JPH01269377A - Sound broadcasting synthesis system for television broadcasting - Google Patents

Abstract

PURPOSE:To improve follow-up performance and to reduce constitution cost by providing a means detecting the carrier of a video signal and an oscillation circuit in PLL constitution and modulating and transmitting a television sound signal and a different multiplexed sound broadcasting signal in a sound carrier. CONSTITUTION:The carrier fv of the video signal is detected in a carrier detection circuit 1, and is added to a phase comparison circuit 3 through a frequency- dividing circuit 2. A voltage control oscillation circuit VCO4 is provided on the output side of the phase comparison circuit 3, and the output is used as the reproduced sound carrier fa and added to said phase comparison circuit 3 through a frequency-dividing circuit 5. The phase comparison circuit 3, VCO4 and the frequency-dividing circuit 5 constitute the oscillation circuit in a PLL system, and loop control is executed so that the phase difference DELTAPHI of two frequencies fv/m and fa/n, both of which have been frequency-divided, becomes zero. Consequently, the sound carrier fa being an output always holds a prescribed frequency relation with respect to the video carrier fv being an input.

Description

[Detailed Description of the Invention] [Summary] Regarding a combined system of television broadcasting and radio broadcasting, a means for detecting a carrier wave of a video signal is provided in a television broadcasting relay device for the purpose of preventing reception interference of radio broadcasting. , a PLI-configured oscillation circuit is provided for reproducing an audio carrier wave having a predetermined frequency relationship with respect to the video carrier wave as a reference, and the audio carrier wave is used to modulate another audio broadcast signal multiplexed with the television audio signal. Configure it to send it.

[Industrial application field]

The present invention relates to a system for combining television broadcasting and radio broadcasting, and in particular to a new television that combines a radio audio broadcast signal with a television broadcast sub-audio signal channel and transmits the signal in order to avoid radio broadcast reception interference. This relates to the John relay system.

It is well known that radio broadcasts in the medium wave band are subject to reception problems in some areas. On the other hand, as recent radio receivers, multi-function receivers that can receive not only AM broadcasts in the medium wave band, but also FM broadcasts and television broadcasts have become popular, allowing them to select from many programs. I am in a situation where I can watch it. Therefore, in areas where there is significant reception interference, by multiplexing and broadcasting a medium-wave band audio broadcast signal on the audio sub-channel of television broadcasting, when the sub-audio of television broadcasting is selected with the multi-function receiver, It becomes possible to listen to the audio broadcast program of product-C without receiving reception problems.

[Traditional technique]

When adopting a method of synthesizing radio broadcasts with television broadcasts in a specific area such as in Japan, it is reasonable to synthesize the radio audio by telephony relay %i. In other words, when converting and amplifying a television channel composite signal to a predetermined broadcast frequency and retransmitting it in a television relay device, the corresponding audio signal is demodulated and the sub-channel portion is replaced with another radio audio signal. It's a neri. In this case, a carrier wave is required to remodulate the audio signal, and an oscillator must be provided to generate the carrier wave.

[Problems to be solved by invention]

A high-precision oscillator will be installed to generate a carrier wave to re-modulate the audio signal, but the broadcasting radio waves must comply with television broadcasting standards. , the current frequency interval between the video carrier wave and the audio carrier wave is 4.
, 5 M It z , and therefore, in order to satisfy this viewing constant, high followability to the video carrier wave is required.

Therefore, the present invention provides a system for synthesizing radio broadcast audio signals into television broadcasts as described in "-".
The purpose of the present invention is to provide a new method for multiplexing and remodulating carrier waves that can be transmitted with high followability to video carrier waves.

[Means to solve the problem]

Briefly stated, in order to achieve the above object, the present invention includes means for detecting a carrier wave of a video signal in a television relay device, and an audio carrier wave having a predetermined frequency relationship with respect to the video carrier wave as a reference. P L L
The present invention is characterized in that an oscillation circuit of the above configuration is provided, and another audio broadcast signal multiplexed with the television audio signal is modulated and transmitted using the audio carrier wave.

[For production]

FIG. 1 is a block diagram showing the basic configuration of an audio carrier wave reproducing circuit incorporated in a television relay device according to the present invention. The carrier wave fν of a video signal is detected by a carrier wave detection circuit 1, and passed through a frequency dividing circuit 2 to a phase comparison circuit. Added to 3. A voltage controlled oscillation circuit (VCO) 4 is provided on the output side of this phase comparison circuit 3, and its output is used as a reproduced audio carrier wave fa, and is also applied to the previous phase comparison circuit 3 through a frequency dividing circuit 5. . The phase comparison circuit 3 and V
A PLL-type oscillation circuit is configured by CO4 and the frequency divider i5, and the two divided frequencies fv/m and fa/
Since the loop control j1■ is performed so that the phase difference ΔΦ of n becomes zero, the output audio carrier wave fa always maintains a constant frequency relationship with respect to the input video carrier wave fv.

