JPH08280001A - Receiver for am pass through system and teletext system - Google Patents

Abstract

PURPOSE: To share a circuit for the receiver for AM pass through and the teletext broadcasting receiver, to improve operability, to reduce a space and to easily view message information as well. CONSTITUTION: A television reception circuit 21B, VBI extraction circuit 22B and error correction circuit 23B are shared for the receiver for AM pass through and the teletext broadcasting receiver at least. Thus, the device can be miniaturized, operability can be improved, the space can be reduced and when the signal of an AM pass through system is inputted, the device is operated as the receiver for AM pass through but when a teletext broadcasting signal is inputted, the device can be operated as the teletext broadcasting receiver. Besides, when the signal of the AM pass through system is inputted, descrambled message information data can be decoded by a video decode circuit 26B and outputted as video signals.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an AM pass-through capable of receiving and demodulating a character multiplex broadcast signal in addition to receiving and demodulating an AM pass-through type signal distributed from a relay device of a common listening facility. The present invention relates to a receiver for system and character multiplex system.

[0002]

2. Description of the Related Art In recent years, in satellite broadcasting, a scrambled broadcasting system in which a broadcasting station encrypts (scrambles) a television signal so that only a subscriber can decipher the cipher and make it available for viewing is increasing. To receive these pay satellite broadcasts, an individual reception system in which a viewer prepares an antenna, a tuner, and a scramble decoder and contracts with a broadcasting station is used. In this individual reception system, there is an AM pass-through system as a system for transmitting scrambled broadcasting to in-house viewers by using in-house transmission facilities in apartment houses and other common houses.

In this AM pass-through type head end, of the scrambled signals transmitted from the satellite, (1) the video signal remains scrambled, (2) the audio is descrambled, and (3) the video scrambled. The descrambled data required to be released by the terminal is scrambled and superimposed on the vertical blanking interval (hereinafter referred to as VBI. VBI = Vertical Blanking Interval) of the video signal, and modulated as the same NTSC signal as the ground wave. Transmit to internal viewer. In the terminal installed at home, the descramble data superimposed on the VBI of the video signal is extracted, the descrambling data is released, the video is descrambled based on the data, and the image is viewed on the television receiver. In the AM pass-through method, in addition to the descramble data, the VBI is also superposed with individual information data for contract management and message information data for transmitting message information. The individual information data includes data such as contract registration code and expiration date, and is data for controlling descrambling of individual devices, and the message information data communicates from a broadcasting station (for example, information such as a program name). Is data for.

FIG. 6 is a block diagram showing an AM pass-through type transmission system. In FIG. 6, the scramble broadcast signal a1 broadcast from the broadcast station 11 performing the scramble broadcast is input to the AM pass-through headend 13 installed in the co-listening facility 16 via the satellite 12. The head end 13 demodulates the received scrambled broadcast signal a1, performs processing such as multiplexing of scrambled data, modulates the television signal b1 and sends it to the transmission cable 14 in the public listening facility. The transmitted television signal b1 is received and demodulated by the AM pass-through receiving terminal 15 of the viewer, the video signal is descrambled, and output as a normal composite video signal c1 and audio signal d1. It is displayed on a display device such as a receiver.

The aerial system for transmitting signals by radio waves from the broadcasting station 11 to the head end 13 via the satellite 12 is the first transmission system, and the cable system for transmitting signals from the head end 13 to the receiving terminal 15 is the second transmission system. The transmission system.

FIG. 7 is a block diagram showing the structure of a conventional AM pass-through receiving terminal 15.

