light is changed by going through ionosphere and troposphere. Minute movement of pole of Earth make coordinate system ambiguous. Earth rotation speed is also changed. And more...

    • 김도운
      김도운 Tahun Yang lalu

      @SamiK Because two years have passed since I took the GNSS class, this comment may be incorrect. From a mathematical perspective, the trilateration of GPS is nothing but solving a nonlinear system. The variables appear in the system are the position (x, y, z) of the receiver and the clock error, thus 4 variables. (assume the position of each satellite is known) Meanwhile, we have one equation for each satellite which is derived from (distance traveled) = (velocity) X (time elapsed). Therefore, we have 4 equations. In summary, we can solve the nonlinear system of 4 equations with 4 variables. Mathematically, the solution may not exist, but we can find a plausible solution that approximately satisfies the equations. (as far as I remember, the solution is an approximate solution in the minimum squared error sense) More specifically, the equation is linearized and the guess of the variables is updated iteratively. I wish my comment is helpful.

    • SamiK
      SamiK Tahun Yang lalu

      @김도운
      Thanks for, that I've been trying to get my head around how they get the atomic clock time down to the receiver. If a satellite broadcasts it to your phone, it's always out of sync because of the time it takes the signal to travel. You could compensate for that if you knew how far the satellite is, but for that, you would need to know your position, which we are trying to get in the first place.
      I can't say I understand it now, but had an "aha moment" from your comment on how it possibly works.
      My idea is it would correct for the time error by comparing the arrival times of the signals from different satellites. Since the positions and orbits of the satellites are know and also their relative distances to each other, I get an idea of how with some math wizardry it would be possible to bring that time error down.

    • Mariano Scholl
      Mariano Scholl 2 tahun yang lalu +1

      This thread is old, but theoreticly you do need 4 sattelites to pinpoint a position. If you map all possible locations in 3d-space based on their distances and locations alone, than you'll get:
      1 sattelite->1 sphere
      2 satellites->2 spheres intersecting->1 sphere intersecting a sphere
      ->some distorted ring/line
      3 sattelites>3 spheres intersecting->1 sphere intersecting some distorted ring/line-> 2 points
      4 sattelites>4spheres intersecting-> 1 Point
      (assuming non of those sattleites spheres are lucky and happen to touch only your location(not intersect, but touch the others spheres) or are unlucky to touch every remaining possible location(for example a sattelite in the middle of the last 2 remaining points, would touch both points). Most of all this is handeled just by having the sattelites orbit earth, so they aren't ever in constelletions in which such edge cases might occur.)
      It works with 3, but only because we can basicly replace the 4th sattelite with the earth. We can eliminate the 2. point based on the assumtion that you are on the surface of earth and the differences between the 2 points is (at those distances) so large we can assume which is the correct one(and by the sattelites positions and them orbiting earth, we know the direction in which earth lies so we know which point to exclude.)

    • Exot1cz 25
      Exot1cz 25 2 tahun yang lalu

      Wait trilation do you mean triangulation

    • Mike C amps
      Mike C amps 2 tahun yang lalu

      the citation was an accuracy of 5 meters...….but then it also factors in magnetic north which has shifted by something like 60 feet this past year and something like 120 feet or more since it got tracked in the 1980's. SO land surveyors that use GPS are not accurate and that's what the industry uses now.....its garbage. A friend of mine used to do "brown field" sites using GPS and he said to get a more accurate survey point....he had to hold the uplink in position for hours as in all day.

  • skullee
    skullee 3 tahun yang lalu +2075

    "2 million dollars"
    me: huh that sounds cheaper than I thought it would be
    "... a day"
    me: oh

    • johnclawed
      johnclawed Tahun Yang lalu

      Now multiply by 365 days, and then divide by 328 million people. Now how much is that per person per day? Is it still a lot?

    • Eric Dew
      Eric Dew Tahun Yang lalu +1

      That's still quite cheap. I think Jeff Bezos's wealth grows at a faster rate.

    • bam-skater
      bam-skater 2 tahun yang lalu

      @Will Poundstone Not only that it means the US military can flick the switch and turn other peoples GPS off. Go to war with 'x' country, flick the switch and suddenly that country doesn't know where all it's tanks, boats, planes + troops are. Europe is currently developing it's own system (GNSS) for this very reason

    • Daniel-Petru Gligor
      Daniel-Petru Gligor 2 tahun yang lalu

      Compare with the 2 billion dollars per day for military, is spare change.

    • Peter Navin
      Peter Navin 2 tahun yang lalu

      That's like a cent for everyone a day (cuz not everyone works or pays taxes) or 3 bucks 65 a year, not much

  • Mike Roberti
    Mike Roberti 5 tahun yang lalu +2753

    Apparently, the Russian GPS is designed to guide automobiles to crash into each other if the driver has a dash cam and is listening to techno music on the radio

  • Tarkov
    Tarkov 2 tahun yang lalu +48

    I remember using a hand-held GPS before 2000, the scrambling was...less than ideal.
    You could go for a hike in a small park and literally get lost.

  • Marcus Menghini
    Marcus Menghini 4 tahun yang lalu +22

    It is my understanding that part of the reason the scrambling was later reduced was because the technology to basically "undo" the reduced accuracy was fairly easily available. If I recall, this amounted to placing base stations in certain areas where their position was fixed and known very precisely. These stations could send out a signal to local devices to help fill in the gaps that were introduced into the precision of the GPS signal.

  • johansson
    johansson 2 tahun yang lalu +8

    By making it "free" but still control it's use, they can put certain limitations and restrictions on it.
    Having the ability to turn the system off or cause random offset/shifts in the calculated gps coordinates if needed.
    Their biggest fear is a foreign drone or attacker using a gps system to target major targets in the US.

  • Kris B
    Kris B 3 tahun yang lalu +7

    It must be an amazing feeling to design and build stuff like this, knowing billions of people rely on it every day. I guess that's why they tell you to study hard and go to a good school, so you can work on stuff like this. There are smart people behind all the stuff you use every day, you're car, smartphone, computer, etc.

