Why no GPS Navigation Unit Aerials

Hello all,

Does anyone know why common GPS navigation units (TomTom) etc have no aerial? They have to be mounted 'bodily' where they can 'see' satellites, meaning the unit has to sit in the sun on top of the dash and is hard to see.

Why can't they have a wire aerial so the unit itself can be mounted in the dash?

This puzzles me??

Thanks Ian
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Reply By: Shaker - Wednesday, Feb 24, 2010 at 20:18

Wednesday, Feb 24, 2010 at 20:18
You can get a soft visor for them, which makes the display easier to see.
AnswerID: 405798

Follow Up By: Imstat - Thursday, Feb 25, 2010 at 20:50

Thursday, Feb 25, 2010 at 20:50
Thanks for that idea, and thanks to all others 'explorer' for helpful inf. Cheers Ian
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Reply By: Michael ( Moss Vale NSW) - Wednesday, Feb 24, 2010 at 20:29

Wednesday, Feb 24, 2010 at 20:29
You can fit one to most units..... Michael
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AnswerID: 405800

Reply By: snailbait (Blue mntns) - Wednesday, Feb 24, 2010 at 20:30

Wednesday, Feb 24, 2010 at 20:30
hi
Yes there is a x xsernails aerial available which has a boster run by 12 volt
see the people who have the knowledge not the people who sell GPS
send me a pm and i will tell you who does the this.
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AnswerID: 405801

Reply By: Member - Tony V (NSW) - Wednesday, Feb 24, 2010 at 20:30

Wednesday, Feb 24, 2010 at 20:30
Imstat

I have an external antenna for my Garmin mounted on the top of my snorkle.

Garmin has a MCX connector. works exceptionally well. Got it on eBay about $10.00
AnswerID: 405802

Reply By: Member - Allan B (QLD) - Wednesday, Feb 24, 2010 at 20:38

Wednesday, Feb 24, 2010 at 20:38
Ian there are dozens of them. Try a Google search for "GPS Navigator Antenna"

Or click here

Cheers
Allan

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AnswerID: 405804

Follow Up By: Imstat - Wednesday, Feb 24, 2010 at 20:50

Wednesday, Feb 24, 2010 at 20:50
Thanks everyone.

You have answered my question. So with an aerial you can indeed mount it in the dash - this makes good sense to me.

Mine is a basic one called TomTom XL.

As far as I can see there is no where to connect an external aerial to it, that is, there are no 'holes' to plug into.

Maybe the better ones have an aerial facility.


Cheers, Ian
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Follow Up By: Member - Allan B (QLD) - Wednesday, Feb 24, 2010 at 23:25

Wednesday, Feb 24, 2010 at 23:25
Ian, are you sure yours does not have an antenna connection?
Look at this
Antenna connection is marked"E".

In any case, you may not need to have the navigator on top opf the dash to see the satellites. I manufactured a mounting to sit the navigator at the front of the dash yet it still sees the satellites. The windscreen in most modern cars sweeps back more than enough for the navigator to see the satellites even when well away from the windscreen.

Cheers
Allan

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Follow Up By: Imstat - Thursday, Feb 25, 2010 at 20:34

Thursday, Feb 25, 2010 at 20:34
Thanks Alan, No mine is a Tom Tom Xl and is a bit different to the "one XL". I will check the TT site online and visit teh handbook. cheers Ian
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Reply By: bruce - Wednesday, Feb 24, 2010 at 20:47

Wednesday, Feb 24, 2010 at 20:47
I have an external aerial for my TomTom...got it from Ebay , reasonably cheap as well...has a magnetic base and sits up on the front of the bonnet when the boat is on the wagon....plenty of them about...cheers
AnswerID: 405808

Reply By: Gone Bush (Mandurah WA) - Wednesday, Feb 24, 2010 at 20:58

Wednesday, Feb 24, 2010 at 20:58
The earlier releases used to be able to take an external antenna, eg the Garmin 660.

But if you mounted them out of the sun they were difficult to adjust without taking your eyes off the road.

Catch 22 Ian. The internal antenna is so good now that an external one is superfluous.



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AnswerID: 405810

Follow Up By: Imstat - Thursday, Feb 25, 2010 at 20:36

Thursday, Feb 25, 2010 at 20:36
Thanks Gone Bush. I always thought the unit had to be mounted on the dash top to receive the signal, but maybe it is so the driver can see it (??), Thanks Ian
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Reply By: The Fox - Wednesday, Feb 24, 2010 at 21:15

Wednesday, Feb 24, 2010 at 21:15
I use a Reradiating gps antenna, bought at a map shop in Parramatta, can't remember the name.

A reradiating antenna system consists of two antennas. The receiving antenna has a magnetic base and is outside the vehicle. In my case, the transmitting, or "reradiating," antenna is inside the cab, on the pass side, taped to the end of f250 dash, and sticks up above the dash. Very small - maybe 5mm dia and 100mm long. The two are connected by a coaxial cable and the system is powered by the 12 volt vehicle supply.

The outside one picks up the signal, and the inside one re-transmits it inside the car. My outside one is flat on the roof and has huge viewing area for satellites, even behind the car to some extent.

A reradiating antenna is necessary if your GPS does not have an external antenna jack, but also handy even if it does have a jack. You can mount the gps anywhere in the vehicle, mine is flat on the dash, down low out of the sun.

