JPS6346084A - Transmission system for television signal - Google Patents

Abstract

PURPOSE:To eliminate interference to an existing television receiver and make high fidelity, high quality image reproduction possible by modulating and multiplexing significant information in a specific frequency area in the lower side-band of video signal carrier. CONSTITUTION:Both side-band waves are fC+ or - 0.75 MHz to video signal carrier fC. High precision information is superposed from fC-0.75 MHz to fC -1.25 MHz as significant information by, for instance, high precision information carrier fH. When such television broadcast wave is received by an existing receiving set, the characteristic is shown by a broken line, and the same one with presently used television signals is obtained. Accordingly, the high precision information multiplexed as significant information causes no hindrance. On the other hand, a high fidelity receiving set that utilizes high precision information can obtain high precision, high quality picture image by reproducing a picture image by using both presently used television signals and high precision information in combination.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a television signal transmission system, particularly a television signal transmission system suitable for transmitting significant information, such as high-definition image information, in a narrow band. Regarding the method.

[Conventional technology]

When transmitting television signals, attempts have been made for a long time to maintain the image quality of the reproduced image on the receiving side at high quality and high definition while narrowing the transmission bandwidth of the transmission path, and there have been many attempts related to this. There are transmission methods.

[Problem that the invention seeks to solve]

Many of the conventional transmission systems are in the form of, for example, frequency-multiplexing new high-definition information as significant information onto the current baseband television signal. However, the frequency multiplexing method has a problem in that the multiplexed high-definition information may cause interference when received by an existing receiver.

An object of the present invention is to effectively utilize the frequency band of television broadcast waves to multiplex significant information, such as high-definition information,
It is an object of the present invention to eliminate interference with existing receivers due to multiplexing, and to enable high-definition, high-quality image reproduction in the receiver according to the present invention.

[Means for solving problems]

In the current television system, the frequency band characteristics of television broadcast waves are determined as shown in FIG. That is, on the transmitting side, a video signal with a band of 4.5 MHz is modulated with a video signal carrier fc, and by the so-called vestigial sideband method, the video signal in a band of 1.25 MHz or less is a double-side band wave, and a band of 1.25 MHz or more is a double-side band wave. It is transmitted in the form of sideband waves. On the receiver side, the transmitted signal is converted into a residual sideband signal by a filter with fc and a gain of 1/2, as shown by the broken line in the same figure, and is converted into a residual sideband signal by synchronous detection etc. The signal is demodulated. That is, the shaded area in the figure is discarded on the receiver side and is not effectively utilized. Therefore, the shaded area, which is currently not effectively utilized on the receiver side, can be used to multiplex meaningful information, such as high-definition information, and high definition can be achieved without interfering with existing receivers. be done.

[Effect]

An example of the frequency characteristics of television broadcast waves according to the present invention is shown in the first example.
As shown in the figure. In this example, a video signal with a band of 4.5 MHz,
The audio etc. are the same as in Figure 2 shown above, but the two-side band waves are fc:l:O-75 for the Eirin signal carrier fc.
The difference is that it is MHz. And f −0,
From 75 MHz to fc-1 and 25 MHz, high-definition information is superimposed on a high-definition information carrier fH as significant information, for example.

When the television broadcast radio waves according to the present invention are received by an existing receiver, the characteristics shown by the dotted line in the figure will be obtained, and the same signal as the current television signal will be obtained. Therefore, high-definition information as multiplexed significant information does not interfere at all.

On the other hand, high-definition receivers that also use high-definition information can obtain high-definition, high-quality images by using the current television signal as well as high-definition information to reproduce images. .

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. Here, an example of high-definition information will be explained as significant information. This figure shows an example of the configuration on the transmitting side. JG, B signals obtained from a TV camera or the like are used in an encoder circuit 1 to generate a current decoded color television signal (for example, an NT80 signal) and a high-definition signal to be described later. This high-definition signal is modulated by the fo carrier wave in the modulation circuit 2 using a technique such as QAM (quadrature amplitude modulation) or QPSK (quadrature phase modulation). Then, in the modulator 3,
Video signal (NTSO signal) is fc, high definition information is fH1
The audio signal is modulated with a subcarrier of fA, limited to a desired band by a bandpass filter 4, and then superimposed by a MIX circuit 5 to form a television broadcast signal as shown in FIG.

Note that the video signal and the audio signal adopt a modulation method that conforms to the current standards, but various methods such as AM, AM-VSB, PM, etc. can be applied as a modulation method for high-definition information. .

