Member Since: 05 Sep 2006
Location: Hradec Kralove
Posts: 1095
two GPS devices on one antena?
Does anybody know if it is possible to connect two GPS devices on one antena?
Not the d3 antena but in general. It seems logical that this is feasable but I can not find the T-connector.
Can anybody advice?
Thanks
18th Sep 2007 10:02 am
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
Member Since: 04 May 2007
Location: Barcelona
Posts: 4317
I think that technically yes you can, although it may attenuate the signal to the point where you lose lock or take a long(er) time to acquire a lock on each unit.
I also seem to remember that you should only do this if sending the GPS signal over some kind of network......sorry but I can't remember much more about this as I looked it up a long time ago...
BTW, we now have a separate Navigation/GPS section to post these questions....
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18th Sep 2007 10:14 am
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
You can split a received signal from one antenna between two devices with a simple T-piece. A drop in signal strength of -3db (1 'S-point') would be expected which is not important providing you have a good signal to start with. However, you cant do the same for transmitters, as splitting the signal in this manner means half of it is feeding back into the second transmitter. The older I get, the more I realise that people confuse wrinkles for wisdom
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18th Sep 2007 10:25 am
captain_sugar
Member Since: 05 Sep 2006
Location: Hradec Kralove
Posts: 1095
so I just need to find the right T-connector:
one exit to the antena
one exit to the tomtom
one exit to the GPS logger (writes the car's position on a flash disk for later analysis)
18th Sep 2007 10:28 am
DarrenG
Member Since: 31 Jan 2007
Location: Hampshire
Posts: 144
There are plenty of reasons why this wouldn't be a good idea, attenuation of signal being the primary problem. At the frequencies used the signal loss through any T-Piece would be very high.Darren Griffin
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Plus many gps antennae are powered through the co-ax........antennas are cheap, just buy another2007 HSE Java Black.....sold
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At the frequencies used the signal loss through any T-Piece would be very high.
Good point..... I was posting in VHF mode. Just get another antenna and tell them Doctor Diesel sent you..... Might get some discount (or some funny looks )The older I get, the more I realise that people confuse wrinkles for wisdom
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18th Sep 2007 6:37 pm
captain_sugar
Member Since: 05 Sep 2006
Location: Hradec Kralove
Posts: 1095
the problem is I bought this stupid scenic for the company and ordered the athermic glass, not knowing it is blinding GPS signals. So each antenna must find some other place, probably the roof, and for two antenna, there will be drilling...
18th Sep 2007 7:53 pm
stapldm
Member Since: 11 Sep 2006
Location: Swine Town
Posts: 2330
Perhaps you could do something creative like this? Then you'd only need one antenae on the roof...Dr. Ian Malcolm:
"Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should."
Transgenic tomato anyone?
I've used a magnetic re-radiating antenna plugged in to the rear 12v point with the GPS cable run out under the tailgate seal and the re-radiating part stuck by the C-pillar. If you get one try and get one with a 2m range or you'll have to get it close to the units trying to get the signalThe End
Member Since: 31 Jan 2007
Location: Hampshire
Posts: 144
captain_sugar wrote:
the problem is I bought this stupid scenic for the company and ordered the athermic glass, not knowing it is blinding GPS signals. So each antenna must find some other place, probably the roof, and for two antenna, there will be drilling...
The scenic's glass won't be affected by a GPS that uses the later chipsets such as SiRFStarIII, HammerHead, MTK. All these will function behind athermic coatings perfectly well. And then you won't need an external antenna at all!Darren Griffin
Editor
PocketGPSWorld.Com
19th Sep 2007 8:14 am
DarrenG
Member Since: 31 Jan 2007
Location: Hampshire
Posts: 144
stapldm wrote:
Perhaps you could do something creative like this? Then you'd only need one antenae on the roof...
Re-radiating antennas were banned a while back in the UK, that's why they suddenly disappeared off the shelves.Darren Griffin
Editor
PocketGPSWorld.Com
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Good point..... I was posting in VHF mode. Just get another antenna and tell them Doctor Diesel sent you..... Might get some discount (or some funny looks 
)