  • Slightly Mad Otter
    Slightly Mad Otter 5 tahun yang lalu +907

    Fun fact: Any commercial GPS unit will stop working at 1900 kph/1200mph and/or(depends on the manufacturer) an altitude of more than 18000m/59000 ft to stop them being used for trageting systems in ICBMs. This is called the COCOM limits.

    • Rustam Ravi
      Rustam Ravi 7 bulan yang lalu

      @Slightly Mad Otter me

    • 57thorns
      57thorns 4 tahun yang lalu

      As a geocacher I can tell you that dense forests, depressions in the ground and cloud cover are bad for the GPS signal. High ground (compared to the nearest environment) and clear skies make for excellent reception.
      Also, mobile phones use more than one location technique, they use the cell towers for location as well. Even WLANs will be used at least for Android as google have wlans around the world pinpointed.
      The main advantage to using cell towers is speed, as getting an accurate GPS reading takes several minutes in bad conditions (ie most days).

    • Mihai Lazar
      Mihai Lazar 4 tahun yang lalu

      Some Guy reminds me of Tom Scott's OH NO, I'M A MISSLE video
      idclips.com/video/zPtbzJlcNKc/video.html

    • toranamunter
      toranamunter 5 tahun yang lalu

      Feriin it does. You're talking about a smartphone. But GPS works on a mountain just fine :-) nothing to do with cellular phone reception

    • Feriin
      Feriin 5 tahun yang lalu

      Some Guy - So why doesn't it work when I go hiking on a mountain, yet starts working as soon as I get a cell signal again?

  • RODS
    RODS 3 tahun yang lalu +133

    Thanks to all those engineer blokes that made this stuff happen. Thanks USA!

    • TheGRERF
      TheGRERF 2 tahun yang lalu

      @RODS haha

    • RODS
      RODS 2 tahun yang lalu +3

      @thedownunderverse and thanks to all those engineer blokes, mothers and the lady that made the sandwiches(ha HA)

    • thedownunderverse
      thedownunderverse 2 tahun yang lalu +1

      What about the sheilas?

  • Chuggiek
    Chuggiek 2 tahun yang lalu +4

    I use offline maps all the time thanks to Gps. Great explanation of how it works. Never knew it was from military date.

  • Acousticmarine
    Acousticmarine 2 tahun yang lalu +1

    Started using GPS in 1983. We only had a few hours a day to fix locations during PLRS EW testing, sure made life easier. Before this, one had to look for survey locations, which is usually a metal stamped disc driven into the ground or set in a concrete slab. Had to find these things during the night sometimes during OT tests, that was fun.

  • DME EMD
    DME EMD 3 tahun yang lalu

    Excellent video! I'm really glad this one over the relativity aspect of GPS satellites. That has always been one of the cooler engineering aspects of GPS satellites to me. It's not mine blowing or anyting but it's just really awesome our precision dictates the need to use it it

  • Leo Sypher
    Leo Sypher 4 tahun yang lalu

    I really appreciate the free GPS service, thank you to all the people who launched and now maintain the global positioning system, my toughbook computer has a gps receiver and has proven very useful

  • mgabrysSF
    mgabrysSF 2 tahun yang lalu

    Question - can't the new mega satellite network from SpaceX be used for a very high resolution GPS? Because that would be amazing. And useful.

  • reid thomas
    reid thomas 4 tahun yang lalu +187

    The reason the US made it free to use was because people were already producing equipment to work around it. I read an article in the mid 80's that said the US Coastguard had found away around it by using ground stations for position fixing to overcome the information scrambled by the military. Since the ground stations were fixed, it was possible to work out any error correction. Other commercial companies latched on to this and had begun to produce their own equipment along similar lines. I worked at Marconi at the time and we had projects in the pipeline for HMG using these ideas. When GPS became freely available, they were all cancelled.

    • Adrian Fernandes
      Adrian Fernandes 2 tahun yang lalu

      or maybe be they can track you with their tech lol

    • Eagle View HD
      Eagle View HD 2 tahun yang lalu

      The LORAN Navigation system was a predecessor to the GPS. It was not as accurate, and had limited range.

    • MrBlackHawk888
      MrBlackHawk888 2 tahun yang lalu

      Sounds weird. Weren't GPS signals encrypted in any way back then?

    • Ritwik Reddy
      Ritwik Reddy 2 tahun yang lalu +3

      @Harmeet Singh gps has 0.5 to 1m for public. And gps modukes are lot cheaper than navIC modules.

    • Harmeet Singh
      Harmeet Singh 2 tahun yang lalu +1

      @Ritwik Reddy NAVIC is more Accurate than GPS because it has 7 working satellite (only for India) ,NAVIC has accuracy of 5-10m (public) and (0.1m encrypted ) . GPS is good at horizontal accuracy but in Vertical accuracy it is worse.

  • Kairon156
    Kairon156 4 tahun yang lalu +4

    While I'm not an engineer I think it's awesome to have an opensource research platform.

  • Kekero
    Kekero 5 tahun yang lalu +4583

    How do satellites work for flat earthers?

    • Edfuad Mo
      Edfuad Mo Bulan Yang lalu

      😂🤣😂

    • Better with Baylee
      Better with Baylee 2 bulan yang lalu

      It’s roped to the flat earth duh 🙄 😂😂😂

    • AZ Park It Storage
      AZ Park It Storage 2 bulan yang lalu

      Don't need them as they are all part of the 'conspiracies'. Since the Earth is basically a flat plane (exempting mountains & valleys) they can use a ruler with a map & compass, correcting for magnetic declination, gradients, terrain features as long as they're wearing their tin (aluminium) foil hats. The only thing more vociferous than a Flat Er is a rabid religious zelot.

    • Tom Sparks
      Tom Sparks 3 bulan yang lalu

      Easy. There is no GPS.

    • Eli
      Eli Tahun Yang lalu

      bounce of dark matter

  • John Z.
    John Z. 2 tahun yang lalu +112

    I know the guy who helped invent gps and figure the calculations for time. He lives outside of Cleve, Oh. Retired NASA optical physicyst. Smartest guy I ever met, math savante (genius). 1 time I asked him whats the answer to something like 12,357 ÷ 5.923 and he figured it out in his head in less than 30 seconds. Ya freaking math genius. I remodeled most of him and his wife's home. He told me how he had security detail back in the 80s- 90s so the Russians/ Chinese didn't kidnap him for gps secrets. Good times!