Furthermore, the high-definition signal is directly supplied to the modulator 3 without going through the modulation circuit 2, and using the fH subcarrier, QAM,
It can also be realized with a configuration that performs modulation such as QAM-VSB and 4-channel UFSX.

Further, the frequency of the subcarrier fH is interleaved with the horizontal frequency fh of the current television signal, or has an offset relationship, for example, fH=-2fh(mi.

If the setting is set as (odd number), it is possible to reduce interference caused by the superimposition of high-definition information even in existing receivers that perform envelope detection.

Next, an embodiment on the receiver side will be described with reference to FIG.

Television broadcast waves are converted into desired intermediate frequency signals by the cheese 6. One side of this signal is ■SB filter 7
This produces a residual sideband signal similar to the currently decoded color television signal, which is amplified by the IP amplifier circuit 9 and then converted into a baseband video signal by the synchronous detection circuit 10.

On the other hand, the intermediate frequency high-definition information extracted by the band-pass filter 8 is returned to the original baseband high-definition information by the LP amplifier circuit 9 and the synchronous detection circuit 10. Then, the demodulator 11 demodulates the signal into the original high-definition signal.

The decoder circuit 12 converts the NTSO signal and the high-definition signal into high-definition image signals R, G, and B.

Next, FIG. 5 shows an example of high-definition signal generation.

In this embodiment, the high-frequency component of the luminance signal (4.2 MHz or higher) is treated as a high-definition signal. A bypass filter 13 extracts high-frequency components of the brightness signal from the brightness signal. The pattern information generation circuit 14 converts the high-frequency component pattern signal or the high-frequency component into a low-frequency component, matches it with the corresponding pattern signal, and generates the code information of the corresponding pattern. And address information of the pattern generation position is generated as a high-definition digital signal.

On the other hand, on the receiver side, based on the high-definition signal, the original luminance signal is reproduced as a high-frequency component at a predetermined position.

Regarding high-definition signals, if a code error occurs,
Since image quality deterioration may occur, it is desirable to add, for example, an error correction code.

Furthermore, high-frequency components of color difference signals can also be used as high-definition signals.

Furthermore, in this embodiment, when the current composite color television signal is received, it is clear that by stopping the reproduction of the high-definition signal, it is possible to reproduce images equivalent to those of existing television receivers.

In the above-described embodiments, the TV broadcast signal has the frequency characteristics shown in FIG. It is clear that the present invention is also applicable to the AM-V8B characteristics of No. 2.

In addition, although the high-frequency component signal of the luminance signal has been explained as an example of meaningful information, in addition to this, there are also chrominance signals, such as color difference signals.
It is also clear that the high-frequency components of the signal, the Q signal, and the combined signal can be used as meaningful information. Further, in the embodiment, the case where the high-definition signal is a digital signal has been described, but it is clear that it is also possible to use an analog signal.

〔Effect of the invention〕

According to the present invention, there is no interference with existing receivers, and it is possible to transmit and receive significant information such as high-definition images,
This has an extremely large effect on increasing the definition and quality of received images.

Note that although the present invention has been described using high-frequency components of luminance or color difference signals corresponding to high-definition information as examples of significant information, it is possible that other information may also be applied as significant information. Not even.

[Brief explanation of drawings]

FIG. 1 is a spectral diagram of a television signal according to the present invention, FIG. 2 is a spectral diagram of a current composite color television signal, and FIGS. 3 to 5 are block diagrams of embodiments of the present invention. encoder circuit, 2. modulation circuit, 3. modulator, 4.
Bandpass filter, 5...MIX circuit, 6. Qi-
7・VSB filter 8・Band pass filter 9
...IF amplifier circuit, 10. Synchronous detection circuit, 11. Demodulator, 12. Decoder circuit, 13. I-pass filter, 14. Pattern information generation circuit, 15. Pattern generation circuit. 1st etc. z ■ Dirt, 3 Bacteria order 4 Concave

Claims (1)

[Claims] 1. Lower band f_c-0.75MHz to f_c-1.25MHz of video signal carrier wave f_c in television broadcast radio waves
A patent for a television signal transmission method 2 characterized in that significant information is modulated and multiplexed in the frequency region of z, and the significant information is a high-frequency component of a luminance signal or a high-frequency component of a color difference signal. A television signal transmission system 3 according to claim 1, wherein the video signal lower sideband in the television broadcast radio wave is from the video signal carrier f_c to fc-0.75 MHz, and from fc-0.75 MHz to f_c-1. A television signal transmission system according to claim 1, characterized in that significant information is multiplexed in a 25 MHz band.