Analog signals and digital signals are commonly referred to in contemporary television and stereo systems. But what do the terms mean? More importantly, what difference to they make in terms of the TV or stereo's performance? Digital is generally regarded as a cleaner and more effective signal, with analog slowly going the way of the dodo. But what is the cause of that transition and how does it impact the way we listen to our music or watch our movies?
An analog signal is a constant electrical signal sent through wires into a speak or television monitor. The signal is analogous to the original data it is copying (i.e., the sound or image), hence the name. It has proven to be an extremely reliable technology, effective for decades and applicable not just to televisions and sound systems but also to telephone lines.
Unlike analog signals, digital signals are not constant. Instead, they constitute a series of pulses, each the exact same amplitude and lasting the same length of time. The pulses thus create a binary code of 1s and 0s, similar to the way computers store data. They don't rise and fall the way analog signals do, and the pulses are cleaner.
Advantages of Analog
The primary advantage of an analog signal is that it's much cheaper than a digital signal. If you have an older TV, phone or stereo system, it won't be able to translate the clarity of digital the same way. Analog also reproduces the subtleties and variances of sounds more readily, since its signal can vary in tone. For those who don't worry too much about extra clarity, analog can work just fine; it's done so for quite awhile without many complaints.
Advantages of Digital
Because digital signals consist of binary code, they can travel through digital lines much more quickly. This allows more data to be transferred, which results in a sharper, clearer signal. Digital signals also lack the distortion and "hiss" of analog signals, which further enhances the clarity (though some would argue at the cost of nuance). In terms of phone signals, the 1s and 0s make it much harder for eavesdroppers to listen in, as well as increasing the range of cordless phones and cell phones.
The principle consideration of digital versus analog remains one of price. Music aficionados also debate the advantages of subtler signals with analog. But digital is largely seen to be the wave of the future, especially with television. As of February 17, 2009, all television stations in the United States will stop broadcasting in analog and start broadcasting in digital. This likely won't affect anyone with cable TV or satellite TV, but viewers who still use their old rabbit ears will need to purchase a digital upconverter if they want to keep receiving television signals. (Upconverters are available at most electronics stores for about $40.)