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Adapting a Garmin Traffic Receiver to car antenna?

Started by DaveC February 23, 2010
Garmin makes an "integrated" FM traffic info receiver for some models of GPS 
that allows connection to the car's AM/FM antenna. But not my model (Nuvi 
660); I must use only the GTM20, a cigarette-lighter-powered model:

<https://buy.garmin.com/shop/shop.do?pID=403>

Benefits of using the car's antenna are mostly stealth: the 
cord-that-is-the-antenna between the cigarette lighter (which will be 
relocated inside the glove box) and the GPS plug that lays on the dashboard 
makes for an advertisement to crooks. And the car's antenna would, arguably, 
work better.

What are my options re. adapting the GTM20 to work with the car's antenna? 
Could this be as simple as splicing in a motorola antenna plug to the cable? 
Or...?

Ideas?

Thanks.

On Feb 23, 3:25=A0pm, DaveC <inva...@invalid.net> wrote:
> Garmin makes an "integrated" FM traffic info receiver for some models of =
GPS
> that allows connection to the car's AM/FM antenna. But not my model (Nuvi > 660); I must use only the GTM20, a cigarette-lighter-powered model: > > <https://buy.garmin.com/shop/shop.do?pID=3D403> > > Benefits of using the car's antenna are mostly stealth: the > cord-that-is-the-antenna between the cigarette lighter (which will be > relocated inside the glove box) and the GPS plug that lays on the dashboa=
rd
> makes for an advertisement to crooks. And the car's antenna would, arguab=
ly,
> work better. > > What are my options re. adapting the GTM20 to work with the car's antenna=
?
> Could this be as simple as splicing in a motorola antenna plug to the cab=
le?
> Or...? > > Ideas? > > Thanks.
The car's antenna probably won't work better. It is tuned for the FM band, not the GPS band (1.2 or 1.4 GHz, if memory serves...?) Also, many GPS antennas that I've played with have built-in amplifiers, tuned to GPS spectrum, which your car antenna won't have. Not saying it won't work -- but I would expect great performance.
> The car's antenna probably won't work better. > It is tuned for the FM band, not the GPS band (1.2 or 1.4 GHz, if > memory serves...?) > > Also, many GPS antennas that I've played with have built-in > amplifiers, tuned to GPS spectrum, which your car antenna won't have. > > Not saying it won't work -- but I would expect great performance.
Maybe I should explain a little... The FM Traffic service is a supplementary broadcast subscription service using some sub-carrier of the FM broadcast band (88-108 MHz). It carries traffic "events" information (accidents, roadwork, etc.). The receiver is located within the cigarette-lighter power adapter, and the antenna is in the 6-foot cable between the adapter and the plug that attaches to the GPS cradle. So we're talking broadcast band here, not GPS band.
On Tue, 23 Feb 2010 12:40:25 -0800 (PST), mpm <mpmillard@aol.com> wrote:

>On Feb 23, 3:25&#2013266080;pm, DaveC <inva...@invalid.net> wrote: >> Garmin makes an "integrated" FM traffic info receiver for some models of GPS >> that allows connection to the car's AM/FM antenna. But not my model (Nuvi >> 660); I must use only the GTM20, a cigarette-lighter-powered model: >> >> <https://buy.garmin.com/shop/shop.do?pID=403> >> >> Benefits of using the car's antenna are mostly stealth: the >> cord-that-is-the-antenna between the cigarette lighter (which will be >> relocated inside the glove box) and the GPS plug that lays on the dashboard >> makes for an advertisement to crooks. And the car's antenna would, arguably, >> work better. >> >> What are my options re. adapting the GTM20 to work with the car's antenna? >> Could this be as simple as splicing in a motorola antenna plug to the cable? >> Or...? >> >> Ideas? >> >> Thanks. > >The car's antenna probably won't work better. >It is tuned for the FM band, not the GPS band (1.2 or 1.4 GHz, if >memory serves...?) > >Also, many GPS antennas that I've played with have built-in >amplifiers, tuned to GPS spectrum, which your car antenna won't have. > >Not saying it won't work -- but I would expect great performance.
I think he's looking for a solution to the "live traffic update" option and not the GPS signal itself. Traffic info (at least in CONUS) is carried on the FM spectrum as a side channel to one or more local stations. I've got one of these gizmos also (came with the GPS) and from the looks of it I'd hesitate to slice into it. It might be enough to just wrap a few turns of wire around it and connect the free end of the wire to the car's antenna lead. You're only interested in traffic info from local stations, which are probably strong enough to work with this. -- Rich Webb Norfolk, VA
"mpm" <mpmillard@aol.com> wrote in message 
news:8cf11ff0-9d6c-486b-a6d4-fcedd6eb3e6b@c5g2000vbh.googlegroups.com...
On Feb 23, 3:25 pm, DaveC <inva...@invalid.net> wrote:
> Garmin makes an "integrated" FM traffic info receiver for some models of > GPS > that allows connection to the car's AM/FM antenna. But not my model (Nuvi > 660);
huh ? The "integrated" FM antenna (for traffic info) is located inside the power adapter module, and does not connect to anything else besides the GPS mini-USB. https://buy.garmin.com/shop/shop.do?cID=203 Exactly what product connects to "the car's FM antenna" ? In case you think the GPS receives location info via that FM module, it does not.... it is only for traffic info from the radio stations. If you are looking for using an external GPS antenna - that is a totally different question.
> I must use only the GTM20, a cigarette-lighter-powered model: > <https://buy.garmin.com/shop/shop.do?pID=403> >
On Feb 23, 3:59=A0pm, DaveC <inva...@invalid.net> wrote:
> > The car's antenna probably won't work better. > > It is tuned for the FM band, not the GPS band (1.2 or 1.4 GHz, if > > memory serves...?) > > > Also, many GPS antennas that I've played with have built-in > > amplifiers, tuned to GPS spectrum, which your car antenna won't have. > > > Not saying it won't work -- but I would expect great performance. > > Maybe I should explain a little... > > The FM Traffic service is a supplementary broadcast subscription service > using some sub-carrier of the FM broadcast band (88-108 MHz). It carries > traffic "events" information (accidents, roadwork, etc.). The receiver is > located within the cigarette-lighter power adapter, and the antenna is in=
the
> 6-foot cable between the adapter and the plug that attaches to the GPS > cradle. > > So we're talking broadcast band here, not GPS band.
Oh. I didn't understand what you were trying to get at. I have a broadcast background. The correct term for what you are talking about is "RDS" Link: http://en.wikipedia.org/wiki/Radio_Data_System Not familiar with your Nuvi GPS (Mine is an old Garmin III, but hey, it still does everything I need it to -- and a few things the newer models DON'T do!!) Since I'm not familiar with yoru GPS, I'll gracefully bow out now.... Good luck! -mpm
On Tue, 23 Feb 2010 12:25:39 -0800, DaveC <invalid@invalid.net> wrote:

>Garmin makes an "integrated" FM traffic info receiver for some models of GPS >that allows connection to the car's AM/FM antenna. But not my model (Nuvi >660); I must use only the GTM20, a cigarette-lighter-powered model: > ><https://buy.garmin.com/shop/shop.do?pID=403> > >Benefits of using the car's antenna are mostly stealth: the >cord-that-is-the-antenna between the cigarette lighter (which will be >relocated inside the glove box) and the GPS plug that lays on the dashboard >makes for an advertisement to crooks. And the car's antenna would, arguably, >work better. > >What are my options re. adapting the GTM20 to work with the car's antenna? >Could this be as simple as splicing in a motorola antenna plug to the cable?
Belay my last... It looks like the newer GTM-20 models do in fact have a receptacle for a connector to an external antenna. Mic'ing it out, the diameter looks like it takes a 1/8" plug (3.5 mm is too large). The (fuzzy) picture in the manual shows just a tip/ring configuration (reasonable for an antenna) and claims that it's available at the Garmin store. Their store search is abysmally bad, though, so if it's even there it'll take patience finding it. -- Rich Webb Norfolk, VA
In article
<0001HW.C7A979C3009EF110B08A39AF@news.eternal-september.org>, DaveC
<invalid@invalid.net> wrote:

