JP2800173B2 - CATV teletext system - Google Patents

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 teletext signals from each of the signals, and converts these teletext signals into a CTV signal.
The present invention relates to a device for superimposing and transmitting an ATV television signal.

[0002]

2. Description of the Related Art In a CATV network or the like for distributing a television signal provided in a set area or an apartment house by wire, conventionally, for example, a television broadcast on which a teletext signal is superimposed is used for transmitting a teletext signal. Receive and demodulate,
A video signal on which a teletext signal is superimposed is modulated into a high-frequency signal of a required CATV channel and transmitted, or a teletext signal is extracted from a television broadcast signal and decoded to an image signal, and then converted to an image signal. There is a method of modulating a signal of a CATV channel set for broadcasting and transmitting the modulated signal. However, in the case where a video signal on which a text signal is superimposed is modulated into a CATV channel signal and transmitted, the text broadcast signal is converted from the video signal each time the channel is switched, similarly to the case of directly receiving a text broadcast by television broadcasting. Requires a wait time to extract and record
There is a problem that the merit of subscribing to the CATV network is poor, and when the channel number of the CATV is different from the channel number of the television broadcast, it is difficult to determine which channel is overlaid with which text broadcast. There are also problems. On the other hand, in the case of decoding into an image signal, it is necessary to set a text broadcasting channel, and there is a problem that image quality is deteriorated in the process of converting the image signal into an image signal. Since a teletext program is received on a CATV network, a teletext program broadcast on a plurality of television broadcast channels can be received without a long waiting time, and is always updated to the latest information. CA if you can receive
This is good news for TV network subscribers.

[0003]

SUMMARY OF THE INVENTION In view of the foregoing, the present invention extracts a text broadcast signal superimposed on a plurality of television broadcast signals and collectively converts it into a one-channel CATV video signal. If the text broadcast receiver receives the signal of this channel so that it is superimposed and transmitted, it can receive the text broadcast superimposed on multiple television broadcast channels with the latest information by receiving one channel Is to provide.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a plurality of tuners for receiving a television signal and demodulating it into a first composite video signal, and a first composite demodulated by the tuner. A plurality of character extraction units for extracting a teletext signal from the video signal, a memory unit for recording the teletext signal from the text extraction unit, and a plurality of teletext signals read from the memory unit for a plurality of horizontal scanning periods A buffer memory unit that divides and records correspondingly, a synchronizing signal generating unit that generates a synchronizing signal, and a second composite video based on the signal from the synchronizing signal generating unit that converts the teletext signal from the buffer memory unit A superimposition processing unit that superimposes an appropriate horizontal scanning period in a vertical blanking period of a signal, and a first that modulates a signal from the superimposition processing unit into a high-frequency signal of a first frequency and outputs the modulated signal.
An object of the present invention is to provide a CATV teletext system comprising an RF modulation section and a control section for controlling the memory section, buffer memory section, synchronization signal generation section and superimposition processing section.

[0005]

With the above-described construction, the CA according to the present invention can be used.
In the teletext system of TV, teletext signals superimposed on signals of a plurality of television broadcast channels are respectively extracted and collectively recorded in a memory. It is divided appropriately to be superimposed in a distributed manner during the scanning period, and is superimposed on an appropriate video signal and CA
The signal is modulated to an appropriate TV channel signal, and the transmission is performed such that the synchronization timing of this video signal matches the synchronization timing of the video signal of another channel of the CATV.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the teletext system will be described in detail. FIG. 1 is a block diagram of a main part of an embodiment of a CATV teletext system according to the present invention. In the figure, 1 is a tuner (plural),
A television broadcast is received, demodulated into a composite video signal, and output. Reference numeral 2 denotes a character extraction unit (plurality) for extracting a text broadcast signal superimposed on the composite video signal from the tuner 1. Reference numeral 3 denotes a memory unit which records a text broadcast signal (program data) from each text extraction unit 2. Reference numeral 4 denotes a buffer memory unit, which divides the program data read from the memory unit 3 into a plurality of horizontal scanning periods of one vertical retrace period and superimposes the divided data, thereby providing a plurality of memory areas corresponding to the number of divisions. For example, they are appropriately allocated 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 retrace period of one composite video signal. Reference numeral 6 denotes an RF modulation unit that modulates a signal from the superimposition processing unit 5 into a high frequency signal of a required channel of CATV.

Reference numeral 7 denotes a signal processing unit (one or more) for processing a composite video signal different from the signal processed by the superimposition 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, records it in the image memory 10, and performs the superimposition processing based on a signal from a synchronization signal generation unit 12 described later. The signal is read out with a delay so as to coincide with the synchronization timing of the signal processed by the section 5, converted into an analog signal, and required processing is performed. Reference numeral 8 denotes an RF modulator (one or more), which modulates a signal from the signal processor 7 to a required CATV channel (one or more) different from the modulation frequency of the RF modulator 6. A mixing unit 9 mixes the signals from the RF modulation unit 6 and the RF modulation unit 8 and sends out the mixed signal to the CATV network. The image memory 10 is a memory capable of recording a composite video signal for one frame or one field. Reference numeral 11 denotes a reference signal generation unit that generates a signal used as a reference for operation of the apparatus. 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 apparatus.

