Sunday, April 10, 2011

Assistive Technology for Access for People with Special Needs/Disabilities: What Makes it Work?

There are 2 kinds of people:
  1. Those who want to know why things work.
  2. Those who just want things to work. Period.
This post is for the first kind of people, kind of. We'll keep it lay-person friendly, cause that's how I roll.

There are a couple of frequencies we will describe here:
  • Infrared (IR)
  • Radio Frequency (RF)
  • X10
  • And the others...
Take a look at the remote control for your TV. Unless you have a high-dollar, complex home theater system, chances are your remote control has an infrared "eye" at the front of it. I would bet money (or maybe not, but you get the gist) that when your child plants directly in front of your DVD player your remote control doesn't work...why?

I'm not going to describe the technical process, but basically infrared communication needs to have an open "line of sight".
The eye on your remote control sends out information when you press a button, communicating with the receiving eye on the DVD Player, TV, Radio (and the list goes on).

Your child blocks the information transmission. When you yell, he moves, and you smack the button again the receiving system processes the information from the incoming code and executes the action (ex. play). Many of our everyday technologies communicate via infrared; there are even phones that communicate through IR (the importance of this to be explained later).

Radio Frequency, also known as RF, is not line of sight. You know your garage door opener? If you are so lucky to have one, when you drive into your driveway you can remain warmly in your car and push the button.

If all goes as planned, the door rises. RF requires a unique code that the command center unit and the remote control share. There is, at times, interference when neighbor's code switches are unknowingly similar. Leading to an eerie feeling that you may get when your neighbor comes home late and you hear your garage door rises.

These troubles are becoming more obsolete with the introduction of rolling code technology, which changes the code shared between the opener and the remote each time the remote is pressed. But anyway. Why should you care?

RF is sometimes used for automatic door openers (read, if you are unable to physically operate a standard door...are you seeing the connection?). Also, some high dollar home theater system remote controls communicate via RF to allow the ugly, messy components of the system remain behind close doors. Basically, yes, to one-up the Joneses. An example...
Source: * Logitech Harmony 900

That is a seriously sweet looking remote. Who wouldn't want one?

X10...X10 is a now older-ish technology, but still quite useful and can be (but is not limited to) simplicity if you only want control over 1 or 2 (up to 16) devices. X10 is toted as the "standard for home automation" and uses existing wiring in the home to communicate between electronic devices.

This technology works with anything that you can turn on, unplug, and plug back in and the device returns to it's previous "on" state. Simple fans, lamps, radios work well. For example, I want to setup a plug-in lamp to turn on and off by remote control, so that when I walk in my home I can activate the "on" button on the remote, the light turns on, and I don't trip over the boots my daughter left on the floor. To set this up I take an X10 module,
source: * 3-pin X10 Appliance Module

plug it into the wall, and plug the lamp into the bottom of the module. Set the code on the module by turning the dials, and pair it with an X10 remote control by setting the same code. Wala! There's X10 at it's very simplest.

And yes, of course there are additional ways for communication between household objects.

  • X10 can be installed directly into the home wiring, allowing for full home automation with lights, fans, and more.
  • IR X10 command console IR signals (read, from a remote) converts into X10...this is a huge idea and will be revisited later.
  • Oh, and anyone heard of the internet? I tell ya, I can make my imaginary DVR record Housewives of Orange County (does this show exist? it sounded right.) on my Droid in the supermarket through the internet it's communication with the DVR. That, my friends, is beauty.
  • Still want more? Insteon technology meshes the X10 idea and the internet. I'm sure you've seen the commercials for people in the airport ready to board a plane to Tahiti (I wish) and leave their lights on? With a flick of a virtual switch they turn them off, and are instantly at peace and on their way. (for more information visit
I'm sure I've forgotten something, but for our purposes these methods of environmental communication are sufficient. In the near future I'll build the bridge to function, answering the question, "So what?".

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