    • Nunya Biz
      Nunya Biz 2 tahun yang lalu

      NEAT STORY

    • Jaganath
      Jaganath 2 tahun yang lalu +1

      PikPobedy Al Gore is famously known for being able to come up with the solution for 2+3 in less then 25 minutes, with a fail rate of only 1 in 12.

    • ҉K҉N҉I҉G҉H҉T҉F҉I҉R҉E҉6҉6҉
      ҉K҉N҉I҉G҉H҉T҉F҉I҉R҉E҉6҉6҉ 2 tahun yang lalu +1

      he may be smart i believe you. but thats not hard to figure out for an enginneer. a bachelor degree could do that in 10-20 sec. its about 2.04 something... i did that in about 5-10 sec.. look there is a trick. let me do it propperlyy now: take 12. and imagine 5.9... as 6. 12/6 = 2. then you take the sum of the remaining. its about 450. that less then 6000. so its 2.0 right now. and 4.5 is less then 6. so add zeros (multiply by 10). and now do 45/6. thats something like 7.5... so the fast and short answer is 2.075 or in short 2.08 something. checking with the calculator. 2.0863... so its roughly true... but i believe you mean that he gave you the precise answer of 2.0863

    • Elite
      Elite 2 tahun yang lalu

      😂

    • Thành Vinh Nguyên Tô
      Thành Vinh Nguyên Tô 2 tahun yang lalu +2

      @M K lol

  • the hell do I call this?
    the hell do I call this? Bulan Yang lalu +1

    Man it blows my mind that technology used in our everyday life has to account for a difference in passage of time for us in comparison to it. The way something like that is just so casually said and accepted makes me feel like Im in Star Trek.

  • TrashPanda -
    TrashPanda - 4 tahun yang lalu

    When I was a infantryman in the army GPS combined with MGRS(military grid reference system) was invaluable. We went from using a device called a PLGR(precision lightweight GPS receiver) that weighed nearly 3 pounds, was big and bulky, and took nearly 60 seconds to get a fix, to a Garmin wrist mountable unit that also included a compass and altimeter. Compasses and protractors are still a must need skill for land navigation, but it’s so nice to be able to take a quick glance at your wrist and have a vast a array of mission critical information.

  • Muskoka Mike
    Muskoka Mike 4 tahun yang lalu

    I can personally attest to the accuracy issues in the 90's. I had a boat on Lake Ontario and GPS was just coming out for civilian use. The units were upwards of $2 to 3000.00 each and the 100 m deficiency was enough to cause some people to drive up on rocks etc at night when it was pitch black. Not a whole lot of people were using it. What I had on my boat was Loran which used a chain of radio towers sending out radio signals with triangulated my position. It was hit or miss and took time to triangulate and obtain 3 or more signals. If memory serves, it was accurate to within 50 feet which (at the time) was amazing.
    I seem to remember there were two modes for GPS: SA (standard accuracy) and MA (military accuracy).
    I can't believe how cheap and easy it is now to navigate using your phone.

  • exurb1a
    exurb1a 5 tahun yang lalu +110

    Well, that was fantastic.

    • Aymanne
      Aymanne 6 bulan yang lalu

      Oh it's the depressed turtle. I never thought I would encounter you here.

    • v x3woots v
      v x3woots v Tahun Yang lalu +1

      Why are you here

    • confuzed pawn
      confuzed pawn Tahun Yang lalu +2

      ahh the time travelling pickle.... i see

    • Alexander Klee
      Alexander Klee Tahun Yang lalu +4

      simply seeing this turtle makes me question my existence

    • SLA
      SLA Tahun Yang lalu +1

      Sure it was!!

  • Riche Bright
    Riche Bright 4 tahun yang lalu

    Excellent explanation on how GPS works. Thank you.

  • Alexander Littlejohn
    Alexander Littlejohn 4 tahun yang lalu

    Aviation uses mode c transponders and onboard radar (mainly used for weather) and ADS-B which does use some gps but it uses ground based towers to be significantly more accurate.

  • alexander balakhontsev
    alexander balakhontsev 3 tahun yang lalu +3

    Bravo for this video! Sophisticated thing explained simply and quickly. Much much much thanks

  • Hypo Thebai
    Hypo Thebai 3 tahun yang lalu

    Actually only the 'C/A code' is available, which is a very small part of the total GPS signal. It is access to this code that provides the 'Standard Positioning Service'. The really valuable access is to the 'P code' (or 'M code') which provides the 'Precise Positioning Service' which is used by the US military.

  • Thinker
    Thinker 5 tahun yang lalu +1244

    I love how GPS proves Einstein's special and general relativity true.

    • Hasnain Gulzar
      Hasnain Gulzar 3 bulan yang lalu

      it showcases special relativity. Nothing to do with general relativity. And it doesn't prove it.

    • Valued Customer
      Valued Customer 3 tahun yang lalu

      You've confused a theory [with proofs] to a hypothesis. Different things. @zomboss5000

    • Lucas
      Lucas 3 tahun yang lalu +1

      @Jannie Schlüter Exactly what this guy said. You believe that something falls because of gravity but maybe in the future we find out that it's because of another thing (maybe something we can't even imagine with today technology). It's in fact the best approximation we have to the truth but we don't know if it's the truth, just like someone said in this thread that tribes used myths to explain certain phenomenon, we use science. Mythology is the science of the tribes. So science can be described as opinions based on a finite number of experiments.
      With that said, it doesn't mean science isn't useful. We clearly see how it allows us to improve as a species (medicine, GPS, phones, cars, etc.) but, again, we mustn't believe all we know is unchangeable because if we do, we won't be able to discover new things.

    • tommy miller
      tommy miller 3 tahun yang lalu

      It doesn't. SR is not needed according to Tom VanFlandern who was an astronomer on the project. Not that anyone cares. You can carry on saying that among friends and still sound smart for another 20 years at least.

