Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: chris on 25/03/2011 08:04:31

Title: Would my GPS device work on the moon?
Post by: chris on 25/03/2011 08:04:31
Ignoring software issues related to the fact that the longitude and latitude wouldn't fit, if a GPS receiver was taken to the moon, would it still work to pinpoint my position, albeit on the lunar surface?
Title: Would my GPS device work on the moon?
Post by: syhprum on 25/03/2011 09:07:07
The GPS system operates by means of 50 or so satellites in orbit around the Earth they would not be of any use on the Moon even if reception of their signals was possible.
A similar system (at vast expense) could be set up on the moon but is unlikely to be set up there until a war starts up there.
Title: Would my GPS device work on the moon?
Post by: imatfaal on 25/03/2011 15:14:10
Syhprum - you are quite correct about the satellites.  But how do they broadcast their signal?  It would not take much leakage for the signals to be receivable on the moon.  And three or more signals and a decent software algorithm and you have an exact position. 

So - If you were on the dark side of the moon (when you are part of the great gig in the sky) I think you would be unlucky - but on the side that faces the earth I reckon a decent receiver could pick up enough signals to make a fairly reasonable approximation.
Title: Would my GPS device work on the moon?
Post by: syhprum on 25/03/2011 15:28:21
To obtain any useful information about your position on the Earth you have to measure the time delay of the signal from three or more satellites all of which carry very accurate atomic clocks.
Even if you could receive their transmissions on the moon there is no way that this information could be used to work out your postion on the Moon to do this a local system of satellites orbiting the Moon would be required.





http://en.wikipedia.org/wiki/Global_navigation_satellite_system
Title: Would my GPS device work on the moon?
Post by: imatfaal on 25/03/2011 16:16:09
Syhprum - not so.  You have a computer model of orbits around the earth - each GPS signal contains an identifier and a time signal.  Your computer on the moon takes each signal calculate the expected position of the transponder and the relative time; you then have three points in three dimensional space with a time signal from each.  The time delays from the three fixed points in space allow you to work out an exact position. 

I happen to correspond with someone who works intimately with GPS - I will seek his much more knowledgable opinion
Title: Would my GPS device work on the moon?
Post by: syhprum on 25/03/2011 16:40:37
You would need large dish type antennae to receive the weak signals, considerable computing power to allow for the large and variable Earth to Moon distance and the ionospheric delay you are certainly not going to get anywhere with the small devices that we find so useful. 
Title: Would my GPS device work on the moon?
Post by: SeanB on 25/03/2011 19:06:48
GPS works up to the altitude of the satellites that broadcast the signal ( and then a little further with reduced accuracy from the sidelobes of the satellites in view but on the other side of the earth), but most of the transmitted signal is sent down with a very directional antenna to improve the signal on the ground as the satellites have a very limited power source. You can use a GPS on the ISS, but it will be confused very quickly as you are moving too fast, and will be outside the limits hard programmed into the cheap chipsets. If you use a receiver designed for supersonic aircraft you will get a lock, and a velocity of 12km per second as well. On the earth facing side of the moon you would get a GPS signal using a big enough antenna and a lot of low noise amplification before the decoding, but the signal would not be much use as the reference is not a fixed point on the lunar surface, but a point on the earth, and you would have very little usable info as to the relation between the earth and moon rotating, though you can use it to get a good and quite accurate clock.
Title: Would my GPS device work on the moon?
Post by: syhprum on 25/03/2011 19:29:04
Thanks, it is a little embarrassing to be told by correspondents that they will talk to someone who understands the subject
Title: Would my GPS device work on the moon?
Post by: chris on 26/03/2011 14:37:39
Interesting debate; thank you everyone; I'm also relieved that I gave the same sorts of answers to the question.

Chris
Title: Would my GPS device work on the moon?
Post by: Madidus_Scientia on 27/03/2011 07:41:18
So - If you were on the dark side of the moon (when you are part of the great gig in the sky) I think you would be unlucky - but on the side that faces the earth I reckon a decent receiver could pick up enough signals to make a fairly reasonable approximation.

Why wouldn't it work on the dark side of the moon facing earth?
Title: Would my GPS device work on the moon?
Post by: Geezer on 27/03/2011 08:15:33
Practically, as Syhprum points out, not a snowball's chance in hell. The signals would be far too weak.

Theoretically, maybe. Assuming the guys who wrote the software contemplated the possibility that the GPS receiver could be at a great distance from Earths's surface so that the software does not go mental (which I'm willing to bet will happen), it might actually work, but even if the signals could be received, the accuracy would be lousy.

Navigation systems rely on triangulation, and GPS is no different. The most accurate triangulation occurs when the triangle is close to an equilateral triangle. The less equilateral the triangle, the less accurate the position.

If you were on the Moon, and your GPS system could actually receive the signals from terrestrial GPS satellites, the triangulation would be so far from equilateral that the resolution of your position would be limited to tens of kilometers. In other words, it would be useless.

Title: Would my GPS device work on the moon?
Post by: syhprum on 27/03/2011 09:04:29
Assuming you could receive the GPS signal that would translate to a position on the Earth at that moment to convert that to a position on the moon would be a very complex computation problem allowing for the time delay between the Earth and the Moon, the rotation rate of the Moon, the eccentricity of its orbit and the deviation of its rotational plane from the elliptic.
Chris was wise to ignor software issues.
Title: Would my GPS device work on the moon?
Post by: Geezer on 27/03/2011 09:24:22
Not really. Assuming the system made no assumptions about location, it would simply try to resolve a three dimensional position based on the signals it received. As the distance and angles from those signals increase or decrease, the less accurate the resolution becomes.
Title: Would my GPS device work on the moon?
Post by: syhprum on 27/03/2011 09:38:02
To obtain a position you make a comparison between the time signals transmitted by the satellites and the time you actually receive them, would not a problem arise because the time signals would be Earth time not Moon time.
What the signals you receive would tell you would be where you are relative to the surface of the Earth as though you were flying above the Earth in an aircraft.
I presume what you are interested in is where you are on the moon, no doubt this could be computed but it would be a complex problem.
Title: Would my GPS device work on the moon?
Post by: Bored chemist on 27/03/2011 10:34:14
According to wiki
"The U.S. Government controls the export of some civilian receivers. All GPS receivers capable of functioning above 18 kilometers (11 mi) altitude and 515 metres per second (1,001 kn)[48] are classified as munitions (weapons) for which U.S. State Department export licenses are required."

So, unless you have a military standard GPS it wouldn't work on the moon.

Another similar question would be  what would happen if I built a really high ladder and took my GPS up it?
GPS is normally set up to give a latitude, longitude and altitude.
How far up the ladder could I climb before the GPS failed?
(in principle- so we ignore the impossibility of the ladder and the need for my air supply).

My guess is that it would get screwy once you were above the astellites, but how far could you get?.
Title: Would my GPS device work on the moon?
Post by: Geezer on 27/03/2011 19:56:39

My guess is that it would get screwy once you were above the astellites,


I think so. The receiver has no idea about the direction of the satelites, only distance based on time. That means the receiver can be in one of two possible positions in three dimentional space; one on the Earth's surface and another far above the Earth's surface. Of course, it "knows" it is on or near the Earth's surface, so the other location is "impossible".

So, if you were to put the GPS in a position beyond the orbits of the satellites, I think it would try to report a position within the orbits.
Title: Would my GPS device work on the moon?
Post by: neilep on 27/03/2011 20:23:08
Hang On, if you are on the moon...do you really need your GPS to tell you that......you're on the moon ?
Title: Would my GPS device work on the moon?
Post by: Geezer on 27/03/2011 20:24:59
To obtain a position you make a comparison between the time signals transmitted by the satellites and the time you actually receive them, would not a problem arise because the time signals would be Earth time not Moon time.
What the signals you receive would tell you would be where you are relative to the surface of the Earth as though you were flying above the Earth in an aircraft.
I presume what you are interested in is where you are on the moon, no doubt this could be computed but it would be a complex problem.

I don't think local time would matter. The satellites send time and position signals and the receiver uses them to determine relative distances from the satellites. I don't think the receiver even needs to be aware of an absolute time reference (they would probably be a lot more expensive if that was the case). Assuming the signals could be received on the Moon, the receiver could (in theory) determine a spatial position that corresponded with a position on the surface of the Moon.

