JPH0964847A - Decoder for security broadcast equipment and its decoding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the security broadcast equipment with high reliability by providing a means separating an information packet, a separate detection means for scrambling data, a means separately detecting a common information packet and a descrambling means to the decoder. SOLUTION: VBI data separated by a VBI separate section 63 are separated into a relation information packet and a scramble timing TS packet at a separate section 65 for each type. A TS packet separated by the separate section 65 is subjected to majority decision at a majority decision discrimination section 85, in which the timing TS and a scramble flag VS are extracted. A descrambler 89 receives a scramble video signal from a separate section 61 through the separate section 63 and descrambles the video signal based on the flag VS from a scramble flag discrimination section 88 and a PN signal from a PN generator 87 and provides an output. Furthermore, the relation information packet separated by the separate section 65 is separated in a separate section 67 into each packet of common information, individual information and message information through discrimination of the type.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for individually receiving a secret broadcast received via an antenna via a cable.
The present invention relates to a decoding device in a secret broadcasting device used in an ATV (Community Antenna TV, Cable TV), a co-listening reception system and the like, and a method for determining the effectiveness of a scramble flag.

[0002]

2. Description of the Related Art In recent years, secret broadcasting (broadcasting in which only specific viewers are allowed to view) has started, and receiving devices for receiving this secret broadcasting are becoming widespread. In a secret broadcast using such a secret broadcast device, a video is broadcast at a broadcasting station so that a person (hereinafter referred to as a non-contractor) other than a viewer who has a viewing contract (hereinafter referred to as a viewer contract) cannot view the video. , A voice signal is encoded or encrypted (hereinafter referred to as scramble) and transmitted. Further, the viewing subscriber uses the decoding device (hereinafter, “decoder”) having a descrambler for decoding the scrambled signal into the original video and audio signals (hereinafter, “descramble”) to decode the signal. It is possible to return to the original and watch it, while the non-contractor cannot descramble and cannot watch.

One example of such a secret broadcasting system is COATEC (COATEC: Conditional Access Technolo), which is one of the pay satellite broadcasting systems currently operated in Japan.
(gy research institute) method will be described as an example. In Figure 8, COATEC
1 shows a configuration of a transmitter 100 of a transmitting-side broadcasting station according to the method.

In the transmitter 100, the scrambler 101,
The video and audio signals are scrambled using 105. Further, a scramble flag is used so that the receiving side can judge whether the program being received is a scrambled broadcast or a non-scrambled broadcast. In the case of the COATEC system, this scramble flag is the 8th bit of the range bit (hereinafter referred to as R # 8) and the 12th bit of the control code (video scramble flag,
Hereinafter, this is referred to as VS).

In order for the scramble flag to be protected by the majority decision by the majority decision section of the receiving side decoder, the transmitter 100 continuously sends the scramble flag a plurality of times (called continuous transmission). There is. Further, in the transmitter 100, this scramble flag is input to the scramblers 101 and 105 to perform on / off control of scrambling of video and audio signals.

In this system, PN (Pseudora
In order to avoid sending the ndom noise) signal (pseudo-random signal) itself from the transmitter 100 to the decoder, the transmitter 100 and the decoder each have a PN generator that generates the same PN signal, and the PN generator generates the same PN signal. The same P to the vessel
The N initial value (encryption key) KS is set at the same timing with respect to the video and audio signals so that the same PN signal is obtained.

A scramble timing TS is a timing signal for setting the PN initial value KS. In the majority decision section of the decoder, this scramble timing T
In order to protect against errors by making a majority decision on S,
The transmitter 100 is supposed to continuously transmit the scramble timing TS. In the transmitter 100, the scramble timing TS is input to the PN generators 103 and 107, and the PN initial value KS is set.

In the above-mentioned pay broadcasting system of the COATEC system, the following three types of encryption keys (also referred to as keys) are used to deal with illegal viewing. next,
The encryption key and the related information packet (four pieces of information of program information, control information, individual information and message information described below are referred to as related information) will be described.

First, the PN initial value KS, which is an encryption key, is
PN generator 1 used for scrambling video and audio signals
PN used for descrambling video and audio signals in the decoder as well as initial values given to 03 and 107
This is the initial value given to the generator. Further, this PN generator is a pseudo-random data generator and is used to scramble the video and audio signals at random to improve confidentiality.

This PN initial value KS is designed to improve security by updating the PN initial value KS every very short period, for example, every second. In the following description, the update cycle will be described as 1 second. This PN initial value K
S is transmitted to the decoder as part of the program information. At this time, as for the program information and the control information, the same information is superposed on the transmission signal a plurality of times on the encoder side and continuously transmitted. On the decoder side, these pieces of information are compared with each other, and majority decision processing is performed to extract correct information at a high frequency of receiving the same information.

Next, the encryption key KW transmitted together with the individual information will be described. The update cycle of the encryption key KW is, for example, once a month, and the next month, the broadcast wave is multiplexed and transmitted from the broadcasting station to the decoder of the person who has a viewing contract. It will not be sent to unpaid decoders.

At the decoder, the received encryption key KW
After decrypting the code, save it in the individual information memory and
In order to decode the program information including the PN initial value KS sent every second, it is read from the individual information memory and used at any time. The encryption key KW is transmitted from the broadcasting station 100 to each decoder as a part of the individual information at every update cycle of the encryption key KW. The encryption key KW is not continuously sent.

Next, the encryption key KMi will be described.
This encryption key KMi holds the security of this encryption key KW when the broadcasting station 100 transmits the individual information including the encryption key KW only to the decoder of the viewer who has subscribed to the viewing and also the decoder who continues to subscribe to the viewing in the next month. Is an encryption key used when encrypting the encryption key KW or the like.

This cipher key KMi is written in the cipher key memory KMi of the decoder when the decoder is shipped from the factory, for example, and is different for each decoder. Therefore, by transmitting the encryption key KMi separately for each decoder, the encryption key KW can be separately transmitted for each decoder. In other words, the decoder having a different transmitted encryption key KMi cannot decrypt the encryption key KW.

Details of the program information, individual information, control information, and message information described above are described in the report of the Council for Telecommunications Technology for Pay Satellite Broadcasting (see pages 48 to 57). Here, these will be briefly described.

