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Neighbor's house alarm triggers when I put my car in reverse

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Re: Neighbor's house alarm triggers when I put my car in reverse

#61

Post by jandrese »

alister wrote: post #45
petar_prog wrote: post #21

Someone explained it properly in the reddit thread, it's the exhaust generating noise while driving in reverse (only happens in the morning when cold and at specific RPM, exhaust generates a specific frequency which vibrates the windows and triggers the alarm).

> Someone explained it properly That's a hypothesis, a very good hypothesis, but the Reddit thread and Hacker News offer many other reasonable-sounding hypotheses. I can't tell you the number of times I've tracked down a bug or other type of malfunction where I was 100% sure of the cause since my hypothesis made so much sense, but it turned out to be wrong. It was something else.

Seems like the neighbors home security system should have a log of which sensor is tripped. Once you know that it should be pretty easy to figure out what is going on.

Re: Neighbor's house alarm triggers when I put my car in reverse

#62

Post by pryelluw »

My brother had a 1991 Ford Mustang 5.0 with a flowmaster 3 inch exhaust system (no cats). It would set off alarms at a specific RPM in 2nd gear (under slight load). He enjoyed annoying people with it (my brother was a hardcore car guy).

View this YouTube video to get a good idea of how the car sounded (my brother's was a bit louder): https://youtu.be/cNWv5WpamPc

Re: Neighbor's house alarm triggers when I put my car in reverse

#63

Post by sundvor »

hocuspocus wrote: post #50
sundvor wrote: post #16

Earlier quoted context omitted.

I have that on my Mazda 3 and it's absolutely brilliant. The range and sensitivity of that system is rather amazing.

FYI car makers are starting to collect data from connected cars using their ultrasonic sensors for collision avoidance, among other sensors. You can indeed use them to map surroundings fairly accurately.

Mine isn't connected but, yep, could certainly see how that'd work. Whilst no fancy auto pilot yet, the AEB and radar cruise are very nice things to have in a car.

Re: Neighbor's house alarm triggers when I put my car in reverse

#64

Post by pcurve »

sundvor wrote: post #16
X-Istence wrote: post #10

Earlier quoted context omitted.

It could have backup sensors. Rear cross detection and blind-spot detection is an option package. This allows my car (2016 WRX Limited) to warn me about cars flying by when I am backing up out of a parking spot for example.

I have that on my Mazda 3 and it's absolutely brilliant. The range and sensitivity of that system is rather amazing.

I have 2014 3. This system has spoiled me. If my next car doesn't have something similar, I'll probably crash it pulling out of dealership.

Re: Neighbor's house alarm triggers when I put my car in reverse

#65

Post by jstanley »

spydum wrote: post #54
jstanley wrote: post #44

Interestingly, I used to have a 433MHz wireless doorbell (a "1byOne", specifically) that would spuriously chime every time a specific one of my neighbour's cars set off. I assumed it was interference from some sort of PIR motion detector transmitting a signal to say it saw some motion, but I suppose it could conceivably have been caused by the car going into reverse. I never debugged it, I just threw the doorbell awa…

Garage door openers frequently operate at 433MHz, very likely your neighbor was hitting the button as they left?

Good thought, but they don't have a garage.

Re: Neighbor's house alarm triggers when I put my car in reverse

#67

Post by taneq »

lostlogin wrote: post #60
mixedCase wrote: post #26

Earlier quoted context omitted.

Not him but I'd bet 5 bucks it was a smoke alarm with depleted batteries.

Wonder if a full battery with a resistor in series would prolong the agony.

Or a NiCd in place of an Alkaline battery.

Re: Neighbor's house alarm triggers when I put my car in reverse

#68

Post by jsmthrowaway »

alkonaut wrote: post #25
drtillberg wrote: post #13

The comment from im_from_detroit [1] seems on-point, possibly ultrasonic sound from a backup sensor on the car being received by an ultrasonic detector in the house. [1] https://www.reddit.com/r/cars/comments/7k12fs/neighbors_hous...

Op mentions later there are no sensors. So either a light/shadow thing or a sound/vibration thing.

Engines sound deeper when you put them in gear, if he’s driving a muscle car or something, though I’d expect coming home in the evening would do it too in that case.

Re: Neighbor's house alarm triggers when I put my car in reverse

#69

Post by [deleted] »

dzhiurgis wrote: post #49
lb1lf wrote: post #11

Is it just me who'd love something like this to happen to me? Would be great fun tracking down the source of the problem (if it was my car; probably less so if I was in the house...) There's a lot of options to try to isolate the problem, just thinking out loud here - a) Back into the driveway returning from work. See if alarm goes off. Next morning, see if alarm goes off as you drive out. b) Remove fuse for reverse…

My fire alarm goes off once every few months at 3 AM. From what I heard this is not uncommon.

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