In FIG. 7, an AM signal is input to the television receiving circuit 21 from a head end (not shown). The television receiving circuit 21 selects a desired channel, demodulates the selected signal, and outputs a video demodulation signal and an audio demodulation signal. The VBI extraction circuit 22 inputs the video demodulation signal and outputs the V
The descramble data, the individual information data, and the message information data superimposed on the BI are extracted. Each of the extracted data is error-corrected by the error correction circuit 23 and supplied to the security circuit 24. Security circuit 2
In 4, the scramble of the error-corrected data itself is descrambled and output. Among the descrambled data, the message information data is output as data from the security circuit 24, and the descrambled data and the individual information data which are descrambled are supplied to the video descramble circuit 25. The video descramble circuit 25 descrambles the video demodulated signal based on the descrambled descrambled data. The descramble permission / prohibition is controlled by the individual information, and the descrambled video signal or Outputs video signals that are not descrambled. The video demodulated signal that has not been scrambled is output without any processing in the video descramble circuit 25. The audio demodulated signal output from the television receiving circuit 21 is output as it is.

On the other hand, similarly to the AM pass-through method, there is character multiplex broadcasting as a broadcasting in which data is superimposed on VBI of a video signal and transmitted. In the character multiplex broadcasting, character data and accompanying musical sound data are superimposed on the VBI of a video signal from a broadcasting station, and the receiving terminal converts the character data into a video signal with characters and a simple pattern to generate a musical sound. The data is converted into an audio signal and viewed on a television receiver.

FIG. 8 is a block diagram showing the configuration of a conventional teletext receiver. The blocks having the same functions as those in FIG. 7 are designated by the same reference numerals.

In FIG. 8, a character multiplex broadcast signal is input to the television receiver circuit 21A from a device (not shown). The television receiving circuit 21A selects a desired channel, demodulates the selected signal, and outputs a video demodulation signal and an audio demodulation signal. The VBI extraction circuit 22A inputs the video demodulated signal and extracts the character data and the musical sound data superimposed on the VBI. The video demodulation signal and the audio demodulation signal obtained by demodulating an ordinary broadcast that is not a character broadcast are output from the television receiving circuit 21A as they are. The respective data extracted from the VBI extraction circuit 22A are error-corrected by the error correction circuit 23A, and the video decoding circuit 26 and the musical sound decoding circuit 2 are processed.
7 is supplied. The video decoding circuit 26 decodes error-corrected character data into a video signal, and the musical sound decoding circuit 27 decodes error-corrected musical sound data into an audio signal. Decoding circuits 26, 2
The character data and the musical tone data from the error correction circuit 23A, which are respectively input to 7, are accumulated in the storage device 28,
You can watch it again later. The information is stored in the storage device 28 as data for each page of the screen, and the user can freely read it page by page using the menu screen generated by the menu screen generator 29. The video demodulation signal and the audio demodulation signal obtained by demodulating a normal broadcast from the television receiving circuit 21A, and the video signal and the audio signal from the video decoding circuit 26 and the musical sound decoding circuit 27 are the video and the audio, respectively. Switching circuit 30
Is switched by the audio switching circuit 31 and output to a television receiver (not shown) for viewing.

By the way, although the AM pass-through receiver and the character multiplex broadcast receiver are constituted by similar circuit blocks as described above, when actually trying to receive each broadcasting service, they are separately received. Need a machine,
The operation was complicated and required a lot of installation space. Further, as a problem peculiar to the AM pass-through receivers up to now, there is no means for outputting message information as a video signal, so that it cannot be immediately displayed on the television receiver.

[0012]

As described above, conventionally,
When the AM pass-through receiver and the teletext broadcast receiver actually try to receive their respective broadcast services, separate receivers are required, which complicates the operation and requires many installation locations. It was Further, conventional AM pass-through receivers have no means for outputting message information as a video signal.

In view of the above problems, the present invention is based on AM.
AM pass-through that allows the pass-through receiver and the teletext receiver to share the circuit, enables downsizing of the device, improvement of operability and space saving, and easy viewing of message information. It is an object of the present invention to provide a receiver for a system and a character multiplex system.