The program information carries information necessary for descrambling such as an encryption key KS and a program number, and is transmitted in a predetermined cycle (for example, 1 second). If the decoder side removes this program information, it cannot be descrambled for a certain period of time. The control information is for temporarily disabling the viewing when the viewing fee has not been paid, and for allowing the viewing to be restored after the payment is made. Forcibly turning on / off the control by designating a specific decoder. can do. The individual information is transmitted by carrying the encryption key KW and the like, and includes the contract service, the contract registration code, the expiration date, and the like, and is transmitted only to the decoder of the person who has the viewing contract. The message information is for transmitting character information such as a program name.

These program information and control information are multiplexed with the individual information and message information by the multiplexing unit 119,
Further, after an error correction code is added by the error correction code addition unit 121, the multiplexing unit 123 time-division-multiplexes the audio signal together with the scramble flag VS, the scramble flag R # 8, and the scramble timing TS, and further the multiplexing unit 1
At 25, the video signal is frequency division multiplexed and transmitted.

By the way, the radio waves transmitted from the pay satellite broadcasting transmitter of the COATEC system shown in FIG.
CATV (Community
A joint reception system has been proposed in which it is supplied to a head end such as an ityAntenna TV, a Cable TV) or a co-listening reception system, and the head end is individually delivered to the decoder of each viewing subscriber via a cable. For the system,
There is a "paid broadcasting device" (Japanese Patent Application No. 4-77936) filed by the applicant of the present invention on March 31, 1992.

FIG. 9 shows a pay satellite broadcasting system relating to the above patent application. The BS broadcast radio wave transmitted from the transmitter (broadcasting station) 100 is received by the BS antenna 2 for joint reception via the BS 1, and is sent to the relay device (hereinafter, referred to as a head end) 3. In the headend 3,
The FM signal is detected by the BS tuner, the scrambled video signal and the bit stream are separated, and the scrambled audio signal and the information signal for descrambling the bit stream (here, the scramble timing T
S and scramble flag VS, R # 8, hereinafter referred to as a signal related to descramble) and related information packet (program information, control information, individual information and message information)
After demultiplexing, the descrambling signal is packetized, the packetized descrambling information packet (hereinafter referred to as descrambling packet) is time-division multiplexed with the related information packet, and then the scrambling is performed. Vertical blanking period of video signal (hereinafter,
Multiplexing (superimposing) on specific lines of VBI)
Then, the VBI-multiplexed scrambled video signal and the descrambled signal of the scrambled audio signal are respectively re-modulated (AM-modulated), frequency-multiplexed and transmitted to the cable 4.

The cable 4 has a plurality of VBIs for each user.
A decoding device (hereinafter, referred to as VBI compatible decoder) 5 compatible with multiplexing is connected. In the VBI compatible decoder 5, AM detection is performed by the VHF / UHF tuner, the scrambled video signal and the audio signal are separated, the packet multiplexed in the VBI of the scrambled video signal is separated, and then the descrambled packet is separated. Descrambles the scrambled video signal based on the packet according to The voice signal is further demodulated by voice. The demodulated video signal and audio signal are input to a television receiver (TV) not shown.

In FIG. 9, the aerial system for transmitting signals by radio waves from the transmitter to the head end via the satellite is referred to as a first transmission system,
A cable system for transmitting signals from the head end to the decoder (terminal side) is referred to as a second transmission system.

FIG. 10 is a block diagram showing the configuration of the headend 3 of the pay broadcasting system shown in FIG.
FIG. 4 is a block diagram showing a configuration of a VBI compatible decoder 5.

In the head end 3 shown in FIG.
After the audio signal is separated by the separation unit 11, the separation unit 13 further separates the scramble flag VS, the scramble flag R # 8, the scramble timing TS, and the related information packet in which the related information is packetized into the audio signal. The separated scramble timing TS is input to the packetizing unit 45 and the PN generator 37 after the majority decision is made by the majority decision unit 15 and the scramble flag VS and the scramble flag R # 8 are given to the majority decision unit 17. After making a majority decision in each case, both are input to the descrambler 39, and the scramble flag VS is also input to the packetizing unit 45. The scramble flag R # 8 is not transmitted to the packetizer 45.

Further, the related information packet is separated into common information (program information, control information), individual information and message information according to the type identification in the data in the separating section 19.
Among these, common information (program information, control information) is input to the decoding unit 25 after the majority determination unit 21 makes a majority determination and the error correction unit 23 makes an error correction. Further, the individual information is input to the decoding unit 33 after being error-corrected by the error correction unit 29. The message information is input to the buffer memory 55 after being error-corrected by the error correction unit 54.

Then, common information (program information, control information)
In the decryption unit 25, the encryption is decrypted using the encryption key KW stored in the individual information memory 35.
Further, the PN initial value KS is input to the PN generator 37, and other data is given to the viewability determination unit 27. Further, the individual information is stored in the individual information memory 35 after being decrypted by the decryption unit 33 using the encryption key KMi.

Further, the audio signal separated by the separating unit 13 is scrambled by the descrambler 39 with a scramble flag R # 8,
The signal is descrambled according to the scramble timing TS and the PN signal and input to the frequency multiplexing unit 53.

Since the related information packets output from the error correction units 23, 29 and 54 are multiplexed into VBI, it is necessary to temporarily hold the data and convert the data rate. Therefore, the buffer memory 41, the buffer memory 43, and the buffer memory 55 are stored and stored in three buffer memories 55, respectively. Of these, common information (program information, control information) packets are stored and stored in the buffer memory 41, and then the same data is read out a plurality of times for continuous transmission processing.

This common information (program information, control information) packet, individual information packet, message information packet, packet in which the scrambling timing TS and scramble flag VS are packetized by the packetizing unit 45 (hereinafter, this packet is scrambled). Timing T
S packet) is time-division multiplexed by the time-division multiplexing unit 47, and bit synchronization and byte synchronization are added by the bit synchronization byte synchronization addition unit 49 similar to character multiplex broadcasting.

Further, this signal is multiplexed by the VBI multiplexer of the VBI multiplexing unit 51 on the VBI of the undescrambled video signal (scrambled video signal) in the same manner as the character multiplex broadcasting.