However, the accuracy would be lousy, and, as you point out, the receiver would have to perform some really fancy gymnastics to map that point in space to a meaningful location on the Moon's surface.
Title: Would my GPS device work on the moon?
Post by: Geezer on 27/03/2011 20:27:35
Hang On, if you are on the moon...do you really need your GPS to tell you that......you're on the moon ?

How else would you find the nearest McDonalds?
Title: Would my GPS device work on the moon?
Post by: Bored chemist on 28/03/2011 19:21:03
Hang On, if you are on the moon...do you really need your GPS to tell you that......you're on the moon ?

How else would you find the nearest McDonalds?
Easy.
Find the place with no atmosphere.
Title: Would my GPS device work on the moon?
Post by: neilep on 28/03/2011 19:27:32
Hang On, if you are on the moon...do you really need your GPS to tell you that......you're on the moon ?

How else would you find the nearest McDonalds?
Easy.
Find the place with no atmosphere.


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Title: Would my GPS device work on the moon?
Post by: chris on 31/03/2011 17:21:30
Why Mcdonalds? In space you'd go to...Starbucks, surely?
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 31/03/2011 21:35:04
Syhprum - you are quite correct about the satellites.  But how do they broadcast their signal?  It would not take much leakage for the signals to be receivable on the moon.  And three or more signals and a decent software algorithm and you have an exact position. 

So - If you were on the dark side of the moon (when you are part of the great gig in the sky) I think you would be unlucky - but on the side that faces the earth I reckon a decent receiver could pick up enough signals to make a fairly reasonable approximation.

Sorry but the satalites that work for GPS are desined for the earth, first, they do not face the moon secound, third they work by trianglurisationaslism so you would need atleast two or three satalites to be involved, and also for those satalites and your GPS devices sofware to have a complete map of the moon.

Never going to happen, not forgetting all the time it would take for any signal to arrive from the moon to any satalite orbiting the earth.
Title: Would my GPS device work on the moon?
Post by: Bored chemist on 01/04/2011 07:21:16
"Sorry but the satalites that work for GPS are desined for the earth"
The clocks in the satellites would run correctly on earth. They are designed for space.
" they work by trianglurisationaslism so you would need atleast two or three satalites to be involved,"
There are 31 so, from the near side of the moon you could typically see a dozen or more.
"and also for those satalites and your GPS devices sofware to have a complete map of the moon."
Nope, you can use a coordinate system based on earth anywhere, including the moon.
"Not forgetting all the time it would take for any signal to arrive from the moon to any satalite orbiting the earth"
That delay is exactly how the system works.


Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 01/04/2011 11:47:10
"Sorry but the satalites that work for GPS are desined for the earth"
The clocks in the satellites would run correctly on earth. They are designed for space.

I was talking about the systems themselves being used with distances and time delays, that are set for earth, it's a given that satalites are designed to work in space.

 

" they work by trianglurisationaslism so you would need atleast two or three satalites to be involved,"
There are 31 so, from the near side of the moon you could typically see a dozen or more.

A dozen or more:- facing the earth.



"and also for those satalites and your GPS devices sofware to have a complete map of the moon."
Nope, you can use a coordinate system based on earth anywhere, including the moon.

You mean based on a sphere shape, except that the all spheres are slightly different in proportions, not forgetting that valleys and mountains also will effect the position of a person. You would need a complete map of the moon to get a correct GPS positon, and satalites arrounds the moon also to get a correct position.
 http://en.wikipedia.org/wiki/Global_Positioning_System
Quote
The receiver uses the messages it receives to determine the transit time of each message and computes the distance to each satellite. These distances along with the satellites' locations are used with the possible aid of trilateration, depending on which algorithm is used, to compute the position of the receiver. This position is then displayed, perhaps with a moving map display or latitude and longitude; elevation information may be included. Many GPS units show derived information such as direction and speed, calculated from position changes.


"Not forgetting all the time it would take for any signal to arrive from the moon to any satalite orbiting the earth"
That delay is exactly how the system works.

No, there are a few ways a GPS system can work, yet we are talking about the one we use.

Quote
"However, even a very small clock error multiplied by the very large speed of light — the speed at which satellite signals propagate — results in a large positional error. Therefore receivers use four or more satellites to solve for the receiver's location and time."

And sending a signal from the moon to a satalite arround the earth would take too long, besides the fact that they are designed to communicate with systems on the earth.


Quote
Although four satellites are required for normal operation, fewer apply in special cases. If one variable is already known, a receiver can determine its position using only three satellites. For example, a ship or aircraft may have known elevation. Some GPS receivers may use additional clues or assumptions (such as reusing the last known altitude, dead reckoning, inertial navigation, or including information from the vehicle computer) to give a less accurate (degraded) position when fewer than four satellites are visible
Title: Would my GPS device work on the moon?
Post by: Bored chemist on 01/04/2011 18:21:51
To say "I was talking about the systems themselves being used with distances and time delays, that are set for earth, it's a given the satalites are designed to work in space."
implies that you already know that answer, I contend that you don't.
Of course, the system was designed to work on earth. So, in a sense, were people. But they still worked on the moon.
There are plenty of instances of things designed for one thing but used for others. The internet wasn't designed for distributing naughty pictures, but that's one of its major uses.

As for "A dozen or more:- facing the earth.", do you not realise that, for one thing , these were designed to spread a signal pretty much from horizon to horizon, and for another, antennae never form "perfect" beams- there's always some transmission in other directions?


"You mean based on a sphere shape,..."
No, I meant what I said.
A coordinate system based on earth (the one I had in mind was latitude, longitude and altitude) which can be used to pinpoint any place in the universe. Please don't presume to tell me what I mean.

"No, there are a few ways a GPS system can work, yet we are talking about the one we use."
There may be several ways you could set up a GPS system.
The one we use depends explicitly on exactly the time delays that you seem to think are a problem.

"And sending a signal from the moon to a satalite arround the earth would take too long, "
Too long for what? The delay would be less than two seconds. How much of a hurry are you in?

"besides the fact that they are designed to communicate with systems on the earth."
Still not important. It's not an issue of what they were designed to do, the question is about what they could do.

In principle, with the right decoding (normally restricted to military systems), a big enough aerial and the right software, you could find out your position on the moon by reference to the GPS system. The problems would be that it would give a result in earth based coordinates. But that's still telling you where you are. The other problem is that the accuracy would suck. That's not the same as saying it wouldn't work.

Title: Would my GPS device work on the moon?
Post by: imatfaal on 01/04/2011 19:03:00
And would the accuracy even suck? It would be worse than on the surface of the earth but you would have a dozen or more points, with separations between them of up to 50,000km (they are in 20,000 km orbits) from a distance of around 400,000 km.  The maths is beyond me, even if I did know what the inherent error margin were, but it doesn't strike me as too bad a deal - especially if there was no alternative.
Title: Would my GPS device work on the moon?
Post by: Geezer on 01/04/2011 19:27:34
And would the accuracy even suck? It would be worse than on the surface of the earth but you would have a dozen or more points, with separations between them of up to 50,000km (they are in 20,000 km orbits) from a distance of around 400,000 km.  The maths is beyond me, even if I did know what the inherent error margin were, but it doesn't strike me as too bad a deal - especially if there was no alternative.

The accuracy is a function of the angles formed at the GPS receiver between three or more satellites. The greater the angles, the more accurate the measurement. As you might imagine, the angles become rather acute when the receiver is on the Moon, so the accuracy won't be good.

I would think the accuracy is a function of the cosine of the angles formed between satellites and the receiver, so a small error in the lengths of the adjacent sides of the triangle produces a relatively large error in the resolved angle when that angle is small.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 01/04/2011 20:27:02
To say "I was talking about the systems themselves being used with distances and time delays, that are set for earth, it's a given the satalites are designed to work in space."
implies that you already know that answer, I contend that you don't.
Of course, the system was designed to work on earth. So, in a sense, were people. But they still worked on the moon.
There are plenty of instances of things designed for one thing but used for others. The internet wasn't designed for distributing naughty pictures, but that's one of its major uses.

As for "A dozen or more:- facing the earth.", do you not realise that, for one thing , these were designed to spread a signal pretty much from horizon to horizon, and for another, antennae never form "perfect" beams- there's always some transmission in other directions?