Next, the operation of the CATV teletext system according to the present invention will be described. A plurality of television signals are received by a plurality of tuners 1 and demodulated into composite video signals. The composite video signal from the tuner 1 is input to the character extracting unit 2 to extract a teletext signal, and the extracted signal is recorded in the memory unit 3 via the control unit 13. That is, if the number of channels of the received television signal is m, and there are n horizontal scanning periods in which the teletext signal is superimposed in the vertical retrace period of these signals, the memory unit 3 stores m × n characters. Broadcast signals will be recorded. The teletext signal recorded in the memory unit 3 is read and transferred to the buffer memory unit 4.
In the buffer memory unit 4, in order to divide these teletext signals into a plurality of horizontal scanning periods of a vertical retrace period of one composite video signal and superimpose them, a plurality of memory areas corresponding to the number of divisions are provided. Based on the signal from the signal generation unit 12, for example, a broadcast channel of a teletext program is appropriately allocated and recorded in each memory area so as to correspond to each horizontal scanning period. At this time, in order to avoid duplication of the program number assigned to each teletext program, the program number 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 shown in an example shown in FIG. 2, each horizontal scanning period of the vertical blanking period 21 of the required composite video signal is performed. , And the RF modulation unit 6
For example, the signal is modulated into an A channel signal and transmitted to the CATV network via the mixing unit 9. The composite video signal (one or more) of the other channels of the CATV is processed by the signal processing unit 7 based on the signal from the synchronizing signal generation unit 12, and is processed by the RF modulation unit 8, for example, B
The signal is modulated into signals of the channel and the C channel, and input to the mixing unit 9. By synchronizing and processing the superimposition processing unit 5 and the signal processing unit 7 according to the synchronization signal from the synchronization signal generation unit 12, the phase of the B channel vertical synchronization signal 22 is changed to the A channel vertical synchronization signal 21.
Is the same as the phase of

[0010] In this way, the phase of the synchronization signal of each channel coincides, so that, for example, in a television receiver having a built-in teletext receiver connected to this CATV network, the tuner is turned on during the vertical flyback period. By switching to channel A and switching the tuner to channel B or C during periods other than the vertical retrace interval, it is possible to receive text broadcasts superimposed on channel A while viewing images on channel B or C. In addition, since the teletext of each television broadcast channel is superimposed on one channel, the "waiting time" required for switching channels and extracting and recording the teletext signal can be reduced, and ,
These teletext signals are always updated to the latest information by updating the broadcast signal transmitting side.

[0011]

As described above, according to the present invention, C
According to the ATV teletext system, a teletext program of each channel of a television broadcast is received and superimposed on one CATV channel and transmitted to a CATV network.
A teletext program of each television broadcast channel that is constantly updated to the latest information can be received with a short waiting time without switching channels. Also, by synchronizing the synchronization timing of each channel of CATV,
If the receiving channel is set to be switched each time the vertical retrace period is performed, there is an advantage that the teletext can be received at the same time as viewing the image of the channel on which the teletext signal is not superimposed.

[Brief description of the drawings]

FIG. 1 is a main block diagram 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]

 DESCRIPTION OF SYMBOLS 1 Tuner 2 Character extraction part 3 Memory part 4 Buffer memory part 5 Superposition processing part 6 RF modulation part 7 Signal processing part 8 RF modulation part 9 Mixing part 10 Image memory 11 Reference signal generation part 12 Synchronization signal generation part 13 Control part

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI H04N 7/035

Claims (3)

(57) [Claims] 1. A plurality of tuners for receiving a television signal and demodulating it into a first composite video signal, and a plurality of characters for extracting a teletext signal from each of the plurality of first composite video signals demodulated by the tuner. An extracting unit, a memory unit for recording a teletext signal from the text extracting 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 synchronizing signal generating unit for generating a synchronizing signal, and a teletext signal from the buffer memory unit during an appropriate horizontal scanning period of a vertical blanking period of the second composite video signal based on the signal from the synchronizing signal generating unit. A superimposition processor for superimposing, a first RF modulator for modulating a signal from the superimposition processor to a high-frequency signal of a first frequency and outputting the same, the memory, the buffer memory, and a synchronization signal generator And a control unit for controlling a superimposition processing unit. 2. An image memory for recording an input third composite video signal, a signal processing unit for reading and processing a composite video signal recorded in the image memory based on a signal from the synchronization signal generating unit, A second RF modulator for modulating a signal from the processor into a high-frequency signal of a second frequency;
2. A mixing unit for mixing and outputting a signal from the RF modulation unit and a signal from the second RF modulation unit and outputting the mixed signal, so that synchronization timings of the superimposition processing unit and the signal processing unit are matched. The described CATV teletext system. 3. The CAT according to claim 1, further comprising a program number setting section, wherein a plurality of teletext signals recorded in said buffer memory section are provided with appropriately set program numbers.
V teletext system.