Here, the packet to be transmitted will be described. In the case of character multiplex broadcasting, according to the Ministry of Posts and Telecommunications Ordinance No. 77 and Notification 803 concerning television character multiplex broadcasting, the number of bits of data that can be transmitted in one line is 272 bits including a prefix, and bit synchronization and byte synchronization are also included in this. In total, there are 296 bits. The related information packet in pay satellite broadcasting (BS) has exactly 272 bits excluding the header, and the packet structure of the character multiplex broadcasting can be transmitted in just one line period.

In the pay satellite broadcasting system, this 2
The first 8 bits of the 72-bit data are the type identification and are used to identify the program information, control information, individual information, and message information. Even in the character multiplex broadcasting, the first 8 bits of the 272-bit data are used. By assigning different data to each packet as a type identification, the receiving side identifies the packet. In this respect, pay satellite broadcasting and character multiplex broadcasting can be treated similarly.

Therefore, the related information packet of the satellite system is transmitted to VB.
In order to perform I-multiplex transmission, the 272 bits excluding the header from the related information packet are subjected to bit synchronization and byte synchronization similar to that of the character multiplex broadcasting, and then VBI-multiplexed to the video signal, so that the receiving side can A signal processing IC for character multiplex broadcasting can be used, and it is advantageous in terms of cost.

Next, the number of lines required for VBI-multiplexing and transmitting this related information packet will be described.
In the pay satellite broadcasting system, the cycle (transmission interval) of related information packets is 9 ms. Therefore, the packet transmission capacity (transmission speed) is about 111 packets / s.
Further, the transmission of the scramble timing TS packets is at most several packets per 1 s (the period of the scramble timing TS = 1 s) even if continuous transmission is taken into consideration. In VBI multiplex packet transmission such as in character multiplex broadcasting, if two lines are used for packet transmission for each field (that is, 60 fields per second and 2 packets are transmitted for each field), the packet cycle The (transmission interval) is 8.35 ms, and the packet transmission capacity is about 120 packets / s. Therefore, since the packet transmission capacity in the character multiplex broadcasting is larger than the transmission capacity of the scramble timing TS packet and the related information packet in the pay satellite broadcasting (core-tech system), the scramble timing TS packet and the related information packet are added to the VBI of the video signal. Can be sufficiently transmitted.

Next, the VBI compatible decoder 5 shown in FIG.
Will be explained. In the VBI compatible decoder 5, first, the demultiplexing unit 61 separates the frequency-multiplexed audio signal and video signal, and the VBI demultiplexing unit 63 separates the packet multiplexed into the VBI of the video signal. A signal processing IC (waveform equalization IC, sync separation IC, character multiplex extraction IC, etc.) developed for receiving character multiplex broadcasting can be used for the VBI separating unit 63. Then, the packet separated by the VBI separating unit 63 is separated into a related information packet and a scramble timing TS packet by type in the separating unit 65.

The scramble timing TS packet separated by the separation unit 65 is majority-determined by the majority decision unit 85, and the scramble timing TS and the scramble flag VS are extracted. The scramble timing TS and the scramble flag VS are respectively supplied to the PN generator 8
7 and descrambler 89.

The related information packet separated by the separating unit 65 is separated by the separating unit 67 into respective packets of common information (program information, control information), individual information, and message information by type identification. Among them, the common information (program information, control information) packet is majority-judged by the majority-judgment determination unit 68, and then is input to the decoding unit 77 through the error correction unit 69. In addition, the individual information packet is input to the decoding unit 73 after passing through the error correction unit 72. Since the message information packet is not encrypted, it is displayed on the message display unit 91 as it is after passing through the error correction unit 74.

Then, common information (program information and control information)
Information such as the encryption key KS of the packet is decrypted by the decryption unit 77 using the encryption key KW, the obtained PN initial value KS is input to the PN generator 87, and the other data is viewable / non-viewable determination unit. Given to 79. The individual information packet is stored in the individual information memory 75 after the decryption unit 73 decrypts the encryption key KW and the like using the encryption key KMi from the encryption key KMi memory 71.

The viewing availability determination unit 79 compares the program information with the data in the individual information memory 75 to determine the viewing availability. Then, according to this determination, the descrambler 89
Turns on / off the descramble operation. That is, even if a contract is made, the content of the individual information does not match the program and the result of the viewability determination result is no, the decoder cannot descramble and cannot view the program.

By the way, in the core-tech pay satellite broadcasting apparatus described above, the VBI-compatible decoder corresponding thereto has the following problems.

That is, the VBI-compatible decoder receives a signal passing through the head end and a signal not passing through it (general NTSC signal). VBI for signals that do not go through the headend
Test signals etc. may be superimposed on the multiplex part,
The test signal or the like becomes a random signal and may be erroneously recognized as a packet signal. In particular, there is a problem that the scramble timing TS packet is erroneously recognized and the scramble flag VS is erroneously determined as "1".

[0041]

As described above, the conventional core-tech pay satellite broadcasting receiving system has a problem that the scramble flag is erroneously determined when a signal which does not go through the head end is received.

Therefore, in view of the above problems, it is an object of the present invention to provide a decoding device and a method of determining the effectiveness of the scramble flag, which can maintain the certainty of recognition of the scramble flag.

[0043]

According to the first aspect of the present invention,
In a decryption device in a secret broadcast device for decoding and outputting a received secret broadcast signal, a first separating means for separating an information packet multiplexed with the secret broadcast signal for descrambling the secret broadcast signal. A second separation unit that separates and detects a scramble flag indicating a confidential broadcast from the packet separated by the first separation unit; and a common information packet from the packet separated by the first separation unit. A third separating means for separating and detecting;
When the presence of the common information packet from the third separating means is determined while the scrambling flag is detected from the second separating means, the determining means validates the scramble flag, and the determination by the determining means. When the result determines that the scramble flag is valid, it comprises a descrambling means for descrambling the secret broadcast signal based on the scramble flag.

