JPH06205382A - Teletext broadcast system for catv - Google Patents

Abstract

PURPOSE:To send an extracted teletext broadcast signal of each television broadcast channel while being superimposed on a video signal of one channel of a CATV. CONSTITUTION:Plural tuners 1 receive a television signal, demodulates the signal into a composite video signal, plural teletext extract sections 2 extract respectively teletext broadcast signals, and they are stored in a memory section 3. Data read from the memory section 3 are transferred to a buffer memory section 4, in which the data are recorded based on a signal from a synchronizing signal generating section 12 to be superimposed on the composite video signal for plural horizontal scanning period of a vertical blanking period, the data are superimposed onto a required composite video signal at a superimposition processing section 5, and an RF modulation section 6 modulates the superimposed signal to a signal of one channel of a CATV. A signal processing section 7 processes other composite video signal synchronously with the signal processed by the superimposition processing section 5, an RF modulation section 8 modulates the processed signal into other CATV channel signal, a mixer section 9 mixes the signals from the sections 6, 8 and the mixed signal is sent to a CATV network.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CATV teletext system, which receives a plurality of television broadcast signals, extracts the teletext signals from each signal, and converts these teletext signals into C
The present invention relates to a signal transmitted by being superimposed on an ATV television signal.

[0002]

2. Description of the Related Art In a CATV network or the like which distributes a television signal by wire provided in a set area or an apartment house, conventionally, when transmitting a teletext, for example, a television broadcast on which a teletext signal is superimposed is transmitted. Receive and demodulate,
A device that modulates a video signal on which a teletext signal is superimposed into a high-frequency signal of a required channel of CATV for transmission, or extracts a teletext signal from a television broadcast signal, decodes it into an image signal, and There is one that modulates a signal of a CATV channel set for broadcasting and transmits the signal. However, in the case where a video signal on which a character signal is superimposed is modulated into a signal of a CATV channel and transmitted, as in the case of directly receiving a character broadcast by television broadcasting, the character broadcast signal is changed from the video signal each time the channel is switched. Waiting time to extract and record
There are problems such as poor merit by joining the CATV network, and when the channel number of CATV and the channel number of television broadcasting are different, it is difficult to judge which character broadcasting is superposed on which channel. There are also problems. On the other hand, in the case of decoding into an image signal, it is necessary to set a teletext channel, and there is a problem that the image quality is deteriorated in the process of conversion into an image signal. Since the teletext program is received on the CATV network, the teletext program broadcast on a plurality of television broadcasting channels can be received without a long waiting time, and it is always updated with the latest information. CA if you can receive
Good news for TV network subscribers.

[0003]

SUMMARY OF THE INVENTION In view of the above, the present invention extracts a teletext signal superimposed on a plurality of television broadcast signals and collectively converts it into a video signal of one channel of CATV. If the teletext receiver receives the signal of this channel by superimposing transmission, the teletext superposed on multiple television broadcasting channels can be received with the latest information by receiving one channel. To provide.

[0004]

In order to solve the above problems, the present invention solves the above problems by a plurality of tuner units for receiving a television signal and demodulating it into a first composite video signal, and a first composite unit demodulated by the tuner unit. A plurality of character extraction units for respectively extracting the character broadcast signals from the video signal, a memory unit for recording the character broadcast signals from the character extraction unit, and a plurality of the character broadcast signals read from the memory unit in a plurality of horizontal scanning periods. A second composite video based on a signal from the sync signal generation unit, a buffer memory unit that divides and records correspondingly, a sync signal generation unit that generates a sync signal, and a teletext signal from the buffer memory unit. A superimposition processing unit that superimposes in an appropriate horizontal scanning period of a vertical blanking period of the signal, and a first signal that modulates the signal from the superimposition processing unit into a high-frequency signal of a first frequency and outputs
The present invention provides a CATV teletext system including an RF modulator and a control unit that controls the memory unit, the buffer memory unit, the synchronization signal generation unit, and the superposition processing unit.