That's very nice, but those directions are not 180 degree. Leaving only satalite on the other side of the earth(realtive to the moons position at the time) being able to send a signal in the moons direction at all, very hit and miss, if returned I think you'll find the satalite that sent it could have moved into a non reciving postion. plus the angles could send any signal retuen in a tottally different direction. Hoirson to horison or not it's not so clear sent signal would reurn to the satalite that sent them, your asking a satialite to perform a function it has not been tuned to doing. 



"You mean based on a sphere shape,..."
No, I meant what I said.
A coordinate system based on earth (the one I had in mind was latitude, longitude and altitude) which can be used to pinpoint any place in the universe. Please don't presume to tell me what I mean.

"No, there are a few ways a GPS system can work, yet we are talking about the one we use."
There may be several ways you could set up a GPS system.
The one we use depends explicitly on exactly the time delays that you seem to think are a problem.

"And sending a signal from the moon to a satalite arround the earth would take too long, "
Too long for what? The delay would be less than two seconds. How much of a hurry are you in?

Not going to matter if only one or two can pick it up, besides the distance would be greater, as the closest satalites to the moon wouldn't be able to transmit.

 


"besides the fact that they are designed to communicate with systems on the earth."
Still not important. It's not an issue of what they were designed to do, the question is about what they could do.

They could do lots of things, if we are talking about "coulds" then fine. Yes one day they could gives us gps on the moon.



In principle, with the right decoding (normally restricted to military systems), a big enough aerial and the right software, you could find out your position on the moon by reference to the GPS system. The problems would be that it would give a result in earth based coordinates. But that's still telling you where you are. The other problem is that the accuracy would suck. That's not the same as saying it wouldn't work.


If it's in accurate it isnt working.
Title: Would my GPS device work on the moon?
Post by: Geezer on 01/04/2011 21:26:22

I think you'll find the satalite that sent it could have moved into a non reciving postion


It doesn't matter if the signal disappears. The GPS receiver only needs to receive the satellite's signal once to determine a position.

You might want to take a look at this  http://en.wikipedia.org/wiki/Global_Positioning_System#Basic_concept_of_GPS
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 01/04/2011 22:21:30

I think you'll find the satalite that sent it could have moved into a non reciving postion


It doesn't matter if the signal disappears. The GPS receiver only needs to receive the satellite's signal once to determine a position.

You might want to take a look at this  http://en.wikipedia.org/wiki/Global_Positioning_System#Basic_concept_of_GPS

I referenced that link: "Although four satellites are required for normal operation, fewer apply in special cases. If one variable is already known, a receiver can determine its position using only three satellites."

You are saying a device having recieved just one signal from one satalite while on the moon, will be able to tell you where you are. Not the case.

It might be able to say: "You're on the moon"
Title: Would my GPS device work on the moon?
Post by: Geezer on 01/04/2011 22:37:42
You are saying a device having recieved just one signal from one satalite while on the moon, will be able to tell you where you are.

No. I am not saying that at all. I am saying the receiver only needs to receive one transmission per satellite. Your point about the satellite moving is irrelevant.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 01/04/2011 23:11:14
You are saying a device having recieved just one signal from one satalite while on the moon, will be able to tell you where you are.

No. I am not saying that at all. I am saying the receiver only needs to receive one transmission per satellite. Your point about the satellite moving is irrelevant.

They are designed to transmit to the earth, the moon is in the other direction to normal opperation. Personally I think only around 10% of the satalites up there at any one time could really transmitt in a luna direction anyway, that' 2.3 satalites but maybe it 20% that would 4.6 satalites.

Best case I see is 4.6 being in a position to do so but there is no garentee that would actually work, besides as I said before the program on the GPS device would have to have a map and record of the moon, to then place you with in that map.   
Title: Would my GPS device work on the moon?
Post by: Geezer on 02/04/2011 04:37:03
Now look here Wybit, either admit you were wrong and you have learned something, or provide some substantial evidence to support your arguments. It looks like all you are doing is trying to change the subject whenever you are challenged.

Sorry, but that's nothing but trolling. You can learn a lot on TNS (I have), but if you are confident you are always right, you are simply being a troll.

It's your call. Are you trying to prove something, or are you trying to learn anything?   
Title: Would my GPS device work on the moon?
Post by: syhprum on 02/04/2011 09:20:16
NASA have already acknowledged that to use the Earths GPS system for navigation on the Moon is all but impossible and to set up a similar system to cover the moon would be extremely expensive.
To this end they have let contracts to private companies to develop simple short range systems that will assist navigation on the moon.

http://www.thaindian.com/newsportal/world-news/nasa-developing-navigation-system-for-moon-lead_10074436.html
Title: Would my GPS device work on the moon?
Post by: Bored chemist on 02/04/2011 14:46:56
"Personally I think only around 10% of the satalites up there at any one time could really transmitt in a luna direction anyway"
Odd that, because, in reality, about half of them would (though the signal strength would be poor).
When you say "it's not so clear sent signal would reurn to the satalite that sent them," are you labouring under the delusion that GPS sends a signal back to the satellites? The GPS receivers are just receivers, not transmitters.
In other words, do you know what you are talking about? If not, perhaps you might think about learning rather than trolling.


Incidentally, if you use Google chrome as a web browser it highlights spelling errors for you. That way you don't end up pontificating about satellites without even knowing how to spell the word.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 02/04/2011 17:57:05
Now look here Wybit, either admit you were wrong and you have learned something, or provide some substantial evidence to support your arguments. It looks like all you are doing is trying to change the subject whenever you are challenged.

Not the case at all. It is you and others that claimed that it would work. I disagreed from the beginning.


Sorry, but that's nothing but trolling.

You know what they say about insulting people.

But to clarify, The question was "Would my GPS work on the moon"

I said no, and that the satlites signal would not get there, that also the device needed a map of the moon to work at all.

Bored Chemist said no you didn't need a map and that GPS could tell you where you were any where in the universe.

He and others said that the signals from satellites, could get there, I replied to that no if that was possible I think "Think" only 10% of the satellites could do that- think, not a statement of fact, what I believed, based on the idea that the signals could get there, and the people making those assertions never backed up there claims with any evidence either I might like to point out.

In fact other than you Geezer I am the only one that actually referenced another site, and the site you reference was the one I did.

But as always there is a mis-communication, and misunderstanding.
 

You can learn a lot on TNS (I have), but if you are confident you are always right, you are simply being a troll.

It's your call. Are you trying to prove something, or are you trying to learn anything?   

I'm trying to answer the question, you all seem to think it would work, I disagree.

As I said before to work it would need a map of the moon

http://www8.garmin.com/aboutGPS/
Quote
Essentially, the GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. Now, with distance measurements from a few more satellites, the receiver can determine the user's position and display it on the unit's electronic map.

This alone is enough to show that a GPS on the moon would not function, let alone be able to plot your position anywhere in the universe.


Another issue with the signals is solar winds which disrupt them, Still looking for the reference for that, but I did read it some where.

Other than that, the Next generation of GPS- WAAS is looking to increase the signal foot print of the GPS system http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System

But even if the current signal was Horizon to horizon as Bored chemist claimed, it would not be beyond that would it, it would concentrate it's signal foot print or zone of sight, to perform it's function in the optimal manner, and that function is on the earth and for the earth, Why waste signal out into space?

 GPS started in 1978 I am not sure what the actual signal foot print is, but the technology from when it started is clearly dated today
http://www.apsattv.com/techinfo/predicting-out-of-footprint-coverage.htm

Site on satellite coverages- footprints and receptions outside of the signal foot print.

also on the signal front
http://www8.garmin.com/aboutGPS/
Quote
◦Number of satellites visible - The more satellites a GPS receiver can "see," the better the accuracy. Buildings, terrain, electronic interference(which I believe includes solar wind interference), or sometimes even dense foliage can block signal reception, causing position errors or possibly no position reading at all. GPS units typically will not work indoors, underwater or underground.

Should add or in space I think really.


"Personally I think only around 10% of the satalites up there at any one time could really transmitt in a luna direction anyway"
Odd that, because, in reality, about half of them would (though the signal strength would be poor).

Based upon what do you make that acertion? AS things stand I don't think any would.



