You’ve probably noticed that fluorescent lights flicker on and off when they start to lose power. But you may not know that fluorescent lights do that even when they’re working perfectly – they just flicker so fast you can’t see it happening. In this Science Update, you’ll hear about a company that wants to turn those flickering patterns into code.
Lights that flicker in code. I'm Bob Hirshon and this is Science Update.
Fluorescent lights brighten the rooms of many offices and homes. Now, one company is working on a way to use them for more than just illumination. Neil Lupton is president of the Talking Lights Company in Boston. He says fluorescent lights can also be used as part of a wireless communications network to transmit information.
This can be analog information, digital information, could contain audio, it could contain graphics, or it could contain computer control codes so that somebody in the vicinity of that light using a receiver can pick up the information that’s coming out of the light.
Their technology is based on the fact that fluorescent lights flicker at a rate of about forty to sixty thousand times a second, too fast for the eye to see. By installing a special device onto a light bulb, that flicker rate can be varied to send coded information. Receivers in the room then detect and interpret those light signals.
And some of the application areas that we’re using, for example, would be assisted technology to individuals like blind users that could then have a receiver. And the light would give them guidance in terms of where things are in a building, or how to go from one place to another.
And because the technology uses light bulbs already in the room, Lupton says the system is inexpensive and energy-efficient. For the American Association for the Advancement of Science, I'm Bob Hirshon.
Making Sense of the Research
It’s one thing to come up with a new kind of technology, but it’s more efficient to come up with a new technology that piggybacks onto something that already exists. Installing a new coded communication system into an office building from scratch would take a lot of time and money. In this case, almost all the equipment you need is already built in to virtually every office building, school, and hospital in America. All you have to add is a way to control the flickering pattern of the lights so you can communicate whatever signals you want.
It might seem like flickering lights couldn’t communicate very much information, but consider that everything your computer can do is encoded by two numbers: 0 and 1. In the case of fluorescent lighting, the flickering patterns could be turned into something like Morse Code, sophisticated and complex enough to send computer data and high-quality audio.
As Lupton says, the technology might be combined with a hand-held computerized receiver and computer to help guide blind people through buildings. For example, if you stepped under one light, your receiver might pick up its position and tell you: “You’re in the southeast corridor. The cafeteria is straight ahead and the door to the women’s restroom is on your right.” As soon as you stepped under a new light, you’d find out about your new position. If your receiver had maps of the building programmed into it, it could use the information from the lights to direct you to a specific destination. Besides visually impaired people, the technology might also be useful for people with brain disorders like Alzheimer’s, who often forget where they are and become lost and confused.
One big advantage to using fluorescent lights is that the signals are very tight and don’t overlap much. Lupton says that as long as you position the lights about three to five feet apart or more, their signals won’t get scrambled together. Also, unlike radio waves, light won’t go through walls. Those might sound like limitations, but when you want a very precise, indoor guidance system, you don’t want big, powerful signals. (Save those for people finding their way across the Pacific on boats!) And because the code is just ordinary light, people who aren’t using it won’t even notice it.
Now try and answer these questions:
- How can fluorescent lights encode information?
- Why can't your eyes see the lights flickering as they send the information?
- If you were testing this technology out, what are some of the questions you would need to answer in order to make sure it would be effective and practical?
- Aside from those already mentioned, what other applications can you envision?
- Can you think of other everyday phenomena that have properties that can be used to create codes? (These can be natural or man-made.)
Find out more about the Talking Lights Company from their website.
Send a Coded Message is an online activity that allows you to create and send encrypted messages, based on a World War II coding machine.
Marshall Brain’s How Stuff Works has loads of information about how different kinds of communications systems work.