> Garmin makes an "integrated" FM traffic info receiver for some models of GPS > that allows connection to the car's AM/FM antenna. But not my model (Nuvi > 660); I must use only the GTM20, a cigarette-lighter-powered model: > > <https://buy.garmin.com/shop/shop.do?pID=403> > > Benefits of using the car's antenna are mostly stealth: the > cord-that-is-the-antenna between the cigarette lighter (which will be > relocated inside the glove box) and the GPS plug that lays on the dashboard > makes for an advertisement to crooks. And the car's antenna would, arguably, > work better. > > What are my options re. adapting the GTM20 to work with the car's antenna? > Could this be as simple as splicing in a motorola antenna plug to the cable? > Or...? > > Ideas? > > Thanks. >
I wired the receiver for my 680 to an accessory jack that's switched with other stuff; it's hidden, and the cord to the 680 runs under the dash. Everything works well, with the wiring hidden.
"Rich Webb" <bbew.ar@mapson.nozirev.ten> wrote in message 
news:evo8o5pank0carhhjd8664l8iqm82gclcb@4ax.com...
> On Tue, 23 Feb 2010 12:25:39 -0800, DaveC <invalid@invalid.net> wrote: > >>Garmin makes an "integrated" FM traffic info receiver for some models of >>GPS >>that allows connection to the car's AM/FM antenna. But not my model (Nuvi >>660); I must use only the GTM20, a cigarette-lighter-powered model: >> >><https://buy.garmin.com/shop/shop.do?pID=403> >> >>Benefits of using the car's antenna are mostly stealth: the >>cord-that-is-the-antenna between the cigarette lighter (which will be >>relocated inside the glove box) and the GPS plug that lays on the >>dashboard >>makes for an advertisement to crooks. And the car's antenna would, >>arguably, >>work better. >> >>What are my options re. adapting the GTM20 to work with the car's antenna? >>Could this be as simple as splicing in a motorola antenna plug to the >>cable? > > Belay my last... It looks like the newer GTM-20 models do in fact have > a receptacle for a connector to an external antenna. Mic'ing it out, the > diameter looks like it takes a 1/8" plug (3.5 mm is too large). The > (fuzzy) picture in the manual shows just a tip/ring configuration > (reasonable for an antenna) and claims that it's available at the Garmin > store. Their store search is abysmally bad, though, so if it's even > there it'll take patience finding it. > > --
Where is the antenna connector you are talking about ? This photo shows the 12v DC tubular connector - with the 12v center pin contact - https://buy.garmin.com/shop/alt-image-lg.do?pID=403&img=productImageLarge and going to the special 18-pin flat connector for the GPS https://buy.garmin.com/shop/shop.do?pID=403#specsTab
"DaveC" <invalid@invalid.net> wrote in message
news:0001HW.C7A979C3009EF110B08A39AF@news.eternal-september.org...
> Garmin makes an "integrated" FM traffic info receiver for some models of > GPS > that allows connection to the car's AM/FM antenna.
All of these receivers have the Traffic FM receiver module embedded in the DC adapter, on inline on the power cable - https://buy.garmin.com/shop/shop.do?cID=203 AND - as per the manuals - some DO HAVE a special connector for an external antenna which in the manual appears to be located directly on the inline module... In looking over this list - and actually downloading the manuals, it's hard to tell the difference between them - and the "18-pin flat plug" is for those special CRADLE mounts, while others are for the mini-USB on the GPS itself... It is a bit confusing - even have the GTM-20 listed twice, but with different hardware features...