Poor GPS lock in Alfa Romeo 156 Sportwagon - windscreen ?

Matrick · Occasional Visitor Joined: Dec 20, 2003 Posts: 31

I'm using a IPAQ H2210 with TT2 and a Royaltek Sapphire receiver.

I have only been using this setup for 3 days and have run into GPS locking problems. Basically first lock can take 20 minutes (the worst case) but typically takes up to five minutes. Signal is frequently lost and takes a while to re-aquire. Today to prove a point I placed the receiver on the roof through an open window - perfect, immediate lock, with more satelites!

I therefore assume that the problem is due to the vehicles windscreen. Global Positioning Systems are sending me a Fortuna Clip On Bluetooth unit to try out.

I am hoping to install this in the boot of the car as there is a spare cigarette socket (then I don't have to worry about re-charging the battery - I can leave it permanently connected). Is the rear windscreen likely to give similar GPS lock problems as the front ?

Alternatively what other solutions are open to me. Re-radiating ariels? The problem here is that I don't really want to mount anything on the roof, so the same with a waterproof GPS receiver....

Any thoughts or ideas appreciated

Regards

Matt J

Dave · Posted: Sat Jan 03, 2004 3:45 pm Post subject:

In that case it is the windscreen which is probably UV coated. Rear windscreen may be the same, but the only way would be to try a Bluetooth Receiver or something you can plug in, in the boot to test this for sure.

A re-rad is another option but it requires having an antenna on the roof of the car and also a powered accessory socket in use by the re-rad all the time.

Matrick · Occasional Visitor Joined: Dec 20, 2003 Posts: 31

Thanks for the reply Dave.

I will try out the receiver in the boot and see what happens. With regard to the re-rad, can it be permantly installed, so that the antenna is always on the roof or does the antenna need to be placed each day ? How near does the antenna need to be to the GPS receiver?

Thanks in advance

Matt

johnnyxx · Occasional Visitor Joined: Jan 03, 2004 Posts: 44

i have the bluetooth reciever and i was told about the windscreen having a front heated windscreen is meant to block the sats seeing the gps reciever. but mine works ok i get about 6 to 8 sats seeing me all the time. can u not wire it to your arial so you get a stronger signal ?

Dave · Posted: Sun Jan 04, 2004 9:48 am Post subject:

Dave · Posted: Sun Jan 04, 2004 9:51 am Post subject:

Matrick · Occasional Visitor Joined: Dec 20, 2003 Posts: 31

Dave

With regard to permanently mounting the re-rad external antenna, am I right in assuming that a hole needs to made in the vehicles roof ?

Regards

Matt

Matrick · Occasional Visitor Joined: Dec 20, 2003 Posts: 31

I've just been talking to one of the techs at Global positioning Systems. He has informed me that there is an external antenna made by by Fortuna specifically for the clip on bluetooth unit. So for £20 I shall give it a try. I will be able to permanently power the bluetooth unit in the boot of the car (using the spare ciggarette socket) and run the external antenna to the roof running the cable shut in the boots door.

I'll let you know how it works.

Regards

Matt

Dave · Posted: Sun Jan 04, 2004 7:16 pm Post subject:

The Re-Rad's always have a magentic base to the external antenna so no holes are needed. You should be able to get an external patch antenna (again which will have a magnetic base) but the cable length on these are only usually 1-2 meters.

johnnyxx · Occasional Visitor Joined: Jan 03, 2004 Posts: 44

so is 6 to 8 sats seeing me all the time any good then, i thought it was Laughing Out Loud

.
and another thing on a route about 60 miles long it took my pda about 10 mins to calulate the route . and thats on fast routing my pda is a compaq 3970 , does this seem right . im new to all this as you can prob see

Dave · Posted: Mon Jan 05, 2004 9:44 am Post subject:

Matrick · Occasional Visitor Joined: Dec 20, 2003 Posts: 31

Sorted!

I haven't yet tried the external antenna but using the Xtrac mode it works.

I have mounted the receiver, permanently to the rear cigarette socket, in the boot and am getting 7 - 10 satellite locks. Interestingly it was hit and miss in ST mode. It also worked the same in Xtrac when mounted on the dash, so it appears that the Xtrac mode can work with the UV windscreen anyway.

I have travelled on the M4 and through very built up areas of central London today and never once lost GPS lock, perfect Laughing

I will try the ST mode again with the external antenna but even if not, I do have a perfectly satisfactory solution.

Thanks for all the advice, it's well appreciated!

Regards

Matt

Matrick · Occasional Visitor Joined: Dec 20, 2003 Posts: 31

I've just connected the Fortuna external antena and switched the unit back to the preferred ST mode:

8 to 12 satelite locks, very strong signals - now I'm really chuffed!

I definitely reccomend this antena, especially at only £20.00

Regards

Matt

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