When you say "it's not so clear sent signal would reurn to the satalite that sent them," are you labouring under the delusion that GPS sends a signal back to the satellites? The GPS receivers are just receivers, not transmitters.

I think you'll find the latest ones do blackberry and such like.
http://us.blackberry.com/smartphones/features/gps.jsp

But that is an assumption, Hence think.



In other words, do you know what you are talking about? If not, perhaps you might think about learning rather than trolling.


Incidentally, if you use Google chrome as a web browser it highlights spelling errors for you. That way you don't end up pontificating about satellites without even knowing how to spell the word.

Bored Chemist I have seen you make spelling mistakes also, Seriously poor show.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 02/04/2011 18:01:00
NASA have already acknowledged that to use the Earths GPS system for navigation on the Moon is all but impossible and to set up a similar system to cover the moon would be extremely expensive.
To this end they have let contracts to private companies to develop simple short range systems that will assist navigation on the moon.

http://www.thaindian.com/newsportal/world-news/nasa-developing-navigation-system-for-moon-lead_10074436.html

Interesting looks like they are going to develop one.
Title: Would my GPS device work on the moon?
Post by: CliffordK on 02/04/2011 18:37:18
So - If you were on the dark side of the moon (when you are part of the great gig in the sky) I think you would be unlucky - but on the side that faces the earth I reckon a decent receiver could pick up enough signals to make a fairly reasonable approximation.

Why wouldn't it work on the dark side of the moon facing earth?
The "Dark Side of the Moon" has nothing to do with the sun or illumination.
Rather, the moon is tidally locked with the earth.  One side of the moon always faces the earth.  One side (the dark side) always faces away from the earth.  Thus, if you were on the side of the moon facing away from Earth...  the GPS satellites would be useless.

As far as whether you could use a GPS system.
Obviously any software pre-programmed to positions on earth would be confused.

Are the antennas omni-directional antennas?  

I don't see why you couldn't make basic triangulation routines to map a position in space above the satellites...  and then map that onto the lunar surface based on lunar topography and the lunar orbit.

A time delay is irrelevant, and would just be part of the calculations.  The geosynchronous orbit is about 36,000 km.  The moon is at about 385,000 km.  It is likely one could pick up satellites on all sides of the earth that are not eclipsed by the planet. In fact, using the satellites on the far side of Earth, one should be able to pinpoint a location 385,000 km below the surface of the planet.

You can use GPS equipment in conjunction with a base station at a fixed location.  Putting a fixed base station on the moon would likely greatly simplify the calculations, and significantly improve the accuracy of the system.

Ahh...
This base station would be essentially one approach for doing the local triangulation.  One might be able to use the base station for calculating the offset even while not in direct sight of the base station.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 02/04/2011 19:39:18
So - If you were on the dark side of the moon (when you are part of the great gig in the sky) I think you would be unlucky - but on the side that faces the earth I reckon a decent receiver could pick up enough signals to make a fairly reasonable approximation.

Why wouldn't it work on the dark side of the moon facing earth?
The "Dark Side of the Moon" has nothing to do with the sun or illumination.
Rather, the moon is tidally locked with the earth.  One side of the moon always faces the earth.  One side (the dark side) always faces away from the earth.  Thus, if you were on the side of the moon facing away from Earth...  the GPS satellites would be useless.

As far as whether you could use a GPS system.
Obviously any software pre-programmed to positions on earth would be confused.

Are the antennas omni-directional antennas?  

I don't see why you couldn't make basic triangulation routines to map a position in space above the satellites...  and then map that onto the lunar surface based on lunar topography and the lunar orbit.

I dont know why you would need the luna orbit, to work it out.


A time delay is irrelevant, and would just be part of the calculations.  The geosynchronous orbit is about 36,000 km.  The moon is at about 385,000 km.  It is likely one could pick up satellites on all sides of the earth that are not eclipsed by the planet.

No I dis agree, The satalites set a signal zone an area they cover, I'm still looking for the exact size but, as the signal travel through the atmosphere it is distorted, meaning that signals that travel through and back out will be even more distorted, Besides I do not believe that really any signals travel out side of a zone of the earth they are designed to cover, there might be a very low frequency at the zone edges.


 In fact, using the satellites on the far side of Earth, one should be able to pinpoint a location 385,000 km below the surface of the planet.

Below the surface? What do you mean? GPS do not work indoors.



You can use GPS equipment in conjunction with a base station at a fixed location.  Putting a fixed base station on the moon would likely greatly simplify the calculations, and significantly improve the accuracy of the system.

Ahh...
This base station would be essentially one approach for doing the local triangulation.  One might be able to use the base station for calculating the offset even while not in direct sight of the base station.

The base staion would have to talk to the device. Personally I think for the size of the moon just 8 satalites, 4 for each face should be enough, but they would have to orbit the moon tho.

If you wanted to use the earths GPS satalites I think you would have to turn them to transmit straight at it, even then there is no garentee, Just look at the earth GPS system if you're indoors with four satalites in a good postions it wont work. Using the ones we have at the moment in there current function is just not possible, plus you would need your GPS to have a moon map also.   
Title: Would my GPS device work on the moon?
Post by: Pumblechook on 02/04/2011 20:28:37
The signals will be directed towards Earth and the distance to the Moon is 20 times further and just on that basis the signals would be 26 dB weaker (400 times less power).  You would need a fair sized parabolic dish.. 3 metre or more.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 02/04/2011 20:30:29
The signals will be directed towards Earth and the distance to the Moon is 20 times further and just on that basis the signals would be 26 dB weaker (400 times less power).  You would need a fair sized parabolic dish.. 3 metre or more.

And point it in the moons direction, I still do not think any of the current signals get to the moon at all.
Title: Would my GPS device work on the moon?
Post by: Pumblechook on 02/04/2011 20:59:24
I meant even if they fired similar power towards the Moon the signals would be 400 times weaker.  If you knew what power was going towards the Moon (by accident) you could work out what size of receiving dish was required. The dish may be so large that the beamwidth might be a tiny fraction of a degree and may have to track the satellites and possibly may have trouble picking up the required 3.  No air and therefore no wind would make it possible to construct huge dishes.

My pal bounces 144 MHz signals off the Moon.

This Swiss bloke can hear his own echos..  Probably 1296 MHz which is not too far from GPS frequencies. 

 
Title: Would my GPS device work on the moon?
Post by: Bored chemist on 02/04/2011 21:20:01
"Bored Chemist said no you didn't need a map and that GPS could tell you where you were any where in the universe. "
Oh no I didn't.

"As I said before to work it would need a map of the moon"
No, it doesn't.
The "satnav" systems used in cars need a map, but the whole point of GPS is that it doesn't.

"This alone is enough to show that a GPS on the moon would not function, let alone be able to plot your position anywhere in the universe."
No it doesn't (though nobody said it would anyway).

"Why waste signal out into space?"
Because it's impossible not to ( with a finite sized antenna).

"Based upon what do you make that acertion? "
based on the fact that roughly half of them would be visible from the moon's earthward side and the laws of physics.

"I think you'll find the latest ones do blackberry and such like.
http://us.blackberry.com/smartphones/features/gps.jsp

But that is an assumption, Hence think."

Red herring. It doesn't matter that Blackberies have a built in transmitter. There is no system on the satellites to receive a signal from them.

You really haven't understood how GPS works.
Title: Would my GPS device work on the moon?
Post by: CliffordK on 02/04/2011 21:56:06

 In fact, using the satellites on the far side of Earth, one should be able to pinpoint a location 385,000 km below the surface of the planet.

Below the surface? What do you mean? GPS do not work indoors.
[ Invalid Attachment ]

You have satellites on the Moon side of Earth (black).
Satellites on the far side of Earth (green).
Satellites eclipsed by Earth (red), which obviously won't give you a good signal.

Those satellites on the Moon side of Earth (black) may or may not give a good omnidirectional signal.  But, the calculations for them would have to be recreated for the signal going in the opposite direction than intended.

Those satellites on the far side of the Earth (green) should be able to give you an X, Y, Z coordinate, similar to having the target being on Earth.  However, the elevation calculation would turn up to be essentially negative.  Obviously not being below ground, but it would look to the GPS as being 400,000 km below ground.

