JPS6269787A - Television casting system - Google Patents

Abstract

PURPOSE:To associate an NTSC system television with an additional information signal and easily transmit the new additional information signal by angle- modulating and transmitting a telecasting video carrier of the NTSC system with the aid of the additional information signal. CONSTITUTION:The output of an angle modulator 2 is modulated by the additional information signal 3 and generates an upper and a lower sideband wave. If the telecasting video carrier is left intact, it is slope-detected by a Nyquist slope in an image receiver and develops amplitude variation by the additional information signal. Said variation cannot be separated from original amplitude variation by a video signal because the video signal of the NTSC system is transmitted through the use of amplitude modulation. To ensure the compatibility, a characteristic compensating part is provided. This characteristic compensating part uses a filter having the reverse of Nyquist slope characteristic, and is provided given the reverse characteristic with respect to the amplitude variation generated in the receiver by the output of the angle modulator 2. This system extinguishes the amplitude variation of the video carrier by the additional information signal and removes interference as a general transmission system including a transmitter side.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to a television (hereinafter simply referred to as television) that is compatible with NTSC color television broadcasting and enables expansion of broadcast information signal capacity. ) related to broadcasting methods.

(Prior technology) Color television broadcasting in Japan uses the 4.2 MHz frequency band using the NTSC system, which skillfully utilizes color signal multiplexing technology and the characteristics of visual perception, with an aspect ratio of 3:4. It's being broadcast.

However, if we focus on a single television broadcasting channel, recently various types of television broadcasting using new technologies such as audio multiplexing, teletext, television facnomy broadcasting, and high-definition television broadcasting have been implemented or put into practical use. As a result, the density of use of video carrier waves, audio carrier waves, and their transmission bands continues to increase.

In addition, as seen in the recently conducted high-definition television broadcast experiment using a broadcasting satellite, there is a strong public demand for high-definition video, but under the current television broadcasting situation, we are still unable to rely on terrestrial television broadcasting. Therefore, it is urgent to improve the quality of terrestrial television broadcast images.

However, to improve the quality of broadcast video, a wide band of video frequencies is required, and in order to satisfy this requirement, the frequency band can be secured without changing the current frequency allocation and by maintaining the NTSC broadcasting standard. It is extremely difficult to do so. This is because a huge number of television broadcasting stations all over the country are currently using a limited number of internationally allocated frequency bands, and in the future it will be difficult to decide which channel bands will be allocated to each station. This is because there is no possibility of it spreading.

In other words, television broadcasting waves as a mass media are being used to near saturation both geographically and in terms of information, and under such circumstances, it is possible to add to the current broadcasting information without changing the frequency allocation, and to Broadcasting other broadcast information (hereinafter, the broadcast information newly added and transmitted in the present invention is simply referred to as additional information, and when it is an electrical signal, it is referred to as an additional information signal), contributing to high quality images. requires some special technical means.

Currently, audio carrier waves are already being used for stereo or bilingual audio multiplex broadcasting in addition to original television audio signals, and it is thought that it is only a matter of time before facsimile signals are multiplexed. ing. Therefore, it is extremely unlikely that additional information can be transmitted using audio carrier waves. Note that, technically, it is possible to send additional information by expanding the amount of transmission information that can be sent in the same band.
The current NTSC system pursues efficient use of frequencies by making full use of technologies such as band compression and vestigial sideband transmission method T1, and given its widespread use, it is unlikely that the amount of transmitted information will expand in this way. .

(Problems to be Solved by the Invention) The present invention has been developed in view of the fact that the current television system refuses to transmit new additional information beyond the current level, as described above.
The objective is to provide a television system that is compatible with the SC system and allows expansion of broadcast information capacity, and has the effect of contributing to improving the quality of television images and increasing appeal.

(Means for Solving the Problem) The present invention achieves the above object by multiplex modulating the video carrier wave by angle modulating the NTSC broadcast video carrier wave using an additional information signal and transmitting the modulated signal. be.

(Function) With the above-described configuration, the present invention uses a current television video carrier wave to generate a new additional information signal, for example, an interpolated video image necessary to change the aspect ratio of a CRT image from the current 3:4 to 3:5. If it is used as a signal, it is possible to construct a screen with a highly appealing aspect ratio, or it is possible to use the information energy to obtain a high-resolution television image.

(Example) Hereinafter, the present invention will be explained in detail using an example and drawings.

FIG. 11 is a schematic block diagram of an apparatus used in an embodiment of the present invention. 1 is an oscillator, 2 is a phase or frequency modulator (hereinafter simply referred to as angle modulator), and the output of the oscillator 1 is angularly modulated by the newly sent additional information signal 3. 4
is a characteristic compensation section which will be described in detail later, and its output is modulated by the original broadcast video signal 6 in an amplitude modulation section 5, and then
The frequency converter 71 converts the frequency to a necessary carrier frequency, and the signal is broadcasted as a broadcast wave by the antenna 8 on television.

Although the present invention angle-modulates the video carrier wave in this manner, it is natural that the upper and lower sideband bands of the video carrier wave are required for distortion-free broadcasting.

