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Old 17 March 2006, 08:16   #11
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From what's been posted on this thread, it seems that integral GPS antennae are ok in an open cockpit. Are there any disadvantages over an ext. antenna, if the GPS unit is mounted on the top of the console?
Curious, as I'm thinking of getting a GPS chartplotter and was wondering whether it's worth going to the additional expense and trouble (No A-frame) of the ext. antenna.
Your views/experiences would be appreciated.
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Old 17 March 2006, 08:20   #12
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If you are mounting your gps on top of the console - best go for integral antenna as its one less wire to sort out. - unless you are planning to take the thing with you to your next boat and theres a chance it might need to be flush mounted.
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Old 17 March 2006, 08:43   #13
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Thanks Roy - no noticeable loss in signal quality then? I'm thinking of a Garmin 172C - quite cheap at the moment - just over 300. Anyone know of any better deals?
Also, any good deals on Garmin charts around
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Old 17 March 2006, 08:47   #14
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If 300 is including the VAT then I'd say thats a very good deal.
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Old 17 March 2006, 09:04   #15
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It is very easy to jam a GPS signal - worrying!!!

Even an active TV aerial can cause block out a wide area.

http://www.gpsworld.com/gpsworld/art...3404&&pageID=1

It has been possible for some time to buy jammers that will take out quite a wide area - same with mobile phones. The joys of digital - with analogue something usually gets through!!!
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Old 17 March 2006, 10:14   #16
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Quote:
Originally Posted by roycruse
A mobile phone will drown out the GPS signal rather than block it.
Must be more to it that that, roycruse, or my Garmin Navtalk phones wouldn't work.

I can see, as Richard said, putting a mobile phone on top of a gps will likely block it's signal cos the mobile will have a good deal of copper circuit inside and that'll likely also include a ground plane. Plus there will probably be other metal inside it too.
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Old 17 March 2006, 10:23   #17
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Quote:
Originally Posted by roycruse
I think if you take a handheld vhf over to your antenna and key up it will also drop all the satelites.
My main VHF antenna is only a couple of feet from my GPS antenna - the only time I lose satellite signal is when it is physically blocked by something (i.e. people leaning over it, or a structure of some sort). Using the radio doesn't affect it.

D...
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Old 17 March 2006, 10:49   #18
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Just did a wee experiment....it's best to know for sure.

Putting my mobile phone at the side of, at the end of, underneath, on the top of but not covering the antenna of the gps, made no difference to the gps. Putting it on top of the antenna section halved the reception indicator bars. But there was very good reception so with poorer satellite recepiton the gps may well loose it's signal.

Calling the speaking clock while the phone's antenna was adjacent to the gps antenna appeared to shorten the bars by just a tad but it was difficult to tell for sure whether it was just the normal movement of the bars or not. My feeling is that there was a very small effect. The phone didn't appear to be bothered by any of this.
This was indoors in a conservatory and so shielded by glass and a plastic roof.
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Old 17 March 2006, 11:02   #19
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Ok ill shut up

but try it with you VHF...
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Old 17 March 2006, 17:02   #20
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Chris why not buy a good hand held gps, then you have a completly seperate
backup with its own power supply (batterys)
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