[0014]

According to the first aspect of the present invention,
In addition to the AM pass-through method signal in which the scrambled broadcast signal transmitted via the first transmission system is remodulated to AM, the character multiplex broadcast signal can be received and demodulated via the second transmission system. Receiver for AM pass-through system and character multiplex system, which selects one channel from a plurality of channels distributed by the second transmission system and demodulates a baseband video signal and a baseband audio signal A circuit, an extraction circuit for extracting a character multiplex broadcast signal and an AM pass-through data signal superimposed on a vertical blanking period of a baseband video signal demodulated by the television receiving circuit, and a signal extracted by this extraction circuit Error correction circuit that corrects the error of the above, and a security circuit that descrambles the data signal of the AM pass-through method that is error-corrected by this error correction circuit When the baseband video signal from the B circuit and the television receiving circuit is scrambled, the video signal is descrambled by the data signal descrambled by the security circuit. A circuit, a storage device for storing a character data signal and a tone data signal of the character multiplex broadcast signal error-corrected by the error correction circuit, and a character data signal of the character multiplex broadcast signal error-corrected by the error correction circuit, A video decoding circuit for converting message information data contained in a data signal of the AM pass-through method descrambled by the security circuit into a video signal, and converting a character data signal stored in the storage device into a video signal. Character data of the character multiplex broadcast signal stored in the storage device A menu screen generator that generates a menu screen for listing and controlling the reading of signal titles, a tone data signal of a character multiplex broadcast signal that has been error-corrected by the error correction circuit, and is stored in a front storage device. A tone decoding circuit for converting a tone data signal into an audio signal, a baseband video signal and a baseband audio signal of a normal television broadcast demodulated by the television receiving circuit, and a base descrambled by the video descramble circuit. A video for selecting an arbitrary output from a band video signal and a baseband audio signal, a video signal converted by the video decoding circuit, an audio signal converted by the musical sound decoding circuit, and a video signal of the message information, and A voice switching circuit is provided.

According to a second aspect of the present invention, in addition to the AM pass-through type signal obtained by remodulating the scrambled broadcast signal transmitted through the first transmission system into AM, the character multiplex broadcast signal is transmitted through the second transmission. A receiver for an AM pass-through system and a character multiplex system that can be received and demodulated through a system, in which one channel is selected from a plurality of channels distributed by a second transmission system and a baseband video is received. A television receiving circuit for demodulating a signal and a baseband audio signal, and an extraction for extracting a character multiplex broadcasting signal superimposed on a vertical blanking period of a baseband video signal demodulated by the television receiving circuit and an AM pass-through data signal Circuit, an error correction circuit for correcting an error of the signal extracted by this extraction circuit, and an AM pass-through type data signal error-corrected by this error correction circuit In addition to descrambling by inputting, the security circuit that inputs and descrambles the scrambled character multiplex broadcasting signal, and the baseband video signal from the television receiving circuit is scrambled, the security circuit A video descrambling circuit that descrambles the baseband video signal by a scrambled data signal, and a memory that stores a character data signal and a musical sound data signal of the character multiplex broadcasting signal that is descrambled by the security circuit. The device and the character data signal of the character multiplex broadcast signal descrambled by the security circuit and the message information data of the AM pass-through method are converted into a video signal, while the character data signal stored in the storage device is converted into a video signal. Video data to be converted And a scrambler by the security circuit, and a menu screen generator for generating a menu screen for enumerating the subject of the character data signal of the character multiplex broadcast signal stored in the storage device and managing the reading thereof. A musical tone data signal of the released character multiplex broadcast signal and a musical tone decoding circuit for converting the musical tone data signal stored in the previous storage device into an audio signal,
Ordinary television broadcast baseband video signal and baseband audio signal demodulated by the television receiving circuit, baseband video signal and baseband audio signal descrambled by the video descramble circuit, and the video decoding circuit It is characterized by comprising a video and audio switching circuit for selecting an arbitrary output from the converted video signal and the audio signal converted by the tone decoding circuit and the video signal of the message information.

According to a third aspect of the present invention, in the AM pass-through type and character multiplex type receivers according to the first or second aspect, the storage device also has a function of storing the message information data. The decoding circuit is also provided with a function of reading message information data stored in the storage device at any time and converting it into a video signal.