Trevor
AnswerID: 405813

Follow Up By: Imstat - Thursday, Feb 25, 2010 at 20:37

Thursday, Feb 25, 2010 at 20:37
Thanks Trevor, I hadn't heard of such a beast as a reradiating antenna!! Ian
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Reply By: Member - Mike DID - Wednesday, Feb 24, 2010 at 21:18

Wednesday, Feb 24, 2010 at 21:18
You don't need an external aerial to mount it in the dash - a dashboard these days is mainly plastic.

The latest GPS are so sensitive that they'll pick up signal coming in through the side windows.
AnswerID: 405814

Follow Up By: Member - Graham H (QLD) - Wednesday, Feb 24, 2010 at 21:51

Wednesday, Feb 24, 2010 at 21:51
Maybe not if you have one of those windscreens that are coated and prevent the unit seeing the sat signal.



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Follow Up By: Imstat - Thursday, Feb 25, 2010 at 20:42

Thursday, Feb 25, 2010 at 20:42
Thanks Mike R,

I actually experimented on the way to work this morning. my sedan has a big pocket in the dash - quite deep. So I put the Tom Tom in that. The top of the dash is about 50mm above the top of the pocket. I placed the unit right up the back of the box, and guess what! Full Satellite reception AND I closed the lid on the front of the box just so I could peep thro the crack, and guess what! Full reception. So many thanks for that one Mike!! Ian
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Reply By: Member - Phil G (SA) - Thursday, Feb 25, 2010 at 07:49

Thursday, Feb 25, 2010 at 07:49
Ian,
Does it not work inside the car?
We also have a Tomtom XL and it works fine inside the car. We do have a sunroof that we never open.
AnswerID: 405860

Follow Up By: Imstat - Thursday, Feb 25, 2010 at 20:44

Thursday, Feb 25, 2010 at 20:44
Yes it does work well in the car, but I was trying to overcome what I understood was the 'need' for the unit to be mounted in the roasting bright sun on top of the dash, so I have been given many ideas here. cheers Ian
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Reply By: obee1212 - Thursday, Feb 25, 2010 at 08:54

Thursday, Feb 25, 2010 at 08:54
I put mine in the glovebox out of the sun and close the lid when not using it. Out of sight. These days the air bags would preclude this. It easily clips in and out and I am hard pressed to find a better place for it in my hilux.

owen
AnswerID: 405870

Follow Up By: Imstat - Thursday, Feb 25, 2010 at 20:48

Thursday, Feb 25, 2010 at 20:48
Thanks Owen, Yes Iam getting a bit weary of removing mine each time I stop, and starting to leave it out of site, cheers Ian
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Reply By: Member - Cantiva Clay (NSW) - Thursday, Feb 25, 2010 at 14:35

Thursday, Feb 25, 2010 at 14:35
I have a Tom-tom XL as well, basically for about a week or 2 after the ephemeris data table (satellite tracking data) has been updated on the internet reception is excellent but as you get further and further from an update its ability to track becomes significantly weaker next to literally useless by about 3 months. This suggests that in fact a low quality read cheap receiver is used in the tom-tom. As a comparison my 7inch gps from ebay with a claimed sirf3 seems to pull lots of satellite's reliably with out updates. I thought the TT was broken and spoke to the Australian service desk who was really helpful, and basically confirmed "the TT is reliant on regular updates"....normally not a problem in the city but can be a problem when your on the road for a few weeks without updates and you go into the heavily wooded Victorian high country when reception is challenged at the best of times.....saved by good old fashioned paper maps! (Pre topo gps) (The phone gps was also useless) Anyway, back to the point I fitted one of the ebay re-radiating aerials the differance is rather subtle vs dramatic, going by the detailed reception meter in the TT, it mean you get a 4~5 satellite fix instead of a marginal 3 - which is enough to get an accurate road location in difficult conditions (high overcast/trees/buildings/long while since update/quicker fix on turn on). here's the one I have but there are lots of others available - the prices seem to vary a bit.http://cgi.ebay.com.au/GPS-Re-radiating-antenna-works-w-Garmin-TomTom-SBG-190_W0QQitemZ230429300509QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item35a6a8171d I think the only caveat with them is that the reciever aerial needs to be as removed from the transmitter as possible - to minimise feedback, eg have the receiver at the rear of the vechicle roof, transmitter around the dash so that the roof metal acts as a sheild. Not also that in the backcountry the tom-tom is not really a replacement for a topo gps - see the gps articule and book.
AnswerID: 405942

Follow Up By: Imstat - Thursday, Feb 25, 2010 at 20:46

Thursday, Feb 25, 2010 at 20:46
Thanks for that. I assume when I go to "Tom Tom Home" I get the necessary satellite update thing, but I don't know really, to be honest. Tks Ian
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Reply By: DesF - Thursday, Feb 25, 2010 at 17:34

Thursday, Feb 25, 2010 at 17:34
Hi , I have a TomTom One V3 and it does not have a antenna connection , I also have Garmin Nuvi 760 which has but I do a bit of trail bike touring and they work fine in my jacket pocket, mainly used to track our travels , but the 760 has a earphone socket and it give you voice guidence in you helmet if needed,
The Nuvi seems to work just as good laying on the front seat or console.
Seems to me they dont have to actually have to see the sky, but the Nuvi needs to when you first fire it up.
Battery lasts about 4 hrs of tracking, Mate has a lighter socket mounted on his bike and charges it in his pocket while travelling.
Cheers Des.
AnswerID: 405981

Follow Up By: Imstat - Thursday, Feb 25, 2010 at 20:29

Thursday, Feb 25, 2010 at 20:29
Thanks, yes I am learning that the unit does not need to be 'seen' by the satellites directly.
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