GPS signal blocked by auto windshield?

March 14, 2003

When I was researching ‘which’ GPS unit to get… I recall reading several threads on the pros/cons of getting an optional external antenna because ‘some’ auto windshields are apparently constructed such that they effectively filter the satellite signal to the GPS unit.

I was wondering what the consensus is out there regarding this windshield filtering issue so far as make/model of auto is concerned.

I’ve got a 2002 Toyota Sequoia and have not noticed any problems establishing a firm lock on the satellites while on the road.

What about the rest of you folks?… are you driving a filter… or not??

Regards,

Rasstag

"Remember... nothing is completly worthless!!... it can always be used as a bad example"!

March 14, 2003

I have used my GPS receivers in my car, in many of my friends' cars, and in dozens upon dozens of rental cars. Not once have I found a windshield that blocked GPS signals. Unless the glass has some sort of bizzarre metallic coating (in other words, Gangsta' Tint), there should be no problems.

--

Scott Johnson (ScottJ)

5.3k · March 14, 2003

I'm glad Scott has had no problems, but the problem does exist. It may not block all of the signal, but it may have an effect.

THIS LINK lists models that have metallic coatings on the windshield. The link comes from Joe Mehaffey and Jack Yeazel's GPS Information Website, a GREAT resource.

"Just because I don't care doesn't mean I don't understand."

[This message was edited by Stunod on March 14, 2003 at 08:37 AM.]

March 14, 2003

My Pontiac Transport Van has this type of windshield. I've got 5 gpsrs, & not one will hold a signal when on the dash. Went the external antenna route(the coating is visible,& there's no coating up in either upper corner of the windshield) & works it out fine.

"Gimpy"

--KC2KNI--

March 14, 2003

Mine has a heated front windshield with wires running through the entire windshield and this causes mine to have issues without the external antenna. It can get a signal through the windshield, but it can't hold it as well as when the external is attached.

March 14, 2003

I am using a Meridian Platinum in a VW Sharan with heated front windshield just on the dash without any problem.

Ed

quote:
Originally posted by 01ROVER:
Mine has a heated front windshield with wires running through the entire windshield and this causes mine to have issues without the external antenna. It can get a signal through the windshield, but it can't hold it as well as when the external is attached.

March 14, 2003

I have a '90 Pontiac Transport that kills signals dead. Does the same for the toll-road transponders.

Also have a '94 Chevy Lumina which doesn't hinder GPS reception but still prevents use of an interior toll-road transponder.

The windshield of the Transport is just plain huge. Uses an aluminum screen (I'm told) to help provide strength.

24.7k · March 14, 2003

quote:
Originally posted by Gimpy:
My Pontiac Transport Van has this type of windshield. I've got 5 gpsrs, & not one will hold a signal when on the dash. Went the external antenna route(the coating is visible,& there's no coating up in either upper corner of the windshield) & works it out fine.

"Gimpy"

--KC2KNI--

Ditto. I have a Pontiac Montana and the Film in the front windhself blocks signals. To use the GPS I have to hold it by a side window.

Wherever you go there you are.

March 14, 2003

If one looks carefully, it is easy to see the fine-mesh dark screen that covers most, but not all, of the windshield in our Chevy Venture minivan. My Vistas work fine through the side windows, but pick up almost nothing on the dashboard. No problem on the dash of my Buick Regal.

March 15, 2003

I have a S10 Blazer and the signal is spotty at best on the dash, if I place GPS to sides of windshield or to a side glass it works just fine. On the dash the it seems the signal comes and goes at will.

March 16, 2003

Get a Jeep Wrangler with a rag top. Works like a charm (excepting under heavy tree cover).

March 18, 2003

Adding to the excellent link Stunod provided, some other european cars have to be mentioned. This are cars not not sold to the US, like brands as Renault (scenic, laguna) and Opel/GME (Zafira, Omega). Its all about metallic films covering the windshield to protect the car from heating up in the sun.

In my Scenic I have reception only through the side windows. So I use for caching tours my old and rusty Ford.

9.2k · March 18, 2003

quote:
Originally posted by rayt333:
I have a S10 Blazer and the signal is spotty at best on the dash, if I place GPS to sides of windshield or to a side glass it works just fine. On the dash the it seems the signal comes and goes at will.

I have a '98 Blazer, and get excellent reception.

March 19, 2003

I don't know if this would apply to the older Luminas, but our 98 Chevy Venture had the radio antenna built into the windshield. Look at one the next time you see one, you will not find an external FM antenna. Maybe this "in the windshield" design is what causes some problems. This would apply to Chevy Ventures, Pontiac Montanas and Oldsmobile Silhouettes.

