co-locating gps
co-locating gps
(OP)
does anyone know how close you can mount two L1/L2 gps antenna before there is a problem with interference ?
thanks flux
thanks flux
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RE: co-locating gps
The only possible consideration might be where you're doing advanced science or extremely accurate surveying where you're tracking the actual phase on the incoming carriers, and then you'd need to be careful to place each antenna on its own little ground plane on its own cute little tripod. You have to keep each one out of the others near field to avoid the possibility of distorting the phase of the carriers. It's very likely that is not a concern for you.
Another option is that you can 'split' (in the Cable TV sense of the word) GPS antenna systems are share the one antenna with as many receivers as you wish. The only exception here is that an airplane connot depend on only one antenna, so the system needs to be designed to fail gracefully if one antenna blows off.
RE: co-locating gps
ive heard of spurious signals interfering with each other if they are in very close proximity
i was hoping to place them about 0.5m apart purely for navigation purposes
so you reckon there is no general guidance for co-locating these 'patch' type antennas ?
i really appreciate your input !
RE: co-locating gps
This sort of concern is most-often associated with embedded local oscillators where Unit A can interfere with Unit B. A classic example of this is where one automotive Radar Detector can trigger off another Radar Dectector.
Normal GPS antennas do not contain a local oscillator. They most often contain a nice LNA powered by 5Vdc on the same coax cable.
A 0.5m gap is pretty big from an EMI point of view (for these circumstances) - I was imagining you meant cheek-to-jowl side-by-side.
On the other hand, 0.5m is perhaps a bit tight if you're planning to use differential methods to extract platform orientation (if I'm reading between the lines correctly).
If the application is in any way life-critical, then it might justify further engineering examination as opposed to relying on some guy on the Internet. Have seen that old New Yorker cartoon where two dogs are surfing the 'net, "On the Internet, nobody knows you're a dog."
RE: co-locating gps
I totally agree with your dog analogy, hee hee, i was checking to see if there was common knowledge out there, you know the type of knowledge 'EVERYONE knows you don't put two patch antenna's within 0.5m of eachother dummy!'
What you have said makes perfect sense to me, i guess i will continue to find some concrete evidence.
Thanks for taking the time to respond
Best Regards
Flux
RE: co-locating gps
And if you DO require two antennas for redundancy, then perhaps they should be further separated so that when something bad happens to one, it doesn't also take-out the nearby backup.