KR970003144B1 - Channel equalization apparatus in hdtv having pip function - Google Patents

Abstract

The channel equalizer circuit of a high definition television, which has at least two or more equalizing units obtaining a restoring signal by equally filtering signal distorted by a channel characteristic to have a picture-in picture (PIP) function displaying two or more pictures through one television receiver, includes: a storing unit (300) for storing equalization filter efficient of a substitute channel capable of being selected upon changing the channel obtained from the other equalizer circuit exclusive of the equalizer circuit performing the equalization of the watching channel, when a viewer watching one channel without using the PIP function; a signal generating unit capable of being selected by a user and generating a channel changing signal; and a substitute channel select logic controlling unit (400) for controlling the channel equalization of the substitute channel, and controlling the filter efficient of the substitute channel corresponding to the change channel stored in the storing unit (300) to be transmitted to the equalizing unit in response of the channel changing signal.

Description

High Definition TV Channel Equalization Circuit with PIP Function

The present invention relates to a channel equalization circuit (HDTV) of a high definition television (HDTV), and particularly, a channel in a high definition television having a picture in picture (PIP) function that shows two or more screens with a single receiver. A channel equalization circuit for performing faster equalization upon switching or starting a PIP function.

In a high-definition TV system, the coded signal from the transmitter is transmitted to the receiver through the channel. In order to transmit a signal over a long distance through a channel, a modulation process must be performed. The modulation method includes frequency modulation (FSK), phase shift keying (PSK), and quadrature amplitude modulation (QAM). Etc. The most commonly used is the 16-QAM (or 32QAM) method, and is expressed as one of 16 (or 32) points by leveling orthogonality and phase. Therefore, in transmission, 16QAM (or 32QAM) signals are transmitted to the receiving end. At this time, distortion is generated by the transmission path, that is, channel characteristics, and is received by the receiver. Distortion is caused by a number of factors, including the location of the transmitter and receiver, distance, topography, and building weather. Such distortion may appear as a deterioration in image quality of an existing analog TV system, but in a high-definition TV system using a digital transmission system, there may be a phenomenon in which the premise of the screen cannot be restored or a completely different image appears on the receiving side. Therefore, the receiving end recovers the signal transmitted from the transmitting end by reducing the distortion as much as possible using the channel equalization circuit.

In general, high-definition TV is expected to play various roles in addition to the existing simple TV function according to the digitalized characteristics. Therefore, the PIP function that shows two or more screens with the receiver is almost basic. For the PIP function, channel equalization for two or more different signals must be performed simultaneously. As a result, two or more channel equalization circuits are required in a high-definition TV having a PIP function. If the user is watching only one channel without using the PIP function, only one equalization circuit is operated. If the channel is changed by the user, the equalization of the newly selected channel is performed by the active equalization circuit. Will be performed. For this reason, there is an equalization circuit that does not operate when the PIP function is not being performed. Therefore, system resources are inefficiently operated, and the same equalization circuit must be newly executed from the beginning for the newly selected channel. There was a problem of degrading the adaptability of the system.

Disclosure of Invention The present invention has been made to solve the above problems, and by using an equalization circuit that does not operate in a high-definition TV having a PIP function, it is possible to perform channel equalization faster and more efficiently when changing channels and to utilize system resources more effectively. It is to provide an equalization circuit that can be.

In order to achieve the above object, the present invention provides at least two equalizers for obtaining a reconstruction signal by equalizing and filtering a signal distorted by channel characteristics, so that a channel equalization of a high-definition TV having a PIP function showing two or more screens with one receiver. In the circuit: storing equalization filter coefficients of candidate channels that can be selected at channel change, obtained from other equalization circuits except for the equalizing circuit which performs equalization of the viewing channel when viewing only one channel without using the PIP function. A storage unit for; And controlling a channel equalization of a candidate channel and including a candidate channel selection logic controller corresponding to the changed channel stored in the storage unit 300 in response to the channel change signal.

Is a channel equalization circuit of a high definition television having a PIP function according to the present invention.

* Explanation of symbols for main parts of the drawings

100: first light unit 200: second light unit,

300: storage unit 400: candidate channel selection logic control unit

500: channel switching signal line 600, 700: filter required coefficient determination unit

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

FIG. 1 is a channel equalization circuit of a high-definition TV having a PIP function according to the present invention, wherein the first and second equalizers 100 and 200, the candidate channel selection logic controller 400, and a candidate for performing channel equalization of the received distortion signal are shown. The channel consists of a storage 300 for storing filter coefficients.

At this time, the first equalizing unit 100 restores the equalizing filter unit 10, the filter coefficient determining unit 600, the derotator 40, the selecting unit 70, the equalizer selecting unit 60, and the determined equalizing carrier. Group 50 to perform conventional channel equalization on the distorted signal. The second light unit 200 also has the same configuration as the first light unit 100. In detail, the equalization filter unit 10 equalizes and filters the distorted received signal using filter coefficients to correct the magnitude, phase, delay, distortion, and the like of the received signal. The filter coefficient determiner 600 provides a filter coefficient necessary for equalization filtering, and includes a blind equalizer 20 and a decision based equalizer 30. Based on the determination, the equalized carrier restorer 50 measures the phase error of the input signal and outputs the phase error. Derotator 40 compensates for the phase distortion of the equalized filtered signal.