Beagle

As soon as you idiot proof something, they go and make a better idiot!

March 20, 2003

I have a Toyota Tundra which is basically the same core vehicle. I have no problem with signal on my etrex legend. Good Luck

March 21, 2003

I'm glad my Honda doesn't have any crap on/in the window to block my signal.

March 21, 2003

1996 Ford Contour GL w/ Garmin Geko 101 works perfectly.

William Barnhill

"NuclearWinter"

http://www.friedsilicon.net

March 23, 2003

quote:
Originally posted by hinds2010:
Get a Jeep Wrangler with a rag top. Works like a charm (excepting under heavy tree cover).

The Jeep or the GPS?

Opinions based on experiences with eTrex Vista...

March 28, 2003

I drive a Chevy Venture and when my GPSR is on the dash I lose virtually all reception, I think it has something to do with the windshield and the radio antennae.

March 29, 2003

Honda Civic - GOOD

Chevy Lumina APV - BAD

Tip for APV users the big main windshield blocks the signal, but the two side windshields are GPSr friendly.

GPSr's...A step in the right direction!

March 29, 2003

We have a 2001 Grand Prix and my Mereidian Gold works great in it. It even works sitting on the seat.

Altree

(you will not starve with a p38 and a can of food)

March 29, 2003

I think the angle and shape of a windshield can be a problem. After all, gps signals are only light waves (radio waves are light waves!), and will be reflected and distorted more easily by a sharply inclined and curved windshield. I have a 94 t-bird and notice signal loss under the center of the glass compared to the sides.

March 29, 2003

Radio waves are not light waves and are not reflected by glass unless that glass contains some type of metallic material. Radio and light waves are both part of the electromagnetic spectrum but are certainly not the same thing.

March 30, 2003

quote:
Originally posted by dotnet:

quote:
Originally posted by hinds2010:
Get a Jeep Wrangler with a rag top. Works like a charm (excepting under heavy tree cover).

The Jeep or the GPS?

No problems with any of the Jeeps (Grand Cherokee) here, either. I prefer the plain, old-fashioned windshield (with hot air blowing on it for defrosting).... keeps it simple and less expensive.

By the way, the Jeep Wrangler works like a charm under heavy tree cover.... unless the trees are too close together .

March 30, 2003

Well , I suggest you read a beginners physics book. All radio waves are light waves, just in a part of the spectrum we can't see. Radio waves are reflected just like light waves, because they are light waves. You can see through your windshield when looking strait through it, the light can be distorted and reflected at an angle. The curvature of a windshield can refract (bend) the light so that images (and radio waves) can be distorted. That's why some people report that they get gps reception through their side windows but not thier curved windshield. Just elementary physics, man.

24.7k · March 30, 2003

quote:
Originally posted by BeDoggy:
Well , I suggest you read a beginners physics book. All radio waves are light waves, just in a part of the spectrum we can't see. Radio waves are reflected just like light waves, because they are light waves. You can see through your windshield when looking strait through it, the light can be distorted and reflected at an angle. The curvature of a windshield can refract (bend) the light so that images (and radio waves) can be distorted. That's why some people report that they get gps reception through their side windows but not thier curved windshield. Just elementary physics, man.

You are close, but not quite there. Regardless. Ventures, Montanas, and Silloetes (sp?) all have a film in the windsheld that block GPS Signals. This film is visible and you can also see the break in it near the top of the window. That break allows garage door openers to function when they are stored in the overhead console.

Wherever you go there you are.

March 30, 2003

you might want to pick up a re-radiating rod. I have one in my pickemup truck and have no trouble. I did however have trouble before this ROD came into my life.

-hitekredneck

-Lock & Load. then shoot it a few more times for fun

March 30, 2003

Hey BeDoggy, thanks for a good laugh

March 30, 2003

Whatever. Obviously by "light" you mean visible light. Even top astronomers refer to radio signals as light. I have met radio astronomers who refer to radio signals as light. Now of course definitions vary. If by "light" you mean infrared to ultraviolet, then radio waves aren't light. But in the way they behave they are light. Here's a way to say it... "nothing can travel faster than light" If radio waves travel at 186,000 miles per second, they are light! They are subject to the laws of physics as light is. They can be bent by gravity, distorted through refraction, and blocked by objects which of course was my point.

Of course you will laugh again. Ok. Check this out....

www.astronomynotes.com/light/s3.htm

Thank YOU for the laugh....he he

BeDoggy

March 30, 2003

You should really do something about that inferiority complex you have.

March 30, 2003

Sore Loser, Poindexter.

