ฝัง
- เผยแพร่เมื่อ 1 มิ.ย. 2024
- GPS (global positioning system) plays a very important role in all of our lives. From allowing you to see where you are on the planet, to helping you get to destinations quickly, GPS has evolved the way in which we live our lives.
Find out how GPS works, some of the roles things such as our own atmosphere has in reducing the accuracy of GPS and also how general relativity effects GPS accuracy too.
Sources:
Basics of the GPS technique: Observation Equations by Geoffrey Blewitt
www.nbmg.unr.edu/staff/pdfs/Bl...
The influence of the ionosphere on GPS operations by Mihail Codrescu
ftp://ftp.ngdc.noaa.gov/STP/GPS_GNSS/Mihail's.pdf
GPS Frequently Asked Questions (FAQ) by USCG Navigation Center
www.navcen.uscg.gov/?pageName=...
GPS.gov: Space Segment
www.gps.gov/systems/gps/space/
GPS: Global Positioning System | Niels Bohr Institute - University of Copenhagen
www.nbi.ku.dk/english/www/spin...
GPS and Galileo Satellite Coordinates Computation
www.navipedia.net/index.php/GP...
Understanding the Global Positioning System (GPS) by Diana Cooksey
www.montana.edu/gps/understd.html
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As opposed to other videos, this one explains everything I needed to know on the topic, in particular “how does it detect the position if my phone doesn’t send the signal”. Also, I loved the drawings that explain why we need 4 satellites (I thought 3 is enough, but with 3 you have 2 possible locations) thank you!
Yup. I've searched on google prior on how GPS works but this is the first time I've come across someone showing real-world figures in the computations.
Three satellites are to determine your position, the fourth one is to mitigate for the time offset as show in this video 4:35
th-cam.com/video/8eTlI19_57g/w-d-xo.html
Satellite 1 is drawn too large, I think only 3 is needed but he said the fourth is to correct for time dilation or something
Hey guys! Has been a while. Here's a new video looking at how GPS works. I'll also be putting a new video up hopefully in the next 48 hours or so, so look out for that!
If you have found this video useful and want to support the channel, we now (as of Jan 2022) have a Buy Me A Coffee Page! www.buymeacoffee.com/scibright
neat!
Whats the next video about?
It was going to be Clinton v Trump but I have uni exams so haven't had time. I'm hoping to put up a new video next week though :)
Was searching on gps and found this video, channel seems very good. Keep it up
You've forgotten to include the French and Japanese systems. Your phone in the video includes QZSS(the Japanese system).
I have to say that out of all the videos I watched about GPS this one was by far the best and the most informative. Great job and thank you, you saved my essay!
Thank you very much! :-)
i would second that.
how when satellites don't exist? this video is a big lie.
@@pedrojello8983 ah yes, of course
@@pedrojello8983 Ahh yes, then I wonder what GPS is controlled by.
This is by far the most accurate short format explanation I have seen on the subject.
You deserve MUCH MUCH more subscribers! Really well explained quality video, keep up the good work
perfect explanation. thanks man.
Thanks! :-)
sciBRIGHT one question is space a vacuum
This was a really useful video. I've actually talked to friends before about GPS's and no one seems to really understand why they work, so this really helped to clear it up!
Great overview, and nicely presented. Thanks for making this video!
Hi, im actually an IB student curretly doing one of my research papers on the use of mathematics and physics in navigation . Though I don't actually take physics so i am a little bit confused . Your explanation is very clear , it is just that i don't really know where the numbers in the relativity and the general relativity equations came from :( if you actually do see this by some miracle , please help 😭
I think this is the best video on GPS! Short but extremely informative. Trilateration.
Nice n' concise vid......excellent!
this is a masterwork of art ._ .
Awesome animation/drawings!
Very helpful... Thanks a lot
Very well done.
You explain it so simply. Although you show the long mathematical equations it is easy to understand that we don't need to understand them fully, just grasp the theory behind it.
Thank you! :-)
A Great video! Thanks man.
Fatih Çalış Thanks heaps!
googling for an explanatory video should lead you to this one first, not that terrible screaming wannabe-entertainer. thx fpr the solid info!
