No Lock, WHY!?!?

nibix · 07-04-2004, 07:30 PM

Ok, I just had my TN-200 GPS unit installed as seen below. My computer is in the trunk so the GPS is connected to two 10' USB extension cables. I can't seem to lock any satellites at all. Here are my three theories:

1) The heated windshield is blocking the signal?
2) The USB cords are too long?
3) A mix of both (I think this might be it)?

Would moving it to where I pointed out make any difference? The heated lines stop at that point, but it is right next to the frame. Is the USB device not getting enough power?

carpcnoobie · 07-04-2004, 08:18 PM

Very likely a possiblility of both. Most of the time I see in the stores, USB cables are powered when the extensions get a certain length. Like USB hubs.

As for the heated windshield.

I never remember seeing the lines for the windsheild in the front like that. You certainly could 'try' to move it, but as I remember, windshields with the problem tend to be coated with a metal laced film (not sure exactly). This blocks the GPS signal. Did you actually try the GPS on the roof or elseware to confirm it is able to get a lock under best conditions?

Q_gamelogic · 07-04-2004, 08:25 PM

those are photoshop lines .... or whatever .... there are no heated windshields like that ..... windshield (FRONT) gets heated by air from heater ...

Yuriy · 07-04-2004, 08:34 PM

My external GPS antenna is sitting behind a heated back window and it still can connect to about 10 sattelites in a matter of seconds.
What your problem might be is incorrect protocol settings. Most GPS receivers will work if you set the protocol to NMEA 4800, but to acheive the optimal performance you might have to play with the software settings a bit.

nibix · 07-04-2004, 08:47 PM

Q_gamelogic,
There are in fact visible hairlines in the front windshield. I am going to try moving the GPS a bit but there is very little slack and all the wires are cleanly installed.

BigAl · 07-04-2004, 08:51 PM

I would find that **** annoying all them lines in the windshield

nibix · 07-04-2004, 10:02 PM

They are barely noticeable. By the way I have seen up to 2 satellites but no lock.

Pudge · 07-04-2004, 10:06 PM

Q....I can... see... that.... you ............like to talk..... with.... lots of dots..... in .... your ....sentences... when... you doubt... some...one.

Q_gamelogic · 07-04-2004, 10:08 PM

hah .... what car is that ?????

never seen that ...

Pudge · 07-04-2004, 10:09 PM

I can see why you were skeptical tho, I haven't seen anything like that either.

Ricky327 · 07-04-2004, 10:54 PM

YUP the front heated windscreen do block GPS signals.

My car have just that, 100s of very fine lines running down the windscreen. They can only be seen when looked at closely. Not alot of cars have them for some reason, they do work nicely though.

Mine didnt have lines on the left and right side of the screen...about 5-6 inches from the sides. You can try placing it just there on the side, it work ok on my car then.

nibix · 07-04-2004, 11:02 PM

Yeah, I tried to draw the lines in a manner that would show that there was room on the side. I am starting to think that the power of the USB gps is bad because of the extension. Is there a way to remedy this from the trunk?

Ricky327 · 07-04-2004, 11:12 PM

I dont think its the USB cable since you already have found 2 satellite. The setting should also be correct. If it doesnt lock then it must be a signal problem and not the cabling problem.

Do this test...open up HyperTerminal set to 4800-8-N-1 (That should be standard setting for an NMEA GPS) You should then see the sentences being sent consistently once every seconds. If you can see this ok without any glitches then you know your GPS is working fine.

Concentrate on placing the GPS else where, try with a another USB cable if you dont wanna disturb the installed one. Place the GPS in clear view for now (outside the car), this should now work else you may have problem with the GPS.

Hope that helps.

EDIT :

You may be better off placing the GPS at the back of the car. The rear heated screen doesnt block the signal that much...it have less heater lines compared to the front screen.

Yuriy · 07-04-2004, 11:53 PM

Like I said - try changing protocols. Some work better than others and some don't work at all. Try moving the receiver out of the car to see if it works at all before changing the software settings though.

yuprules · 07-05-2004, 01:08 PM

nibix, what kind of car is that? A Land Rover?

You need a clear view of the sky, if your GPS is magnetic...for the fun of it...stick it to the upper side of your passenger window. Yeah you can't open the door anymore, but at least you'll know if it is that front windshield or not.

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