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Does Cloud Cover Effect Gps Reception?


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Good study! It does make perfect sense, when you consider that GPSrs detect radio waves emitted from the orbiting satellites. The question is analogous to asking if a voice signal on your cell phone is changed due to clouds, or if my keyless entry will work during a rain storm.

 

Check out the chart below for some technical info about devices we use everyday.

 

Devices and their operating frequency within the radio wave spectrum:

Garage door openers, alarm systems, etc. - Around 40 megahertz

Standard cordless phones: Bands from 40 to 50 megahertz

Baby monitors: 49 megahertz

Radio controlled airplanes: Around 72 megahertz, which is different from...

Radio controlled cars: Around 75 megahertz

Wildlife tracking collars: 215 to 220 megahertz

MIR space station: 145 megahertz and 437 megahertz

Cell phones: 824 to 849 megahertz

New 900-MHz cordless phones: Obviously around 900 megahertz!

Air traffic control radar: 960 to 1,215 megahertz

Global Positioning System: 1,227 and 1,575 megahertz

Deep space radio communications: 2290 megahertz to 2300 megahertz

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Thanks for a interesting, thought provoking cache. Radio waves, regardless of frequency, travel at near the speed of light. The ionosphere and troposhere atmospheric layers can "bend" radio waves in varing degrees, due to the heating of the sun. Do you think this accounts for the slight differences in reported position? Do the satellites near the horizon have to travel thru more of the atmosphere, (0.00x) Or is it the different GPSr?

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This doesn't really mean anything. There's no true measure of accuracy or signal strength. You don't even indicate if you timed this so you would have the same satellite constellation over head each day. Or that the same satellites were always in service over the period of the test.

 

The only thing worse than anecdotal evidence is pseudo-scientific evidence.

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I read that heavy storms have been know to effect survey GPS by 2cm.

And considering some countries actually "move" 3 times more than per year, 2cm isn't as much of an issue either, especially considering that for survey type cm accuracy there must be at least 2 receivers and basically what generally affects one affects the other, dependent on separation distance.

 

Cheers, Kerry.

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This doesn't really mean anything. There's no true measure of accuracy or signal strength. You don't even indicate if you timed this so you would have the same satellite constellation over head each day. Or that the same satellites were always in service over the period of the test.

 

The only thing worse than anecdotal evidence is pseudo-scientific evidence.

Rather than bite on this obvious attempt at flame, let me direct you here: GPS Theory and Practice. B. Hofmann-Wellenhof, H. Lichtenegger, and J. Collins. Springer-Verlag Wien. New York.

 

If you want evidence, read it. Or, trust my summary: GPS technology is so impervious to normal weather effects, it is now being used to fly our missiles, our fighter planes, guide our ground troops, and drive remote hummers equipped for mine detection and removal. Iraq is all the evidence you should need.

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If you want evidence, read it.  Or, trust my summary:  GPS technology is so impervious to normal weather effects, it is now being used to fly our missiles, our fighter planes, guide our ground troops, and drive remote hummers equipped for mine detection and removal.  Iraq is all the evidence you should need.

 

And can you imagine how good it will be when they get more sats and better WAAS type coverage???

 

This doesn't really mean anything. There's no true measure of accuracy or signal strength. You don't even indicate if you timed this so you would have the same satellite constellation over head each day. Or that the same satellites were always in service over the period of the test.

 

The only thing worse than anecdotal evidence is pseudo-scientific evidence.[END QUOTE]

 

Geees, we try to setup a different type of cache with a lopsided attempt to see how different people at different times with different types of equipment get their readings from sats that are moving around in the sky and we get..........

 

It don't prove nuttin. And that's right. It hasn't proven a dadgum thing cept that cloud cover doesn't effect a GPSr. And that's the point of the whole thing.

 

Edited because I wasn't done yet

Edited by Rosco Bookbinder
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GPS technology is so impervious to normal weather effects, it is now being used to fly our missiles, our fighter planes, guide our ground troops, and drive remote hummers equipped for mine detection and removal. Iraq is all the evidence you should need.

The military only expects 30 meters of accuracy. There were alot of missed targets in Iraq.

I definitely want to get closer than 30 meters.

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The military only expects 30 meters of accuracy.

 

If you're talking about "Selective Availability" (SA) you're almost right. It's accurate to 150 feet. However, as I'm sure you know, this feature can be enabled/disabled. Current legislation prevents enabling of this feature, and as a result we have the current, industry accepted 2meter accuracy.

 

As for military expectations, believe what you will. All I can say is you're wrong. GM-130 Missile, AGM-154 Joint Standoff Weapon, AGM-158 Joint Air-to-Surface Stand-Off Missile... are three unclassified weapons that come to mind that rely on GPS technology. The unclassified, listed accuracy for these is 3 meters (if gov lore is to be believed, this number is inflated by a factor of 8).