Some of the far side satellites might have atmospheric interference (light green).  But, this would not be all the satellites.

We've believed for a long time that Earth's radio signals do in fact escape from Earth's atmosphere, and could potentially be picked up at great distances, even other star systems, with the obvious time lag. 

Your GPS accuracy outside of the Earth/Moon system would be low, unless someone added GPS-like transmitters to other satellites such as some of the sun orbiting satellites.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 02/04/2011 22:08:41
"Bored Chemist said no you didn't need a map and that GPS could tell you where you were any where in the universe. "
Oh no I didn't.

Oh yes you did!



"Based upon what do you make that acertion? "
based on the fact that roughly half of them would be visible from the moon's earthward side and the laws of physics.

Rather than just making a stament couldnt you actually provide some evidence?



"I think you'll find the latest ones do blackberry and such like.
http://us.blackberry.com/smartphones/features/gps.jsp

But that is an assumption, Hence think."

Red herring. It doesn't matter that Blackberies have a built in transmitter. There is no system on the satellites to receive a signal from them.

You really haven't understood how GPS works.

GPS Global position system, and there are a few, My hence think statement was based upon, the notion that a mobile phone which does communicate with the satlites, your conversation passes through then as you chat, can also generate a position not using the acutal GPS satalite systems no red herrings at all, or none intended. 
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 02/04/2011 22:14:45

 In fact, using the satellites on the far side of Earth, one should be able to pinpoint a location 385,000 km below the surface of the planet.

Below the surface? What do you mean? GPS do not work indoors.
[ Invalid Attachment ]
Ok looking at the position of the satalites and the direction they will project their signals, they do not project into the area of the moon, it was based upon that that I said possibly only 10% could at all, draw the area and directions they would cover. It's clear to see they wouldnt, I still think none would but, if it was in anyway possible I "think" only two satalites on that picture could and that's the two closest to the red and there signals would also travel through the atmosphere.   

http://www.apsattv.com/techinfo/predicting-out-of-footprint-coverage.htm
GPS satalites are about 30 years old, this site list the coverage foot prints for some satalites.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 02/04/2011 22:28:34
The actual satalites are Block 2 f

http://en.wikipedia.org/wiki/GPS_Block_IIF

Still looking for their specs

In the 1990s they sent up block 2A

And im looking for their specs too

"The reception foot print"
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 02/04/2011 22:33:16
http://www.outdoorbits.com/satellite-systems-a-5.html

Dont know about the whole horizon to horizon the A2 doesn't even cover Europe completely

Quote
One of the more important aspects of satellite reception is the footprint of the satellite broadcasts you wish to receive. The footprint is the theoretical area covered by each satellite broadcast on the earth. Reception within this footprint will depend on dish size / LNB specs / receiver used also.
Title: Would my GPS device work on the moon?
Post by: Bored chemist on 02/04/2011 22:42:02
""Bored Chemist said no you didn't need a map and that GPS could tell you where you were any where in the universe. "
Oh no I didn't.

Oh yes you did!"

OK, for a start either show a quote where I said that or leave.



"Rather than just making a stament couldnt you actually provide some evidence?"
Let me get this straight.
Do you need evidence that about half the satellites would be visible, or you need evidence that you cannot produce a perfectly defined beam with a finite aperture?
Both are clear enough to me.

"GPS Global position system, and there are a few, My hence think statement was based upon, the notion that a mobile phone which does communicate with the satlites, your conversation passes through then as you chat, can also generate a position not using the acutal GPS satalite systems no red herrings at all, or none intended"

I'm sorry, but I simply don't understand that. Could you try reading through it then sorting it out please?
 I will just point out that I don't normally experience satellite delays on my mobile phone.

Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 02/04/2011 22:51:26
""Bored Chemist said no you didn't need a map and that GPS could tell you where you were any where in the universe. "
Oh no I didn't.

Oh yes you did!"

OK, for a start either show a quote where I said that or leave.

Quote
I said "have a complete map of the moon."
Nope, you can use a coordinate system based on earth anywhere, including the moon."

You said nope you do not need a map

Quote
A coordinate system based on earth (the one I had in mind was latitude, longitude and altitude) which can be used to pinpoint any place in the universe.

Even though we do not actually know how big the universe is or what it really looks like!



"Rather than just making a stament couldnt you actually provide some evidence?"
Let me get this straight.
Do you need evidence that about half the satellites would be visible, or you need evidence that you cannot produce a perfectly defined beam with a finite aperture?
Both are clear enough to me.

"GPS Global position system, and there are a few, My hence think statement was based upon, the notion that a mobile phone which does communicate with the satlites, your conversation passes through then as you chat, can also generate a position not using the acutal GPS satalite systems no red herrings at all, or none intended"

I'm sorry, but I simply don't understand that. Could you try reading through it then sorting it out please?
 I will just point out that I don't normally experience satellite delays on my mobile phone.



Oh really you never get signal problems?
Title: Would my GPS device work on the moon?
Post by: Madidus_Scientia on 03/04/2011 06:26:18
The "Dark Side of the Moon" has nothing to do with the sun or illumination.
Rather, the moon is tidally locked with the earth.  One side of the moon always faces the earth.  One side (the dark side) always faces away from the earth.  Thus, if you were on the side of the moon facing away from Earth...  the GPS satellites would be useless.

Doesn't the term "dark side of the moon" in itself imply it is to do with illumination? Unless it is meant that that side is evil. "Far side of the moon" I would accept, but I disagree that the dark side of the moon is the side facing away from earth.

The dark side of the moon is the side facing away from the sun. If you've ever seen a half-moon you'll know that the dark side of the moon is still visible from earth.
Title: Would my GPS device work on the moon?
Post by: Geezer on 03/04/2011 06:35:34
The "Dark Side of the Moon" has nothing to do with the sun or illumination.
Rather, the moon is tidally locked with the earth.  One side of the moon always faces the earth.  One side (the dark side) always faces away from the earth.  Thus, if you were on the side of the moon facing away from Earth...  the GPS satellites would be useless.

Doesn't the term "dark side of the moon" in itself imply it is to do with illumination? Unless it is meant that that side is evil. "Far side of the moon" I would accept, but I disagree that the dark side of the moon is the side facing away from earth.

The dark side of the moon is the side facing away from the sun. If you've ever seen a half-moon you'll know that the dark side of the moon is still visible from earth.

I think you are quite correct. We only see one hemisphere of the Moon from Earth, but both hemispheres are illuminated by the Sun.
Title: Would my GPS device work on the moon?
Post by: Madidus_Scientia on 03/04/2011 06:36:33
""Bored Chemist said no you didn't need a map and that GPS could tell you where you were any where in the universe. "
Oh no I didn't.

Oh yes you did!"

OK, for a start either show a quote where I said that or leave.

Quote
I said "have a complete map of the moon."
Nope, you can use a coordinate system based on earth anywhere, including the moon."

You said nope you do not need a map

Where did he say that GPS could tell you where you were anywhere in the universe? I don't see it.

Quote
Quote
A coordinate system based on earth (the one I had in mind was latitude, longitude and altitude) which can be used to pinpoint any place in the universe.

Even though we do not actually know how big the universe is or what it really looks like!

That's irrelevant, the coordinates are still plottable.

Quote
Oh really you never get signal problems?

Are you also labouring under the delusion that a mobile phone transmits directly to the satellites?
Title: Would my GPS device work on the moon?
Post by: Geezer on 03/04/2011 06:45:07
Are you also labouring under the delusion that a mobile phone transmits directly to the satellites?

That's silly. Everyone knows mobile phones get their signals from black helicopters.
Title: Would my GPS device work on the moon?
Post by: Madidus_Scientia on 03/04/2011 07:45:19
Did someone say black helicopters?! Where?! where are they!? Where's my aluminium foil
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 03/04/2011 10:20:24
""Bored Chemist said no you didn't need a map and that GPS could tell you where you were any where in the universe. "
Oh no I didn't.

Oh yes you did!"

OK, for a start either show a quote where I said that or leave.

Quote
I said "have a complete map of the moon."
Nope, you can use a coordinate system based on earth anywhere, including the moon."

You said nope you do not need a map

Where did he say that GPS could tell you where you were anywhere in the universe? I don't see it.