Thank you very much! :)
I saw this one first
Not really. There are a lot of misconceptions and false statements he made in this video, despite the very purpose of the video being to clear those up. Shouldn't blame him too much as most of the information on the internet is actually wrong and so were his sources I suppose. I see the comment is 5 months old but if you are still interested I could further elaborate on that.
p.s. even documentaries often give inaccurate and false information on this topic
sciBRIGHT
sciBRIGHT
Thanks for this great insight ! But this leaves me with two questions : 1. How do satellites know their exact position relative to earth and 2. How does your phone calculate the time it took for the signal to travel without knowing the current time with the precision of an atomic clock ?
I believe one of the satellites is used to compute the difference between the receiver's clock's time and satellite time.
1. How do satellites know their exact position relative to earth?
ans: these are geo stationary satellites and are ALWAYS at one particular point above the earth, 24/7/365.
@@roshanantony7467 They are tracked from Earth. They are not geostationary.
- Each sat has an identifier. The orbits are known on beforehand. As the sats tend to drift a little, location measurements are done on earth, send to the sats and they also send the deviation next to the time stamp. Your gps device has LUTs (+math) to know which sat is where at which moment.
- This is where the video simplifies a bit too much: you don't calculate the diff between current time and the time the message was sent. You know that all sats send the message at the very same atomic clock precision moment. You receive them however with some time delta. It is this time delta which is used in the equations (with also some correction for special and general relativity). Solving the equations gives you then x,y,z and t.
@@_clemens_ Thank you!
wow, some solid info here! S2
Exactly what I was looking for, thank you!
After having gone to Wikipedia and found a totally non-useful, non-user friendly explanation (as usual), I came here and the fog lifted. Thanks
No worries, thanks for watching!
very nicely explained, indeed.
Very well explained. You know what you are talking about. Well done mate.
Terrific educational stuff on GPS.. Thanks
Thank you so much! This was incredibly helpful :).
Awesome video-thank you!
Glad you liked it!
sciBRIGHT! Awesome video!
I'm searching videos about GPS at TH-cam and your`s is very good. Thanks!
There are 2 points that i'd like to comment:
1) When you said that sattelites' clock goes faster than clocks at the Earth, you wrote "slower". It got a little difficult to understand.
2) To calculate the distance we do d=v*t. But, if the sattelites are moving (since they're not geostationary), the speed of light should depend on the sattelite's velocity (classical mechanics). Therefore, when we use d=v*t regardless of sattelite's movement, we're already using Relativity :)
Thanks!
About comment #2) If we take satellite's speed into account using classical mechanics the error will be under 30 cm in 1ns interval. Then, to calculate distances, it's effect will be very small.
Therefore, Relativity will not be evident by distance measurements. It will appear only in time registry of satellites's clocks or other effects (interference, etc)
désolé pour l'anglais ...
Regardez ça et dites moi ce que vous en pensez ... Je suis sûr que vous trouverez une vidéo comme celle-ci dans votre langue!
Actuellement, 99,8% du trafic Internet intercontinental passe par 366 câbles sous-marins, plus d'un million de kilomètres de câbles à fibre optique parsèment le fond océanique. Une fois à la surface, ils sont attachés aux stations d'atterrissage.
Regardez la vidéo ORANGE / MARINE OFFICIAL LINK ici! www.universfreebox.com/article/37831/Le-saviez-vous-99-8-du-trafic-internet-intercontinental-transite-via-366-cables-sous-marins Les satellites n'existent pas!
This is a really good quality channel!
Excellent presentation. Thank you.
Thank you very much!
Brilliant video! This deserves instant subscribe!
Can the satellites that stay stationary be manipulated say to change time time on computers being used? Thanks for the equations don't know if it's correct but I appreciate the work done.
Mind. Blown.Literally.
great work man :-)
+Nedko Kostadinov Thank you very much 😊
AAh this helped so much thank yoU!
Thank you! Awesome work!
Excellent excellent excellent description of how GPS works. And you talked so fast that nobody got bored
Finally a decent explanation
make satellite faster to cancel out gravitational effect, or calculate the propagation delay cause by ionosphere and use it to make accurate time syncronization.