    • elvin l.
      elvin l. 3 tahun yang lalu

      what is a theory?? watch the damn thing everyone >>>
      idclips.com/video/lqk3TKuGNBA/video.html

  • Geof Dowdell
    Geof Dowdell 3 tahun yang lalu +9

    Doubtless developed for missile guidance, but I suspect it's not 'free' - I assume that GPS device manufacturers have to pay a licence fee to USA. Nonetheless, it's a fantastic development.

    • William Weber
      William Weber 2 tahun yang lalu +1

      no license fees, but also no guarantees that it will be available forever or free. so you pay this way.

  • Tennouseijin
    Tennouseijin 4 tahun yang lalu

    It's also worth mentioning that AFAIK during the time when GPS was scrambled for public use to make it less accurate... there existed solutions that would circumvent the scrambling.
    I think one way to go about it was by placing devices at known positions that would read what position the GPS tells them they have, compare it to their actual known position, and thus know the 'scrambling error' at the given time and place. They would then transmit this error to nearby civilian GPS devices, so they could apply the same correction. The accuracy would be worse than when using unscrambled GPS, but considerably better than if using just the scrambled GPS.
    Also, as an unrelated note, I find it weird if people have GPS constantly on in their mobiles. I only turn it on when I actually need it, but I have it turned off most of the time. Why would I want Google and my mobile operator (and anyone else who manages to install malicious code on my mobile) to constantly know my location with pinpoint accuracy is beyond me. It's enough if they can find the rough position from the triangulation that happens between mobile transceiver stations, and there's not much I can do about it other than turning off the phone completely.

  • Sephok
    Sephok 2 tahun yang lalu

    Actually, do drones really _need_ GPS? I thought it was just used to ensure drones can't fly too high, or possibly even to keep them out of restricted areas. While it is important to keep drones from crashing into planes near airports I wouldn't call GPS something drones wouldn't be possible without. It just makes it easier to ensure regulations are obeyed.

  • crimony
    crimony 4 tahun yang lalu

    GPS was originally available without scrambling, so if you captured your precise location before the scrambling began, then you could use those original coordinates to unscramble the scrambled system later for other coordinates.

  • jrrn
    jrrn 5 tahun yang lalu +13

    This is a great video. The information was presented well and professionally! One thing you didn't mention is the "COCOM Limit", which is in place to disable GPS on objects traveling faster than 1,000 knots at an altitude higher than 18,000m. This way, we can have extremely accurate tracking worldwide, but we still prevent the use of long range missile networks.

  • EggyRepublic
    EggyRepublic 2 tahun yang lalu

    Imagine 100 years ago how advanced and futuristic it'd sounded to say any person carrying a tiny chip is able to pinpoint their location down to the nearest meters anywhere on Earth.

  • Jim Devilbiss
    Jim Devilbiss 4 tahun yang lalu

    I went to a conference many years ago ‘ I can’t remember how many,a Marine captain had a military GPS receiver. About the size of a small attaché case. I wanted to see it actually work but after the first demo the batteries went bad or dead and they did not have the charger.

  • Scott Family
    Scott Family  3 tahun yang lalu

    I remember in the 90s, most gps handhelds had ways to circumvent the scrambled signals for increased resolution. That might also explain why they stopped scrambling...

  • Denis-Carl Robidoux
    Denis-Carl Robidoux 3 tahun yang lalu

    Just FYI, in your video you said that drones wouldn't be possible without GPS but even if drones use it they do not absolutely depend on it. The navigation technology that drones really depend on is the accelerometer. The GPS as with other technologies, like the digital compass, the sonar and the vision-base navigation are there just to make more features available.

  • Grizzlycougar
    Grizzlycougar 5 tahun yang lalu +7

    Wow, never knew GPS had to take into account special and general relativity, I didn't think such a small distance in terms of the universe would matter.

  • Tashkiira
    Tashkiira 4 tahun yang lalu

    A small note: cellphone GPS defaults to checking cell towers in urban areas if enough towers are available to check. This isn't always the case, though, so it's not unusual to be using both towers and satellites at the same time.

  • Piotr Sarnacki
    Piotr Sarnacki 4 tahun yang lalu

    Really interesting : ) but missed one point , how much US companies got from "license" fee for the technology developed and used in GPS ? how much is going to the federal coffin and how much to their pockets ? just curious :)

  • Hahaa Ha
    Hahaa Ha 2 tahun yang lalu

    How they invented this and made it free just amazing, I don't think other country would have think to make this system

  • datGreg
    datGreg Tahun Yang lalu

    fun extra fact, I heard from my teachers from the aviation industry told us that there had been a request denied from USmilitary to allow civilian use of the GPS & they only changed their mind after USSR offered its GLONAS for free..

  • denelson83
    denelson83 4 tahun yang lalu

    A GPS receiver also has to compensate for something called the Sagnac effect when calculating its position, as the Earth rotates with respect to the distant stars, but the satellites' orbital planes do not, that is to say they do not precess.

  • David Robert Gibson
    David Robert Gibson 4 tahun yang lalu

    Marvellous video - I updated my knowledge of GPS. Incidentally John Cadogan on IDclips reports there are now 31 main system GPS satellites.

  • gold elmo
    gold elmo 3 tahun yang lalu

    You are partly right in the use for the GPS for the US military.. but its primary reason for existing was to guide nukes during a exchange with incredible accuracy.. its why the US didn't need to make nukes as big as the USSR at the time because they couldn't match the accuracy back then.. But yeah GPS is amazing

  • ValoLP
    ValoLP 2 tahun yang lalu

    I came for GPS and now I am totally fascinated by Simscale... really nice tool

  • Apace
    Apace 5 tahun yang lalu +41

    Awesome video! Will you do videos about other satellite constellations? I know there isn't much information about this yet, but I really want to know why internet over satellite sucks and how SpaceX wants to change that, but needs 7500 satellites to do this.

