GPS Through Metal? - Page 2

NOS TANG · 03-18-2004, 03:23 PM

Quote: Originally Posted by Maeveth

Hey all, I'm looking to get a NMEA compliant GPS reciver. However I'm not sure which to get. It would be nice if it was accurate and would work efficiently though my metal roof. Any suggestions?

Hi Maeveth,

Here is a suggestion, check out this Garmin GPS 35 external gps that will connect by USB or RS 232. Considering this one for my latest project also. Comes with a 10 foot cable so you can mount it just about anywhere on the vehicle. I have a handheld from Garmin that works fine through my soft top, but in the other cars it only works good when on the dash.

http://www.garmin.com/products/gps35/

Good Luck

Laidback · 03-18-2004, 03:48 PM

Quote: Originally Posted by NOS TANG

Hi Maeveth,

Here is a suggestion, check out this Garmin GPS 35 external gps that will connect by USB or RS 232. Considering this one for my latest project also. Comes with a 10 foot cable so you can mount it just about anywhere on the vehicle. I have a handheld from Garmin that works fine through my soft top, but in the other cars it only works good when on the dash.

http://www.garmin.com/products/gps35/

Good Luck

It doesn't mention USB on that link...

Maeveth · 03-18-2004, 03:49 PM

He did say its RS232

Laidback · 03-18-2004, 04:08 PM

Quote: Originally Posted by Maeveth

He did say its RS232

and USB

Falken · 03-19-2004, 07:08 AM

Quote: Originally Posted by ProCos

Hi Falken,

Sorry if I sounded like a jack ***..... did not mean to!

I have checked the fortuna U2 and it is based upon the Sirf Star II. This is a well know chipset but it is not more or less sensitive than other GPS chipset (at least if you compare same generation).

The sensitivity first of all obtained by the Antenna and LNA (Low Noise Amplifier) and secondly by the GPS front-end chip.

The trick is to get a low Noise Figure and high gain within the LNA, but if the gain gets to high your GPS front end will end up in compression when other L-band signals are present.

How was the Furtuna's U2 demo setup? I can't believe that it was totally covered in metal. Could you describe the setup?

/ProCos

Hi, you emphatically didn't sound like a Jackass!
First of all, I haven't SEEN the Fortuna installation. It is installed in the back of a saloon behind the rear seat. I've seen them dial into it and have the current position reported back to them. (They also said that when fitted to a Transit van under the dashboard it didn't work.) So it seems that the Fortuna manages to get a fix in marginal conditions when other GPS units couldn't.
My experience and my advice to customers is to install GPS where is can get an electronically clear view of the sky. The Haicom units work fine though plastics, composites and fibre glass. In my car it's in the glovebox and in the RV it's in the locker above the drivers seat.

Doug

NOS TANG · 03-19-2004, 05:49 PM

Quote: Originally Posted by Laidback

It doesn't mention USB on that link...

Correct

it does not show it there, but at the dealer sites they list it as below. Looks to be just a RS232 to USB adapter anyways. Here is another link to the info below.

This site has anything GPS related you could ever ask for..

http://www.gpscity.com/gps/brados/10.../oem35lvc.html

GPS35-PC: Attached 10 foot power/data cable with female DB-9 serial connection, ready to attach to your PC. Additional 8 foot power cable extension from the DB-9 connector terminates in a cigarette lighter plug for --easy application of power supply voltage between 6 and 40 VDC (same as GPS 35HVS). Asynchronous serial data interface via a single serial port with true RS-232 voltage level output.

GPS35-USB: With USB Connection. Attached 12 foot power/data cable with USB Converter Connection, ready to attach to your PC. The USB port supplies both power and data to the GPS 35. A CD-ROM is included with USB Device Drivers for Windows 98/ME and 2000 NOT Windows 95, Windows NT or MAC.

-NOS

Maeveth · 03-23-2004, 06:59 PM

Will this GPS Mouse work with CoPilot?

Enforcer · 03-23-2004, 07:13 PM

Back to an observation on the original topic: Does a gps receiver work under metal (or indoors)?

How many of you people have got (or seen) a working TV Satelite Dish indoors or under a metal roof?

Thought not, wonder why, because the signal is line of sight and very weak by the time it hits.

skippy76 · 03-24-2004, 10:31 PM

Ok, so here are my 2 cents.... Having worked heavily with GPS in defence environment, the thing works by line of site. E.g. If a plane flies inverted, the computer system normally tracks based on the direction, speed, etc. that it was flying in prior to going inverted.

It is obviously more advantagious to have the antena mounted flat on the roof of the car, however, it will work through glass as glass will not weaken the signals greatly. However, don't do what a manufacturer did to a type of aircraft which I won't mention... They painted the antena which totally screws things up, especially when the paint is metalic!

Jamez_Warner · 04-01-2004, 07:52 AM

my gps unit will track from cold indoors no problem, given a few hours - metal in cars presents a bigger attenuation however - unless your in a soft top

James

lopan · 04-01-2004, 01:15 PM

I have a really old (earthmate? I think) I hacked a few years ago for my ipaq, works fine laying in the backseat of my rsx.... not much glass back there...

XMfan · 04-01-2004, 01:19 PM

Quote: Originally Posted by lopan

I have a really old (earthmate? I think) I hacked a few years ago for my ipaq, works fine laying in the backseat of my rsx.... not much glass back there...

The earthmates are nice units. I've got the one with WAAS capability. It usually locks onto 8 satellites when placed under the front windshield. I've gotten good accuracy with 3 satellite locks too and that's when it was placed on the front passenger seat.

XMfan · 04-01-2004, 01:30 PM

You could get a device that will allow undercarriage placement. Is it cost effective for the consumer market though?

http://www.covert-gps-vehicle-tracking-systems.com/