According to a second aspect of the present invention, in a decoding device in a secret broadcasting device which decodes and outputs a received secret broadcasting signal, the synchronization signal of the secret broadcasting signal is detected and the periodicity of the synchronization signal is correct. And a first demultiplexing unit that demultiplexes the information packet for descrambling the secret broadcast signal, which is multiplexed with the secret broadcast signal, and the first determining unit. Second separating means for separating and detecting a scramble flag indicating a secret broadcast from the packet separated by the separating means, and the first separating means when the scramble flag is detected by the second separating means. Second determining means that validates the scramble flag when the determining means determines the validity of the synchronization signal, and the scrambler when the determination result of the second determining means is valid. It is obtained by and a descrambling means for descrambling the confidential broadcast signal based on Rufuragu.

According to a third aspect of the present invention, in a decryption device in a secret broadcast device for decoding and outputting a received secret broadcast signal, data at a packet multiplexing position of the secret broadcast signal is detected and synchronized with the data. First determining means for determining whether or not a code exists, first demultiplexing means for demultiplexing the information packet for descrambling the secret broadcast signal, which is multiplexed in the secret broadcast signal, Second separating means for separating and detecting a scramble flag indicating confidential broadcasting from the packet separated by the first separating means, and the second separating means for detecting the scramble flag when the second separating means detects the scramble flag. The second determining means that validates the scramble flag when the first determining means determines the presence of the synchronization code, and the determination result of the second determining means is valid. A, it is obtained by including a descrambling means for descrambling the confidential broadcast signal based on the scramble flag.

According to a fourth aspect of the present invention, in a decoding device in a secret broadcasting device which decodes and outputs a received secret broadcasting signal, the synchronization signal of the secret broadcasting signal is detected, and the periodicity of the synchronization signal is valid. And a second determining means that detects data at the packet multiplexing position of the secret broadcast signal and determines whether or not a synchronization code exists in the data. A first separation means for separating an information packet for descrambling the secret broadcast signal, which is multiplexed with the secret broadcast signal, and the packet separated by the first separation means is a secret broadcast Second separating means for separating and detecting a scramble flag indicating the above, a third separating means for separating and detecting a common information packet from the packets separated by the first separating means, and the second separating means. When the scramble flag is detected from the stage, the common information packet from the third separating means is present, the synchronization code is present in the second determining means, and the first determining means. In the case where it is determined that the synchronization signal is valid, the third determination unit that validates the scramble flag, and when the determination result of the third determination unit is valid, based on the scramble flag, And a descramble means for descrambling the secret broadcast signal.

According to a fifth aspect of the present invention, there is provided a decoding method in a decoding device for decoding and outputting a received secret broadcast signal, wherein the scramble flag multiplexed in the secret broadcast signal is separated and extracted, A common information packet is separated and extracted from the information packet multiplexed in the secret broadcast signal, it is determined whether the scramble flag and the common information packet are both present, and if both are present, the scramble flag is validated, The secret broadcasting signal is descrambled based on the scramble flag.

According to a sixth aspect of the present invention, there is provided a decoding method in a decoding device for decoding and outputting a received secret broadcast signal, wherein the scramble flag multiplexed in the secret broadcast signal is separated and extracted, Detects the synchronization signal of the secret broadcast signal, determines whether the periodicity of the synchronization signal is valid, and validates the scramble flag when the validity of the synchronization signal is determined, and concealment based on the scramble flag It is characterized in that the broadcast signal is descrambled.

According to a seventh aspect of the present invention, there is provided a decoding method in a decoding device for decoding and outputting a received secret broadcast signal, wherein the scramble flag multiplexed in the secret broadcast signal is separated and extracted, while The data at the packet multiplex position of the secret broadcast signal is detected, it is determined whether or not a sync code exists in the data, the scramble flag is validated when the presence of the sync code is determined, and based on the scramble flag It is characterized in that the secret broadcast signal is descrambled.

The invention according to claim 8 is a decoding method in a decoding device for decoding and outputting a received secret broadcast signal, wherein the scramble flag multiplexed in the secret broadcast signal is separated and extracted, Common information packet is separated and extracted from the information packet multiplexed in the secret broadcast signal, it is determined that the common information packet exists,
Further, the sync signal of the secret broadcast signal is detected, it is determined that the periodicity of the sync signal is valid, the data at the packet multiplexing position of the secret broadcast signal is detected, and the sync code exists in the data. If it is determined that the scramble flag is valid, the scramble flag is validated, and the secret broadcast signal is descrambled based on the scramble flag.

According to the first and fifth aspects of the invention, the fact that the common information packet always exists when the scramble flag is "1" is utilized, and when both are compatible, the scramble flag "1" is validated.

In the inventions according to claims 2 and 6, if the synchronization signal of the received signal is disturbed, the timing of the VBI multiplexer may be erroneously recognized. Therefore, when the synchronization is established, the scramble flag "1" is set. Validate.

In the third and seventh aspects of the invention, since a packet is always present in the VBI multiplexing section in the signal passed through the head end, the synchronization code (bit synchronization code,
The scramble flag “1” is validated when the presence of a packet can be determined by using the recognition of the byte synchronization code).

In the inventions according to claims 4 and 8, when the scramble flag is "1", there is a common information packet, the correctness of synchronization of the synchronization signal is established, and the packet multiplex position. When it is determined that the sync code exists in the scramble flag, the scramble flag “1” is validated. Since the scramble flag is validated when the three conditions are met in this way, the validity of the scramble flag determination can be made more reliable.

[0055]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a decoding device according to the present invention. The same parts as those in FIG. 11 are designated by the same reference numerals for description. The present embodiment shows a VBI-compatible decoder in a core-tech pay satellite broadcasting receiving system.