[0005]

With the above structure, the CA according to the present invention
In the teletext broadcasting system of TV, the teletext signals superimposed on the signals of a plurality of television broadcasting channels are respectively extracted and collectively recorded in a memory, and then a plurality of horizontal horizontal lines in a vertical blanking period of one video signal are extracted. Since it is dispersed and superposed in the scanning period, it is appropriately divided and superposed on an appropriate video signal to be CA.
Transmission is performed by modulating the signal into an appropriate channel signal of the TV, and synchronizing the timing of this video signal with the timing of synchronizing the video signal of another channel of CATV.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENT A CATV according to the present invention will be described below with reference to the drawings.
An example of the teletext system will be described in detail. FIG. 1 is a block diagram of essential parts of an embodiment of a CATV teletext system according to the present invention. In the figure, 1 is a plurality of tuners,
Receives television broadcast, demodulates to composite video signal and outputs. Reference numeral 2 is a character extraction unit for extracting the character broadcast signals superimposed on the composite video signal from the tuner 1. A memory unit 3 records the character broadcast signals (program data) from each character extraction unit 2. A buffer memory unit 4 divides the program data read from the memory unit 3 into a plurality of horizontal scanning periods of one vertical blanking period and superimposes them, so that a plurality of memory regions corresponding to the number of divisions are provided. For example, it is appropriately distributed in the order of broadcast channels and recorded in each memory area. Reference numeral 5 denotes a superimposition processing unit which appropriately superimposes the program data read from the buffer memory unit 4 on a plurality of horizontal scanning periods of a vertical blanking period of one composite video signal. An RF modulator 6 modulates the signal from the superposition processor 5 into a high frequency signal of a required channel of CATV.

A signal processing unit (one or more) 7 processes a composite video signal different from the signal processed by the superposition processing unit 5. At the time of this signal processing, the signal processing unit 7 converts the input composite video signal into, for example, digital data and then records it in the image memory 10, and based on a signal from a synchronization signal generation unit 12 described later, the superimposing process. The signal is delayed and read so as to coincide with the synchronization timing of the signal processed by the unit 5, converted into an analog signal, and required processing is performed. Reference numeral 8 is an RF modulator (one or more) that modulates the signal from the signal processor 7 into a required channel (one or more) of CATV different from the modulation frequency of the RF modulator 6. A mixer 9 mixes the signals from the RF modulator 6 and the RF modulator 8 and sends them to the CATV network. The image memory 10 is a memory capable of recording a composite video signal for one frame or one field. A reference signal generator 11 generates a signal that serves as a reference for the operation of the device. 12
Is a synchronization signal generation unit that generates a required synchronization signal based on the signal from the reference signal generation unit 11. A control unit 13 controls each unit of the device.

Next, the operation of the CATV teletext system according to the present invention will be described. A plurality of tuners 1 receives a plurality of television signals and demodulates each into a composite video signal. The composite video signals from the tuner 1 are input to the character extracting unit 2, the character broadcasting signals are extracted, and are recorded in the memory unit 3 via the control unit 13. That is, when the number of channels of the received television signal is m and there are n horizontal scanning periods in which the character broadcasting signal is superimposed in the vertical blanking period of these signals, the memory unit 3 has m × n characters. The broadcast signal will be recorded. The teletext signal recorded in the memory unit 3 is read out and transferred to the buffer memory unit 4.
The buffer memory unit 4 divides and superimposes these teletext signals into a plurality of horizontal scanning periods of a vertical blanking period of one composite video signal, so that a plurality of memory areas corresponding to the number of divisions are provided and synchronization is performed. For example, in order of the broadcast channel of the teletext program, the signals are appropriately distributed and recorded in each memory area so as to correspond to each horizontal scanning period with the signal from the signal generation unit 12 as a reference. At this time, in order to avoid duplication of the program number assigned to each teletext program, the program may be replaced with a new program number and recorded.