If I remember correctly the ionospheric error is calculated. The satellite's data is sent on the two different (now 3) frequencies at the same time. As the amount of refraction and diffraction by the ionosphere are both affected by the frequency, the amount can be calculated by comparing the 2/3 different signals.
from www.e-education.psu.edu/geog862/node/1715
Another consequence of the dispersive nature of the ionosphere is that the apparent time delay for a higher frequency carrier wave is less than it is for a lower frequency wave. That means that L1, 1575.42 MHz, is not affected as much as L2, 1227.60 MHz, and L2 is not affected as much as L5, 1176.45MHz
This fact provides one of the greatest advantages of a dual-frequency receiver over the single-frequency receivers. The separations between the L1 and L2 frequencies (347.82 MHz), the L1 and L5 frequencies (398.97 MHz) and even the L2 and L5 frequencies (51.15 MHz) are large enough to facilitate estimation of the ionospheric group delay. Therefore, by tracking all the carriers, a multiple-frequency receiver can model and remove, not all, but a significant portion of the ionospheric bias. There are now several possible combinations, L1/L2, L1/L5 and L2/L5. It is even possible to have a triple frequency combination to help ameliorate this bias.
@@mrifixplanes1813 "Are both effected" *x* --> "Are both _affected_ " ✓
You busted some GPS myths.
And thanks for the excellent technical explanation.
Thanks for watching!
That class was dope
Thank you . Your video helped me in understanding gps
Thanks you best explained
Awsome.... Speachless... Thanks for the explanation
Clever. Make a video I have to watch 8 times.
Audio sounds really good on this video, nice job scibright
Thanks! Exact same setup, just more post-recording editing
what is the app name that u were using in mobile , really AWESOME explanation
I'm watching this video to prepare for my finals and has helped me a lot!!
Did you pass?
Thanks a lot brother
Great ¡ Please show more videos like this. Greetings
Thank you very much! :-)
Thnx a lot i finally understood wht happens with GPS tomorrow inchallah i ll do my test exam in confort !!
Wish me luck 😉
Wonderfully Explained. Thank you so much.
I before E except after C, receiver. Come on guys! Great topic though, thanks.
Glad you noticed that too.
Hi , I am Currently making my project regarding DGPS , is the components of making GPS is the same components with the DGPS? how is this two differ in implementation? Thank you sir .
It works by skewing time from multiple antennae to targetted coordinates. Confused time reception
I want to know what's that augmented reality app scanning the sky at 4.33? Is it stellarium?
needs more views! great video, a shame this channel is so small!
Thank you very much!
Video is quite popular now
hi from Nigeria ! always wondered how GPS worked
good job man
Interesting fact? I interview intermittently throughout the year to keep relevant and Keep interview skills up to speed. I took an interview for a multimillion dollar intonational company that was looking for a global network lead specialising in managing transatlantic cabling projects ... one of my interview questions was: Do you think satellites exist? I said yes and the gentleman smiled/chuckled and said no, and continued my interview. At the end I went back to that same question and asked him to elaborate. He said if I honestly think satellites are transmitting data across the earth then I am not the right person for this job.
The One so have you found more info about this ?
GPS = LORAN
google it
How you make and edit your videos.
Can you please tell me ?
thanks a lot!
Googling for homework thanks man
Happy to help!
I think the speed difference between the speaking and the listening in this video, relativity applies as well :D
So precise and consice, wonderful!
Thank you!
so, according to this video, the time gap between a GPS receiver and the satellite clock is measured. But what if I change the time on my phone? Wouldn't that mess up with the all calculation? I do not see it happening...
Great question. I did some research found couple of neat sources. Turns out the 4th satellite's timestamp also helps calculate the phone's time error, along with pseudo random code. I didn't went through it thoroughly yet. Looks interesting, will read it tomorrow.
www.trimble.com/gps_tutorial/howgps-timing.aspx
th-cam.com/video/pQqU-PMfPt4/w-d-xo.html
grazie
Very good
Hi, what software do u use to make videos?