As shown in FIG. 1, the VBI compatible decoder 5
Is a demultiplexing unit 61 that demultiplexes and outputs the descrambled audio signal, and a VBI multiplexing unit 51 of the headend 1.
(See FIG. 10) The scrambled video signal VBI-multiplexed is separated and output to the descrambler 89, while the data (V
(BI data) and outputs it to the synchronization determination unit 62, and a synchronization determination that separates the synchronization signal from the video signal from the VBI separation unit 63 and determines the periodicity of the horizontal and vertical synchronization signals. The unit 62 and related information packets (common information (program information, control information), individual information and message information packets) and scramble timing TS packets (packetized scramble flag VS and scramble timing TS) from the VBI data. A separating unit 65 for separating, a separating unit 67 for separating each packet of common information (program information, control information), individual information, and message information from the separated related information packet, and separated common information (program information, control) (Information) majority decision unit 68 for making a majority decision on packets, and error correction for common information packets for which a majority decision has been made. An error correction unit 69, separating unit 67
Error correction unit 72 for error-correcting the individual information packet separated by 1., encryption key KMi memory 71, decoding unit 73 for decoding the error-corrected individual information packet using encryption key KMi, and the decoded individual information packet. Individual information memory 75 for storing information, and error-corrected common information (program information,
Control information) Decryption unit 77 for decrypting the packet using the encryption key KW, the decrypted program information and the individual information memory 7
5, the viewing permission / inhibition determination is performed, and the viewing permission / inhibition determination unit 79 for ON / OFF controlling the descrambler 89 according to the determination, and the majority determination for the scramble timing TS packet separated by the separation unit 65 The error determination unit 86 outputs the scramble flag VS to the scramble flag determination unit 88 and the scramble timing TS to the PN generator 87, and the scramble timing TS.
And a PN generator 87 that generates a pseudo-random (PN) signal by using the PN initial value KS, and VS after the majority decision from the error determination unit 86 and the synchronization determination signal from the synchronization determination unit 62 to V.
A scramble flag determination unit 88 for determining a reliable scramble flag VS from the VBI data from the BI separation unit 63 and a signal indicating the presence of common information from the error correction unit 69, and a scrambled video signal from the VBI separation unit 63. The scramble flags VS and P from the flag determination unit 88
A descrambler 89 that descrambles and outputs based on the PN signal from the N generator 87, an error correction unit 74 that error-corrects the message information packet separated by the separation unit 67, and error-corrected message information. And a message display unit 91 for displaying.

In the pay satellite broadcasting system, the first 8 bits in the 272 bit data area are the type identification,
It is used to identify program information, control information, individual information, and message information. Even in character multiplex broadcasting, the first 8 bits of the 272-bit data are used as the type identification to assign different data to each packet, so that the receiving side As described above, pay satellite broadcasting and character multiplex broadcasting can be handled in the same way in that packet identification is performed.

Therefore, in order to transmit the related information packet in this embodiment by VBI multiplexing, the 272 bits excluding the header from the related information packet in the pay satellite broadcasting are bit-synchronized and byte-synchronized similarly to the character-multiplexed broadcasting. To make it 296 bits.

FIG. 2 shows a configuration example of the related information packet (common information packet, individual information packet, message information packet), and FIGS. 3 and 4 show a configuration example of the scramble timing TS packet. 296 bits for both the related information packet and the scramble timing TS packet are bit synchronization code CR 16 bits, byte synchronization 8 bits, and 2 bits.
It consists of a 72-bit data area, and in the 272-bit data area, the type identification is 8 bits, the packet data is 182 bits, and the error correction code (redundant bit) is 82 bits. The VBI multiplex period is the first of the video signal.
These are the 17th and 19th lines of the field and the 280 and 282 lines of the second field.

FIGS. 3 and 4 show an example of the structure of this scramble timing TS packet. The type identification of the common information (program information and control information) is "011110.
00 ”, and the type identification of individual information is“ 1000011 ”.
1 ".

First, FIG. 3 shows the scramble timing TS.
And the scramble flag VS each transmit 91-bit data. The scramble timing TS and the scramble flag VS data are all 0s or 1s.
Therefore, it is assumed that the receiving side makes a majority decision on this data. The majority decision is a process in which, for example, if the data of 91 bits or more in a predetermined number of bits is 0, it is regarded as 0, and if it is less than that, it is regarded as 1 and, for example, the scramble timing TS is 72 bits or more. If the data is 1, it is regarded as the scramble timing TS, and the scramble flag VS is 1 for data of 72 bits or more.
If it is, the data is scrambled, and if the data of 72 bits or more is 0, it is non-scrambled.

Next, FIG. 4 shows the scramble timing TS.
And the scramble flag VS each transmit 91-bit data, which is the same as in FIG. 3, except that the scramble timing TS and the scramble flag VS are divided and transmitted alternately, for example, bit by bit or more bits. The error in the scramble timing TS and the scramble flag VS is halved with respect to the transmission error that occurs in a burst form to improve security.

Next, the operation of the VBI compatible decoder 5 shown in FIG. 1 will be described. In the VBI-compatible decoder 5, first, the audio signal and the scrambled video signal that have been frequency-multiplexed by the demultiplexing unit 61 are demultiplexed, and the VBI demultiplexing unit 63 multiplexes the packet data (that is, the VBI data ) Is separated. This VBI
A signal processing IC (waveform equalization IC, synchronous separation IC, character multiplex extraction I) developed for receiving the multiplex character broadcasting is provided in the separation unit 63.
C etc.) can be used. Then, the packet data (VBI data) separated by the VBI separation unit 63 is separated by the separation unit 65.
In step S1, the related information packet and the scramble timing TS packet are separated by type.

The scramble timing TS packet separated by the separation unit 65 is majority-determined by the majority decision unit 85, and the scramble timing TS and the scramble flag VS are extracted. In the majority decision judging section 85, FIG.
As described above, the majority decision processing is executed within the data of the scramble timing TS packet. The extracted scramble timing TS, scramble flag VS, and the combination (TS, VS) thereof are used as the error determination unit 8.
An error is judged in 6. Scramble timing T
S and the scramble flag VS are the PN generator 87, respectively.
Is input to the scramble flag determination unit 88. The scramble flag determination unit 88 inputs VS after the majority determination from the error determination unit 86, determines whether the synchronization is “presence” by the synchronization determination signal from the synchronization determination unit 62 and the VBI data “present” from the VBI separation unit 63. And the error correction unit 6
It is judged from the signal indicating the common information “present” from 9 that the input VS after the majority decision is surely the scramble flag VS, and it is decided that it is the reliable scramble flag VS. , Descrambler 89
To supply. The descrambler 89 inputs the scrambled video signal from the separation unit 61 through the VBI separation unit 63, and descrambles it based on the scramble flag VS from the scramble flag determination unit 88 and the PN signal from the PN generator 87. Output.