It was in the post I quoted from sec-2.1. As I said he was talking about sphere shapes he said no and that using Long- Latt and attitude from an earth based system you could plot anywhere in the universe. I think "Think" his point was that using an x Y Z axis you could plot your position, long and latt are for the sphere shape of the earth, we were discussing GPS at the time.



Quote
Quote
A coordinate system based on earth (the one I had in mind was latitude, longitude and altitude) which can be used to pinpoint any place in the universe.

Even though we do not actually know how big the universe is or what it really looks like!

That's irrelevant, the coordinates are still plottable.

Quote
Oh really you never get signal problems?

Are you also labouring under the delusion that a mobile phone transmits directly to the satellites?

Maybe I am.
Title: Would my GPS device work on the moon?
Post by: Madidus_Scientia on 03/04/2011 10:25:05
They do not. They transmit to the nearest tower, and from there the signal is forwarded elsewhere.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 03/04/2011 10:49:35
They do not. They transmit to the nearest tower, and from there the signal is forwarded elsewhere.

Some phones can
http://www.ehow.com/how-does_5593221_satellites-information-during-natural-disasters.html
 
Quote
A satellite phone is a portable phone that communicates using satellites in orbit as opposed to land cell towers like cell phones. Satellite phones send a signal to and receive a signal from the satellite in use.

Just saying

Title: Would my GPS device work on the moon?
Post by: Madidus_Scientia on 03/04/2011 10:57:19
We weren't talking about satellite phones.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 03/04/2011 11:19:01
We weren't talking about satellite phones.

What you mean is you weren't. I knew some portable phones could or did talk directly to satalites, some might also have GPS options. Delusions aside, because there are so many options, it is kind of a nightmare and easy to cross-wires.
Title: Would my GPS device work on the moon?
Post by: Madidus_Scientia on 03/04/2011 13:44:15
Then why is it relevant whether BC has signal problems

Whether a phone has GPS capability or not has nothing to do with whether it can transmit or not
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 03/04/2011 14:12:25
Then why is it relevant whether BC has signal problems

Whether a phone has GPS capability or not has nothing to do with whether it can transmit or not

So what's your point? Isnt it realtive to what phone he has, shall we ask him?

And what has any of this got to do with the being on the moon and recieving a GPS signal?

Title: Would my GPS device work on the moon?
Post by: Madidus_Scientia on 03/04/2011 14:18:48
Exactly.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 03/04/2011 14:44:01
Exactly.


I will say Bored chemists are just the sort of people that buy satalite phones.

that aside where are we in this discussion? I'm still sure no signal from a GPS satalite would reach the moon at all.

I'm still for the specs tho on the 2f satalite, signal foot print. Any ideas of a good place to look?
Title: Would my GPS device work on the moon?
Post by: Bored chemist on 03/04/2011 16:12:36
Wiybit,
Shocking as you may find this, if I had meant to use X,Y and Z coordinates I would have said so.
I didn't
I said that you could label any point in the universe by giving its latitude, longitude and altitude from earth.
Whether or not you could do that with GPS is another matter. Clearly there are some places you can't use GPS (like in a tunnel) but the system of coordinates is still valid.
You might want to look here.
http://en.wikipedia.org/wiki/Polar_coordinates
It shows how to convert from Cartesian (X,Y,Z) to polar (R, θ,φ) coordinate systems.

The point was that you can use an earth based set of coordinates to navigate anywhere, including on the moon, so your idea that it would only work on earth is cobblers.

"I will say Bored chemists are just the sort of people that buy satalite phones"
Also cobblers. It's only about 4 years since I got a mobile phone at all.

However I said that my phone doesn't give satellite delays so you should have known that it's not a satellite phone. The problem is that you don't read what I post.

I still don't understand why you brought mobile phones into this thread. It's about the GPS system and GPS  receivers don't transmit a signal back to the satellite.
As far as I can tell you only mentioned this because you didn't understand the GPS system.

"I'm still for the specs tho on the 2f satalite, signal foot print. Any ideas of a good place to look?"
Anywhere you like. Because it won't help much.
The diagram will look something like this
http://en.wikipedia.org/wiki/File:FAA_WAAS_coverage_next_generation.jpg
It will differ in detail, but that's not the issue.
That pretty picture shows a contour  on the earth where the signal is over some specified strength. I don't know what the spec. is, but it doesn't matter because it's arbitrary.
I could still use a receiver just outside that area if I had a better antenna or if I was lucky with the local conditions.
On the other hand, even inside that "cone" I might not be able to get a usable signal.

So the area covered by the satellite depends on the antenna.
On the moon I can use as big a dish as I like, so it doesn't matter how poor the signal is.
(There's a way round the problem with pointing accuracy, but if I mention it, Wiybit will fail to understand it and probably say that I have said that all dogs like banana peel or something).

Now, back to the question of the maps.
Bits of Japan recently moved a few metres. The maps are now wrong.
GPS still works. It can still (even in a recently mobile bit of Japan) give you a latitude, longitude and altitude.
In fact, the reason they know how far and in which direction the tectonic plates moved is that they can monitor it with GPS.
Does anyone still think GPS needs a map?




Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 03/04/2011 16:39:18
Wiybit,
Shocking as you may find this, if I had meant to use X,Y and Z coordinates I would have said so.
I didn't
I said that you could label any point in the universe by giving its latitude, longitude and altitude from earth.
Whether or not you could do that with GPS is another matter. Clearly there are some places you can't use GPS (like in a tunnel) but the system of coordinates is still valid.
You might want to look here.
http://en.wikipedia.org/wiki/Polar_coordinates
It shows how to convert from Cartesian (X,Y,Z) to polar (R, θ,φ) coordinate systems.

The point was that you can use an earth based set of coordinates to navigate anywhere, including on the moon, so your idea that it would only work on earth is cobblers.

Well we were getting mixed up you were talking about navigation coordinates, as a system. I was talking about a GPS device.



"I will say Bored chemists are just the sort of people that buy satalite phones"
Also cobblers. It's only about 4 years since I got a mobile phone at all.

However I said that my phone doesn't give satellite delays so you should have known that it's not a satellite phone. The problem is that you don't read what I post.

I still don't understand why you brought mobile phones into this thread. It's about the GPS system and GPS  receivers don't transmit a signal back to the satellite.
As far as I can tell you only mentioned this because you didn't understand the GPS system.

"I'm still for the specs tho on the 2f satalite, signal foot print. Any ideas of a good place to look?"
Anywhere you like. Because it won't help much.
The diagram will look something like this
http://en.wikipedia.org/wiki/File:FAA_WAAS_coverage_next_generation.jpg

Yes I know about that site I referenced it eariler, the WAAS is the next generation for GPS, the coverage on the old system is smaller and that is the system we use at the moment.



It will differ in detail, but that's not the issue.
That pretty picture shows a contour  on the earth where the signal is over some specified strength. I don't know what the spec. is, but it doesn't matter because it's arbitrary.
I could still use a receiver just outside that area if I had a better antenna or if I was lucky with the local conditions.
On the other hand, even inside that "cone" I might not be able to get a usable signal.

So the area covered by the satellite depends on the antenna.

Sorry but the footprint has a huge impact, on the devices ability to function, and I debate how wide the satalite signal is, effects of the atmosphere and the solar winds.

I still do not believe any signal will get there, and no one has shown any evidence, to suggest otherwise.



On the moon I can use as big a dish as I like, so it doesn't matter how poor the signal is.

true but I still debate any signal getting there at all, again based on the diagrams put up by others if any signal did I think it would only come from arround 10% of the satlites, 2.4, you need three minimum, and four for best function, With the low frequency I cannot see it happening.

 

(There's a way round the problem with pointing accuracy, but if I mention it, Wiybit will fail to understand it and probably say that I have said that all dogs like banana peel or something).

No you can explain the poining accuracy, please do more input. and you did say dogs like banana peels.




Now, back to the question of the maps.
Bits of Japan recently moved a few metres. The maps are now wrong.
GPS still works. It can still (even in a recently mobile bit of Japan) give you a latitude, longitude and altitude.
In fact, the reason they know how far and in which direction the tectonic plates moved is that they can monitor it with GPS.
Does anyone still think GPS needs a map?

