GPS interference

Wanted to report a weird signal interference near the dashboard. Recently bought a y61 and installed a gps tracker as i always do, everything worked fine. Couple of days after, had the entire dashboard replaced at the dealer because it was in bad condition, they also installed a car alarm and central locking system. After that, the gps tracker had trouble locking a gps signal. First, i tried with another tracker, changed antennas, power cables and still couldn't get the gps signal to lock, so I moved the GPS antenna to sit over the dashboard, at plain sight, instead of below. Didn't work either. At some point I noticed that holding the antenna a couple of meters away from the vehicle, the gps unit worked just fine. This morning I installed a GPS diagnostics app into my phone and every time I had the phone near the dashboard it lost all satellite signal locks, 1 meter away and 11 sats come back. I know about some "gps jammers" devices that sell on ebay to interfere with the gps signal so i was suspicious about the car alarm the dealer installed (maybe it works at the same frequency). I disconnected the vehicle´s battery and still the gps could not get a lock. Finally installed the antenna behind the front grill and got it working for now. In the past years i installed several gps trackers on diverse vehicles and never had this problem. I find it odd that even being near the dashboard with the car battery disconnected there is an interference. Anyone had something similar happening?

Nope... only thing I have ever seen interfere with GPS was a 'leaky' Radar Detector (other than jammers of course).

Has the alarm got a glass break detector?

Yes, the alarm has a glass break detector indeed.

Disconnecting the vehicle's battery will not always stop the alarm. Most have a built in battery back up that lasts for some time. To see if it is the alarm you would have to ensure that it is switched off - to the point that it would be easier to unplug it and remove it from the car.

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Originally Posted by jsgbrl

Yes, the alarm has a glass break detector indeed.

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Then the Alarm would be my prime suspect.
Also agree with Bill vis a vis power but personally I would just live with the new GPS antenna location.

As a point of interest does the GPS diagnostics drop out when driving around or is the GPS on the phone/navman/whatever OK when moving?

Thanks for your input guys, i will test the alarm hypothesis by removing it this weekend and have another go with the gps diagnostics app (gps status & toolbox from android store).

Either with the vehicle parked or moving, my phone starts to lock some sats but then loses all signals at once, this happens at periodic intervals of maybe 10 seconds.

I also mounted a dashcam at the top area of the windshield and without surprises it won't get gps signal. I'll report back my findings after the weekend and thanks again for your input.

cheers

earths,are all your earths clean?

Have heard of some alarm proximity sensors mucking around with GPS signals. So could be that as well if that was part of the alarm package as well as the glass breakage detector.
Most aftermarket alarm systems just have your standard box with the inputs plugged into it. Eg knock sensor , proximity sensor and so on. You could maybe pull off each connection and test which one is giving you grief

Sent from my SM-G920I using Tapatalk

WIndows tinted? Some of the film (V-Cool) has metallic content and plays havoc with GPS signals.

Hello again, reporting back after some experimients i did this morning:

First took some gps readings with my phone to have some control data:
18 sats locked at plain sky sight
11 sats locked inside the garage, sitting on the dashboard of another vehicle
0 sats inside the garage, sitting on the patrol's dashboard

Attachment 75055

As you guys mentioned, i took the alarm module (and central locking module) off the vehicle and stored them a good 15 meters away.

Attachment 75054

Made the same readings in different order, multiple times, giving the phone some minutes before each reading ... and got exactly the same results, nothing changed. Then i moved the vehicles (switched spots) inside the garage just in case and made all the readings all over again, no changes.

At this point i already solved the problem with the new antenna location, at least partially, as i still have some minor gps signal loss, but am really curious about what is happening.

The only other change is the dashboard and it is hard for me to believe it is causing interference.

So i guess i'll leave it here for reference in case someone else has this problem in the future, if you guys have any other ideas i'll gladly try them just for the sake of experimenting.

also the patrol does not have any tinted windows, not factory nor aftermarket.

cheers and sorry for my english, not my native language.

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Originally Posted by the evil twin

As a point of interest does the GPS diagnostics drop out when driving around or is the GPS on the phone/navman/whatever OK when moving?

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yes sir, moving or parked, the is no gps signal lock.

when i disconnected the car battery, the gps tracker was directly connected to the battery so i assume no earthing problems

Other than using a spectrum analyser and scanning the frequency spectrum inside the vehicle for anything that should not be there - this problem has me stumped!