 

Edit: the above military info is as of 1999 by the way; thats 5 years ago, if you are counting...

Edited by CacheCreatures
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Yeah but guided missiles of generally all varieties do not solely rely on GPS and actually have several navigation systems, which either co-exist or take over as required.

 

.... and as a result we have the current, industry accepted 2meter accuracy ...
says who? possibly go take a read of the Global Positioning System Standard Positioning Service Performance Standard, october 2001 2 meters indistry accepted standard, be buggered.

 

If anybody wants a correct definitive of some of the actual affects then Try this light reading but recreational receivers will certainly not be able to determine cloud type issues one way or another.

 

 

Cheers, Kerry.

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Click on the following link to see the results (so far) of our experiment......

 

GPS Service Cache

I thought the claim was that clouds would affect signal strength. When coupled with other local problems (like tree cover) that could mean that you can't get a good lock.

 

You seem to have shown that under good reception conditions it doesn't make any difference in position, but that doesn't mean the signal was the same strength.

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Hehe nice read. You might want to note, though, that the paper characterizes the worst case, one direction effect as being 20mm, or 2cm; far beyond the current capabilities of consumer GPSrs.

 

Also, those other guidance systems you refer to are redundant in the case of main navigational failure. Why have 1 system when you can have 2 at twice the price?

 

As for the industry standard, perhaps I spoke out of turn. I'll rephrase and say the 2 meters is the current goal of consumer grade GPS.

 

Really, this and all your other questions can be answered here: http://gps.faa.gov I mean, they are using GPS to guide airliners down into weather so bad mountains cannot be seen.

 

And to quote a very wise man: "...thats all I have to say about that."

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This doesn't really mean anything. There's no true measure of accuracy or signal strength.  You don't even indicate if you timed this so you would have the same satellite constellation over head each day. Or that the same satellites were always in service over the period of the test.

 

The only thing worse than anecdotal evidence is pseudo-scientific evidence.

Rather than bite on this obvious attempt at flame, let me direct you here: GPS Theory and Practice. B. Hofmann-Wellenhof, H. Lichtenegger, and J. Collins. Springer-Verlag Wien. New York.

 

If you want evidence, read it. Or, trust my summary: GPS technology is so impervious to normal weather effects, it is now being used to fly our missiles, our fighter planes, guide our ground troops, and drive remote hummers equipped for mine detection and removal. Iraq is all the evidence you should need.

Excuse me, but where in my message am I claiming that clouds effect GPS signals? My comment was about the "experiment".

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.... characterizes the worst case, one direction effect as being 20mm, or 2cm; far beyond the current capabilities of consumer GPSrs.

 

That's about it so any conclusions about cloud one way or the other based on consumer receivers is totally irrelevant, meaningless and whatever one wants to label it.

 

Also, those other guidance systems you refer to are redundant in the case of main navigational failure. Why have 1 system when you can have 2 at twice the price?

 

So what's a main navigation failure? Inertial systems in essence are really the the brains in accurate guidance hence the general term is "GPS aided Inertial Navigation System" and in any case accuracy is one thing but one must also know quite accurately exactly where one wants to actually put the thing.

 

.... I'll rephrase and say the 2 meters is the current goal of consumer grade GPS

 

The thing is industry doesn't control the system that provides the signal in the first place. As with all accuracy it comes at a cost be it SBAS augmentation, standard differential or whatever. Consumer grade GPS won't even begin to approach 2 metres until the new civil freq are up and running.

 

... I mean, they are using GPS to guide airliners down into weather so bad mountains cannot be seen.

 

GPS? no technically they are not and neither can GPS (as such) land a FA-18 on a carrier under auto-pilot but that also can be done but that's not simply "GPS" either and we can go further into that any time.

 

Cheers, Kerry.

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If its one thing I hate, it's arguing facts. At this point, if anyone is still interested, please do some research for yourself and don't just trust what you read here. This isn't some arbitrary, ambiguous ether derived technology that behaves in a mysterious and subjective way. Its limitations are known, as are its uses and applications.

 

The study is a good one because it makes no claim at completeness, nor global validity. It seems like it was a fun thing to do for a given set of circumstances.

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If its one thing I hate, it's arguing facts. At this point, if anyone is still interested, please do some research for yourself and don't just trust what you read here. This isn't some arbitrary, ambiguous ether derived technology that behaves in a mysterious and subjective way. Its limitations are known, as are its uses and applications.

 

The study is a good one because it makes no claim at completeness, nor global validity. It seems like it was a fun thing to do for a given set of circumstances.

CacheCreatures......