Awesome video and great explanation! although I mainly came to the comments to see if there were flat earthers saying satellites aren't real lmao
désolé pour l'anglais ...
Regardez ça et dites moi ce que vous en pensez ... Je suis sûr que vous trouverez une vidéo comme celle-ci dans votre langue!
Actuellement, 99,8% du trafic Internet intercontinental passe par 366 câbles sous-marins, plus d'un million de kilomètres de câbles à fibre optique parsèment le fond océanique. Une fois à la surface, ils sont attachés aux stations d'atterrissage.
Regardez la vidéo ORANGE / MARINE OFFICIAL LINK ici! www.universfreebox.com/article/37831/Le-saviez-vous-99-8-du-trafic-internet-intercontinental-transite-via-366-cables-sous-marins Les satellites n'existent pas!
Is there any difference between the GPS receiver in my phone and my standalone GPS receiver? Example, if I download maps to the North Pole on my phone for offline use, and I have my Android/Apple cellphone with me and it has a clear view of the sky, would it work the same as any standalone GPS device?
Thanks for answering my awesome, thought-provoking question!
That depends on class of the receiver in your phone, the difference is in locking process, in past phones had cheaper AGPS which could not lock satellite positions independsly without extra information from internet, even now phone software helps it self with internet data to speed you locking process which can take minutes without it. Phones also use different sources of location data starting with IP address geolocation (precision here depends on design of ISP network that you connected to and address methodology), phone base station triangulation, there also WiFi location databases which allows Wifi base triangulation, good example of that is first iPhone and various iPod touch models which didn't have GPS yet used wifi databases to track the location.
Awesome
Excellent
Thank you!
Wonder if between phones there's much of a difference in gps chips or if they all have the same GPS chips
I like this video!
Man you did it great! ❤
nice well done
So how many GPS's do you typically see? I know you said you need at least 4, but is there usually only four or five above you and if you stand behind say a large tree it won't work because you've blocked one?
Eight is usually the average from my own experiments. You can see at 1:05 that I'm receiving data from eight at that time.
Even better, go buy yourself a high power telescope and count how many you see....good luck with that.
I'm really confused as to relativity role in GPS technology.
Our handheld receivers certainly don't have an atomic clock to know precise time difference.
So after a bit of "research", I kind of convinced that the receiver actually uses time received by the fourth satellite to cancel out the time error given by our not-so-precise clock in our devices.
Now then it means that the satellites don't need to account for the time difference between time on the satellite and time on the earth, which translate to the relativistic effects cancels out too?
I'm confused.
If the system still uses our devices' clocks, then how are measurements still so accurate.
I don't think our devices communicate with Observatory's atomic clock via internet because GPS system still works without internet connection..
Please help.
Never mind, I found the answer here by mrspeedybob
www.physicsforums.com/threads/how-does-gps-receiver-calculate-time-delay.742318/
I don't know if that's really the case, but it's really reasonable.
He said that if the clock on our handheld device is perfectly synchronized with the satellites, we'd only need 3 satellites to pin point our position.
But since we don't have such receiver, we need the fourth satellite.
The fourth satellite's signal is first used to calculate distance to our devices by comparing the time difference in 4th sat's time and our device's clock.
As expected the result will disagree with the last 3 result.
Then the data is used to do the problem backwards and adjust the receiver's clock so that all of the results agree with each other.
And from that, now I can really see why relativistic effects do need to be taken into account since the GPS still uses the receiver's clock.
Check this to understand it does not eventually... www.alternativephysics.org/book/GPSmythology.htm
@@kovanovsky2233 that was very helpful thanks:)
@
That helped. Thanks
The clue is that measuring the time of a message happens indirect. You use the fact that all sats fire at exact the same moment with atomic clock precision. All sat messages will however reach you with some delta in between. This deltas will depend on your position. Because you use deltas, internal constant hw/sw delays which might be diffferent for different hw also don't matter, as long as they are constant for the specific device you are using.
great
Good collection of information. However...guys...you will never be smarter by watching youtube videos. You don't have the moment to the "why" of the first information until new information arrives that you need to follow..
