Trilateration only works on a surface and literally means three sides. GPS uses quadrilateration. It really isn't any more complicated. It's just more difficult to represent on a flat screen. Your time of flight instead of representing the circle is instead a shell, the surface of a sphere. When you have 2 distances then you have 2 spheres and where they intersect is a circle instead of 2 points. Your third distance shell cuts through that circle in 2 places. So now you need a fourth distance shell in order to know which of those two places is the correct one. If you do things like add additional distances, and look at Doppler effects then you can calculate additional information such as velocity and direction. If instead of distances you look at differences between a nearby known position and yours, then you can enhance the accuracy of the GPS by several orders of magnitude. This is initially how the military got their accurate GPS back before portable computers.
you all prolly dont give a damn but does anybody know a method to log back into an instagram account?? I somehow forgot the password. I appreciate any help you can offer me.
Thank you. Great Explanation. Until now, I thought there is two way signal transmission between GPS receiver and the Satellites. Now I now the tracking actually happens by one way transmission and that is amazing.
Yes, there is only one-way communication going on! I don't think having GPS transmitters that send data to satellites in our phones would help with the battery life.
A very nice graphic as shown from 2:10 onwards. The point not to be missed is that your point X could be anywhere within the reciever range of those three satelites, so therefore there are many other possible locations for you to be at. At each location when the three signals are received you will be at your own three circle cross point. Your circles will be a diferent sized circles to the one demonstrated here. So many users at slightly diferent locations all get an accurate fix. A very smart system. I loved your graphic explanation.
For those who are thinking this is a simple concept, don't forget there is Einstein's Theory of Relativity involved in calibration of the clocks in those Satellites.
I'm not a GPS engineer, so I don't really know that. But I expect them to use the same tech that NASA or SpaceX use for missions control. They could be using a bunch of ground-based transmitters with known locations on the Earth's surface, and calculate their positions around the Earth the same way, that GPS receivers do. That'd be funny, because that'd mean the GPS system is actually double-layered, using similar tech to locate the GPS satellites, and then locate GPS recievers. That's just a wild guess though.
In other words 4 satellites in a straight line would be somewhat of Marginal value and you need to have them aligned in a some what triangle composition in order for them to send a good position Is that correct? They are triangulated to each other in order to trilaterate to you and you are a part of that triangle
I had the misconception too, how are positions calculated... And asked a question on some of these websites, and learned much... The thing is the atom-based clock on every satellite, and if you have such a clock on the floor, too, you need less satellites (i think 3 will do) to create your position. Without such a device you will need more satellites, i thinks its four...
How does the receiver's clock know the start point of the timeline? Unless it's synchronised with the satellites' clocks, it can't know the travel time of the signal.
Yeah, he completely glossed over that point. What you do know however is that the signal from satellite A reached you a certain number of microseconds before the signal from satellite B. And since you know the speed of light you know that you are a certain number of miles closer to A than to B. So that narrows your location to a specific circle in 3D space. The delta between B and C is another circle and between A and C is the third and they should all intersect at one point.
Wouter G., that's right. It takes a little over 3 nanoseconds for the signal to travel 1 meter so I doubt any consumer level receiver would have that kind of timing accuracy (quartz has a frequency of only 32768 Hz). So you would need that 4th satellite to make the triangulation work.
TheWonkyAstronomer What's not discussed is the gps signal. The signal has time of transmission along with clock corrections. And phase inversions. And a unique code, the CA code, modulated on the carrier wave. Lots of data. The satellite clocks are monitored and corrections are part of the data stream. And known offsets are synchronization.
One question - how do you find animations like this? I have a video project due on GPS and would like to use something like these. Thank you! - A student who needs help
But how does the phone calculate how much time has elapsed since the satellite has sent its signal? The phone does not have a precise atomic clock so it would not know the exact time of receiving the signal.
I don't know for sure. Possibly by comparing times reported and delay between messages from various satellites and the position they report it can calculate relative distance to each one and converge into a single point. But that's just a loose theory.
Can you help me plz ? I am network student and i work on my project gradution I use 3 arduino to determine certain loction By using trilateration equation But the coordinates are not suitable for jbs I need an equation to convert it to jbs coordinates
Thank you for this well explaned video. I've just got one question: How can we manage to know the position of these satellites at all times? I know that the satellites used for GPS are geostationary ones, but how could we know their precise location?
GPS satellites aren't all the way out at GEO, they're actually in 12 hour orbits so they go around the earth twice a day. Orbits are extremely predictable. The net forces from the moon and the sun are the primary factors in calculating any perturbations. (But if you want to be precise, the other planets have a tiny effect.) Also, since the satellites are so far above the atmosphere, that particular drag effect is negligible too. That's not true for LEO which makes the new constellations like Starlink very interesting to keep calculating their orbits. It's a solvable problem, but has a lot more factors to keep track.