The related information packet separated by the separating unit 65 is separated by the separating unit 67 into respective packets of common information (program information, control information), individual information, and message information by type identification. Of these, the common information (program information, control information) packet is majority-judged by the majority-judgment determination unit 68, and the determination result is input to the decoding unit 77 through the error correction unit 69. The majority decision unit 68 makes a majority decision on the data of the common information packet continuously sent from the headend 3 (see FIG. 10). In addition, the individual information packet is input to the decoding unit 73 after passing through the error correction unit 72. Since the message information packet is not encrypted, it is displayed on the message display unit 91 as it is after passing through the error correction unit 74.

Common information (program information and control information)
The decryption unit 77 decrypts the encryption key KS and the like in the decryption unit 77, the obtained PN initial value KS is input to the PN generator 87, and other data is given to the viewability determination unit 79. To be The individual information packet is stored in the individual information memory 75 after the encryption key KW and the like are decrypted by the decryption unit 73 using the encryption key KMi.

The viewing availability determination unit 79 compares the program information from the decoding unit 77 with the data in the individual information memory 75 to determine the viewing availability. Then, according to this determination, the descrambler 89 turns on / off the descramble operation. That is, even if a contract is made, the content of the individual information does not match the program and the result of the viewability determination is negative, so that the VBI-compatible decoder cannot descramble and cannot view the program.

In the VBI-compatible decoder described above, when a signal is received via the head end, the scramble flag VS after the majority decision is input to the scramble flag determiner 88, and the synchronization determiner 62 determines the synchronization. The signal indicates that there is synchronization, a signal indicating that there is common information is input from the error correction unit 69, and the VBI separation unit 63
The presence of VBI data is detected from the
Bit synchronization signal CR included in the packet data of the period,
By detecting the presence of the byte synchronization signal FC), it is possible to determine that the scramble flag VS is valid and supply the scramble flag VS to the descrambler 89 to perform a descramble operation. However, when a signal that does not go through the head end is received, the descrambler 89 does not satisfy the validity of the scramble flag in the above-described determination processing in the scramble flag determination unit 88.
Is not supplied as a scramble flag to
The descramble operation is never performed. Therefore, a highly reliable device that does not malfunction as a decoder can be realized.

FIG. 5 is a block diagram showing an example of the synchronization determination unit 62 in FIG. In FIG. 5, a sync determination unit 62 includes a sync separation circuit 621 that separates horizontal and vertical sync signals H and V from a scrambled video signal, a voltage controlled oscillator circuit (VCO) 624, and a counter 625 that divides the oscillation signal by 364. And a horizontal synchronizing signal generating means for generating a local horizontal synchronizing signal HL, and a horizontal synchronizing signal H from the synchronizing separating circuit 621. And a horizontal synchronizing signal HL from the horizontal synchronizing signal generating means.
And a phase determination circuit 622 for outputting a local horizontal synchronizing signal HL synchronized with the horizontal synchronizing signal H as an output, and 262.5 of the horizontal synchronizing signal HL.
Vertical synchronizing signal generating means for generating a local vertical synchronizing signal VL, which is composed of a counter 626 for frequency dividing and a decoder 627 for generating a vertical synchronizing signal VL based on the frequency divided signal, and the sync separation circuit 621. Of the vertical synchronization signal V and the vertical synchronization signal VL from the vertical synchronization signal generating means are compared in phase, and when the phases match, a phase determination circuit 628 which outputs a synchronization determination signal "1" as an output.
It is configured.

In the above configuration, the scrambled video signal input from the input terminal 620 is transferred to the sync separation circuit 621.
And then separates the composite sync signal, and further separates it into a horizontal sync signal H and a vertical sync signal V. On the other hand, in the voltage controlled oscillator circuit (VCO) 624, (8/5) fsc (f
sc is oscillated at a color signal frequency of 3.58 MHz). The relationship with the frequency fH of the horizontal synchronizing signal H is (8/5) fsc
= 364 fH, the counter 625 divides the frequency by 364, the decoder 623 decodes and outputs the local horizontal sync signal HL, and the horizontal sync signal H separated by the sync separation circuit 621 and the local horizontal sync signal HL are phased. The determination circuit 622 compares the phases, and the output is output from the voltage controlled oscillation circuit 6
By inputting it to 24, (8/5) fsc frequency-locked with the horizontal synchronizing signal H from the received video signal is oscillated by the voltage controlled oscillation circuit 624.

Further, the local horizontal synchronizing signal HL is input to the counter 626 and divided by 262.5. The decoder 627 decodes the local vertical sync signal VL and outputs it, and the vertical sync signal V separated by the sync separation circuit 621.
And the local vertical synchronization signal VL are compared in phase by the phase determination circuit 628, and if the phases match, "1" is output from the output terminal 629 as the synchronization determination signal.

FIG. 6 is a block diagram showing an example of the scramble flag determination unit 88 in FIG.

In FIG. 6, the scramble flag determining unit 88 includes an AND circuit 882 for ANDing the synchronization determination signal and the VBI data, and the synchronization code C from the VBI data.
When the sync code detection circuit 883 for detecting R and FC in the vertical sync signal cycle and the clock input occur twice in succession "
Counter 888 that outputs a high-level signal indicating "present"
And an inverter 889, an AND circuit 885, and an AND circuit 886, and once the counter 888 outputs a "presence" signal (that is, when the synchronization code detection circuit 883 determines whether VBI data is present twice). A means for blocking the clock input and the reset input to the counter 888, and when the clock input occurs eight times in a row "
A counter 892 that outputs a high-level signal indicating "none"
And an inverter 890 and an AND circuit 891, and once the counter 892 outputs a "no" signal (that is, when the synchronous code detection circuit 883 makes no judgment of VBI data eight times), the counter 892 Means for blocking the clock input of the counter 888, and the counter 892 outputs 8 when the counter 888 once outputs the "present" signal.
The counter 88 until the "absent" signal is output consecutively
OR circuit 887 for blocking reset input to 8
And a delay circuit 884 for slightly reducing the "presence" detection signal of the synchronous code detection circuit 883 to make it a reset input to the counter 892, and for ANDing the effective output of the counter 888 and VS after the majority decision. AND circuit 894
Then, the signal is reset by the negative edge of the output of the AND circuit 894, the signal indicating the common information “present” is used as the clock input, the D input is fixed to “1”, and V after the majority decision is made.
It comprises a D-type flip-flop 897 for making the scramble flag VS an effective output as a Q output when S is "1" and a signal indicating common information "present" is input.

