JP2800174B2 - 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 method of transmitting a signal superimposed on an ATV channel 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 superimposes it on the video signal of each channel of CATV collectively. When a teletext receiver receives a signal of any channel, a teletext broadcast superimposed on a plurality of television broadcast channels can be received with the latest information without switching channels. To provide.

[0004]

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 plurality of tuners demodulated by the tuner. A plurality of character extracting units for extracting a teletext signal from each composite video signal, a memory unit for recording the teletext signal from the character extracting unit, and a plurality of horizontal scans for the plurality of teletext signals read from the memory unit A buffer memory unit for recording dividedly so as to correspond to a period,
A synchronizing signal generating unit for generating a synchronizing signal, and an appropriate horizontal scanning period of a vertical blanking period of the plurality of second composite video signals based on the teletext signal from the buffer memory unit based on the signal from the synchronizing signal generating unit A plurality of superimposition processing units for superimposing the signals on the R, a plurality of RF modulation units for modulating signals from the respective superimposition processing units into high-frequency signals having different frequencies, respectively,
A CAT comprising a mixing unit for mixing and outputting a plurality of signals from the F modulation unit, and a control unit for controlling the memory unit, the buffer memory unit, the synchronization signal generation unit, and the superimposition processing unit
V is provided.

[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, and then distributed to a plurality of horizontal scanning periods of a vertical flyback period. The signal is appropriately divided for superposition and superimposition, is superimposed on a plurality of video signals transmitted to the CATV network, respectively, is modulated into signals of a required CATV channel, and is mixed by a mixing unit.
Send to network.

[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. 5 is a superimposition processing unit (plural)
Then, the program data read from each memory area of the buffer memory unit 4 is superimposed on a plurality of horizontal scanning periods of a vertical blanking period of the composite video signal. Reference numeral 6 denotes an RF modulation unit (plural) which converts the signals from the superimposition processing unit 5 into CATs, respectively.
V is modulated to a high frequency signal of a required channel.

[0007] A mixing unit 7 mixes the signals from the plurality of RF modulation units 6 and sends out the mixed signals to the CATV network. Reference numeral 8 denotes a reference signal generator, which generates a signal used as a reference for operation of the apparatus. Reference numeral 9 denotes a synchronization signal generation unit which generates a required synchronization signal based on the signal from the reference signal generation unit 8. A control unit 10 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 signals from the tuner 1 are input to the character extracting unit 2 to extract a teletext signal, and the extracted signals are recorded in the memory unit 3 via the control unit 10. 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 each 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 generation unit 11, for example, it is appropriately allocated and recorded in each memory area in the order of the broadcast channel of the teletext program 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 out from the buffer memory unit 4 are input to the respective superposition processing units 5, and as shown in an example shown in FIG. 2, each of the signals for CATV A channel, B channel and C channel is used. The A channel and the B channel are superimposed on each horizontal scanning period of the vertical blanking period 21, 22, or 23 of the composite video signal by a plurality of RF modulators 6, respectively.
The signal is modulated into a channel or C channel signal, mixed by the mixing unit 7, and transmitted to the CATV network.

As described above, since the teletext signal of each channel of the television broadcast is superimposed in the required horizontal scanning period of the vertical retrace period of the composite video signal of each channel of the CATV, Even if received, a text broadcast broadcast on each television broadcast channel can be received without a channel switching operation. 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 Is always updated to the latest information by updating on 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 television broadcasting is received and superimposed on each channel of CATV and transmitted to the CATV network. The teletext program of the television broadcast channel is always updated to the latest information and can be received with a short waiting time.

[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]

 Reference Signs List 1 Tuner 2 Character extraction unit 3 Memory unit 4 Buffer memory unit 5 Superposition processing unit 6 RF modulation unit 7 Mixing unit 8 Reference signal generation unit 9 Synchronization signal generation unit 10 Control unit

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

Claims (2)

(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 appropriately performing horizontal scanning of a teletext signal from the buffer memory unit based on a signal from the synchronizing signal generating unit during a vertical blanking period of a plurality of second composite video signals A plurality of superimposition processing units for superimposing the signals in the respective periods; a plurality of RF modulation units for modulating the signals from the respective superimposition processing units into high-frequency signals having different frequencies; And a control unit that controls the memory unit, the buffer memory unit, the synchronization signal generation unit, and the superimposition processing unit.
Teletext broadcasting system for TV. 2. 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.