The equalizer selector 60 provides a selection signal of the selection means 70 such that one of the filter coefficients from the filter coefficient determiner 600 or the storage 300 is selected by the selection means 70. .

Looking at the channel equalization process in the first equalizing unit 100 is configured as follows. First, when a user selects a channel to be watched, a signal whose size and phase are distorted due to channel characteristics is received by the receiver. At this time, the equalization filter unit 10 in the first equalizing unit corrects the magnitude distortion of the received signal using the filter coefficient. In this case, the filter coefficients are provided from the filter coefficient determiner 600, that is, the blind equalizer 20 or the decision based equalizer 30 through the selection means 70. Is performed. The blind equalizer receives the equalized filtered signal and outputs filter coefficients. In addition, the decision based equalizer 30 receives an input signal from the equalization filter unit 10, the derotator 40, and the decision based equalization carrier decompressor 50, and outputs filter coefficients. At this time, the filter coefficient of the blind equalizer 20 has an effect of correcting the coarse distortion, and the filter coefficient of the crystal equalizer is excellent in correcting the fine size distortion. Therefore, the equalizer selector 60 receives a signal from the diro data 40 and when the error degree between the average value of the reconstructed emerging and the 16-QAM signal pattern is less than or equal to the preset value, for example, the error degree can be visually known. The selection signal is outputted so that the filter coefficient of the blind equalizer 20 is selected until the opening degree is opened above the predetermined value level, and the filter coefficient of the equalizer 30 is selected based on the determination when the error degree is less than the predetermined value. Output a selection signal to be selected by the means. The derotator 40 corrects phase distortion of the equalized filtered signal using the phase error provided from the equalized carrier recoverer 50 based on the decision. The signal whose correction for the phase error is performed in the derotator 40 is transmitted to the decision based equalizer carrier restorer 50, the decision based equalizer 30, the equalizer selector 60, and the decoder of the next stage. do.

During the conventional equalization process for one channel as described above, the candidate channel selection logic controller 400 sends the candidate channel selection logic signal to the main IC (Main IC, not shown) through the channel telephone signal line 500. send. At this time, the candidate channel may be registered by the user or the least recently used (LRU) algorithm in the candidate channel selection logic controller 400. Are automatically determined, and channels with high selectability are selected. Therefore, the video signal of the candidate channel is received through a tuner (not shown). The received image signal is subjected to a conventional channel equalization process by the second equalizer 200, and the filter coefficient value output from the equalizer 230 is determined under the control of the candidate channel selection logic controller 400 based on the determination. 300). Subsequently, the above process is repeated for another equalization candidate channel selected or registered under the control of the candidate selection logic controller 400. At this time, the candidate channel selection logic controller 400 is connected to the equalizer selectors 60 and 260 so that the blind equalizer 20 or 220 or the decision equalizer 30 is determined at the start of the channel switching signal or the PIP function. ), A signal is generated to block the input from the 230 and to load the filter coefficients from the storage unit 300 to the equalization filter unit 10 or 210 first.

In addition, when the user inputs a channel telephone signal to the main IC to switch only the channel to be watched instead of starting the PIP function, the channel switching signal is transmitted to the candidate channel selection logic controller 400 through the channel telephone signal line 500. Is entered. At this time, the candidate channel selection logic controller 400 sends the control signal to the storage 300 to convert the filter coefficients of the switching channel stored in the storage 300 to the selection means 70 of the first equalizer 100. To be sent.

In contrast, when a user selects a channel of a mother screen and a channel of a child screen to initiate a PIP function, the coefficient value of a candidate channel stored in the storage unit 300 corresponding to at least one selected channel is selected as a candidate channel selection logic. Under the control of the controller 400, the filter coefficients of the mother screen channel and the mother screen channel are transmitted to the first and second equalizers 100 and 200, respectively.

As a result, the coefficient of the filter is obtained in a state where the error is reduced to a considerable level unless the sudden change of the channel state due to a change in function or the adjacent channel interference is large. By omitting the equalization by the operation 220 or the execution time thereof, the execution time is significantly shortened so that the system can immediately enter the decision-based mode, which enables the channel equalization to be performed considerably faster than the conventional method, and can exhibit stable performance.

In addition to the above, it can be applied to high-quality high-definition TVG that can receive more than three channels at the same time in the PIP system, so that it is faster to operate the PIP function or switch channels by using an extra device (tuner, equalizer, filter). Channel equalization is possible.

Claims (2)

High-quality TV channel equalization with picture-in-picture (PIP) function that includes at least two equalizers for equalizing and filtering the signal distorted by the channel characteristics to obtain a reconstruction signal. A circuit for storing equalization filter coefficients of candidate channels that can be selected when changing a channel obtained by an equalization circuit other than an equalization circuit that performs equalization of a viewing channel when the user is watching only one channel without using the PIP function. Section 300; Signal generating means selectable by a user and generating a channel change signal; A candidate channel selection logic controller 400 for controlling channel equalization of a candidate channel and controlling a filter coefficient of a candidate channel corresponding to a changed channel stored in the storage unit 300 to be transmitted to the equalizer in response to the channel change signal; High-definition TV channel equalization circuit comprising a). The channel of claim 1, wherein the candidate channel can be registered by a user or automatically determined by a least recently used (LRU) algorithm in the candidate channel selection logic controller 400 so that the channels having a higher selection possibility are selected. Selected high-quality TV channel equalization circuit.