In the above circuit, the synchronization determination signal output from the synchronization determination section 62 is input to the input terminal 880, and V
The VBI data output from the BI separation unit 63 is input to the input terminal 8
The VBI data, which has been input to 81 and which has been validated by AND gate of both signals by the AND circuit 882, is input to the synchronous code detection circuit 883. The synchronization code detection circuit 883 outputs a high level signal indicating “present” from the detection output terminal a when the bit synchronization code CR and the byte synchronization code FC included in the VBI data can be detected during the VBI multiplex period, and the detection can be performed. If not, the detection output terminal b
Outputs a high level signal indicating "absence". Therefore,
A low level signal is output from the terminal a when the sync codes CR and FC cannot be detected, and a terminal b when the sync code CR can be detected.
It outputs a low level signal from.

The sync code detection circuit 883 has the bit sync code CR and the byte sync code F included in the VBI period.
When C can be detected, the high level signal output from the “existence” detection output terminal a is input to the counter 888 as a clock and counted, and when the counter 888 counts “existence” twice in succession, The output of the counter 888 becomes high level. The high-level output state of the counter 888 is maintained unless a high-level signal is input to the reset terminal. Sync code detection circuit 8
83 is the bit synchronization code CR included in the VBI period
If the byte sync code FC cannot be detected, "
The high level signal output from the "no" detection output terminal b
When the counter 892 counts as a clock and counts eight times in a row, the counter 892 outputs a high level signal. The high-level output state of the counter 892 is maintained unless a high-level signal is input to the reset terminal. Therefore, when the sync code detection circuit 883 detects "present" twice in succession, VBI
Validate the data, and once it is determined to be valid, it will be 8 times in a row.
The VBI data is not invalidated unless it becomes "None". And the validity judgment output of the counter 888 and the input terminal 893.
The AND circuit 894 AND gates the VS after the majority decision, which is the output from the error determination unit 86 (see FIG. 1), to the AND circuit 894. From the AND circuit 894, effective outputs of VBI data and VS after majority decision are obtained. The output of the AND circuit 894 is input to the reset input terminal R of the D-type flip-flop 897 as an edge input, and the clock terminal CK is input from the input terminal 895 as a signal indicating the common information "Yes", and the common information is "Yes". When is "effective output" 1
In order to output "to the output terminal Q," the D input terminal is always set to "1" from the input terminal 896. Therefore,
After the majority decision, VS "1" is input, then common information "
When a signal indicating “present” is input as a clock, the output terminal 89
8 is an output "1" that enables the scramble flag VS.
Will be output.

In the above-described embodiment, (1) the existence of the scramble flag and the compatibility of the common information packet, (2) the existence of the scramble flag and the periodic validity of the synchronization signal of the secret broadcast signal, and (3) the scramble flag And the presence of a packet in the VBI multiplex part of the secret broadcast signal can be used to determine the scramble flag VS with higher certainty. Therefore, even when a signal not passing through the headend is received, it is regarded as a scramble flag. There is no erroneous judgment.

In the embodiment shown in FIG. 1, the above (1),
Although the one provided with the circuit means that simultaneously satisfies the three conditions of (2) and (3) is shown, the present invention is not limited to the configuration of the above-mentioned embodiment, and (1), (2), (3 ) May be provided with circuit means satisfying any one of the conditions.

FIG. 7 shows a main part of another embodiment of the VBI-compatible decoder according to the present invention. In FIG. 7, (a), (b) and (c) are the above (1), (2) and
It is a block diagram corresponding to the condition of (3), and shows only the part different from FIG.

FIG. 7A shows the VS after the majority decision in FIG. 1, the sync decision signal, the VBI data, and the common information.
Instead of the scramble flag determination unit 88, which receives four signals of “present” signals and validates the scramble flag “1” only when all of these four signals are present,
A scramble flag determination unit 88A that receives two signals, a VS after the majority determination and a synchronization determination signal, and validates the scramble flag "1" when these two signals are present is provided. is there. Other configurations are the same as those in FIG.

FIG. 7B shows the VS after the majority decision, the sync decision signal, the VBI data, and the common information in FIG.
Instead of the scramble flag determination unit 88, which receives four signals of “present” signals and validates the scramble flag “1” only when all of these four signals are present,
Two signals of VS and VBI data after the majority decision is input, and a scramble flag determination unit 88B is provided which validates the scramble flag "1" when these two signals are present. . Other configurations are the same as those in FIG.

FIG. 7C shows the VS after the majority decision, the sync decision signal, the VBI data, and the common information in FIG.
Instead of the scramble flag determination unit 88, which receives four signals of “present” signals and validates the scramble flag “1” only when all of these four signals are present,
A configuration in which a scramble flag determination unit 88C that receives two signals of a VS after the majority decision and a signal of common information “present” is input and validates the scramble flag “1” when these two signals exist together It is what
Other configurations are the same as those in FIG.

As shown in FIGS. 7 (a), 7 (b) and 7 (c), the scramble flag VS can be used if the configuration realizes any one of the above conditions (1), (2) and (3). The certainty of the determination can be increased. Needless to say, the configuration may be such that two of the conditions (1), (2), and (3) are realized.

[0083]

As described above, according to the present invention, it is possible to improve the certainty in recognizing a scramble flag and to realize a highly reliable decoding device and decoding method in a secret broadcasting device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a VBI-compatible decoder in a secret broadcasting apparatus according to the present invention.

FIG. 2 is a diagram showing a structure of a related information packet corresponding to FIG.

FIG. 3 is a diagram showing an example of the configuration of a scramble timing TS packet corresponding to FIG.

FIG. 4 is a diagram showing another example of the configuration of a scramble timing TS packet corresponding to FIG. 1.

5 is a block diagram showing an embodiment of a configuration of a synchronization determination unit in FIG.

6 is a circuit diagram showing an embodiment of a configuration of a scramble flag determination unit in FIG.

