Thread: WiFi Card/gps inside dashboard.

Originally Posted by vinsta18

Just curious, how much does thick plastic or fiberglass impede a gps or wifi signal? I just found a neat little place in my dashboard that looks like it would take both my gps reciever and my wifi card no problem. So, obviously, the question is, will my dash itself obstruct their signal? Neither one will be visible, hidden inside the dash.

Well, first of all, the plastic will degrade the signal. How much can't be told, yu just got to check.

Next, putting a transmitter (the WIFI card) near a receiver (The GPS reciever) will additionally degrade the signal.

In my opinion, it isn't the best idea.

Michael

In my experience, if you use a bu-303 under the dash, it won't be able to acquire a signal. Of course, YMMV with other gps units.

I'm about to try out the bu-353 bu-355 and we'll see if that works better.

If you use a GPS with SIRFstar III chipset, it will probably work fine. That chipset is very good with weak signals and interference. I was amazed at the difference in signal strength I got when I upgraded from an old GPS to a new SIRFstar III. I had my old GPS on my dash, visible to the world (and the sky), and it's reception wasn't that great. My new GPS sits in front of my speedometer, where it doesn't even have a clear view of the sky and my car's metal roof blocks a good portion of the sky. I still get better reception with the new one than the old.

As for obstruction of the GPS' view of the sky:
Metal = bad
Plastic = OK, but try to limit it
Glass = no prob (beware of metalic/reflective treated glass available in some expensive autos like Saab, Lexus, and such)

Originally Posted by tom2112

Glass = no prob

Absolutely not true. Just because light waves pass through Glass, does not mean that Radio waves pass through just as easy. This is a common misperception. True, Metal is probably the worse, and Plastic is second, but GLass is certainly not "No Problem"

While the new Sirf III chips may be more sensitive, that still does not mean that you won't have problem. Again, you will have a tranmitter near a receiver. Any RF energy will interfere with reception, no matter what the frequency. Also, WIFI is in the 2.4ghz range, while GPS is int he 1.2. That means that the WIFI is transmitting on the second harmonic of the GPS frequency. That will make the interferencestronger then if it was not on a harmonic. Additionally, a more sensitive receiver USUALLY means that it is probably more prone to RF interference

No matter what, the only way to know if it will work is to try it. No one can say with any certaintly that it will or it wont, unless they have tried it, in the same place, in the same car, with the same equipment, and prehaps, even in the same geographic location.

Michael

Originally Posted by Wiredwrx

Absolutely not true. Just because light waves pass through Glass, does not mean that Radio waves pass through just as easy. This is a common misperception.

It's cler you know your stuff, but just to be picky and clarify:
It's all electromagnetic energy, light waves are a certain frequency band, "radio" waves (that's a vague word) are a different frequency band, microwaves are a different band, etc.

For an example of something that you can see thru but is nearly impassabe for wifi (2.4Ghz) look at water. The same reason you microwave oven is so good at heating things up is the same reason it's hard to pass wifi signals thru water (snow, rain, leaves of a tree, etc). Water absorbs this frequency very well.


Now, to help with your problem. I would put the GPS reciever at one end of the car and the wifi tx/rx at the other. Even better, get an external wifi antenna and mount it under the dash.

I have my GPS tucked under my dash with absolutely no problem for somewhere near a year (I think).

I don't know about the interference though. GPS is around 1.5 GHz, and WiFi is around 2.4 GHz. Thats a large difference, and WiFi, unless using a high gain antenna, is pretty low power. You can't damage either one, so try it. Use some signal analysis programs (netstumbler, visualGPS) to check. Establish a base line, (don't use one) and then bring the other into the picture.

There has been reports of strange things happening with GPS signals (better signal with a refrigerator magnet, etc.) Heck, you might be able to lock onto to all 24 satellites if you have a wifi antenna parked right next to it.

Post your results! Whatever they may be, I think everyone would be interested in them.

Originally Posted by kbyrd

It's cler you know your stuff, but just to be picky and clarify:
It's all electromagnetic energy, light waves are a certain frequency band, "radio" waves (that's a vague word) are a different frequency band, microwaves are a different band, etc.

For an example of something that you can see thru but is nearly impassabe for wifi (2.4Ghz) look at water. The same reason you microwave oven is so good at heating things up is the same reason it's hard to pass wifi signals thru water (snow, rain, leaves of a tree, etc). Water absorbs this frequency very well.


Now, to help with your problem. I would put the GPS reciever at one end of the car and the wifi tx/rx at the other. Even better, get an external wifi antenna and mount it under the dash.

Thank you for the clarification. Certainly you know your stuff as well. Sometimes I need to speak less technical for the less technical to understand.

Michael

Originally Posted by kiltjim

I have my GPS tucked under my dash with absolutely no problem for somewhere near a year (I think).

I don't know about the interference though. GPS is around 1.5 GHz, and WiFi is around 2.4 GHz. Thats a large difference, and WiFi, unless using a high gain antenna, is pretty low power. You can't damage either one, so try it. Use some signal analysis programs (netstumbler, visualGPS) to check. Establish a base line, (don't use one) and then bring the other into the picture.

There has been reports of strange things happening with GPS signals (better signal with a refrigerator magnet, etc.) Heck, you might be able to lock onto to all 24 satellites if you have a wifi antenna parked right next to it.

Post your results! Whatever they may be, I think everyone would be interested in them.

Actually, GPS is a range of between 1.1 and about 1.8ghz. Wifi is in 2.4. You should read up on Radio Frequency Harmonics to understand how a signal SO FAR AWAY can interfere with a signal.

I just read where a scanner, with an internal IF on a 2nd or 3rd Harmonic, was interfering with an Ametuer radio Repeater 4 to 5 miles away.

Do not under estimate the power of electromagnetic radiation (That was for you kbyrd)

He is right though, you can't damage anything, and the only way to know is to try it out.

Good luck, and report back.

Michael