 

Thanks!! :)

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While the GPS signal itself is not hammpered by clouds or rain, it is quite possible that the extra water in and on the overgrowth can cause signals to be blocked more than normal.

 

So.... while out in the open you should notice no difference, when under a canopy of trees you could very well notice a big difference.

Wet trees and also depending on the type of tree are more reknown for causing multipath issues, even can occur out in the open but again the effects that could/might cause issues with recreational receivers, well that's rather difficult to actually prove with this technology

 

For something factual, anybody like to list the current equipment that is actually certified for aircraft use for some of the conditions claimed, the spec's might interest some even though there isn't that many to list.

 

The study is a good one because it makes no claim at completeness, nor global validity. It seems like it was a fun thing to do for a given set of circumstances.
Fun thing to do, might be but really a waste of time, and that's a fact.

 

Cheers, Kerry.

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Fun thing to do, might be but really a waste of time, and that's a fact.

Since when did it stop being fun no matter what kind of cache it is? Some people like to log a cache just for the fun of it. Others like the different approach to caching other than having to wack weeds and roll rocks. And yet others just may be interested in what others report using the same exact location under different weather conditions.

 

We all know how often it's said............."My GPS was jumping around because it was cloudy"........No one has said that yet during this experimental setup and we've had sunny days and snow storms while it was being done. Given the fact that there is NO tree cover has a direct bearing on it. That is why we are going to do another one under canopy. Just enough to see what happens there. I'm sure there will be some out there on this forum that don't see this as a scientific approach to the true measure of GPS reception. Look up the GC # of the cache we are doing now and the one later and put it on your DON'T DO List.

 

Happy caching all. :)

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Rosco, sure all this type of stuff might be fun but really reality must start and stop somewhere. Attempting experiments like this with equipment like this really doesn't prove a thing and I'm sorry but that's simply the way it is and there can be absolutely no conclusions made by doing this.

 

Technically GPS is affected by weather conditions and weather forecasting actually uses GPS in determining weather conditions but for a similar question asked here then the answer is No.

 

There has been an extreme amount of work done on issues like this as if there really were major issues with clouds, rain etc then there would be some fairly major problems accepting and using GPs especially in critical safety-of-life situations.

 

But your right this ............."My GPS was jumping around because it was cloudy"........ comments comes up time and time again similar when a user doesn't have a signal then ....."they must have turned the signal off 'cause of the war" ..... and all these types of comments really need to be squashed before some tturn myth in belief.

 

As for under tree cover now that's a totally different issue again to weather related matters and probably more of make comparison (as such all things being equal) than a system thing but again GPS being very dynamic unless ALL the users do the trial under the exact same conditions (satellite conditions, satellite geometry, same satellites etc) then what does it really mean? What I'm trying to say is, if someone rolls up with a perfect 10-12 satellite geometry visible through some convienient gaps in/under/through the tree and 30 minutes latter someone rolls up with when only 5 sat are visible and all obstructed by branches etc then what will the deduction be? The tree, the GPS, the User, the System, the Time etc and one reason why system spec's are Signal-In-Space (SIS) as the owners/operators have absolutely no control over some of the things people want/expect to do with GPS.

 

One of the most important things a user can do especially when working in obstructions (trees, buildings etc) and even out in the open to some extent is being where one has to be (wants to be) at the right time to take advantage of the best conditions possible.

 

Cheers, Kerry.

Edited by Kerry.
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Rosco, sure all this type of stuff might be fun but really reality must start and stop somewhere. Attempting experiments like this with equipment like this really doesn't prove a thing and I'm sorry but that's simply the way it is and there can be absolutely no conclusions made by doing this.

And I agree 100%. I've found many caches where I didn't even need the GPS so what's the point in having one. Just do the 1x1's with good spoilers and pictures and stuff......... :D

 

Just kidding.

 

I do realize that it's not a scientific study we are doing. It's not even close. And that's not the issue here. There has to be some element of truth to the study though when people see that on a miserable day when it's snowing and the wind is blowing that they came up with the same numbers as we did to start with on a bright and sunny day. It's got to prove something. The only real thing it proved is that those people that came out there that day are true to live cacher dashers.. :D

 

In the spirit of caching and having something to do that's a bit different is what draws people. What they get from it is up to them. Just like some people love doing puzzle caches. Some don't. Some like multi's and some don't. I like all aspects and since starting this hobby/sport only 4 1/2 months ago I have learned a lot about caching. Do what you want and the people will show up that want to...

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Rosco,you'll never stop people reading too much into things at times,so don't go beating your head against the wall,it'll just start to hurt.

If the cache was nearby,i'd do it.If for nothing else than to simply enjoy what this is all about...having FUN. :D

It already hurts. It's way past my bed time... :D

 

Thanks for your support and comments

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