According to a fourth aspect of the present invention, in the AM pass-through type and character multiplex type receivers according to the first or second aspect, the storage device also has a function of storing the message information data. The decoding circuit also has a function of reading message information data stored in the storage device at any time and converting the message information data into a video signal, and the menu screen generator includes the subject of the message information data in the generated menu screen. It is characterized by the fact that it is a waste.

According to a fifth aspect of the present invention, in the AM pass-through type and character multiplex type receiver according to the first or second aspect, the menu screen generator is a normal television broadcast demodulated by the television receiving circuit. Of the baseband video signal and baseband audio signal, the baseband video signal and baseband audio signal descrambled by the video descramble circuit, and the video signal converted by the video decoding circuit and the tone decoding circuit It is characterized in that it has a function of generating a menu screen for selecting either of the voice signal thus generated and the video signal of the message information.

According to a sixth aspect of the present invention, in the AM pass-through type and character multiplex type receiver according to the first or second aspect, the service content of the signal error-corrected by the error correction circuit is identified, and the identification content is identified. According to the present invention, a service identification circuit for switching and controlling the video / audio switching circuit is provided.

[0020]

According to the first aspect of the present invention, the circuit of the AM pass-through receiver and the character multiplex broadcasting receiver can be shared, and the AM pass through receiver and the character multiplex broadcasting receiver can be operated. This makes it possible to reduce the size of the device, improve operability, save space, and output message information as a video signal.

According to the second aspect of the invention, the AM pass-through message information is stored in the storage device together with the video and tone information of the character multiplex broadcast receiver, which is read out and supplied to the video decoding circuit. Since the message information of the AM pass-through method is once stored, it can be easily viewed.

According to the third aspect of the invention, a menu screen can be displayed on the subject of the message information data of the AM pass-through method, and the operability can be improved.

According to the invention described in claim 4, when the character multiplex broadcasting scrambled by the same scrambling method as the AM pass-through method is carried out in the future, the user can view the program without separately providing a descrambler.

According to the present invention of claim 5, the user can freely and easily select any of the plurality of services on the menu screen, and the operability can be improved.

According to the present invention as set forth in claim 6, when the service discriminating circuit has one broadcasting service being performed, the video and audio of that service are output, and when a plurality of broadcasting services are being conducted. It is possible to preferentially output a broadcast service designated in advance to a television receiver, and to eliminate the complexity of user service selection.

[0026]

EXAMPLES Examples will be described with reference to the drawings. 1 is a block diagram showing an AM pass-through type receiver and a character multiplex type receiver according to a first embodiment of the present invention. The blocks having the same functions as those in FIGS. 7 and 8 are designated by the same reference numerals.

In FIG. 1, an AM pass-through type signal or a character multiplex broadcast signal is input to the television receiving circuit 21B. The television receiving circuit 21B selects a desired channel, demodulates the selected signal, and outputs a video demodulation signal and an audio demodulation signal. The VBI extraction circuit 22B inputs the video demodulation signal and extracts the AM pass-through descramble data, the individual information data and the message information data superimposed on the VBI, while extracting the character data and the musical sound data of the character multiplex broadcasting. Each of the extracted data is error-corrected by the error correction circuit 23B and supplied to the video decoding circuit 26, the musical sound decoding circuit 27, and the security circuit 24. The video decoding circuit 26 decodes character-multiplexed broadcast character data of the error-corrected data into a video signal, and the tone decoding circuit 27 converts the character-multiplexed broadcast tone data of the error-corrected data into an audio signal. It is the one to decode. Decode circuit 2
The character data and the musical sound data respectively input to Nos. 6 and 27 are accumulated in the storage device 28 and can be viewed again later. The information is stored in the storage device 28 as data for each page of the screen, and the user can freely read it page by page using the menu screen generated by the menu screen generator 29. The security circuit 24 descrambles the descramble data of the AM pass-through method, the individual information, and the message information among the error-corrected data, and outputs the descrambled data. Video descramble circuit 25
Is to descramble the video demodulation signal based on the descrambled descrambled data, wherein descramble permission / prohibition is controlled by the descrambled individual information data, and the descrambled video signal or Outputs video signals that are not descrambled. The descrambled message information data output from the security circuit 24 is converted into a video signal in the video decoding circuit 26 in the same manner as the character data of the character multiplex broadcasting, and is output to a television receiver (not shown) through the video switching circuit 30. It should be noted that the video demodulation signal of the normal broadcast that has not been scrambled is output without any processing in the video descramble circuit 25. The audio demodulated signal output from the television receiving circuit 21B is output as it is. An image demodulation signal and an audio demodulation signal obtained by demodulating an ordinary broadcast from the television receiving circuit 21B, a decoded video signal and a tone signal of a character multiplex broadcast from the image decoding circuit 26 and the tone decoding circuit 27, and an image. The AM pass-through descramble video signal and audio signal from the descramble circuit 25 are switched by the video switching circuit 30B and the audio switching circuit 31B for each of video and audio, and output to a television receiver (not shown).