Yes the GPS works inside a bad map, your device would still need a moon map. What good is a map of the earth going to do you on the moon? You are looking for your postion on the moon, the device will need a map to do that. and even if you want to argue that it can just give you coordiates in numbers, it would have to have a program that extended beyond the earth to do so.

Why are we arguing this anyway? You already said in your first or secound post GPS on the moon wouldn't work(correction you said if you have a military GPS it would).

I debate that, so we argue. great 
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 03/04/2011 17:03:50
But I think also we need to clarify the Question

It was "would My GPS device work on the moon"

No super big antennas, no extra programs in the device for outer space co ordinations(although he already excepted that as a given).

His hand held device.

The answer is no!
Title: Would my GPS device work on the moon?
Post by: JP on 03/04/2011 17:14:56
But I think also we need to clarify the Question

It was "would My GPS device work on the moon"

No super big antennas, no extra programs in the device for outer space co ordinations(although he already excepted that as a given).

His hand held device.

The answer is no!

No, that wasn't the initial question.  His initial question was:

Quote
Ignoring software issues related to the fact that the longitude and latitude wouldn't fit, if a GPS receiver was taken to the moon, would it still work to pinpoint my position, albeit on the lunar surface?

So he was assuming the software wouldn't be a limitation.
Title: Would my GPS device work on the moon?
Post by: Bored chemist on 03/04/2011 17:36:59
So, it wouldn't work with a standard GPS.
Just like I said a while ago.

So, any subsequent posts must have referred to non-standard GPS receivers.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 03/04/2011 18:03:22
But I think also we need to clarify the Question

It was "would My GPS device work on the moon"

No super big antennas, no extra programs in the device for outer space co ordinations(although he already excepted that as a given).

His hand held device.

The answer is no!

No, that wasn't the initial question.  His initial question was:

Quote
Ignoring software issues related to the fact that the longitude and latitude wouldn't fit, if a GPS receiver was taken to the moon, would it still work to pinpoint my position, albeit on the lunar surface?

It's the title of the thread.


So he was assuming the software wouldn't be a limitation.

Yes as I said= (although he already excepted that as a given) to say that he knew it would be a problem but assuming for the question it wouldn't be. Makes sense, it's given that the program would need to be improved, the question is one of a hand held device being able to recieve a signal on the moon.

Or maybe better said "knowing about the software issues, so ignoring them for the sake of the question(so we assume it would be fine), would the GPS device be able to tell me my position when on the moon? 

I should have worded it better actually, but asuming the device would be fine means "no extra programing needed" I can totally see how that can come across differently.
Title: Would my GPS device work on the moon?
Post by: Geezer on 03/04/2011 18:20:00

Or maybe better said "knowing about the software issues, so ignoring them for the sake of the question(so we assume it would be fine), would the GPS device be able to tell me my position when on the moon?
 

...and the answer is still yes, although, as has been pointed out more than a few times, the accuracy would not be very good.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 03/04/2011 18:23:49

Or maybe better said "knowing about the software issues, so ignoring them for the sake of the question(so we assume it would be fine), would the GPS device be able to tell me my position when on the moon?
 

...and the answer is still yes, although, as has been pointed out more than a few times, the accuracy would not be very good.

No, Bored said no, I dont think it would either, there is a disagreement here.

It's a hand held device, that will not work indoors. It has the programming(as a given) but I do not think the reception capability.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 03/04/2011 19:18:03
Maybe if we knew the reception specs on the device.

What hand held GPS device is it, just a standard one I assume.

Lets go shopping:-

Weighing in at $259.99 it's the "Garmin GPSMAP 76CSx Handheld GPS Devices"
http://www.amazon.com/Garmin-GPSMAP-76CSx-Handheld-Devices/dp/B003PQHDX8
Quote
The GPSMAP 76CSx is designed for serious outdoor enthusiasts. Includes a built-in Americas autoroute basemap with automatic routing capabilities, including highways, exits, and tide data. Internal memory is preloaded with a marine point database. 1,000 user waypoints with name and graphic symbol; 50 reversible routes. Position formats include Lat/Lon, UTM, Loran TDs, Maidenhead, MGRS, user grid, and more. 10,000-point automatic track log; 20 saved tracks (500 points each) let you retrace your path in both directions. Trip computer provides odometer, stopped time, moving average, overall average, total time, max speed, and more. Elevation computer provides current elevation, ascent/descent rate, minimum/ maximum elevation, total ascent and descent, average and maximum ascent and descent rate. Navigation instructions can be shared with repeaters, plotters, and autopilots using NMEA protocols through the dedicated serial port. Built-in celestial tables for sun and moon calculations and the best times to fish and hunt. Compatible with most MapSource products. Large-numbers option for easy viewing; dual-position display mode. LED backlit display and keypad. New high-sensitivity WAAS-capable GPS receiver by SiRF acquires satellites faster and lets users track their location in challenging conditions, such as heavy foliage or deep canyons. Built-in quad-helix receiving antenna with remote antenna capability. Sensors: Electronic compass displays accurate heading while standing still. Barometric altimeter for extremely accurate elevation data. Includes a USB interface cable, MapSource Trip Waypoint Manager CD, lanyard, owners manual and quick-start guide. MicroSD card slot allows for storage of optional MapSource detail (128 MB microSD included). Battery life: 18 hours (typical use) using two AA alkaline batteries. Water resistant: The GPS case can withstand accidental immersion in one meter of water for up to 30 minutes. Unit floats w

Weighing in at $499.99 it's the "Garmin Oregon® 450"
http://www.zappos.com/garmin-oregon-450-t-n-a
Quote

■Hit the moon trail with the handheld Garmin® Oregon® 450T GPS equipped with a rugged, touchscreen along with preloaded topographic maps, 3-D map views, a high-sensitivity receiver, barometric altimeter, electronic compass, picture viewer and more.
■3" diagonal, sunlight-readable, color, touch screen display that offers crystal clear enhanced colors, high-resolution images and easy-to-use interface.
■Preloaded U.S. or European topographic maps, 3-D map view and a built-in worldwide basemap with shaded relief give you all the tools for serious climbing or hiking. Map detail includes national, state and local parks and forests, along with terrain contours, elevation information, trails, rivers, lakes and points of interest.
■Share your waypoints, tracks, routes and geocaches wirelessly other compatible Oregon®, Colorado® and Dakota® users.
■Barometric altimeter tracks changes in pressure to pinpoint your precise altitude.
■Geocaching-friendly: a high-tech version of hide-and-seek where you explore the outdoors in search of hidden treasure and adventure. Maintained by a worldwide community of geocachers, Cache locations are hidden high and low around the globe.
■Built-in 3-axis tilt-compensated electronic compass shows where you are heading even when you're standing still, without holding it level.
■Plot barometric pressure over time to keep an eye on changing weather.
■With a high-sensitivity, WAAS-enabled GPS receiver and HotFix™ satellite prediction, Oregon® 450 locates your position quickly and precisely and maintains its GPS location even in heavy cover and deep canyons.
■When connected to your computer and the internet, you can get a detailed analysis of your activities and send tracks to your outdoor device using Garmin Connect™.
■Additional Features:
•Automatic routing: turn by turn routing on roads.
•Electronic compass.
•Touch screen.
•Barometric altimeter.
•Custom maps compatible.
•Outdoor GPS games.
•Hunting and fishing calendar.
•Sun and moon information.
•Tide tables.
•Area calculation.
•Custom POIs: ability to add additional points of interest.
•Picture viewer.

■Maps & Memory:
•Basemap.
•Ability to add maps.
•Built in memory: 850 MB.
• Accepts microSD™ data card(not included).
•Waypoints: 2000.
•Routes: 200.
•Track Log: 10,000 points, 200 saved tracks.
■Waterproof (IPx7).
■Interface: high-speed USB and NMEA 0183 compatible.
■Requires 2 AA batteries (not included) for up to 16 hours of battery life.
■Dimensions: 2.3" W x 4.5" H x 1.4" D.
■Display Size: 1.53" W x 2.55" H.
■Display resolution (WxH): 240 x 400 pixels.
■Display type: transflective color TFT touch screen.
■Weight: 6.8 oz with batteries.
■Comes with:
•Oregon® 450T.
• Carabiner clip.
•USB cable.
•Quick start manual.

■Zappos Retail, Inc. makes every attempt to provide accurate information for each electronic product. Manufacturer packaging and specifications may be different from the information provided.