By finding the intersection of the surfaces of the spheres defined by this information. I've shown how this works on 2D - 3D gets a bit more complex - you have sphere's instead of circles, and you need 4 satellites instead of 3, but the idea of finding intersections is still used.
I rewatched this and thought about it in 3d. With 2 transmitters, the possible locations are lying on an intersection of two spheres, which is a circle. with 3 transmitters this narrows down to the intersection of a sphere and a circle, which is two points. Finally, a 4th transmitter is needed to decide which one of these two points is the right one.
You would only need 3 satellites because after 3 you'll narrow it down to 2 points, one will be on the surface of the earth and the other will be in space. A fourth satellite is needed but for clock synchronization.
You would still need the 4th one to identify any error due to atmospheric effects or any lag that may occur. GPS or GNSS usually use at least 4 satellites.
Rohit Patil Apart from similar systems to GPS, you could use an offline WiFi network map to determine location based on local WiFi network names and other data. You could use the mobile baseband transmitters in the same way too I guess.
That's a very good and complete explanation. Aren't you a musician? I have a bachelors in geoespatial engineering, and although that isn't necessarily the most advanced topic, you explained a part that generally people skip over
Thanks! I'm an artist, musician and an educator :) After making this I've been making music production tutorials with libre software and Linux in mind.
@@unfa00 I've seen some of your tutorials, yeah! Actually the fact that you answered my comment is quite handy... I have a small and short question: Would it be feasible to record a rock/grunge (drums, guitars, bass and vocals) with a 'libre' DAW?
@@afonsorafael2728 Absolutely! You could use Ardour, sequence some MIDI drums in there if you don't have a dumkit (the included AVL Drumkit plug-ins sound great and give you multiple outputs you can mix with a lot of flexibility).
But there IS an angular component to the calculation. The satellites positions must be expressed with intrinsic angular information or the trilateration cannot work. This is just another way of looking at triangulation.
I believe that in a three dimensional world, the distance to each satellite will result in a sphere (not a circle). With two satellites we have a circle (the intersection of the two spheres). The third satellite will reduce the circle to two points (one on Earth´s surface, one in space that is eliminated).
Yes, that's why to get a GPS lock a receiver needs to get data from 4 different satellites. My simplified 2D model was to make the it easier to understand.
Except... Is this explanation correct? It is reasonable to assume the clocks on the transmitters are (mostly) synchronized. But the receiver's clock won't be precisely synchronized with the satellites (or will it?), so it will be at an unknown offset from the the satellite's clocks. Which means you *don't* know exactly how long it took for a signal to reach you from a satellite -- you just know the difference in times of arrival for the various satellite's signals. If you take any pair of satellites and you know the difference in time between their signal's arrival, that defines a hyperbola (not a circle!). So to solve for position with three satellites, you need to intersect the three hyperbolas formed by each pair of satellites. So now I'm left wondering what the hole in my logic is...
And they can do that while travelling 66000miles ph to keep with the earth and magically escaping the gravity of earth and the moon. While the moon affecting the earths tides. Also, 3 satellites determines your position and you loose signal in rural areas. None of the satellite dishes directly pointing upwards either...
Now I'm just trying to wrap my head around the fact that satellites literally have their clocks set at different time scales to account for relativity otherwise this whole system wouldn't work... because time runs at a different speed the further away from earth's gravity you are... I'm going to need a fucking drink...
Did you get to the part where I say I am making the demonstration flat for simplicity, but in reality we've got one extra dimension (and one extra satellite) to work with?
Except 3 satellites give you 6 transmitters and receivers. Each satellite has 2 transmitters. Actually 3 but one is command and control. It sends 2 markers the difference is the distance to the satellite. This guy is full of crap!
Trilateration only works on a surface and literally means three sides. GPS uses quadrilateration. It really isn't any more complicated. It's just more difficult to represent on a flat screen.
Your time of flight instead of representing the circle is instead a shell, the surface of a sphere. When you have 2 distances then you have 2 spheres and where they intersect is a circle instead of 2 points. Your third distance shell cuts through that circle in 2 places. So now you need a fourth distance shell in order to know which of those two places is the correct one.
If you do things like add additional distances, and look at Doppler effects then you can calculate additional information such as velocity and direction. If instead of distances you look at differences between a nearby known position and yours, then you can enhance the accuracy of the GPS by several orders of magnitude. This is initially how the military got their accurate GPS back before portable computers.