    • Acb Thr
      Acb Thr 5 tahun yang lalu +1

      A bit late, but think about it. Satellites tend to be about 1-2x the size of a car not including the solar panels at full extension. Now that's big, but not nearly as big as the racks upon racks of state of the art servers that sit on top of the junctions in the fiber optic network that comprises the internet, not to mention the cooling the building itself provides form the air. Satellites have to deal with the heat in other ways. There is only so much computing power you can cram into a satellite along with the engine, batteries, transformer, and active cooling system, not to mention it has to be energy efficient, and also has computing power restricted by the components having to be radiation hardened to some degree to resist possible bit flipping corrupting information. This satellite is also at least 1000km above the surface of the earth, possibly 20,000km up in geostationary orbit, and has to receive an uplink from ground stations, provide its own uplink to a base station, provide downlinks to dozens maybe hundreds of said ground stations stations all on its own and in the middle of all of this, its trying to supply a steady, usable internet connection. Not exactly easy when you have the data center volume equivalent of a flaming shoebox to work with

    • BlackZero Rs
      BlackZero Rs 5 tahun yang lalu +1

      Apace Sucks, because the satelites does not exist! They told to us that in space orbiting 37000 satelites but some places on the world even dont have GPS signal! How is that even posible! hahah! Google for it! Use your damn brain!

    • FALprofessional
      FALprofessional 5 tahun yang lalu

      Or in-formation space flight. That would be cool. Lots of research going into that for space junk retrieval and asteroid capturing.

    • DIYTyler
      DIYTyler 5 tahun yang lalu

      I don't know all the reasons but I have read that SpaceX's constellation is going to be MUCH lower than the GPS orbit so they will need more to cover the area. And smaller (easier to produce satellites) will result in less powerful signals=more and an explanation for the lower orbit. I wonder if the lower orbit will make the quality of internet better??

  • Jim Johnson
    Jim Johnson 2 tahun yang lalu

    I find the story with Real Time Kinematic GPS Funny. Military puts out two frequencies in their code, one low (less accurate) for civilians and one high frequency for military use. The civilian band is accurate to 30 feet or so, good for driving, but that is it. Civilians at Trimble figured out how to use the carrier wave, correct it with a nearby receiver at a known position and get sub-centimeter accuracy. Surveyors use this all the time.

  • John Ernst
    John Ernst 4 tahun yang lalu

    The real reason the accuracy was increased was that the inventor of the GPS system (Trimble) came to Australia to assist crop dusting pilots to develop a mechanism to instantly account for the built inaccuracy by integrating the GPS signal with two fixed ground location - they used the JJJ Radio station transmitters - by having two fixed location on the ground it was then just a matter of modifying to the GPS receiver to reconcile the differences in location through a mathematical calculation. This rendered the US scrambling useless and as a result, the GPS scrambling was stopped.

  • Nick routhier
    Nick routhier 8 bulan yang lalu

    amazing video as always, but RIP for the crew members of the Scandies Rose. The ship shown at 6:14 sunk on new years 2019 outside Kodiak Alaska losing 5 hands including her captain.

  • Wickie I
    Wickie I 4 tahun yang lalu

    Worth to mention is, that gps-devices will shut themselves, if they reach a certain height or velocity. The system then thinks, it is a missile and therefor shuts down. Tom Scott made a great video about it

  • LMF5000
    LMF5000 5 tahun yang lalu +200

    Strictly speaking there are workarounds these days if you don't have GPS, as there are several other position-determining systems that can be used. On the ground, phones can triangulate their position based on the signal strength of surrounding cellphone towers and their known, fixed locations. They can also use known WiFi networks in the area. I believe they actually use these to get your coarse position on startup to speed up GPS acquisition.
    On aircraft, there are even more backups. They have an inertial reference system (3 accelerometers and 3 gyros) that calculates position by integrating acceleration and angular velocity measurements over time, from the known starting position (departure airport). This is normally used in conjunction with the GPS as both systems complement each other, make up for one another's shortcomings. IRS tends to drift over time (because it can only calculate relative position) but is very accurate; GPS gives absolute position, but with a lower degree of accuracy than IRS. So you use GPS to correct out the drift of the IRS, and you use the IRS to interpolate your position to an accuracy beyond that which GPS is capable of alone. In case all the GPS systems on board the aircraft fail, the IRS functions as a fallback for navigation - in conjunction with old-school navigation devices like VORs, NDBs and the magnetic compass!

    • Marcus Langendorff
      Marcus Langendorff 3 bulan yang lalu

      @Mr. Grieves the inertial Reference System is no laughing matter though. It's one of the most important systems on board of commercial airplanes. Far more important than GPS. You can compare iRS with the human vestibular system. Without it, you're not even able to walk.

    • willgtl
      willgtl 3 tahun yang lalu

      meehhhe Of You, alternatives are good, but they're not as accurate as GPS. IMU has issues with drift over time, VPS works only in extremely select applications, VIO is based off IMU and still has problems with error accumulation. And finally, GLONASS is half as accurate as GPS at low attitudes (and more accurate at high altitudes).

    • meehhhe Of You
      meehhhe Of You 4 tahun yang lalu +1

      Even DJi drones have many backup systems if GPS takes a shit. Just to name a few backup methods that my little mavic air has: IMU, VPS, VIO, and Glonass (Russian satellites) so if US turns off GPS mid flight, it will still completely functional, and controllable

    • James Hall
      James Hall 4 tahun yang lalu +2

      Actually they really aren't, while the video states that your phone uses "GPS" most do not coordinate with satellites. they use this tower signal method. which is why when you are out of cell coverage your maps do not update. Most modern phones dont bother with deciphering GPS data, just cell tower location fixes.

    • Leonaяdo DiCapяio
      Leonaяdo DiCapяio 4 tahun yang lalu

      Wi-Fi spots and cells position data is collected with a help of GPS

  • Martin
    Martin 4 tahun yang lalu

    The advantage of Galileo is that one can actually make contracts with the EU-Agency responsible regarding the service level and availability, which is really awesome.

  • TheBlueMeanie
    TheBlueMeanie 4 tahun yang lalu

    Would have been neat to mention that non .mil GPS units shut themselves off at a certain speed or above a certain altitude so they can't be used in ICBMS

  • BlueDreamKush23
    BlueDreamKush23 Tahun Yang lalu +1

    I never knew that literally all countries relied on our satellites for GPS

  • Andrea Salomone
    Andrea Salomone Tahun Yang lalu

    There's a little error in the minute 3:29.
    The G constant is 6,67E-11 and not 6,67E11, you have probably forgot the "-"

  • Keith Weiss
    Keith Weiss 2 tahun yang lalu

    The first generation of public GPS had a built-in error so that they couldn’t be used as a weapon. But smart companies set up vans at known and accurate locations that radioed the error direction and amount to survey crews in the field. You see the error was the same for a certain amount of time. The survey crew received the error data and corrected their location. This caused the government to give up and simply send accurate locations on the GPS system. The military GPS also allowed cruise missiles to quit looking straight down and comparing the landscape to maps pre-loaded into the computer to go instead to high altitudes and then drop from the sky and accurately hit their targets.

