Driveway alarm fail

As many of you may know, I work from home as often as possible. My office is above the garage, and we keep the space minimally conditioned, mainly because we’re too cheap to pay for the oil. So I run an electric heater, which is nice because my office gets toasty, but bad because I can’t hear what’s going on in the rest of the house. Come to think of it, the latter is both a good AND bad thing…

But no matter, for Mr. Paranoid has installed the latest in electronic surveillance and early warning systems so that the zombies never get the drop on us. Not to list all of my “elint” assets, but I have a motion-sensor driveway alarm, as well as a DVR system. I feel pretty comfortable knowing that these systems are available, and I’ve come to rely on them as my first line of defense. 

Or not. I took a short break from my desk a few days ago, and imagine my surprise at seeing this image in my email when I got back: 

white zombie van
Who doesn’t like to see a white rental van backing up to their garage?


My tinfoil-hat ZPAW detector always pegs the needle when a vehicle comes up the driveway, but a white rental van backing up to my garage is DEFCON 1 in my book. But the point is – the driveway sensor didn’t go off, so I had no idea there were potential bad guys on the property. Not good. 

Turns out it was a FedEx contractor dropping off a seed order, but that’s not the point. My EWS failed, and left me in a potentially bad situation. What’s worse, I knew the detector had been acting wonky, but I didn’t do anything about it. Not acceptable. 

First, the quick fix – replace the driveway sensor. It’s about 7-8 years old and has worked pretty reliably for all that time, so it doesn’t owe me anything. I was hoping to just replace the transmitter, but it turns out they don’t make the same unit anymore – mine was branded “Reporter” years ago, which seems to have been bought by Chamberlain. And it turns out that a new system won’t help me, because the new receivers don’t have dry contacts to interface to our alarm system – I have a special chime that sounds on the alarm panel when the driveway is entered. So, time to do some shopping.

The only brand I could find with dry contact outputs is Dakota Alert. Their sensor is much larger, but it’s in a weather-tight case, which probably contributes to longevity. What’s more, they have a MURS-based system, and the base station is a MURS transceiver that can talk to any MURS portable unit. And, the transmitter sends alerts in the standard MURS spoken-English format – “Alert Zone 1,” etc. So you can carry an HT and still hear driveway alerts.

The system has been up and running for a couple of weeks now, and everything has been fine, until today. The driveway alarm has failed to trip despite several vehicles up and down the driveway, along with my wife walking the dog. We’ve had heavy rain all day, and I suspect that has something to do with it. I’m going to have to pull the sensor down tomorrow and see what’s up. Might be some water down in the antenna BNC connector. Stay tuned for details.

1 Comment

  1. me

    Update: I took down the sensor today and gave it a once-over. No apparent signs of water intrusion, although I still have my doubts about the integrity of the BNC antenna connector on the top of the case – seems like a short-circuit waiting to happen. I noticed that I set the sensitivity of the PIR detector inside the sensor to its lowest setting, so I bumped that up a notch and reinstalled it. I’ll see how that goes. If there’s still an issue, I might need to lower the sensor a foot or so on the tree it’s mounted to – it may just be a little too high to “see” engine and exhaust heat blooms as vehicles pass by.


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