A chineese company making GPS products e-mailed me asking for business cooperation becasue of this video.
I'm a musician.
What do I do?
LOL
Tobiasz Karoń
realize satellites do not exist .
the earth is flat and GPS works with ground based towers.
Tobiasz Karoń
I'm a musician as well.
great videos btw.
Sample GPS data and make music with it!
@@jimbo8150 you are a moron who failed physics
Thank you. A well explained video with great graphics. I will use with my year 5 and 6 students to extend their thinking about mapping.
you all prolly dont give a damn but does anybody know a method to log back into an instagram account??
I somehow forgot the password. I appreciate any help you can offer me.
Thank you. Great Explanation. Until now, I thought there is two way signal transmission between GPS receiver and the Satellites. Now I now the tracking actually happens by one way transmission and that is amazing.
Yes, there is only one-way communication going on!
I don't think having GPS transmitters that send data to satellites in our phones would help with the battery life.
After watching many videos, this is the only one I could understand. Thank you!
This is great! Using ground based positioning on a flat plane allows this to work as well and makes even more sense.
Exactly
Thank you for a great simple explanation, for great visuals, and for sharing the animation software you used. Stellar.
Thanks!
Love your use of timeline to explain the distances.
thanks for helping!!! people like you make life easy .....thanks a lot and keep helping
Nice video..thank you for explaining the concept of GPS so easily
best video on youtube about gps
A very nice graphic as shown from 2:10 onwards. The point not to be missed is that your point X could be anywhere within the reciever range of those three satelites, so therefore there are many other possible locations for you to be at. At each location when the three signals are received you will be at your own three circle cross point. Your circles will be a diferent sized circles to the one demonstrated here. So many users at slightly diferent locations all get an accurate fix. A very smart system. I loved your graphic explanation.
Wonderful explanation...the complexity of this technology is so well turned into simplicity...kudos..
We the students expect such type of explanation, Good work!
Well explained with fantastic graphics. Great video!
For those who are thinking this is a simple concept, don't forget there is Einstein's Theory of Relativity involved in calibration of the clocks in those Satellites.
great video. very helpful in clarifying the concept of how GPS works. Thank you
Best video about gps on youtube. Thank you.
Damn that was really nicely put, simple principle but quite effective, who would have thought ?
Thank you, in case we are using beacons RSSI value for distance, what would be the algorithm to calculate the position?
BRAVO!! Excellent!
thank you so much .... for explaining with great graphics.
Explained with ease. Kudos to Unfa 👍🏻
very well explained! nice animations! love it
thx very useful, clear, basic answer to all of my questionsthx again!
This video is exactly what I was looking for to share with my physics students. Thank you.
Glad I could help!
great video, but i would like to know if this concept is any different than with the european system galileo. Does anyone know?
great explanation! make complex things much easier to understand
Thanks a lot, very clear as it can be for me :-)
The best ilustraciones i seen
Do you know of any good offline GPS and mapping software for Linux
Oh my God, Thank you, I understood it perfectly
good one. keep up the good work.
GOOD DESCRIPTION.Thank you SIR
Hi, how do the satellites know their accurate position? position in which reference frame are we talking about?
I'm not a GPS engineer, so I don't really know that.
But I expect them to use the same tech that NASA or SpaceX use for missions control.
They could be using a bunch of ground-based transmitters with known locations on the Earth's surface, and calculate their positions around the Earth the same way, that GPS receivers do.
That'd be funny, because that'd mean the GPS system is actually double-layered, using similar tech to locate the GPS satellites, and then locate GPS recievers.
That's just a wild guess though.
@@unfa00 Thx for the answer, I took it the lazy way betting on the fact you could provide an answer without have to search :P, interesting guess Thx.
This video is very helpful in understanding gps
Good explanation!!! Helps quite a bit using 2D visualization instead of 3D.
it's very useful...thank you!!
In other words 4 satellites in a straight line would be somewhat of Marginal value and you need to have them aligned in a some what triangle composition in order for them to send a good position Is that correct? They are triangulated to each other in order to trilaterate to you and you are a part of that triangle
Best video about gps
Great job...
Thanks man ;)
Lol 😂 duuude 🤣I kept waiting for the punchline or the sarcasm
Why so? :) This video is purely educational, have you expected some kind of joke?
I had the misconception too, how are positions calculated... And asked a question on some of these websites, and learned much...
The thing is the atom-based clock on every satellite, and if you have such a clock on the floor, too, you need less satellites (i think 3 will do) to create your position. Without such a device you will need more satellites, i thinks its four...
best video that can help you
thank you sir for giving valuable information
you should do more infographics, you have a knack for it
How does the receiver's clock know the start point of the timeline? Unless it's synchronised with the satellites' clocks, it can't know the travel time of the signal.
