Mazda 6 car alarm
Had an interesting case of interference, which I was finally able to
track down. For several months, a friend's mesh network had been
experiencing vastly increased noise between the hours of 5.30pm and
7am, and most of the weekend. It was almost like clockwork, and caused
parts of the mesh to drop out. We spent ages looking for video senders,
wifi cameras and the like. The weirdest thing was that the noise was
only at the gateway, and not on any of the neighbouring nodes, yet it
was picking up ~30db of noise.
Anyway, we switched the meshnodes to channel 1 away from channel 11,
and saw a weird signal at channel 9. This was a constant signal, which
revealed itself because the average was close to the peak. After some
moving around, we homed in on a Mazda 6 parked nearby which was
emitting the signal.
Turning the car alarm off eliminated the noise. Turning it on brought
it back. Turning the alarm on and disabling the internal motion sensors
gave no problem. Culprit found. Most cars use ultrasonic motion
detectors for their alarms. Mazda 6s use channel 9. Which stomps on 11
*and* 6. Great!
I'll try and get a recording including going up to the car, rather than just at the gateway antenna.
Cheers,
Joel
Yesterday I had exactly the same problem while investigating an issue at a school!
It was my first time out with a wi-spy, and well it's possibly the most useful wifi related tool I have seen.....
I was able to trace the source of the interference to the PIR's
(Passive Infra-Red detectors) in several classrooms. There were two
types within the school, and only one showed this behaviour!
It seems that they must have been doing motion detection along side the PIR function.
I had 2 5mhz wide transmissions, that were showing an average equal to
the peak, one around channel 8 and one around channel 9. Unfortunately
had to set entire network to channel 1 for now. (Channel 13 was good,
but too many fcc devices without support in school!)
Without wi-spy, this would have certainly taken some time to trace.... (without a spectrum analsyer that is).
I am one happy customer :)
In addition to Mazda 6s, we can add Mitsubishi Shoguns and Toyota Rav
4s. Again seems to be recent models. Possible problem from a Chrysler
Crossfire, but not confirmed - could have been another vehicle nearby.
Cheers,
Joel
Joel,
Very, very nice video you made there.
Iam getting more in love with the EaKiu software, just cant wait for a port in to windows.....
Posted more on this with a video link at http://www.pateley.net/blog/?p=5 and links to the wispy recordings.
Cheers,
Joel