In the above configuration, the television receiving circuit 21
When AM pass-through AM signal is input to B,
The descramble data, the individual information and the message information superimposed on the VBI of the demodulated video signal are extracted by the VBI extraction circuit 22B, error-corrected by the error correction circuit 23B, and then supplied to the security circuit 24. The video descramble circuit 25 descrambles the video demodulated signal using the descrambler data and individual information data descrambled by the security circuit 24, and outputs the signal via the video switching circuit 30B. The descrambled message information data from the security circuit 24 is converted into a video signal by the video decoding circuit 26B. If the control means (not shown) switches the video switching circuit 30B, the video signal of the message information can be output from the video switching circuit 30B.

On the other hand, when a character multiplex broadcasting signal is input to the television receiving circuit 21B, the VBI of the demodulated video signal is input.
The VBI extraction circuit 22B extracts the character data and the musical sound data that are superimposed on each other, and the error correction circuit 23B corrects the error, and then each data is supplied to the video decoding circuit 26B and the musical sound decoding circuit 27. Video decoding circuit 26
In B, the character data is decoded into a video signal, which is output via the video switching circuit 30B. In the musical sound decoding circuit 27, the musical sound data is decoded into an audio signal which is output via the audio switching circuit 31B. When viewing the audio multiplex broadcast, the menu of the character data signal can be displayed on the screen by the menu screen generator 29. In addition, the video demodulation signal and the audio demodulation signal at the time of receiving the normal broadcast from the television receiving circuit 21B are
At 5, the signal passes through without being subjected to the descrambling operation and is supplied to the video switching circuit 30B and the audio switching circuit 31B. At this time, if the video switching circuit 30B is switched by the control means (not shown), the video signal and the audio signal at the time of receiving the normal broadcast can be output from the video switching circuit 30B and the audio switching circuit 31B.

According to the embodiment of FIG. 1, the circuit of the AM pass-through receiver and the character multiplex broadcast receiver of the conventional configuration can be shared, and the input signals of the video switching circuit 30B and the audio switching circuit 31B are simply switched. The receiver can be operated as both an AM pass-through receiver and a teletext receiver, and the device can be downsized, the operability can be improved, and the space can be saved. Moreover, since the message information of the AM pass-through method can be converted into a video signal by using the video decoding circuit 26 for the character multiplex broadcasting, the message information can be easily viewed and a separate conversion means to the video signal is not required. .

FIG. 2 shows an AM pass-through type receiver and a character multiplex type receiver according to a second embodiment of the present invention. The difference from the embodiment of FIG. 1 is that, in addition to storing character data and musical sound data of character multiplex broadcasting in the storage device 28B,
Message information data of the AM pass-through system from the security circuit 24 (this data is the video decoding circuit 26
That is, data that has not been converted into a video signal in B) is stored. The message information data stored in the storage device 28B is read in the same manner as the character data of the character multiplex broadcasting and input to the video decoding circuit 26, so that the message information can be converted into a video signal for viewing at any time.