Yeah, he completely glossed over that point. What you do know however is that the signal from satellite A reached you a certain number of microseconds before the signal from satellite B. And since you know the speed of light you know that you are a certain number of miles closer to A than to B. So that narrows your location to a specific circle in 3D space. The delta between B and C is another circle and between A and C is the third and they should all intersect at one point.
Kent Briggs but the quartz clock isnt accurate enough for that right?
Wouter G., that's right. It takes a little over 3 nanoseconds for the signal to travel 1 meter so I doubt any consumer level receiver would have that kind of timing accuracy (quartz has a frequency of only 32768 Hz). So you would need that 4th satellite to make the triangulation work.
GPS is not based on TDOA geometry. LORAN-C, however, does work this way.
TheWonkyAstronomer
What's not discussed is the gps signal. The signal has time of transmission along with clock corrections. And phase inversions. And a unique code, the CA code, modulated on the carrier wave. Lots of data.
The satellite clocks are monitored and corrections are part of the data stream. And known offsets are synchronization.
Thank you, it was quite helpful😄
Nicely done.
useful information, even the track is very suit for educational purpose.
Thanks! I composed the music myself :)
One question - how do you find animations like this? I have a video project due on GPS and would like to use something like these. Thank you!
- A student who needs help
I made the animation here myself using Blender - an amazing free and open source 3D creation program.
thanks this was godly
best explanation ever ...... thnx
Very well explained....!!
But how does the phone calculate how much time has elapsed since the satellite has sent its signal? The phone does not have a precise atomic clock so it would not know the exact time of receiving the signal.
I don't know for sure. Possibly by comparing times reported and delay between messages from various satellites and the position they report it can calculate relative distance to each one and converge into a single point. But that's just a loose theory.
Damn good explanation!
Great video. Would you mind if I use this video as supplement material to my class?
My pleasure! No problem :)
Can you help me plz ? I am network student and i work on my project gradution
I use 3 arduino to determine certain loction
By using trilateration equation
But the coordinates are not suitable for jbs
I need an equation to convert it to jbs coordinates
Hey, sorry but I have no idea how you'd actually implement this. My development skills are in the video game domain, not hardware.
Random Unfa knowledge drops 👍😎
excellent
Thank you for this well explaned video. I've just got one question: How can we manage to know the position of these satellites at all times? I know that the satellites used for GPS are geostationary ones, but how could we know their precise location?
I have no idea :)
GPS satellites aren't all the way out at GEO, they're actually in 12 hour orbits so they go around the earth twice a day. Orbits are extremely predictable. The net forces from the moon and the sun are the primary factors in calculating any perturbations. (But if you want to be precise, the other planets have a tiny effect.) Also, since the satellites are so far above the atmosphere, that particular drag effect is negligible too. That's not true for LEO which makes the new constellations like Starlink very interesting to keep calculating their orbits. It's a solvable problem, but has a lot more factors to keep track.
good explanation!!
Very nice
Good stuff
I love the fact that you used blender to make this!
nice work
Awesome........
Excellent
But how we determine own location based on satellites' location and distance from them?
By finding the intersection of the surfaces of the spheres defined by this information. I've shown how this works on 2D - 3D gets a bit more complex - you have sphere's instead of circles, and you need 4 satellites instead of 3, but the idea of finding intersections is still used.
Thank you
Please do another video explaining how it works in 3 dimensions. This is awesome stuff.
Digital Insan1ty
Same thing, just with spheres instead of circles.
I rewatched this and thought about it in 3d. With 2 transmitters, the possible locations are lying on an intersection of two spheres, which is a circle. with 3 transmitters this narrows down to the intersection of a sphere and a circle, which is two points. Finally, a 4th transmitter is needed to decide which one of these two points is the right one.
+Digital Insan1ty you're right - in 3D you need 4 satellites to pinpoint location of a GPS reciever.
You would only need 3 satellites because after 3 you'll narrow it down to 2 points, one will be on the surface of the earth and the other will be in space. A fourth satellite is needed but for clock synchronization.
You would still need the 4th one to identify any error due to atmospheric effects or any lag that may occur. GPS or GNSS usually use at least 4 satellites.
Thanks!
Is it possible to get current location without using GPS and internet
Rohit Patil Apart from similar systems to GPS, you could use an offline WiFi network map to determine location based on local WiFi network names and other data. You could use the mobile baseband transmitters in the same way too I guess.
Thank you...
I'll get more info on It
Is this required wifi access point?
