A TV remote control uses pulses of infrared (IR) light to communicate.The pulses are transmitted with an IR LED as a series of bursts separated by off periods. Figure I shows a typical transmission. Note that the total signal is almost 90 milliseconds long, contains approximately 78 bursts, and the durations of bursts and off periods vary. With an understanding of the IR codes, a wide range of devices can be built delivering new remote control capabilities. An example is a channel surfer that automatically flips cable channels similar to the scan function on radios. Another example is a customized remote that turns on all entertainment center components with a single button, and manages all component switching with single button presses (turn on the DVD and select the appropriate input on the TV).This might help a grandparent who struggles getting three components configured properly. Other examples include prank devices that change channels, volume, or turn off a large number of TVs with a single button press such as the TV-B-Gone advertised on the Internet.
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