What is the Cliff Effect?

Digital television, like all newer wireless digital communications systems, can suffer from a malady known as the “Digital Cliff.” If you have a digital TV, you’ve probably experienced this effect! You may switch on your television one day and see a perfect picture. A few hours later and without warning, the picture may be very badly distorted or disappear altogether.

The Cliff Effect may be best explained this way: analog television’s gradual degradation (that is, the farther from the analog transmitter you go, the worse the picture gets) is a result of the weaker analog signal being overcome by atmospheric noise or even electronic noise in the television’s circuitry. A noisy or “snowy” picture may be annoying, but it still can be watched.

Digital television, by its nature of conveying a picture by a series of numbers or “digits,” can send extra information or numbers along with the broadcast to ensure the picture’s clarity. This means that even if the signal is weak or noise interferes with reception, the extra information can correct the errors to ensure a perfect picture. However, the corrections can only work up to a certain point. When there are too many errors, the error correction system will break down and the picture will disappear. It is hard to tell how close you are to the digital cliff without falling off!

Most new digital TV sets and set-top converter boxes feature a built-in signal quality meter display, which let you know if you are sufficiently far enough away from falling over the digital cliff. Be sure to read the instructions provided with your digital TV receiver or set-top converter box, which will explain how to use the meter to maximize your received signal and identify the best position for your antenna.