Rohit Patil GPS doesn't rely on Wi-Fi. However there are location services that do use a global Wi-Fi map.
why does the circles does not have equal radius?
okay i get it now after watching the video 3 times. the radius of the circle depends on the tower distance and the gps receiver
@@samharmonies Yes, the circle is to visualise the distance, and all possible locations based on that piece of information.
That's a very good and complete explanation.
Aren't you a musician?
I have a bachelors in geoespatial engineering, and although that isn't necessarily the most advanced topic,
you explained a part that generally people skip over
Thanks! I'm an artist, musician and an educator :) After making this I've been making music production tutorials with libre software and Linux in mind.
@@unfa00 I've seen some of your tutorials, yeah! Actually the fact that you answered my comment is quite handy...
I have a small and short question:
Would it be feasible to record a rock/grunge (drums, guitars, bass and vocals) with a 'libre' DAW?
@@afonsorafael2728 Absolutely! You could use Ardour, sequence some MIDI drums in there if you don't have a dumkit (the included AVL Drumkit plug-ins sound great and give you multiple outputs you can mix with a lot of flexibility).
DrumGizmo also has amazing free drumkits but you'd be required to give credit to the authors in your music release.
There isn't a little person in there reading from a map.? so i can stop feeding him.?
Yes, stop feeding it. Unless you want your GPS gear to smell very bad very soon.
nice
thanks
2:03 and it really is
*m8*
elegant
But there IS an angular component to the calculation.
The satellites positions must be expressed with intrinsic angular information or the trilateration cannot work.
This is just another way of looking at triangulation.
pretty good
I believe that in a three dimensional world, the distance to each satellite will result in a sphere (not a circle). With two satellites we have a circle (the intersection of the two spheres). The third satellite will reduce the circle to two points (one on Earth´s surface, one in space that is eliminated).
Yes, that's why to get a GPS lock a receiver needs to get data from 4 different satellites.
My simplified 2D model was to make the it easier to understand.
classic...!!!
Except... Is this explanation correct?
It is reasonable to assume the clocks on the transmitters are (mostly) synchronized. But the receiver's clock won't be precisely synchronized with the satellites (or will it?), so it will be at an unknown offset from the the satellite's clocks.
Which means you *don't* know exactly how long it took for a signal to reach you from a satellite -- you just know the difference in times of arrival for the various satellite's signals.
If you take any pair of satellites and you know the difference in time between their signal's arrival, that defines a hyperbola (not a circle!). So to solve for position with three satellites, you need to intersect the three hyperbolas formed by each pair of satellites.
So now I'm left wondering what the hole in my logic is...
pls correct the speed of light C=300 km/s and nor C=300 000 km/s in the video. nice presentation
Oh dear. Sorry for that mistake.I must have been changing it from km/s to m/s or vice versa and somehow used wrong unit.
Uuuu... Widzę, że kroi się przymiarka do jakiejś grubszej produkcji... ;)
Masz nosa! ;)
But how each satellite knows their own locations?
I don't know, I'm not a space engineer :)
Can someone please help me in tracing location with help of phone number
AFAIK only Police is allowed to get that information from the GSM service providers.
@@unfa00 but I need to find someone's phone as soon as possible
blender
Blender for life! Or even for living. I actually use Blender all the time in my current daily work :)
khuda karnay yaari
Ground Positioning System.
Oh I See you Wikipedia says it's "global", not "ground": en.wikipedia.org/wiki/Global_Positioning_System
And they can do that while travelling 66000miles ph to keep with the earth and magically escaping the gravity of earth and the moon. While the moon affecting the earths tides. Also, 3 satellites determines your position and you loose signal in rural areas. None of the satellite dishes directly pointing upwards either...
So much ignorance and flat out stupidity in your comment is commendable, even by flerf standards.
Now I'm just trying to wrap my head around the fact that satellites literally have their clocks set at different time scales to account for relativity otherwise this whole system wouldn't work... because time runs at a different speed the further away from earth's gravity you are...
I'm going to need a fucking drink...
i am now convinced that the earth is indeed flat
@@unfa00 the part with the circle
Did you get to the part where I say I am making the demonstration flat for simplicity, but in reality we've got one extra dimension (and one extra satellite) to work with?
@@unfa00 th-cam.com/video/S3n8aY1GK8Y/w-d-xo.html
@@hezuikn You're right.
Don't change your mind, stay ignorant.
It's your choice.
Nobody cares cuz you're irrelevant
That’s still triangulation lol!
Except 3 satellites give you 6 transmitters and receivers. Each satellite has 2 transmitters. Actually 3 but one is command and control.
It sends 2 markers the difference is the distance to the satellite. This guy is full of crap!
O hai.