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Macintosh Home Monitoring

by Gordon Meyer, author of Smart Home Hacks
04/04/2006

Editor's note: In this article you'll learn how to use a few simple home automation techniques to have your Mac send you a message when your mail is delivered, your kids come home, or your dog uses the pet door to go into the backyard.

When I'm away from home but expecting something to happen there--like an important FedEx delivery--my concentration will suffer because of that little voice that occasionally reminds me about what I'm waiting for. In the parlance of Getting Things Done, this is called an "open loop" and it's detrimental to personal productivity. One way to eliminate the distraction is to put a trusted servant in charge of worrying, or at least watching, on your behalf. And that's exactly what this article will describe: a home sentry, made from your Mac and a few home automation pieces, that sends a message to your cell phone the instant your important event occurs.

This approach is quite flexible, you could use it to learn when your kids come home from school, when your mail carrier opens the mailbox, or even when your dachshund uses the pet door to visit the backyard. Next time you find yourself thinking, "I wonder if that has happened yet..." you just might have the solution to stop wondering, and start knowing, right at hand.

Now don't let the words "home automation" frighten you. The approach here only scratches the surface of home automation, and uses sensors and software that are inexpensive and easy to use. In addition, we're sticking with wireless devices, so no pulling of cables or replacing existing wiring will be necessary. You won't quite be living like George Jetson, but your house will be a tad bit smarter.

The Hardware You Need

In addition to a broadband-connected home computer that you leave running while you're away from home, you need:

  • One or more wireless motion sensors
  • A wireless-to-computer home automation controller
  • Home automation software

You have a few choices to make for each of these, so let's go over the options. You should make your choices based on your budget, what you want to monitor, and how much effort you want to put into customizing your setup.

Choose a Sensor

Briefly put, a sensor is a device that, well, senses when something has happened and then relays that information to the home automation controller connected to your Mac. If you want to know about general activity in an area, such as your front porch, then a motion detector will do the trick. On the other hand, if you want to know that your kids are home safe, you'll want to monitor something that's inside the house, and something that you know they're going to interact with when they come home. For example, you might install a door sensor in their bedroom, or on the fridge.

Motion Detectors

Motion detectors are about the size of an Altoids tin and function by sensing movement with passive infrared detection. That is, they constantly scan for moving objects that are of significantly different temperature than the surrounding area. When you walk into a room, the sensor sees you as a moving 98-degree blob of heat. (Don't take it personally.) When this happens, the unit wirelessly transmits an On signal and then continues to transmit another every few seconds until you've left its sight, or have stood very still for several minutes. When it finally decides that all is quiet, it sends an Off signal.

The X10 Indoor Wireless Motion Sensor is the best choice for this project. It can mount on the wall with double-stick tape and its AAA batteries last months, if not longer, before having to be replaced. Figure 1 shows a motion detector positioned to watch a front porch for visitors.

figure 1
Figure 1: A sensor in the eaves of a front porch

There are some things to keep in mind when deciding where to mount a motion detector. Because they work by detecting movies bodies of heat, they can be fooled by hot air from a heating vent, moving cars, or similar objects. Also, if you're trying to detect that a person has entered a room, position the sensor so that it "sees" the person walk past. A little experimentation will be needed to find the best position; remember that you can mount the sensor orientated in any direction, such as sideways on the ceiling, if that's what works best for you.

Smart Home Hacks

Related Reading

Smart Home Hacks
Tips & Tools for Automating Your House
By Gordon Meyer

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