6.4k · March 31, 2003

quote:
Originally posted by BeDoggy:
Whatever. Obviously by "light" you mean visible light. Even top astronomers refer to radio signals as light. I have met radio astronomers who refer to radio signals as light. Now of course definitions vary. If by "light" you mean infrared to ultraviolet, then radio waves aren't light. But in the way they behave they are light. Here's a way to say it... "nothing can travel faster than light" If radio waves travel at 186,000 miles per second, they are light! They are subject to the laws of physics as light is. They can be bent by gravity, distorted through refraction, and blocked by objects which of course was my point.

Of course you will laugh again. Ok. Check this out....

http://www.astronomynotes.com/light/s3.htm

Thank YOU for the laugh....he he

BeDoggy

You should REALLY read what you refer to for proof. From your link:

quote:
Light, electricity, and magnetism are manifestations of the same thing called electromagnetic radiation.

That does NOT mean radio waves are light.

By your logic: men and dogs are both mammals, so all men are really dogs (I hear you women snikering!). Or, because I can run 15MPH, alongside a bird flying 15MPH, I must therefore be a bird.

Why doesn't your logic work the other way? Maybe light is REALLY radio waves. Lets see, if I go in my closet and close the door, no light can get to me, yet my FM radio works fine. Explain that? I'll tell ya why.

Radio waves and light have different wavelengths, and different wavelengths behave differently. Even radio waves at different frequencies behave differently. Longer wavelengths like MF(AM radio) tend to follow along the ground, and will follow the curvature of the earth. Shorter ones like VHF (FM radios) tend to go more in a straight line, so instead following the curvature or the earth, they go straight off into space. Shorter ones still (SHF or Microwave) go in such a straight line, the antennas need to be pointed at each other line of sight to work.

If the radio waves that a GPS picks up are reflected away by a curved piece of glass, how could they possibly penetrate the (curved) watertight sealed shut GPSr to reach the antenna inside? The answer is that electromagnetic radiation in that part of the radio spectrum does not behave the same as electromagnetic radiation in the light spectrum. The signal at that frequency has no trouble penetrating glass or plastics, but does have a problem with metal and water. The metallic coating on some heated or reflective windshields is the problem with some cars, and the moisture in tree limbs and leaves is your problem in the woods.

I see you have an interest in astronomy, and perhaps you are confused because stars emit huge amounts of electromagnetic radiation in both the light and radio spectrum. Astronomers oten use radio waves to listen for stars, because radio waves can sometimes penetrate the earth's atmosphere better then light can.

Lots of people here (myself included) come from electronic and radio backgrounds. We're only trying to show you where you're wrong. I was required BY FEDERAL LAW to understand how electromagnetic radiation in the radio spectrum behave before I could get my FCC license. This is the best I can do without handing you a 400 page textbook. Put down your astronomy books for a few hours and google on radio wave propagation to learn for yourself how radio waves behave differently then light waves.

Tae-Kwon-Leap is not a path to a door, but a road leading forever towards the horizon.

1.4k · March 31, 2003

I don't know about the dog and bird part, and I'm no expert on light and radio waves but the rest of this sounds pretty reasonable.

Thanks for the lesson Professor Mopar.

-----

March 31, 2003

Hey Mopar, you took the words right out of my mouth. Now I can bow out of this debate. I too am an FCC licensed technician as well as an extra classed ham with 27 years in the electronics field. I could say more about this guy but I think I'll just clam up...with a grin

March 31, 2003

quote:
Originally posted by appletree:
If one looks carefully, it is easy to see the fine-mesh dark screen that covers most, but not all, of the windshield in our Chevy Venture minivan. My Vistas work fine through the side windows, but pick up almost nothing on the dashboard. No problem on the dash of my Buick Regal.

Thank you so much for posting that comment. I just got my first GPS unit, a Vista, and I was completely frustrated by the lack of signal lock from any more than maybe one satellite while driving and holding the unit under my Chevy Venture's front windshield. I think that mesh is the radio antenna, IIRC. I'll try it out the side-window (clearly can't drive and use it well).

Geosaur :: Geocaching Lizard

March 31, 2003

Anyways, this is getting silly. That radio waves are a form of light is beyond dispute. Unless you wish to dispute top physicists and astonomers. Even Einstein. That visible light and radio are different in many ways is also beyond dispute. You may have had to study a "400" page text book, but eminent scientists who have spent their whole lives studying the properties of physics say that radio is a form of light. A couple of you guys claim to be "fcc licenced techs" Whoop defriggindoo. Thats like saying a computer tech really understands how to design microchips, or the cable guy can design plasma televisions.

