proximity of gps and wi-fi antennas and potential signal interference, etc.

Ok this isn't really relevant to the GPS or wi-fi threads, so I'll start it seperately.

I'm going to mount the RP-SMA connector of a wi-fi pigtail on the GPS antenna 'bump' of my CF28 since I figured out that a small active GPS antenna will fit just fine and allow a RP-SMA connector to mount on the side of the bump as well (will put up a few pics later).

At present I don't have the GPS properly functioning and I'm going to buy an EM-408 to wire in to the RIM board shortly. I noticed the EM-408 has it's own active antenna already and I considered using it with the module itself fitted into the bump though I suspect others have already tried that and found it doesnt quite fit very well.

Anyway would there be any potential problems with signal interference, etc. with an active wi-fi antenna mounted on an RP-SMA connector directly near a bump-mounted active GPS antenna? I have nothing to lose my trying out a wi-fi antenna mounted on the bump, as the hole could easily be re-used for a GPS antenna pigtail in the future if required, so let me know if you've tried what I'm suggesting and noticed (or actually measured with proper gear) signal problems from having a wi-fi and GPS antenna in very close proximity.

Craig.

 

Your first hurdle is to get the GPS functioning. You should make that happen first... Then worry about mounting the SMA connector there...

 

True... but I have wi-fi working now and don't (yet) have long enough leads to reach the top of the LCD housing.

So trying the wi-fi antenna location on the GPS bump first off.

When I receive the EM-408 I've ordered then GPS is on the go again. I have tried a different antenna with the factory GPS module and the result is the same, so it might be a dry solder joint.

Craig.

 

No... I doubt it... The Factory GPS engine is junk really. I had moderate success in adding a larger copper ground plane to capture a little bit better signal. As far as the signal goes... I have purchased several of the SMA and MMCX ended GPS antennas that are encased in the plastic... I never really had any luck with them. A moderate signal at best. I bought several from USGLOBALSAT and a few other places along the way. They all turn out to be a little too large as well... Which may have been the problem. I am using a 12mmX12mmX7mm active patch antenna now and still had a hard time fitting that one into the CF-28. I guess the plastic is a little too thick or just dense because I couldn't get a signal at all. The GPS antennas supposedly need to be tuned to where they will ultimately be. (Encased in plastic, have a rubber covering, etc.) I junked all the old antennas I bought on that round and still have a few I'll save just to have them around.

 

Hey Rick,
Have you tried that new small active patch antenna in place of the old patch
in a 29 OEM gps sled yet?
I'm thinking on trying it over here.

 

Craig,
As far as interference is concerned.
If you stick with a GPS antenna that includes a SAW filter in it.
That may be enough isolation from the wi-fi from causing any problems.
You are going to mount them side-by-side, Correct?

 

Ok I've mounted the wi-fi pigtail on the GPS antenna 'bump' as planned. That wasn't a problem. wi-fi works fine although the pigtail isn't quite as secure as I'd like. I think I'll need to file off a bit more plastic from the outside of the bump to level off the outer face some more...



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I will try the GPS software out when I'm a different part of Australia once I get to Darwin and see if there is any difference in behaviour of the factory engine. I'm ordering an EM-408 anyway but in the meantime I can keep plugging away at ideas for the factory engine.

Here's a trial-fit of the new active GPS antenna in the bump to show that it fits very well, even with the larger coax (which is quite flexible so):



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At present I don't have any way to modify it's cable so I won't try adapting it to connect to the factory GPS engine until I get the right tools.

Craig.

 

Very nice. It looks like you have an idea and your bring it fruition.

 

What's the difference between your GPS antenna and the original OEM one?

 

Size about the same.

Coax is very different - the ones I bought (in little black plastic cases with two magnets to secure them to a steel surface) have a long 5 metre cable with SMA connector on the end. The coax it nice RG-174 so I'll definitely be hanging on to whatever I cut off.

I don't know if the factory GPS antenna is an active one or not. Also the factory antenna has a short cable with h.fl connector (to connect to the engine on the RIM board) and I'm going to wait for am EM-408 to arrive before I worry about hacking the cabling. I have pigtails and adaptors to work with ipx (aka u.fl) conectors, though I think the EM408 has an MCX or MMCX connector. Pigtails for those are around.

Craig.