In a digital television broadcast, signals transmitted from a broadcast station to a television receiver as well as the signals within a television receiver are all digital signals, so that more distinct pictures and clearer sounds are provided than those in an analog television broadcast. The digital television broadcast signals include a radio broadcast channel to broadcast only audio sound and a data broadcast channel to broadcast data such as computer programs, in addition to usual broadcast channels for both the video and audio broadcasts. The digital television broadcasting includes a plurality of image formats differing in the scanning system (interlace scanning, non interlace scanning), number of scanning lines, number of pixels, and aspect ratio. The structure of a television receiver per se directed to the television broadcasting has also become versatile. Digital TV systems simultaneously transmit the video and audio components of several TV programs through a single transmission channel, and additional information if needed from other services by means of a transport time multiplexer. A digital TV broadcasting system in general uses a terrestrial VSB (Vestigial Side Band) transmission system. In the digital TV broadcasting system, a video data and a synchronizing signal are transmitted, separately. And, on a receiver side, a position of the synchronizing signal should be accurately detected from the video data. Linearity of the DTV signal during its transmission and reception must be preserved, so that the data slicing procedures have low enough rate of errors that the errors are nearly always correctable in reliance upon forward-error-correction coding. A typical digital television signal is first encoded according to the standard adopted by the Moving Picture Experts Group (MPEG) to provide a digital bit-stream. The digital bit stream is then used to modulate a radio frequency (RF) carrier using quadrature amplitude modulation (QAM) or trellis coded vestigial side-band (VSB) modulation techniques. A digital TV receiver receives and decodes a video signal compressed in the MPEG2 format at a decoder to display the video on a screen. In a digital TV receiver, the decoder processes a bit stream corresponding to each class inclusive of discrete cosine transform (DCT) coefficients and motion vector information. The digital data signal for video is MPEG encoded and for audio is Dolby AC-3 processed and must be subjected to decompression before application to conventional video and audio circuitry. Depending upon the number of picture elements in relation to the resolution and image reproductivity or picture quality, a digital TV supports two classes of video signals, namely the high definition TV (HDTV) and the standard definition TV (SDTV). A general digital TV receiver having at least two reception modes is capable of receiving an analog broadcasting signal and a digital broadcasting signal. In a digital broadcasting signal, a pattern of the synchronizing signal is in general inserted in the video data so that the synchronizing signal can be detected on the receiver side. In analog TV broadcasting, only one program can be transmitted through a specified frequency band of an RF channel. In a digital TV broadcasting system for a next generation system such as an HDTV (high definition TV), the number of RF channels is much greater than in the analog TV broadcasting system. In digital TV broadcast systems, such as currently realized digital satellite TV broadcasts using a communication satellite (CS), digital satellite TV broadcasts using a broadcasting satellite (BS), and ground-wave digital TV broadcasts, program data is transmitted after being compressed using a compression method, such as the MPEG (Moving Picture Experts Group) 2 method. When recording program data, it is possible to record the program data in a compressed state, so that many programs can be recorded in a recording apparatus. Furthermore, since many programs of various types are transmitted as digital TV broadcasts, the number of programs recorded by a user increases, and program data relating to a plurality of programs of digital TV broadcasts may be recorded in a plurality of recording apparatuses.

A television receiver (TV) that displays images by restoring broadcasting signals, which have been compressed into digital signals, through a decoder built in or outside the receiver is called a digital TV. A digital television receiver includes a tuner and a VSB demodulator for developing the baseband signal, which is in compressed form. The demodulated signal is applied to an equalizer for equalizing the received signal. The baseband signal is applied to a transport demultiplexer which directs the data to an appropriate MPEG decoder and a Dolby decoder for recovering the video and audio in proper form for application to video and audio processing circuitry. A digital television receiver may be constructed with a tuner feeding an intermediate frequency module. Digital television receivers receive the various radio frequency signals either through the atmosphere or via a cable like an analog signal broadcast. In order to receive a program transmitted on a DTV channel, a receiver must tune the receiver to the channel frequency, phase-lock the tuner to the DTV signal, demodulate the signal and then decode the demodulated signal. For a typical DTV signal, this process may take four to ten seconds for each major channel. The radio frequency tuner that is first tuned under the control of a microprocessor exhibits a frequency deviation from its regular frequency band as it passes through several intermediate apparatuses. The tuner tunes to one radio frequency channel among the several broadcast signals received via an antenna, under the control of a microprocessor. An intermediate frequency stage module receives an IF signal from the tuner and converts that signal into a baseband signal while a channel decoder produces a data bitstream by decoding the baseband signal output from the intermediate frequency stage module. A TS decoder then separates audio data, video data and additional data from the data bitstream output by the channel decoder. Digital signals from other sources, such as DVD (digital video disk) players, VCRs (video cassette recorders), PCs (personal computers), digital cable boxes, satellite receivers and the like will be supplied to digital television receivers, as is the case for present analog television receivers. In a digital television receiver, the quality of the displayed picture does not bear a direct, continuously-varying relationship to the received signal quality. This is due to the sharp threshold of the receiver's error-correction capability when faced with a compromised input signal. Generally, a process of setting and adjusting functions of a digital TV receiver is carried out through a function of an OSD (on-screen display) menu. This is because the construction and functions of the digital TV receiver get complicated lately, thereby requiring explanation of the construction and functions consequently.