Would my GPS device work on the moon?

Pumblechook · « **Reply #40 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.

Jolly- Joliver · « **Reply #41 on:** 02/04/2011 20:30:29 »

Quote from: 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.

And point it in the moons direction, I still do not think any of the current signals get to the moon at all.

Pumblechook · « **Reply #42 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.

Bored chemist · « **Reply #43 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.

CliffordK · « **Reply #44 on:** 02/04/2011 21:56:06 »

Quote from: Wiybit on 02/04/2011 19:39:18

Quote from: CliffordK on 02/04/2011 18:37:18

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.

Jolly- Joliver · « **Reply #45 on:** 02/04/2011 22:08:41 »

Quote from: 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.

Oh yes you did!

Quote from: Bored chemist on 02/04/2011 21:20:01

"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?

Quote from: Bored chemist on 02/04/2011 21:20:01

"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.

Jolly- Joliver · « **Reply #46 on:** 02/04/2011 22:14:45 »

Quote from: CliffordK on 02/04/2011 21:56:06

Quote from: Wiybit on 02/04/2011 19:39:18
Quote from: CliffordK on 02/04/2011 18:37:18

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.

Jolly- Joliver · « **Reply #47 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"

Jolly- Joliver · « **Reply #48 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.

Bored chemist · « **Reply #49 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.

Jolly- Joliver · « **Reply #50 on:** 02/04/2011 22:51:26 »

Quote from: 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.

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!

Quote from: Bored chemist on 02/04/2011 22:42:02

"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?

Madidus_Scientia · « **Reply #51 on:** 03/04/2011 06:26:18 »

Quote from: CliffordK on 02/04/2011 18:37:18

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.

Geezer · « **Reply #52 on:** 03/04/2011 06:35:34 »

Quote from: Madidus_Scientia on 03/04/2011 06:26:18

Quote from: CliffordK on 02/04/2011 18:37:18
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.

I think you are quite correct. We only see one hemisphere of the Moon from Earth, but both hemispheres are illuminated by the Sun.

Madidus_Scientia · « **Reply #53 on:** 03/04/2011 06:36:33 »

Quote from: Wiybit on 02/04/2011 22:51:26

Quote from: 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.

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?

Geezer · « **Reply #54 on:** 03/04/2011 06:45:07 »

Quote from: Madidus_Scientia on 03/04/2011 06:36:33

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.

Madidus_Scientia · « **Reply #55 on:** 03/04/2011 07:45:19 »

Did someone say black helicopters?! Where?! where are they!? Where's my aluminium foil

Jolly- Joliver · « **Reply #56 on:** 03/04/2011 10:20:24 »

Quote from: Madidus_Scientia on 03/04/2011 06:36:33

Quote from: Wiybit on 02/04/2011 22:51:26
Quote from: 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.

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 from: Madidus_Scientia on 03/04/2011 06:36:33

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.

Madidus_Scientia · « **Reply #57 on:** 03/04/2011 10:25:05 »

They do not. They transmit to the nearest tower, and from there the signal is forwarded elsewhere.

Jolly- Joliver · « **Reply #58 on:** 03/04/2011 10:49:35 »

Quote from: 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.

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

Madidus_Scientia · « **Reply #59 on:** 03/04/2011 10:57:19 »

We weren't talking about satellite phones.

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Would my GPS device work on the moon?

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