I don't claim to be an expert, but trust the people who are acknowledged to be. I could send you literally DOZENS of articles by various physics depts of major universities where it is stated PLAINLY that radio is a form of light. Einstein said so, thats good enough for me.

Visible light penetrates glass, but would you maintain that glass cannot reflect light? Simple observation shows that it can. Gps signals are reflected by metal. A sharply inclined and highly polished pane of glass is reflective like metal, both with visible light and varieties invisible. Tilt a plane of glass and see. Radio penetrates some solid matter, but not all, or to the same degree. Ever lost gps signals under tree cover? Beside a rock face? Are you saying that gps signals can't be reflected or refracted? That line of sight plays no part? If they follow the laws of physics they can and must. Or was Einstein full of H.S.?

As for the cases of gps units they are made of plastic, not glass. Plastic is far more transparent to radio than glass.

As for radio, have you never heard of people catching radio bounces from places that are very far away and definately not in the line of sight? The reason is reflection by layers in the atmosphere. Radio is susceptible to reflection and distortion by the atmosphere as visible light is, so I simply suspect that under the right conditions radio can be reflected/distorted by glass as visible light is.

Of course the conditons must be different than for visible light. Is it unreasonable to expect that gps signals could be reflected by a sharply inclined pane of glass? Maybe not totally but perhaps enough to cause a disruption in a weak signal. Which was my point. I didnt say that an inclined or curved windshield was the whole or even major reason for lost gps signals, just that it may be a factor. It is even possible that some batches of glass contain higher trace amounts of metallic elements that make it more difficult for radio to penetrate or cause it to be reflected. All I did was make a suggestion and some people tried to roast me for it(I've had far worse comments from others on my private E-mail)

This is horsesh*t and not worthy of my time. All I wanted to do was get involved in the discussion boards and got tackled by a bunch of elitist A-holes.(you guys who posted on the public board are amongst the most mild, believe it or not) I have too much of a life to waste too much time here splitting very thin hairs with people who want to think in small, narrow ways. You have your beliefs and not even a sledgehammer would disuade you from beliefs you have always held and cherished. You will read articles and glean from them only what YOU want to, Which I suppose is the mark of an unteachable fool. I suppose some will feel the need to dissect all this, take it out of context, and make cracks about it on the board. Thats fine. Go on and do it, I'll go on reading what Einstien had to say and leave you to be the big fish in a very small bowl.

March 31, 2003

Primarily to BeDoggy, I just wanted to explain why maybe you feel beat up by the elite so to speak regarding this subject. (I saw the other thread) Part of it may have to do with stating as an absolute fact, something that isn't in fact accepted fact by all, or even most. (How's that for a phrase )

Working in the electronics industry, I have a fairly good collection of Physics, and electronic books at home, and access to many of them at work as well. None of them define light as the entire electromagnetic spectrum. As somewhat of an amature astonomy buff, I have seen it described that way in some of my astonomy mags however. In electronic and physics books, you'll generally get a definition saying something like this:

"light: In a strict sense, the region of the electromagnetic spectrum that can be perceived by human vision, i.e. , the visible spectrum, which is approximately the wavelength range of 0.4 um to 0.7 um. (188) Note 1: In the laser and optical communications fields, custom and practice have extended usage of the term light to include the much broader portion of the electromagnetic spectrum that can be handled by the basic optical techniques used for the visible spectrum. Note 2: The region embraced by the term light has not been clearly defined, but by convention and usage, is considered to extend from the near-ultraviolet region of approximately 0.3 um, through the visible region, and into the mid-infrared region to approximately 30 um."

Just out of curiosity though, I also asked a couple design engineers as there are many around where I work. They both describe "light", as a subset of the electromagnetic spectrum.

Not trying to be elitist, just pointing out that your definition of light isn't the accepted definition in the electronics industry.

Because of that, you'll find many who don't accept your astronomy based definition as fact.

That said, had you used the term electromagnetic radiation instead of "light" this whole thread would probably have been about wavelengths, and whether or not glass was opaque, transparent, or in between to it.

March 31, 2003

I think the simple answer to this whole mess is that glass is not used manipulate radio waves.

I build telescopes and also do some radio work...there just isn't much practical overlap between optics and radio.

George

April 1, 2003

BeDoggy:

Wow, you really do have a serious problem. If you really think you know everything and can never admit when your wrong or even consider that you might be, and must ramble on and on just to satisfy yourself, I suggest you stay out of these forums.

6.4k · April 1, 2003

I gotta go with searching-ut and poindexter on this. Your problem Bedoggy, goes back to the example I put in my earlier post. Just because A=C, and B=C, does NOT mean that A=B in this case.