In addition, the transmission band of the NTSC television system is a vestigial sideband system, which is illustrated in the well-known figure 2,
In order to save the transmission band, only the vicinity of the video carrier wave fv remains in the lower side band. Therefore, the double-side band waves that are angularly modulated with the additional information signal to achieve distortion-free broadcasting that satisfy the NTSC standard are 1.25 MHz above and below the video carrier fv in the band shown in Figure 2. bandwidth is required.

On the receiving side, in order to compensate for the transmission band of the residual sideband so that the frequency versus amplitude characteristic of the demodulated output is flat, as in the conventional device, the band characteristic shown in FIG. It has a slope n characteristic. Note that in FIGS. 2 and 3, fA is an audio carrier wave, f@ is a color signal subcarrier, and n is a Nyquist slope.

Now, in the configuration shown in FIG. 1, the output of the angle modulator 2 is modulated by the additional information signal 3 and naturally generates upper and lower sideband waves. 'n, sweep detection is performed, and the video carrier wave generates an amplitude change due to the additional information signal. N
Since this is amplitude modulation for the transmission of video signals in the TSC system, it is no longer possible to separate the amplitude change due to the generated additional information signal from the amplitude change due to the original video signal, and therefore compatibility with the NTSC system is lost. .

The characteristic compensator 4 shown in FIG. 1 is provided to solve the problem of ensuring compatibility. That is, the characteristic compensation section 4 described above
is generated inside the receiver by the output of the angle modulator 2 in advance by using a filter with an inverse Nyquist slope i characteristic as shown in FIG. An inverse characteristic is given to the amplitude change, and as a comprehensive transmission system including the transmitting side, the amplitude change of the video carrier wave due to the additional information signal is canceled out, and interference with the original video signal is eliminated.

FIG. 5 is a flow diagram showing the main parts of the receiver corresponding to the transmitting section of FIG. 1. As in the conventional case, the radio waves received from the antenna 9 are mixed with the output of the local oscillator 11 and converted into an intermediate frequency (IF) in the head end unit 10 including a high frequency amplifier, a frequency mixer, etc. The signal passes through an intermediate circuit 12 such as a band-pass filter having a filter, and is subjected to amplitude detection by an amplitude detector 13, and a video signal is extracted as in the conventional case. On the other hand, the output of the head end 10 is applied to an angle modulation demodulator 14 including an IF multiplied signal amplitude limiter, and the additional information signal 3 shown in FIG. 1 is demodulated. Here, 15 is a digital processing unit showing an example of the use of the additional information signal, and the amplitude detector 1
3 and the demodulated additional information signal 3 are analog-to-digital (A/D) converted and temporarily stored, and then serially read out in an appropriate order, the conventional video The signal and the additional information signal are combined to form a new video signal with an aspect ratio of 3:5, and the CRT display section 16 displays an image with an aspect ratio of 3:5.

Note that if the additional information signal is intended to improve resolution, it goes without saying that a high-resolution image can be obtained by the same compositing process as described above. In addition, when the additional information signal has a different band from the audio multiplex signal including the normal TV audio signal and facsimile signal, it is sufficient to angle-modulate the video carrier wave as is. In this case, in intercarrier type receivers, interference such as buzz noise may be mixed into the audio system, so in order to eliminate this, the additional information signal is modulated by shifting the frequency by one frequency outside the audio band. , on the receiving side, the demodulated output of the additional information signal is sent back to the pace channel ζ
It is necessary to perform a reversal operation. Since this operation is the transport method itself, it will not be particularly explained here.

As is clear from the detailed explanation above, the present invention is different from the conventional N
In other words, it is a transmission method for additional information signals that is compatible with the NTSC method, and the additional information signals can be used not only for changing the aspect ratio, etc., but also for any other purposes. Of course, it may be. Further, since the above-mentioned frequency shift of the additional information signal is for eliminating buzz noise, it goes without saying that it is irrelevant in a split carrier type receiver.

(Effect of the invention) As explained in detail above, according to the present invention, the current domestic NT
This was implemented because it is compatible with SC system television, new additional information signals can be easily transmitted using the same video carrier wave, and it can be easily used for improving aspect ratios, increasing image quality, or transmitting new information. and benefit greatly.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an overview of a broadcasting device for explaining an embodiment of the present invention, FIG. 2 is a television carrier band characteristic diagram according to the NTSC system, and FIGS. FIG. 5 is a block diagram showing an example of a broadcast wave receiving device according to the present invention. 1... Oscillator, 2... Angle modulator,
3...Additional information signal, 4...Characteristic compensation section, 5...Amplitude modulation section, 6......
Video signal, 7... Frequency converter, 10...
...Head end section, 11...Local oscillator,
12... Intermediate circuit, 13... Amplitude detector, 14... Angle modulation demodulator, 15...
...Digital processing section. Figure 1 + 4.2MI (z 3rd MI)

Claims (1)

[Claims] In the NTSC television system, a video carrier wave is angle-modulated using an additional information signal to be sent out, and then the video carrier wave is amplitude-modulated by a video signal and sent out as a television broadcast wave. or P
The additional information signal is demodulated by M detection, and the additional information signal is used to interpolate a display image based on a video signal that is separately detected at the same time, thereby changing the aspect ratio or improving the quality of the display image. A television broadcasting system characterized by image processing.