Further, as another embodiment of the present invention,
The storage device 28B also has a function of storing the message information data, and the video decoding circuit 26B also has a function of reading the message information data stored in the storage device 28B at any time and converting it into a video signal. In addition, the menu screen generator 29 may be configured to include the subject of the message information data in the generated menu screen.

FIG. 3 shows an AM pass-through type receiver and a character multiplex type receiver according to a third embodiment of the present invention. 1 and 2 is different from the embodiment shown in FIG. 2 in that the menu screen generator 29B enumerates the subject of the character data signal of the character multiplex broadcast signal and the subject of the message information data and enables the read management. , A video demodulated signal and an audio demodulated signal obtained by demodulating a normal broadcast, a decoded video signal and an audio signal of a character multiplex broadcast, an AM pass-through descramble video signal and an audio signal, and an AM pass-through message video signal. The point is that a menu screen for selecting one is generated. The user can freely and easily select any one broadcasting service while looking at the menu screen.

FIG. 4 shows an AM pass-through type receiver and a character multiplex type receiver according to a fourth embodiment of the present invention. This embodiment is an embodiment in the case where the character multiplex broadcast is scrambled. The difference from the embodiment of FIGS. 1 to 3 is that scrambled character data and musical sound data of character multiplex broadcasting are input to the security circuit 24B, the data is descrambled by the security circuit 24B, and the data is descrambled. The data is decoded by the video decoding circuit 26.
B and the musical sound data circuit 27B, and the video decoding circuit 26B and the musical sound data circuit 27.
A decoded video signal and a decoded audio signal are output from B. The teletext signal is not scrambled.
The configuration differs from that of the embodiment shown in FIG. 3 in that the character data and the tone data that have been error-corrected by the error correction circuit 23B are supplied to the video decoding circuit 26B and the tone data circuit 27B, respectively.

In the above structure, the television receiving circuit 21
When AM pass-through AM signal is input to B,
The descrambled data, the individual information and the message information superimposed on the VBI of the demodulated video signal are extracted by the VBI extraction circuit 22B, error-corrected by the error correction circuit 23B, and then supplied to the security circuit 24B. In the video descramble circuit 25, the security circuit 24B
The descrambler data and the individual information data descrambled in (1) are used to descramble the video demodulation signal and output via the video switching circuit 30B. Also,
The descrambled message information data from the security circuit 24B is converted into a video signal by the video decoding circuit 26B. If the control means (not shown) switches the video switching circuit 30B, the video signal of the message information can be output from the video switching circuit 30B.

On the other hand, when the scrambled character multiplex broadcasting signal is input to the television receiving circuit 21B, the character data and the musical sound data superimposed on the VBI of the demodulated video signal are extracted by the VBI extracting circuit 22B. After being error-corrected by the error correction circuit 23B, these data are descrambled by the security circuit 26B and then supplied to the video decoding circuit 26B and the musical sound decoding circuit 27. In the video decoding circuit 26B, the descrambled character data signal is decoded into a video signal, which is output via the video switching circuit 30B. In the tone decoding circuit 27, the descrambled tone data signal is decoded into an audio signal and the audio switching circuit 31.
It is output via B. When viewing the audio multiplex broadcast, the menu of the character data signal can be displayed on the screen by the menu screen generator 29. In addition, the television receiving circuit 21
The video demodulation signal and the audio demodulation signal at the time of receiving the normal broadcast from B pass through without being descrambled by the video scramble circuit 25 and are supplied to the video switching circuit 30B and the audio switching circuit 31B. At this time, if the video switching circuit 30B is switched by the control means (not shown), the video signal and the audio signal at the time of receiving the normal broadcast are switched to the video switching circuit 30.
It can be output from the B and voice switching circuit 31B.