Just because lightwaves = electromagnetic radiation, and radiowaves = electromagnetic radiation does not mean that therefore radiowaves = lightwaves. Again, just because dogs = mammals and human = mammals does not mean dogs are human.

You seem to think electromagnetic radiation is a form of light, where the CORRECT answer is light is a form of electromagnetic radiation.

You contention that glass and plastic react so totally different to RF is laughable to anyone who knows the tiniest bit about radio. Plastic and glass are virtually invisible to radiowaves so the actual shape of the glass has no bearing.

The fact that you are so closed in your own little distorted world of science that you can't even understand something as simple as this would be funny, if it wasnt so scary.

Tae-Kwon-Leap is not a path to a door, but a road leading forever towards the horizon.

24.7k · April 1, 2003

Let's make it simple.

Light doesn't penetrate through a carboard box.

X-rays do.

Don't give a a rash that some light does, I KNOW that but not as much as X-rays.

Gee, maybe they have different properties even if they are all Electro Magnetic Whatsit who the hell cares about the nomenclature unless you are writing a paper waves.

Wherever you go there you are.

April 1, 2003

I still don't see why everyone is so concerned about absolute definitions here. People may be stubborn for whatever reason on the issue, but it doesn't mean they are completely wrong. To me, the issue seems to be with the ever changing English language. I don't see anyone being completely right or wrong on this issue, and don't really see attacking individuals as constructive. Scan the web, you'll find that some, especially in the astronomy field, do describe the entire spectrum as "light", while others define light as a specific portion of the spectrum.

Whatever they choose to call it, the distinctions are becoming less and less over time. I get amazed at some of the strides they're making in imaging technology. First, light amplification to see better at night. Not good enough, lets expand the spectrum a little, take in more data we can shift to visable. Of course that doesn't see through walls etc, so now they're working on shifting other parts of the spectrum to something we can view.

Anyway, it was looking like my previous posting was kind of a beat up Bedoggy thing. I was just trying to point out that the stubborn insistance of being absolutely right was not necessarily useful for getting the point across. At the same time, I don't see insisting he is absolutely wrong is correct either. The definition of the term "Light" doesn't appear to be absolute to me, but varies with the target audience.

April 1, 2003

quote:
Originally posted by Searching_ut:
... To me, the issue seems to be ...

Gentlemen (..and Ladies),

Actually, the issueis “GPS signal blocked by auto windshield?”. Had I known I was posting such a controversial and emotionally charged question I may have reconsidered.

Thank you all that responded to my ‘question’.

(.. now sitting back and taking deep breath..)

Rasstag

April 1, 2003

I can confirm that my eTrex Vista barely works in my wife's Oldsmobile Silhouette minivan that has a radio antenna built into the windshield, while I've had no problems on other cars.

April 1, 2003

And that vehicle is on the list of vehicles with special windshields that contain metal in the glass.

April 1, 2003

I just looked at that list. My car is on it, but I don't any trouble with my GPS at all.

George

April 1, 2003

quote:
Originally posted by BeDoggy:
I think the angle and shape of a windshield can be a problem. After all, gps signals are only light waves (radio waves are light waves!), and will be reflected and distorted more easily by a sharply inclined and curved windshield. I have a 94 t-bird and notice signal loss under the center of the glass compared to the sides.

I've got a '96 bird and have my MeriGreen suction cupped to the center of the glass w/o any problems..the top of the unit is almost touching the windshield....however I used to have problems with a II+ when I used to have it on the dash directly below the place where my MeriGreen resides now. I never thought about it, but I wonder if the windshelds on our T-birds effect the signal enough to where it's ok right at the windshield, but about 8" down the signal has been messed up. Hmmmm.

Mr. 0

"Remember that nature and the elements are neither your friend or your enemy - they are actually disinterested."

Department of the Army Field Manual FM 21-76 "Survival" Oct. 1970

24.7k · April 1, 2003

quote:
Originally posted by nincehelser:
I just looked at that list. My car is on it, but I don't any trouble with my GPS at all.

George

My Montana is a 2000. Is your's old enough to not have the film in the window? Or did you get one that doesn't...Or do you have one of them thar huge external anteana's that give you great reception?

Wherever you go there you are.

April 1, 2003

It's a 2001 Infiniti I30.

I've never located the car's radio antenna. If it's in the windshield, I sure can't tell.

Regardless, my eTrex hasn't had a problem. Maybe it's getting enough signal through the sunroof?

George

April 1, 2003

Strange, but we have an 02' Montana and our E-trex seems to work perfectly on the dash.

GPS signal blocked by auto windshield?

Recommended Posts

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment

Link to comment