Thereafter, these signals read from the buffer memory unit 4 are input to the superimposition processing unit 5 and, as in the example shown in FIG. 2, each horizontal scanning period of the vertical blanking period 21 of the required composite video signal. To the CATV by the RF modulator 6.
, For example, it is modulated into a signal of A channel and is sent to the CATV network through the mixing unit 9. The composite video signal (one or more) of the other channel of the CATV is processed by the signal processing unit 7 based on the signal from the synchronization signal generation unit 12, and each is processed by the RF modulation unit 8 by, for example, B
The signals are modulated into a channel signal, a C channel signal, etc., and input to the mixing section 9. By synchronizing and processing the superimposition processing unit 5 and the signal processing unit 7 with the synchronization signal from the synchronization signal generation unit 12, the phase of the vertical synchronization signal 22 of the B channel is the vertical synchronization signal 21 of the A channel.
It matches the phase of.

In this way, since the phases of the synchronization signals of the respective channels match, for example, in a television receiver incorporating a teletext receiver connected to this CATV network, the tuner is turned on during the vertical blanking period. By switching to the A channel and switching the tuner to the B channel or the C channel outside the vertical blanking period, it is possible to receive the text broadcast superimposed on the A channel while listening to the image of the B channel or the C channel. Moreover, since the teletext of each television broadcasting channel is superimposed on one channel, it is possible to shorten the "wait time" required for switching the channel, extracting and recording the teletext signal, and ,
These teletext signals are always updated to the latest information by updating the broadcast signal sending side.

[0011]

As described above, C according to the present invention
According to the teletext system of ATV, a teletext program of each channel of television broadcasting is received, superposed on one CATV channel, and transmitted to the CATV network.
It is possible to receive a teletext program of each television broadcast channel, which is constantly updated with the latest information, in a short waiting time without switching the channel. In addition, by matching the synchronization timing of each channel of CATV,
If the receiving channel is set to be switched each time the vertical blanking period is set, it has an advantage that the teletext can be simultaneously received while listening to the image of the channel on which the teletext signal is not superimposed.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of an embodiment of a CATV teletext system according to the present invention.

FIG. 2 is a diagram for explaining the operation of the CATV teletext system according to the present invention.

[Explanation of symbols]

 1 tuner 2 character extraction unit 3 memory unit 4 buffer memory unit 5 superposition processing unit 6 RF modulation unit 7 signal processing unit 8 RF modulation unit 9 mixing unit 10 image memory 11 reference signal generation unit 12 synchronization signal generation unit 13 control unit

Claims (3)

[Claims] 1. A plurality of tuner units that receive a television signal and demodulate into a first composite video signal, and a plurality of characters that respectively extract a teletext signal from the plurality of first composite video signals demodulated by the tuner unit. An extraction unit, a memory unit for recording the teletext signal from the character extraction unit, and a buffer memory unit for dividing and recording a plurality of teletext signals read from the memory unit so as to correspond to a plurality of horizontal scanning periods. A sync signal generation unit for generating a sync signal, and a teletext signal from the buffer memory unit based on a signal from the sync signal generation unit in an appropriate horizontal scanning period of a vertical blanking period of the second composite video signal. A superimposing processing unit for superimposing, a first RF modulating unit that modulates a signal from the superimposing processing unit into a high frequency signal of a first frequency and outputs the high frequency signal, the memory unit, a buffer memory unit, and a synchronization signal generating unit. And a CATV teletext system configured with a control unit that controls the superposition processing unit. 2. An image memory for recording an input third composite video signal, a signal processor for reading out the composite video signal recorded in the image memory based on a signal from the synchronization signal generator, and a signal. A second RF modulator for modulating a signal from the processor into a high frequency signal having a second frequency; and the first RF modulator.
2. A mixing section for mixing and outputting a signal from the RF modulation section and a signal from the second RF modulation section is provided, and the synchronization timings of the superposition processing section and the signal processing section are matched. The described CATV teletext system. 3. The CAT according to claim 1, wherein a program number setting section is provided, and a plurality of teletext signals recorded in the buffer memory section are given appropriately set program numbers.
V teletext system.