JPH04367169A - Television receiver - Google Patents

Abstract

PURPOSE:To protect erroneous action of the successive circuit in a television receiver by deriving out an image signal that sets at a pedestal level a horizontal blanking period during which a voice signal that was superposed in a horizontal blanking period for the image signal was extracted. CONSTITUTION:An image signal that was converted into a digital signal by an A/D conversion circuit 2 is supplied to a gate circuit 7 and to a mask circuit 6, while a voice signal is processed after the gate circuit 7. The maskcircuit 6 uses a synchronous signal supplied from a synchrnous separation circuit 3 to extract a color burst signal, and supplies it to an image processing circuit 9. In the image processing circuit 9, a pedestal signal whose pedestal level is set at the half value of the amplitude of the color burst signal is generated, and is inserted in the section where a digital voice signal was superposed to derive an image signal. Thus, the influence can be reduced on the circuits at the successive stages, a synchronous separation circuit, and the pedestal circuit.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention relates to a television receiver, and more particularly to a television receiver that receives a television signal in which a digital audio signal is superimposed on a horizontal blanking portion while maintaining compatibility with the current NTSC color television signal. John's receiver.

0002

2. Description of the Related Art Several methods have been proposed in the past to attempt to widen images and improve image quality by adding auxiliary signals to improve image quality while maintaining compatibility with current NTSC video signals. On the other hand, as image quality has become higher, several methods have been proposed for adding, transmitting, and demodulating high-quality digital audio signals. One conventionally proposed method will be explained using FIGS. 2 and 3.

[0003] On the transmission side, the audio signal is, for example, 32K.
Sampling at Hz and digitizing, time compression,
The digital audio signal is encoded by performing operations such as adding an error correction signal, and is superimposed on the horizontal blanking of the video signal as shown in FIG. 3(a).

[0004] Also, as shown in FIG. 2, on the receiving side,
A video signal input from the video signal input terminal 1 is supplied to an A/D conversion circuit 2, a synchronous separation circuit 3, and a video clock generation circuit 5. The video clock generation circuit 5 locks to the burst signal of the video signal, and also locks to the subcarrier frequency f.
4 times the frequency of sc, 4fsc (14.3181MHz
) is generated and supplied to each circuit as a system clock. The synchronization separation circuit 3 separates the synchronization signal from the video signal and supplies the synchronization signal to the gate circuit 7.

[0005] Further, the A/D conversion circuit 2 samples the input analog video signal at a 4fsc sampling frequency, digitizes it, and supplies the digitalized signal to the gate circuit 7 and the video processing circuit 9. The video processing circuit 9 improves the image quality,
The signal is widened and supplied to the D/A conversion circuit 10, which converts the video-processed digital signal into an analog signal and supplies it to the video signal output terminal 12.

On the other hand, the gate circuit 7 extracts the digital audio signal superimposed on the horizontal blanking portion of the video signal using the synchronization signal supplied from the synchronization separation circuit 3 and supplies it to the audio signal processing circuit 8 . The audio signal processing circuit 8 processes the digital audio signal, that is, performs time expansion and error detection/correction processing from the digital audio signal, reproduces audio data, generates an audio clock fa (32 KHz), and performs D/A conversion. Supplied to circuit 11. The D/A conversion circuit 11 converts the digital audio signal into an analog audio signal using the audio clock fa, and supplies the analog audio signal to the audio signal output terminal 13.

[0007]

[Problem to be Solved by the Invention] When a digital audio signal is superimposed on the horizontal blanking portion of a video signal and the video signal is supplied to the next stage circuit or other system, the portion where the digital audio signal is superimposed This has had an adverse effect on clamp circuits such as DC component regeneration circuits that utilize , that is, so-called pedestal clamp circuits and synchronous separation circuits.

[0008]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides for receiving a television signal in which a digital audio signal is superimposed on the blanking part while maintaining compatibility with the current NTSC color television signal broadcasting. The television receiver includes an audio signal processing means for extracting the digital audio signal, processing the audio signal, and outputting an audio signal, and a video signal in which a horizontal blanking section from which the audio signal is extracted is adjusted to a pedestal level. The video signal is configured to output the video signal independently of the audio signal, thereby preventing synchronization separation of circuits connected to the next stage and other systems and malfunction of the clamp circuit. .

[0009]

[Operation] According to the above structure, the digital audio signal superimposed on the horizontal blanking period of the video signal is extracted by the audio signal processing means, and then subjected to signal processing and output as an audio signal. The horizontal blanking portion of the extracted video signal is adjusted to a pedestal level by a level adjustment means. Therefore, this video signal prevents malfunctions of circuits connected to the next stage and synchronous separation and clamp circuits of other systems.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an embodiment of the present invention. Portions corresponding to the conventional example shown in FIG. 2 are designated by the same reference numerals, and description thereof will be omitted.

First, the A/D conversion circuit 2 supplies the video signal converted into a digital signal to the gate circuit 7 and the mask circuit 6, and the audio signal is processed by the gate circuit 7 and the subsequent circuits in the same manner as in the conventional device. Mask circuit 6 is synchronization separation circuit 3
The color burst signal is extracted using the synchronization signal supplied from the sync signal and supplied to the video processing circuit 9. The video processing circuit 9 generates a pedestal signal whose pedestal level is half the amplitude of the color burst signal, and inserts the pedestal signal into the portion where the digital audio signal was superimposed to produce a video as shown in FIG. 3(b). Derive the signal. This video signal is supplied to the next stage D/A conversion circuit 10, converted into an analog signal, and outputted from the video signal output terminal 12.

That is, the horizontal blanking section supplies a video signal with no digital audio signal multiplexed therein, and the horizontal blanking section supplies the video signal at the pedestal level to the next stage circuit or other system independently of the audio signal. Can be done.

[0013]

[Effects of the Invention] Since the present invention has the above configuration,
A high-quality audio signal obtained by extracting the digital audio signal superimposed on the horizontal blanking part of the video signal and performing audio processing,
Since the video signal with the digital audio signal multiplexed at the pedestal level can be supplied independently to the next stage circuit or other systems, it is possible to The influence on the circuit can be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional example.

[Fig. 3] Waveform explanatory diagram.

[Explanation of symbols]

6 Mask circuit 7 Gate circuit 8 Audio processing circuit 9 Video processing circuit

Claims (1)

[Claims] Claim 1: A television receiver that receives a television signal in which a digital audio signal is superimposed on a horizontal blanking part while maintaining compatibility with current NTSC color television signal broadcasting, wherein the digital audio signal is extracted and the audio It is equipped with an audio signal processing means for processing a signal and outputting an audio signal, and a level adjustment means for deriving a video signal obtained by adjusting a horizontal blanking section from which the audio signal is extracted to a pedestal level, and converting the video signal into the audio signal. A television receiver characterized in that it outputs signals independently.