According to the embodiment shown in FIG. 4, when the character multiplex broadcasting scrambled by the same scrambling method as the AM pass-through method is performed in the future, the character multiplex can be easily performed without adding another device for descrambling. It becomes possible to watch the broadcast.

FIG. 5 shows an AM pass-through type receiver and a character multiplex type receiver according to a fifth embodiment of the present invention. The difference from the embodiments of FIGS. 1, 2 and 3 is that the signal corrected by the error correction circuit 23B is input, the service content thereof is identified, and the video / audio switching circuit 30C is identified by the identified content. The point is that a service identification circuit 32 for switching and controlling 31C is provided.

According to the embodiment shown in FIG. 5, the service identifying circuit 32 is used to output the service when one broadcasting service is being implemented, and to output the service when a plurality of broadcasting services are being implemented. The broadcast service designated in advance by the identification circuit 32 can be preferentially output to the television receiver. Therefore, the complexity of service selection by the user can be reduced.

In the present invention, in addition to the configuration of each of the embodiments shown in FIGS. 4 and 5, the characteristic configuration of the embodiment of FIGS. 2 and / or 3 (message information data should be stored in a storage device). , And / or the menu screen generated by the menu screen generator may include a subject of message information data).

[0041]

As described above, according to the present invention, the AM
By sharing the circuit between the pass-through receiver and the teletext receiver, it is possible to realize a dual-use receiver that has excellent operability and does not take up space. In addition, the message information can be easily viewed and viewed even when the character multiplex broadcast is scrambled.

[Brief description of drawings]

FIG. 1 is a block diagram showing an AM pass-through receiver and a character multiplex receiver according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an AM pass-through receiver and a character multiplex receiver according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing an AM pass-through and character multiplexing receiver according to a third embodiment of the present invention.

FIG. 4 is a block diagram showing an AM pass-through type and character multiplexing type receiver according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing an AM pass-through receiver and a character multiplex receiver according to a fifth embodiment of the present invention.

FIG. 6 is a block diagram showing an AM pass-through transmission system.

FIG. 7 is a block diagram showing a configuration of a conventional AM pass-through receiving terminal.

FIG. 8 is a block diagram showing a configuration of a conventional teletext receiver.

[Explanation of symbols]

 21B ... Television receiving circuit 22B ... VBI extracting circuit 24, 24B ... Security circuit 25 ... Video scramble circuit 26B ... Video decoding circuit 27 ... Musical sound decoding circuit 28, 28B ... Storage device 29, 29B ... Menu screen generator 30B, 30C ... Video Switching circuit 31B, 31C ... Voice switching circuit 32 ... Service identification circuit

Claims (6)