  • Rogun987
    Rogun987 2 tahun yang lalu +2

    As a surveyor I use GPS (I think the GLONAS system) to measure sub centimeter measurements both vertically and horizontally. Its pretty amazing

    • nick leader
      nick leader Tahun Yang lalu

      From squad level radar to heat seekers that read differences in background radiation; Russian tech and the cognitive patterns it reflects are innovative and admirable. Doesn't suprise GLONAS is so precise.

  • Steve Dong
    Steve Dong 3 tahun yang lalu

    I think the most important reason is that by making it public-available can pull down the cost of all GPS devices. Because the suppliers no longer have to make them exclusively for the military. Nowadays a GPS chip can cost just a few dollars.

  • Jammin Wrenches
    Jammin Wrenches 3 tahun yang lalu

    Another interesting note, GPS Sattilites are also designed to detect the heat from a rocket launch like a nuclear missle anywhere in the world instantly and track it, imo this was the biggest driver for spending so much on the program. Also the us military uses them to communicate from anywhere to anywhere. They are too high to get detailed spy photos but can get less than optimal photos of ground troops movements.

  • Tim Campbell
    Tim Campbell 4 tahun yang lalu +5

    As I recall... part of the reason GPS “scrambling” (called “Selective Availability” or just “SA”) was disabled was because it didn’t matter anymore. Differential GPS had been invented for civilian use. The idea was simple... the SA system causes each satellite to lie about the time by a tiny fraction ... causing ground receivers to believe your position is shifted. When you do this to all the satellites it creates a circle of probability... an area where you may be, but not a point. Someone realized that if you have a fixed point on the ground and it’s position is known to a high degree of accuracy and THEN install a GPS receiver at that point, you can simply watch the difference between the GPS-computed position vs. the true position. You can then broadcast the difference to other “Differential GPS receivers” (DGPS) and they now know their position to a high-degree of accuracy even when Selective Availability is enabled. DGPS started showing up in civilian use and it obsoleted the ability to scramble positions based on SA. If ordinary civilians can do this, then hostile governments with more funding certainly can. Selective Availability was switched off ... presumably forever.

  • Eagle View HD
    Eagle View HD 2 tahun yang lalu

    In 1980 I was on a team that installed two LORAN-C transmitter sites in Korea for the US Air Force. This Navigation System preceded the GPS System. It is still used by the S. Korean’s because the N. Koreans are jamming the GPS Signals in the area. One of the sites is near Hampyeong, Korea at 35 2’ 23” N and 126 32’ 28 E., and the other near PoHang, Korea at 36 11’ 5 N and 129 20’ 25” E. You can see them on the Google Earth App.

  • Abhinav Tripathi
    Abhinav Tripathi 3 tahun yang lalu

    You don't really need a separate calculation for special relativistic effects for the satellite. If you do the calculations for just the general relativistic effects correctly it'll give you the complete answer.

  • Ishi is Busy
    Ishi is Busy 2 tahun yang lalu +472

    And yet Google Maps still can't figure out that I'm not in the ocean

    • Robert Crawshaw
      Robert Crawshaw Tahun Yang lalu

      My dad's charging app: Are you sure you want to select this charger? You are [Half the world] away.

    • Moneeb Khan
      Moneeb Khan Tahun Yang lalu

      Apple maps**

    • You know I’m right.
      You know I’m right. 2 tahun yang lalu +1

      Google’s never wrong, it knows all and see’s all. If google says you’re in the ocean 🌊 you better start swimming. Praise be the mighty google.

    • Noah Arnold
      Noah Arnold 2 tahun yang lalu

      you can calibrate your compass....

    • Flyboy
      Flyboy 2 tahun yang lalu

      @Trygve Evensen It also greatly depends on the strength of the mobile data signal the device is able to receive. There's no point in being able to accurately plot your position with GPS if the map data can't be displayed. It may as well just be a dot on a screen with no reference points. This is why GPS is still useless if you can't get a phone signal.

  • Samuel Zehdenick
    Samuel Zehdenick 2 tahun yang lalu

    The plane disaster could have been avoid by using Loran. That is good enough for overland flights, but not for landing approaches.

  • isrumm
    isrumm 2 tahun yang lalu

    at work in our sprayers that we use in the field they use GPS and for accurate steering they have to have anywhere from 11 to at least 14 satellites that they're locked onto. a few years ago we couldn't get any signal to run our machines and the companies had to get permission to use some Russian GPS satellites.

  • Syed Imran SHAH
    Syed Imran SHAH 3 tahun yang lalu

    This can be answered by taking internet as an example. Internet was used exclusively by US Military for many years before it was released for public. They used it for communications. But releasing internet for everybody allowed USA to spy on everybody too. It was a gift to the world but also allowed USA to monitor the whole world. GPS has also been allowed to the whole world but due to hidden security risks of tracking the movements or intentional shut down, Russia has built its own system like the Europe, China etc. This is the official version of the story. In reality, the confrontation or mistrust among the powers is not at the level to cause them to invest billions in own satellite navigation systems. All countries that make and export aviation-related products operate satellite systems. Those without satellite network were forced to stop the export of aviation products like the South Africa or Brazil etc. The reason for allowing GPS free of charge is that it is not free of charge. The receivers for GPS cant be made by everybody, it must be through licence. Edit : No revision is needed for earlier reply but some comments can be added to further clarify the situation. It would seem at first glance that USA has given a sensitive navigation technology free of cost to the world, which can be used militarily (against USA or its allies). There is civilian GPS and military GPS. Civilian GPS lacks accuracy of the military version. Allowing a civilian use of GPS does not really endanger US interests and its lack of accuracy means its use for precision navigation is limited. Military GPS receivers with high accuracy are only issued to authorised and cleared users. Buying a Civilian GPS kit from market and using it in a military application would not yield the desired results, especially for a mobile application like a missile or precision munition.