Please note, Zappos Retail, Inc. gladly accepts returns on all electronic products for up to 365 days from the original purchase date. In order to process your return and refund, returned electronic products must be unused and in the original condition and packaging in which it was purchased and include any manuals, cabling and accessories. Video Games, software, DVD and Blu-ray™ Disc must be returned unopened in their original shrink-wrap for a refund.

And last but not least
 
Weighing in at $149.99 it's the "Garmin eTrex Legend H Mapping Handheld GPS"
http://www.target.com/gp/detail.html/186-0199465-9889623?asin=B001OMGVJW&AFID=Froogle_df&LNM=|
Quote
•Mobile GPS Features: High-Sensitivity GPS Receiver, Sun/Moon Information, Built-In Base Maps, Hunt/Fish Calendar
•Mapping Features: Routes
•Points of Interest: 0
•Number of Waypoints: 1000
•Electronic Display Features: LCD Screen
•Display Size: 1.1 "
•Screen Resolution: 160 x 240
•Emergency Call Device: No
•Battery Life: Up to 18 Hours



Right so Top middle and bottom of the price range.

Basically I think we pick one, and then use that as the basis of the question. What do you think?

On the moon full battery, has the programs needed, could it get a signal and so give us a position?
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 03/04/2011 19:20:15
Not sure about no. three it has a calendar to hunt fish. Actually they all do.

But then no. 3, has 0 points of interest, and no call for emergencies device, although why you would want a device that gets you an emergency, I don't know.

Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 03/04/2011 19:49:38
Where is Cilla Black when you need her?

I think I'll go with no. 2. Price is no object is it.
It's WAAS.

 
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 03/04/2011 22:38:23
Where is Cilla Black when you need her?

I think I'll go with no. 2. Price is no object is it.
It's WAAS.


So are there any objections to going with the WAAS? no 2? It's WAAS so it'll be better than the older GPS hand held devices.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 11/04/2011 22:22:41
Have we still not decided on a GPS device? Money being no object and all I think for the sake of a far test we go with number one.

Ouu and I found these on youtube:

GPS 30 satalites 6 orbits of 4 per orbit, at a given time between 4 to 9 satalites can see a GPS reciever, on earth.

It shows a signal footprints at different sizes but I'm not sure how close they are.
Title: Would my GPS device work on the moon?
Post by: JP on 12/04/2011 02:21:37
Have we still not decided on a GPS device? Money being no object and all I think for the sake of a far test we go with number one.

Since it's your question, why not pick one from your list and ask how good a signal it can get from the moon?
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 12/04/2011 12:57:12
Have we still not decided on a GPS device? Money being no object and all I think for the sake of a far test we go with number one.

Since it's your question, why not pick one from your list and ask how good a signal it can get from the moon?

Already have number one, it's the middle price one.

Although though I am quiet sure even if it was adapted to deal with space and had the needed software, it's reception still wouldn't be good enought to pick up a signal, All three are W.A.S.S tho. So next generation and probably better than the orginal devices.
Title: Would my GPS device work on the moon?
Post by: Bored chemist on 12/04/2011 20:49:20
So, knowing that none of them will work, you have chosen one.
Fair enough.
Title: Would my GPS device work on the moon?
Post by: Jolly- Joliver on 12/04/2011 21:28:41
So, knowing that none of them will work, you have chosen one.
Fair enough.

Hey some were suggesting it could, I suggested choosing a device first to then know the reception specs. I even ungraded to W.A.S.S.

I still think it's a no, but then I'm not an expert.

You suggested some signal would reach the moon, so how much? I still debate that but... That's the point
Title: Re: Would my GPS device work on the moon?
Post by: Kirkaiya on 12/03/2013 23:13:37
So, knowing that none of them will work, you have chosen one.
Fair enough.

Hey some were suggesting it could, I suggested choosing a device first to then know the reception specs. I even ungraded to W.A.S.S.

I still think it's a no, but then I'm not an expert.

You suggested some signal would reach the moon, so how much? I still debate that but... That's the point

I know this is an old topic, but after reading the thread, it's clear that some of you were "talking past each other" (or, in fact, talking about different things).

There are two basic questions:

The answer to #1 is (fairly obviously) no. Hand-held or even boat or commercial aircraft GPS receivers don't have sufficiently large antennae, and in any case use chip-sets that are hard-coded for calculating positions inside a fixed range of possible locations.

The answer to #2, as Bored Chemist and others pointed out, is "probably yes".  Given that on the moon, one could construct an receiving antenna of arbitrary size, capable of receiving signals from GPS satellites; even with directional antennas, the strength of the signal heading away from the Earth would be far stronger a mere 260,000 miles away on the lunar surface than the strength of transmissions from Voyager and Pioneer probes were at Earth when the probes were transmitting from past Jupiter).   Since GPS satellites are not (all) in-plane with the moon, there would always be a triangle of them (at least) visible from the side of the moon facing Earth.  Caveats are that you'd need a large antenna, and you'd probably need a custom chip-set (or at least, custom software) to convert the time-pulses into useful coordinates, but since the original question said to ignore that, then yes, it's almost certainly possible to get some position (how accurate it might be is another question altogether).
Title: Re: Would my GPS device work on the moon?
Post by: Pmb on 12/03/2013 23:43:43
The answer to number two is still now. The GPS system wasn't designed for that. It is a system that is calibrated to earth orbits relating to earh bound recievers. The signals are meaningless to a receiver on the moon. For example: Suppose we constructed artificical moons around the earth each with different zeros if lat and long. How would the recievers be able to tell which one it was on? Remeber that it can't receive a signal if its on the opposite side of the earth either. Nope. The GPS system is for Earth based receivers only.
Title: Re: Would my GPS device work on the moon?
Post by: evan_au on 13/03/2013 09:34:23
Quote
if you were to put the GPS in a position beyond the orbits of the satellites, I think it would try to report a position within the orbits

With line-of-sight to 4 satellites and a strong signal, you can solve 4 equations in 4 unknowns, producing: X, Y, Z and Time (or Latitude, Longitude, Altitude & Time).

This will allow you to work out your correct position, whether it is inside or outside the satellite's orbit.
...so when you set up your Moon base, don't plan on saving a bit of money by taking the GPS receiver from your car on Earth.
 
Title: Re: Would my GPS device work on the moon?
Post by: Lmnre on 13/03/2013 14:39:59
If you could receive a decent signal and bypass the govt restriction about use in space, the receiver would triangulate a position in Earth coordinates — say, somewhere over the tropical Pacific Ocean, but at an altitude of about 1,250,000,000 feet. 
Title: Re: Would my GPS device work on the moon?
Post by: syhprum on 13/03/2013 18:03:46
Apart from the geometric and time of flight problems there is the problem of the received signal strength at 800 Km where the satellites operate the received signal strength is pretty marginal imagine how weak it would be at 400,000 Km
Title: Re: Would my GPS device work on the moon?
Post by: Bored chemist on 13/03/2013 22:18:47
The answer to number two is still now. The GPS system wasn't designed for that. It is a system that is calibrated to earth orbits relating to earh bound recievers. The signals are meaningless to a receiver on the moon. For example: Suppose we constructed artificical moons around the earth each with different zeros if lat and long. How would the recievers be able to tell which one it was on? Remeber that it can't receive a signal if its on the opposite side of the earth either. Nope. The GPS system is for Earth based receivers only.

Did you not read the earlier posts?
I pointed out that, while people were "designed" to work on earth they worked OK on the moon.

In principle the system would still tell you latitude (relative to Earth's equator) , longitude (Relative to Greenwich) and altitude (relative to the earth's surface).
That identifies a unique position in the universe so it tells you where you are.
It would, for example, be able to show you the way home.

In practice there would be problems, but the idea that it wouldn't work in space because it was designed to work on earth is absurd.
Title: Re: Would my GPS device work on the moon?
Post by: Don_1 on 14/03/2013 11:23:51
"At the next meteor, enter roundabout and take the third exit."



It would, for example, be able to show you the way home.


C'mon everybody, let's all sing........ ♫ I'm garmin home baby now.♫
Title: Re: Would my GPS device work on the moon?
Post by: Bored chemist on 14/03/2013 19:47:03
Would sound better with percussion: bongo drums or something.