DTV

Short for Digital Television. DTV is the transmission of television signals using digital rather than conventional analog methods. Analog transmission is in the form of a constantly variable wave; digital transmission consists of an electrical pulse that has two possibilities: on and off (or positive and negative),which are represented by a one and a zero (this is binary data, the same type of information that a computer understands), that is then modulated into an analog transmission. A digital signal can be more precise than analog due to the fact that the electronics at the receiving end will either be able to retrieve enough of the digital information to reconstruct a pretty good signal, or it will be incapable of reconstructing anything resembling a good signal. It’s pretty much all or nothing, with very little area in between. Although both signals are transmitted in the same basic way and supposedly have the same range, they behave differently at the limits of their ranges. An analog signal gradually degrades over distance (mostly in amplitude, though there can be other distortions introduced) and may be barely detectable at the farther reaches of the broadcast area – this is why the signal from a distant radio station fades in and out. As the signal reaches the farther limits of its range, the signal-to-noise ratio decreases and the quality of the broadcast suffers, although the range remains the same. In comparison, when the signal-to-noise decreases in a digital signal, the quality of the broadcast does not visibly degrade very much (until it drops out all together) depending upon the error correction capabilities of the system or generally how effective it is at reconstructing a usable signal from partial information, but the range shrinks.