Gotta laugh at the nutcases and trolls claiming that GPS doesn't use satellites. None of them would have the faintest clue how to determine how GPS works.
i have question please answer. im curious. why smartphone with gps module doesnt need big antena dish. why 1 fiber wire antena can do the job. thank you.
Ssst Ufo Is Flat: The size of antenna required (for any radio transmission) is determined by the wavelength / frequency used. Satellites use UHF (Ultra High Frequency) so only a very small antenna is needed.
A 38 microseconds delay means that the clock on board the satellite is slower or faster than the clock on earth?
All this "Science" then a random self-proclaimed scientist will say the Earth is FLAT.
I think that the Earth is flat in relation to the natural place where humans live and not in relation to satellites
What is the input,process,and output data of the the gps?
Very cool explanation. But a 15 meter error seems like a lot when you are driving in a strange area!
Immediate Reviews: Modern GPS units are accurate to about 5 or 6 feet (1 - 2 metres)......those used by surveyors and archaeologists are accurate to 1 cm (1/2 inch) but they are VERY expensive and large.
Ty Ya Love
You are genius!
Thanks for watching :)
How does your gps know it’s exact time so it can determine the time delay from the satellite? Thanks.
It doesn't have to know it perfectly, actual time is send via GPS satellite signal.
@@tgstudio85 I wish you would explain more fully.
What about the Sagnac effect?
hi, i just confused..
In open ocean did the GPS works without internet connection ?
Can an app for GPS works if i want to know the latitude and longitude in the ocean..
with my limited knowledge, what i know is an apps need internet, and how come an app works to locate the latitude and longitude through apps in open ocean?
No you don't need an internet connection to use GPS, but some GPS applications on your phone such as mapping services most likely need an internet connection to download and display where abouts you are on the map :-)
alright, get it =)
and one more, in open ocean, is there can be internet connection ?
If you use satellite internet connection there would be
0:24 - phone and GPS satelite DOES NOT talk to each other, satelite only sends signal, they don't recive any signal from our devices
The script/subtitles say that this is a common misconception, not how it works :)
the video indeed is very well explained....but the speed of explanation can be reduced...
thanks for how gps working
what is the app he was using at the end?
GPS Satellite Viewer: play.google.com/store/apps/details?id=com.stgrdev.gpssatellitesviewer
:)
thanx for the incredibly fast and good response.
No worries! 1:23am here, so I was just checking TH-cam before bed as I have a uni exam at 9:30am!
Hope you enjoyed the video and it helped explain how GPS's work :)
how to trace the km
How?? you find the the distance between you and the 3 or more satellites, that does not give your coordinates, latitude and longitude?
triangulation
How does receiver know when satellite signal is sent ?
this is my favorite fort nite. Video
1:31 "Reciever"🙄 Undermines his overall intelllect.
Knowing your position between 4 or even 24 satellites does not help placing you on a specific defined grid on earth.
You need a specific grid of coordinates to pinpoint your location on earth, which is only achieved by triangulating your signal between signal posts scattered all over the globe which define a predetermined grid. The WGS84 system uses a network of hundreds of signal posts which your signal is bounced to in order to locate your position on the grid, and GPS is based on this WSG84 grid. The exact specifics of the WGS84 grid is exclusively for the Department of Defense (DoD), as is the entire GPS system.
Those "signal posts" that make up the grid are also used to measure tectonic plate movement. So it's possible I guess that the prime meridian moves as those posts move due to tectonic movement.
You can have a shift through different geodetic datums also yeah. If you use Japanese ones for instance when calling artillery strikes, and the artillery uses the American WSG84, the strike will land quite a bit away from where you intended it to.
But WSG84 has been around since the 80's, and it hasn't been changed I think in its core. Longitude is just a definition though, it doesn't rely on physical observation like latitude when viewing the pole star. Can't remember by how far it has moved from Greenwich observatory, maybe 100 meters or so, not sure if tectonic plate movement can account for all that, but there's nothing stopping you from redefining zero meridian to right on top of Greenwich observatory again and call it the new updated geodetic datum of WSG84.