〔Example〕

Preferred embodiments of the present invention will be described in more detail below with reference to the drawings.

FIG. 2 is a block diagram showing a schematic configuration of the entire broadcasting system to which the present invention is applied. Generally, television broadcasting emits broadcast waves from a key station 10 to a predetermined service area via relay stations 11 in various places. . - On the other hand, since it is difficult to listen to medium wave radio broadcasts in areas where there is a lot of reception interference, the radio broadcast key station 12 transmits television broadcasts close to the area via a specific line (microwave line or cable) 13. The broadcast signal is once transmitted to the relay station 11, and the relay device of the relay station broadcasts the audio signal of the radio broadcast in a synthesized form with the sub-audio signal channel of the television broadcast. Therefore, by selecting the sub-audio signal of the television broadcast from the relay station 11 with a television receiver compatible with audio multiplexing, it is possible to listen to the radio broadcast program separately from the television broadcast.

FIG. 3 is a block diagram showing an example of the configuration of the audio carrier reproduction system part according to the present invention applied to the relay device of the relay station. In FIG. 3, the high-frequency radio wave rf of the television is first mixed with a signal of a predetermined frequency from the local oscillator 15 in a mixing circuit 14, and frequency-converted so that the carrier frequency of the video signal is, for example, 17.75 MHz.

Next, the image carrier wave fv is applied to one frequency dividing circuit 16 through a filter 22 for detecting selection of the video carrier wave fv, and is divided by 71 to a phase comparator circuit 17 with a center frequency of 250 KHz.
Applied to round. 22.2 on the output side of the phase comparison circuit 17
A VCO 18 that oscillates a 5 MHz audio carrier wave is connected, and a part of its output fa is divided into 89 by another frequency dividing circuit 19.
After being frequency-divided, it is input to the other comparison input of the phase comparison circuit 17.

In this way, an audio carrier wave fa of 22.25 Mtlz is obtained from VC018, but this m wave number is ]7.75 MHz
The relationship is such that the variation in the video carrier wave fν is always automatically followed at a frequency interval of 4.5 MHz, and it satisfies the standards for television broadcast waves.

The carrier wave fa of the audio reproduced in this way is added to the FM modulator ff 19, and is multiplexed in a separate multiplexing device 20 so that the main channel becomes the television audio signal and the sub channel becomes the aforementioned radio audio signal. The resulting composite audio signal is frequency modulated and supplied to the synthesis circuit 21. In this synthesis circuit 21, the frequency-modulated audio signal carrier wave is synthesized with the video signal component extracted through another filter 23 and output. Therefore, by amplifying this composite signal to a predetermined level and emitting it as a television broadcast radio wave, it is possible to perform a television broadcast including a radio program on the sub-audio channel.

In addition, in the above example, 22.25 is directly sent from VColB.
The method for extracting the audio carrier wave fa of M II z has been described, but the point is that if a signal that follows the video carrier wave fv is created by using an oscillation circuit with a PLL configuration, the frequency interval can also be adjusted in the modulation device 19. is possible.

〔effect〕

Now, as is clear from the above explanation, in short, the present invention employs a method in which an audio carrier wave is regenerated using a PLL-configured oscillation circuit using a video carrier wave extracted in a television relay device as a reference, so that it is not suitable for synthesizing radio broadcasts. Despite this, it does not disturb the standards of television broadcast waves,
Furthermore, compared to the case where an independent oscillator is provided, there is an advantage that the tracking performance is excellent and the structure is inexpensive. Therefore, the present invention can be applied to a system in which a broadcast program is synthesized with a sub-audio channel of a television broadcast and broadcast in an area where there is a lot of reception interference of medium wave radio broadcast, and is extremely effective in practical use.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of an audio carrier regeneration circuit introduced into a television relay device according to the present invention, FIG. 2 is a block diagram showing a schematic configuration of the entire television relay system to which the present invention is applied, FIG. 3 is a block diagram showing the configuration of an embodiment of the audio carrier reproduction system. In the figure, 1 is a video carrier detection circuit, 2 is a frequency dividing circuit, 3 is a phase comparison circuit, 4 is a VCO 5 is another frequency dividing circuit, 10 is a key station for television broadcasting, 11 is a relay station for television broadcasting, 12 is a key station for radio broadcasting, and 13 is a dedicated line. Agent Patent Attorney Sada Igata −

Claims (1)

[Claims] (1) In a television broadcast relay device, a means for detecting a carrier wave of a video signal and an oscillation circuit with a PLL configuration for reproducing an audio carrier wave having a predetermined frequency relationship with respect to the video carrier wave as a reference are provided, and the audio carrier wave is An audio broadcast synthesis method for television broadcasting, characterized in that a separate audio broadcasting signal multiplexed with a television audio signal is modulated and transmitted.