  • Steven Taylor
    Steven Taylor 4 tahun yang lalu +1

    One of the best presented channels I've seen in all my years of watching IDclips. Must be said.

  • ABY ALEX
    ABY ALEX 4 tahun yang lalu

    You are a great person.thanks for your valuable information.actually I am a medical student....but I love engineering...

  • Calby Pflager
    Calby Pflager Tahun Yang lalu +3

    The effects of gravity influence time dilation more, so wouldn’t the satellite’s clock need to tick slower than at the surface of earth in order for them to be in sync?

    • EffectHunter
      EffectHunter 10 bulan yang lalu

      As an object experiments more gravity, time will pass slower, this effect also applies to fast moving objects, which is the case for gps satellites, so overall, time passes faster on earth than on those satellites, though, if they orbited at say, 100 times the speed, their clocks would definitely need to tick slower than on earth.

  • gk10002000
    gk10002000 4 tahun yang lalu +1

    They made it "Free" because 1: the civilian government told them to. 2: It is expensive to field thousands of military systems that required the option to use the previous degraded links. 3: The smart engineers out there had come up with cheap ways to give basically the same resolution and precision as the fancy links, so there was little bang for the buck to keep the classified high performance link.

  • fireflyfinesse
    fireflyfinesse 4 tahun yang lalu

    What a fantastic video! So informative and interesting.

  • Starwolf
    Starwolf 3 tahun yang lalu

    I was told a long time ago by an engineer that worked with GPS that the only reason why GOS is free is because no one knew how to charge people for it.
    And you know what... I believe that statement is accurate.

    • ted kaczynski
      ted kaczynski 3 tahun yang lalu

      i always figured it was free to thwart other countries from doing the same and to maintain a strategic monopoly. also, the more people over the world pinging GPS make it ever more accurate?

  • Bear up
    Bear up 3 tahun yang lalu +1

    Another reason the USA allowed use of the GPS was that countries like Australia and New Zealand were needed to operate the system ie Pine gap

  • Max P.
    Max P. 2 tahun yang lalu

    If you think about it it's not actually that complicated. The maths behind it is fairly straightforward. But getting it to work reliably and accurately is what really made this a challenge. Not everybody has 24 atomic clocks laying around.

  • bonob0123
    bonob0123 3 tahun yang lalu

    unless you're in a remote area, why not use radio signals from stationary ground based sources (cell/radio towers) to supplant/replace triangulation from satellite signals? especially in cities where urban canyons can have difficulty with GPS signal reception.

  • Liu Leo
    Liu Leo 4 tahun yang lalu

    So, conbining both the general and special relativities, the clock onboard a satellate is 38 microseconds quicker than the one on ground and just needs to adjusted 38 slower accordingly. But in the video the contrary is stated. Did I get it wrong?

  • Mitchell Maytorena
    Mitchell Maytorena 5 tahun yang lalu +14

    Your content is really high quality and very interesting. Thank you so much for making it!

  • Jim Vaughan
    Jim Vaughan 4 tahun yang lalu

    History of The GPS System. (1) Originally was for military use only. (2) The government considered licensing the system for a fee to private enterprise. (3) When the government learned Russia was building a less reliable, free to use system they were afraid the Russian free system would become the worldwide standard but the US wanted their system to become the worldwide standard. I learned this from a family member who was on the GPS design team.

  • Mehrdad Nekouei
    Mehrdad Nekouei 2 tahun yang lalu

    A big missinformation here imo. The current GPS was initially designed on CDMA technique and GLONASS was based on FDMA. The americans had the technology to encrypt and later implement SA (selective availability) on the CA code (civilian GPS). The russians simply didn't have the encryption and DSP technology for that, and hence the GLONASS signal(s) were freely available to all people from the very beginning.
    There was no other way, other than letting GPS to be free to the public (at least the CA code) or otherwise the GLONASS could be accepted as the main navigation system. Nowadays, current constellation of both systems deliver arguably comparable accuracies for civil applications, and are used together in many GNSS systems, sometimes with addition of Galileo and Beidu.

  • Karthik Puvvula
    Karthik Puvvula 2 tahun yang lalu

    US made gps free to discourage other countries from making their own and they can control access to it for other countries and use it as leverage. India was denied access during a war with Pakistan.

  • Sacto1654
    Sacto1654 4 tahun yang lalu

    I also think that Korean Air Lines Flight 007 would not have been shot down had the plane been equipped with an OMEGA navigation receiver (which was starting to enter airliner use at the time), which would have given the plane's position within an accuracy of 2,200 meters. Even at that level of accuracy, the KAL flight crew would have immediately noticed they were potentially straying into Soviet air space well before overflying the Kamchatka Peninsula.

  • jm22186
    jm22186 4 tahun yang lalu

    Very well explained! Love the accident!

  • Jon Bartel
    Jon Bartel 2 tahun yang lalu

    Greetings ... did a double take as I watched this well done episode. Near the end you showed B roll of a combine, a fishing vessel and an airplane. The fishing vessel, Scandies Rose, sunk on New Years Eve 2020. Five men died. Thought you’d like to know. www.nationalfisherman.com/alaska/scandies-rose-sinking-marks-grim-start-to-2020

  • Joel Mason
    Joel Mason 3 tahun yang lalu

    The thing about relativity is that they have not ruled out the fact that the sat is in orbit neutralizng Earth's gravitational field. They've gotten probes of different kinds moving much faster than 17000 MPH toward outlying planets etc but I have never reads single shred of the time dilation being greater at the greater velocities. Why?

  • John Thane
    John Thane 2 tahun yang lalu

    I worked on the development of GPS (well, did research on the jamming of GPS). Originally, GPS transmitted a commercial less accurate signal and a more accurate military signal. Later, commercial systems were allowed to use the more accurate military signal. If needed, the military can "change" the GPS system to deny other users to access it. This is problematic as our "telephone network" now obtains its synchronization from GPS. I also heard that the military has launched a new GPS, but then the media went silent on it. We MUST NOT make so many of our weapons systems so reliant on GPS, as we see now in Syria where Russia is jamming GPS.