FIG. 7 is a block diagram showing a main part of another embodiment of a VBI-compatible decoder according to the present invention.

FIG. 8 is a block diagram showing a schematic configuration of a core-tech type transmitter.

FIG. 9 is a diagram illustrating a pay satellite broadcasting system of an already filed application.

10 is a block diagram showing a schematic configuration of a head end of the pay broadcasting system shown in FIG.

11 is a block diagram showing a schematic configuration of a VBI decoder of the pay broadcasting system shown in FIG.

[Explanation of symbols]

 5 ... VBI-compatible decoder 61 ... Separation unit 62 ... Synchronization determination unit 63 ... VBI separation unit 65 ... Separation unit 69 ... Separation unit 73 ... Decoding unit 75 ... Decoding unit 79 ... Viewability determination unit 85 ... Majority determination unit 86 ... Error determination unit 87 ... PN generator 88 ... Scramble flag determination unit 89 ... Descrambler

Claims (8)

[Claims] 1. A decoding device in a secret broadcasting device for decoding and outputting a received secret broadcasting signal, wherein an information packet for descrambling the secret broadcasting signal, which is multiplexed with the secret broadcasting signal, is separated. A first separating means; a second separating means for separating and detecting a scramble flag indicating a secret broadcast from the packet separated by the first separating means; and a packet separated by the first separating means. A third separating means for separating and detecting the common information packet from the third separating means, and a case where the presence of the common information packet from the third separating means is determined when the scramble flag is detected from the second separating means. The determination means that validates the scramble flag, and if the determination result of this determination means determines that the scramble flag is valid, the scramble flag Decoding device in concealment broadcasting apparatus characterized by comprising a descrambling means for descrambling the confidential broadcast signal based. 2. A decoding device in a secret broadcasting device for decoding and outputting a received secret broadcasting signal, detecting a sync signal of the secret broadcasting signal, and determining whether or not the periodicity of the sync signal is valid. First determining means for determining, first separating means for separating the information packet for descrambling the secret broadcast signal, which is multiplexed in the secret broadcast signal, and separated by the first separating means Second separating means for separating and detecting a scramble flag indicating a confidential broadcast from the packet, and the first determining means for detecting a sync signal when the scramble flag is detected by the second separating means. The second which validates the scramble flag when the correctness is determined
And a descrambling means for descrambling the secret broadcasting signal based on the scramble flag when the judgment result of the second judging means is valid. Decoding device. 3. A decoding device in a secret broadcasting device for decoding and outputting a received secret broadcasting signal, wherein data at a packet multiplexing position of the secret broadcasting signal is detected, and whether or not a sync code exists in the data. A first determining means for determining whether or not, a first separating means for separating an information packet for descrambling the secret broadcast signal, which is multiplexed in the secret broadcast signal, and the first separating means. Second separating means for separating and detecting a scramble flag indicating a confidential broadcast from the separated packet; and the first determining means for synchronizing when the scramble flag is detected by the second separating means. Second determining means for validating the scramble flag when the presence of the code is determined, and the scrambling if the determination result of the second determining means is valid Decoding device in concealment broadcasting apparatus characterized by comprising a descrambling means for descrambling the confidential broadcast signal based on the flag. 4. A decoding device in a secret broadcasting device which decodes and outputs a received secret broadcasting signal, detects a sync signal of the secret broadcasting signal, and determines whether or not the periodicity of the sync signal is valid. First judging means for judging, second judging means for detecting data at a packet multiplexing position of the secret broadcast signal, and judging whether or not a synchronization code exists in the data, and the secret broadcast signal First demultiplexing means for demultiplexing the information packet for descrambling the concealed broadcast signal that has been multiplexed, and demultiplexing the scramble flag indicating the concealed broadcast from the packet demultiplexed by the first demultiplexing means. Second separating means for detecting, third separating means for separating and detecting a common information packet from the packets separated by the first separating means, and scrambling from the second separating means When the flag is detected, the common information packet from the third separation means is present, the synchronization signal is valid in the first determination means, and the synchronization signal is synchronized in the second determination means. Third determination means that validates the scramble flag when it is determined that the code exists, and a secret broadcast signal based on the scramble flag when the determination result of the third determination means is valid. And a descramble means for descrambled. 5. A decoding method in a decoding device for decoding and outputting a received secret broadcast signal, wherein a scramble flag multiplexed in the secret broadcast signal is separated and extracted while being multiplexed in the secret broadcast signal. Common information packet is separated and extracted from the existing information packet, it is determined whether the scramble flag and the common information packet are both present, and if they are both present, the scramble flag is validated, and the concealment is performed based on the scramble flag. A decoding method in a decoding device, characterized in that a broadcast signal is descrambled. 6. A decoding method in a decoding device for decoding and outputting a received secret broadcast signal, wherein a scramble flag multiplexed in the secret broadcast signal is separated and extracted, while a synchronization signal of the secret broadcast signal. Is detected, it is determined whether the periodicity of the synchronization signal is valid, the scramble flag is validated when the validity of the synchronization signal is determined, and the secret broadcast signal is descrambled based on the scramble flag. A decoding method in a decoding device characterized by the above. 7. A decoding method in a decoding device for decoding and outputting a received secret broadcast signal, wherein a scramble flag multiplexed in the secret broadcast signal is separated and extracted while packet multiplexing of the secret broadcast signal is performed. The data at the position is detected, it is determined whether or not a sync code exists in the data, the scramble flag is validated when the presence of the sync code is determined, and the secret broadcast signal is descrambled based on the scramble flag. A decoding method in a decoding device, comprising: 8. A decoding method in a decoding device for decoding and outputting a received secret broadcast signal, wherein a scramble flag multiplexed in the secret broadcast signal is separated and extracted while being multiplexed in the secret broadcast signal. Common information packet from the existing information packet is separated and extracted, it is determined that the common information packet exists, and the synchronization signal of the secret broadcast signal is detected, and the periodicity of the synchronization signal is determined to be correct. Further, when the data at the packet multiplex position of the secret broadcast signal is detected and it is determined that a sync code exists in the data, the scramble flag is validated, and the secret broadcast signal is generated based on the scramble flag. A decoding method in a decoding device characterized by descrambling.