[Claims] 1. A character multiplex broadcast signal is received via a second transmission system in addition to an AM pass-through system signal in which a scrambled broadcast signal transmitted via a first transmission system is remodulated into AM. A receiver for AM pass-through method and character multiplex method capable of demodulation, in which one channel is selected from a plurality of channels distributed by the second transmission system and a baseband video signal and a baseband audio signal are selected. A television receiving circuit for demodulating the signal, an extracting circuit for extracting a character multiplex broadcasting signal and an AM pass-through data signal superimposed in a vertical blanking period of the baseband video signal demodulated by the television receiving circuit, and the extracting circuit An error correction circuit that corrects the error of the signal extracted in step S1 and the scramble of the AM pass-through data signal that is error-corrected by this error correction circuit And a security circuit for removing the baseband video signal from the television receiving circuit, when the baseband video signal is descrambled, the video signal is descrambled by the data signal descrambled by the security circuit. A descrambling circuit, a storage device for storing a character data signal and a musical tone data signal of the character multiplex broadcasting signal error-corrected by the error correction circuit, and a character data signal of the character multiplex broadcasting signal error-corrected by the error correction circuit And converting the message information data contained in the AM pass-through type data signal descrambled by the security circuit into a video signal,
A video decoding circuit for converting a character data signal stored in the storage device into a video signal, and a list of character data signals of the character multiplex broadcast signal stored in the storage device for enumerating and managing the reading thereof. A menu screen generator for generating a menu screen, a tone data signal of a character multiplex broadcast signal error-corrected by the error correction circuit, and a tone decoding circuit for converting the tone data signal stored in the front storage device into an audio signal. An ordinary television broadcast baseband video signal and a baseband audio signal demodulated by the television receiving circuit, a baseband video signal and a baseband audio signal descrambled by the video descramble circuit, and the video decoding circuit The video signal converted by the above, the audio signal converted by the tone decoding circuit, and the message And a broadcast video signal, AM pass-through method and receiving apparatus for character multiplexing method characterized by comprising a video and audio switching circuit for selecting any output. 2. A character multiplex broadcast signal is received via a second transmission system in addition to an AM pass-through system signal in which a scrambled broadcast signal transmitted via a first transmission system is remodulated into AM. A receiver for AM pass-through method and character multiplex method capable of demodulation, in which one channel is selected from a plurality of channels distributed by the second transmission system and a baseband video signal and a baseband audio signal are selected. A television receiving circuit for demodulating the signal, an extracting circuit for extracting a character multiplex broadcasting signal and an AM pass-through data signal superimposed in a vertical blanking period of the baseband video signal demodulated by the television receiving circuit, and the extracting circuit An error correction circuit that corrects the error of the signal extracted in step S1, and the AM pass-through data signal that is error-corrected in this error correction circuit are input and scrambled. In addition to releasing the
A security circuit for inputting and descrambling a scrambled character-multiplexed broadcast signal, and when the baseband video signal from the television receiving circuit is scrambled, by the data signal descrambled by the security circuit, A video descrambling circuit that descrambles the baseband video signal, a storage device that stores a character data signal and a musical tone data signal of a character multiplex broadcast signal that is descrambled by the security circuit, and descrambles by the security circuit. A video decoding circuit for converting the character data signal of the character multiplexed broadcast signal and the message information data of the AM pass-through system into a video signal, and converting the character data signal stored in the storage device into a video signal, and the storage device. Remembered by A menu screen generator that generates a menu screen for enumerating the subject of the character data signal of the character multiplex broadcast signal and managing the reading of the same, and a tone data signal of the character multiplex broadcast signal descrambled by the security circuit. A tone decoding circuit for converting a tone data signal stored in a pre-storage device into an audio signal; a normal television broadcast baseband video signal and a baseband audio signal demodulated by the television receiving circuit; and the video descrambler. Any of a baseband video signal and a baseband audio signal descrambled by a circuit, a video signal converted by the video decoding circuit, an audio signal converted by the musical sound decoding circuit, and a video signal of the message information. And a video and audio switching circuit for selecting the output of AM pass-through method for and a receiver for teletext system. 3. The storage device also has a function of storing the message information data, and the video decoding circuit also has a function of reading the message information data stored in the storage device at any time and converting it into a video signal. The receiver for AM pass-through system and character multiplex system according to claim 1 or 2, wherein 4. The storage device also has a function of storing the message information data, and the video decoding circuit also has a function of reading the message information data stored in the storage device at any time and converting it into a video signal. The receiver for AM pass-through system and character multiplex system according to claim 1 or 2, wherein the menu screen generator includes the title of the message information data in the generated menu screen. 5. The menu screen generator includes a baseband video signal and a baseband audio signal of a normal television broadcast demodulated by the television receiving circuit, and a baseband video signal descrambled by the video descramble circuit. And a menu screen for selecting one of the baseband audio signal, the video signal converted by the video decoding circuit, the audio signal converted by the tone decoding circuit, and the video signal of the message information. The AM according to claim 1 or 2, wherein the AM has a function.
Receiver for pass-through system and character multiplex system. 6. A service discriminating circuit for discriminating the service content of a signal error-corrected by the error-correcting circuit and controlling switching of the video / audio switching circuit according to the discriminating content. Alternatively, the receiver for the AM pass-through method and the character multiplex method described in 2.