    • John Thane
      John Thane 2 tahun yang lalu

      @Philip Cooksey Seems like I watched some special on terrain mapping. Can't recall if they did it with satellites or drones.

    • Philip Cooksey
      Philip Cooksey 2 tahun yang lalu

      @John Thane I've heard of some companies doing that. It's just very intensive, requires more driving around than Google maps already does

    • John Thane
      John Thane 2 tahun yang lalu

      @Philip Cooksey Cool. Makes sense. Been retired a long time, so haven't been involved for many years. Seems like incorporating maps and terrain mapping would be even better.

    • Philip Cooksey
      Philip Cooksey 2 tahun yang lalu

      @John Thane on a high level, inertial systems measure acceleration and calculate their movement based on that. So it would work off the last valid gps location it received and go from there.

    • John Thane
      John Thane 2 tahun yang lalu

      @Philip Cooksey Interesting. How do the inertial systems work? Do they have internal maps installed so they can guide themselves using the maps?

  • Karlsson
    Karlsson 5 tahun yang lalu +1588

    I think this is the best kind of product placement, because it fits your channel, is interesting and you seem to really like it yourself

    • Xistence Studios
      Xistence Studios 4 tahun yang lalu

      Blox117 no one cares about you

    • Xistence Studios
      Xistence Studios 4 tahun yang lalu

      Karlsson the person who hooked the two parties together would be soo proud and may have gotten a raise after showing this comment to his boss and that hundereds of people agree as well

    • Machiel van der Schoot
      Machiel van der Schoot 5 tahun yang lalu

      I totally agree with you. Untill the end, I didn't realize it was an advertorial and suddenly he was talking about SimScale. In my head I was like: "What just happend and why is this add suddenly beyond my personal ad-firewall?" This video is also a nice example of planning and engineering

    • Well then.
      Well then. 5 tahun yang lalu +1

      It's actually good though. I've been looking for something exactly like this for myself, just personal ideas.... and well, something like this is what I needed. So it's relevant to me, not just as some background ad.

    • The Kaiser
      The Kaiser 5 tahun yang lalu +3

      Duane Hulm - If you don't know how to get from A to B without a gadget, you are not safe out on your own.

  • madwatcher1
    madwatcher1 3 tahun yang lalu

    the *commercial* aviation industry does not use it for navigation and collision avoidance, as far as I know (aero engineer here with not much experience in air traffic) navigation relies on radio beacons on the ground, and the Traffic Alert and Collision Avoidance System works via radio signals emitted and received by every plane. But, there are plans indeed to integrate GNSS (GPS) into aviation navigation in the near future!

  • Abe Dillon
    Abe Dillon 4 tahun yang lalu

    Back in 2009, I worked for a company that built geo-location systems for the Navy. They had a special box that they could use to unscramble GPS signals to achieve higher accuracy than consumer GPS systems are capable of, so I think the signal is still partially scrambled.

    • Thomas Kundera
      Thomas Kundera 4 tahun yang lalu

      It used to be, but afaik now it's no more.
      What you can get is orbit recomputations (a few days after) that gives you better data to replay the computation and get a delayed better location (useful to monitor volcano or tectonics, when one wants a few cm resolution but can wait a few days to get it).

  • Sohail Ahmed
    Sohail Ahmed 2 tahun yang lalu

    btw... time on your phone is not set by satellite or GPS .. it is set by service provider like AT&T or Verizon which sync thier time with Satellite
    Great Video .. Thanks for excellent info

  • Irkz
    Irkz 4 tahun yang lalu

    Ever since I watched Interstellar I've been total fasinated by general relativity. I cannot wrap my head around it at all.

  • WhaT Video
    WhaT Video 2 tahun yang lalu +3

    Thank you real Engineering. You have never failed to quench my curiosity

  • TheBitchiness
    TheBitchiness 3 tahun yang lalu +1

    You mentioned in this video that Einstein was responsible for the theory of relativity. While today this discovery is generally accepted as attributable to him, without the mathematical genius of Constantin Karatheodory it would not have been made possible. Also of interest, is the fact that within Aristotel's apanta it is mentioned that, and I give you a word for word translation, energy is mass multiplied by the square of the light. That is how it is worded, no mention of the word speed. Enough said.

    • Timeless
      Timeless 3 tahun yang lalu

      @Ritwik Reddy; Classic????........Tell Me What You Know???......I Have an Extra 10 Seconds....

    • Ritwik Reddy
      Ritwik Reddy 3 tahun yang lalu

      This video is made for Americans. They don't know anyone other than Einstein.
      Classic American ignorance.

  • Canary Biker
    Canary Biker 3 tahun yang lalu +1

    0:25 not sure if you're going to tell this in more detail later in the vid, but GPS is not paid by the US taxpayer .. every company seeling a GPS device is actually paying licence fees for using GPS. The consumer never recognized this, but it's how things work. Like if you buy a bluray player from samsung, sony does get licence money from each sale.

  • quickloris
    quickloris 2 tahun yang lalu

    Jeez, your videos are good. Really well produced throughout.

  • David Lloyd-Jones
    David Lloyd-Jones 4 tahun yang lalu

    Love that guy at the beginning who wants his telephone to talk to GPS -- so he holds it up in the air, to be closer t the satellite!

  • Conner Harkness
    Conner Harkness 4 tahun yang lalu

    I'm not an expert in how GPS systems work, but I don't think it's even possible for anyone to control whether or not GPS can be a paid service. To my best understanding, all a satellite does is broadcast some kind of identifier that GPS-equipped devices can use to approximate location based on the differences in time between the acquired signals and their periodic beacons. I'm sure it's a little more sophisticated than that, but attempting to charge someone for GPS would be like trying to charge someone to see a lighthouse.

  • hbarudi
    hbarudi 4 tahun yang lalu

    Interesting story about a technology we take for granted today.

  • Fri Tanke
    Fri Tanke 4 tahun yang lalu

    The GPS signal was so easy to decode that there was no reason to keep it "a secret" when the cat was out of the bag.