JP2722652B2 - Data transmission equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission apparatus, and is suitably applied to, for example, a satellite television broadcasting signal transmitting apparatus and a receiving apparatus.

B. Summary of the Invention In the data transmission apparatus of the present invention, reference data having a predetermined pattern and having a length of N bits is continuously transmitted at least twice from a data transmission system into digital data, and the digital data is transmitted in a unit of N bits in a data reception system. By detecting the coincidence between the received N-bit data and the immediately preceding received N-bit data, the timing of the reference data can be reliably detected.

C Prior Art Conventionally, as a data transmission device of this type, for example, a CA for broadcasting from a predetermined broadcasting station using a television broadcasting relay satellite is used.
A system for supplying a program to a central station (so-called head end) of a TV (cable * television) has been proposed.

In such a case, the transmitted television broadcast signal is scrambled by various methods such as replacement of horizontal scanning lines (so-called line shuffling), and even if a person other than the subscriber receives the television broadcast signal, the television broadcast signal is transmitted normally. It has been made impossible to view and listen to various images and sounds (Japanese Patent Application Laid-Open
-256287).

Therefore, in such a satellite television broadcast signal transmission / reception system, a decoder having a built-in descrambler is provided to a person who has contracted with a broadcast station, and the scrambled television broadcast signal is reproduced in its original form using this decoder. Thus, normal images and sounds can be viewed.

D. Problems to be Solved by the Invention By the way, in the transmission method of scrambled and transmitted television broadcasting signals, information on how to scramble the television broadcasting signals (hereinafter, referred to as “scrambled”).
This is referred to as scramble data) to the contractor.

This scrambled data is stored in a ROM (read * only)
* Memory) and send it to the subscriber at the time of the contract. In this case, for example, when the scramble data is changed, the
There is a problem in that it takes time to create a ROM and send it to all the subscribers, and it takes time to attach the sent ROM to the decoder, which makes it difficult to change the scrambled data.

As a result, if the frequency of changing the scrambled data is reduced, the scrambled data may be easily deciphered accordingly, and a person other than the contractor may illegally receive the television broadcast signal and view the image and the audio. Gender increases.

In order to solve this problem, a method has been proposed in which scrambled data is superimposed on a part of a television broadcast signal and transmitted in real time. In this case, the scrambled data is replaced with a video signal having a large amount of information and is multiplexed with the video signal. The signal is transmitted by being superimposed on a part of the transmitted audio signal.

That is, by doing so, the content of the scrambled data superimposed on the audio signal can be easily changed, and furthermore, the scrambled data can be changed every predetermined period, so that the decoding of the scrambled data can be performed. An extremely difficult scrambling transmission method can be realized.

However, in practice, in such a scramble transmission method, the scramble data is transmitted, for example, including a synchronization signal in frame units.

For this reason, if a data pattern that periodically appears in the data stream of the transmitted audio signal is detected, the configuration of the audio signal and the contents of the scrambled data included in the audio signal are analyzed from the outside. The problem was that it became easier, and the solution was still insufficient.

The present invention has been made in consideration of the above points, and dramatically improves confidentiality with a simple configuration when transmitting reference data that periodically appears in digital data from a data transmission system to a data reception system. It is intended to propose a data transmission device that can perform the data transmission.

In the present invention for solving means above problems to solve E problems, in digital data SD _AD, data transmission for transmitting including reference data of N bit length comprising a predetermined pattern which periodically appearing In the apparatus 1, digital data is received in units of N bits of reference data, and the received N bit data and the immediately preceding received N bit data coincide with the data transmission system 2 which continuously transmits reference data of a predetermined pattern at least twice. And a data receiving system 4 that detects whether or not to perform the operation and obtains the timing S _{SYN of the} reference data based on the detection result.

The reference data of N bit length comprising a predetermined pattern from F acts data transmission system 2 in the digital data SD _AD sent in succession at least twice, digital data SD _AD in the data receiving system 4
Is received in units of N bits and the coincidence between the received N-bit data and the immediately preceding received N-bit data is detected, so that the timing S _{SYN of the} reference data can be reliably detected, and thus the pattern of the reference data is sometimes changed. By being able to change every moment, confidentiality can be remarkably improved.

G Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

(G1) Overall Configuration of the Embodiment In FIG. 1, reference numeral 1 denotes a satellite television broadcasting signal transmission / reception system to which the present invention is applied as a whole, and a satellite television broadcasting signal transmitted from a transmitting device 2 is used as a relay satellite. The signal is transmitted to the receiving device 4 through the satellite line 3 including the data.

In the case of the transmitting device 2, the video signal _SVD is input to the video scramble circuit unit 5, and the horizontal scan lines corresponding to the scramble data SDA input from a control circuit (not shown) are arranged in the order of one frame unit. Shuffling is performed, and as a result, a scrambled video signal SD _VD is transmitted.

The audio signal D _AD becomes in PCM audio data, the scrambled data SDA is supplied to the video scramble circuit unit 5 is input to the data scramble circuit unit 6.

The data scramble circuit unit 6 formats the input digital audio signal D _AD0 and the scramble data SDA based on a predetermined format, and then scrambles the data digitally according to the key data KEY input from the control circuit. It sends a scrambled audio signal SD _AD obtained as a result.

In this case, the digital audio signal D _AD0 is formatted according to the audio format of the satellite television broadcasting signal in the standard sound quality mode (A mode) or the high sound quality mode (B mode).

Note scramble data SDA, this is superimposed on defined by and independent data portion during voice the format, and scrambled with digital audio signal D _AD0.

Thus, the multiplexing circuit 7 is _added to the scrambled audio signal SDAD sent from the data scramble circuit section 6.
, Scramble control information SIF including key data KEY input from the control circuit and a decoder identification number DID corresponding to the plurality of receiving devices 4 is written.

Furthermore, this scrambled audio signal SD _AD1 has a frequency of 5.7
4-phase PSK (phase * shift * k) with subcarrier of [M * Hz]
eying) modulated, frequency-multiplexed with a scrambled video signal SD _VD having a frequency band up to a frequency of 4.5 [M * Hz], FM-modulated at a predetermined carrier frequency, and used as a satellite television broadcast signal for relay satellites. Satellite line 3 including
Sent to

The satellite television broadcast signal is received by the receiving device 4 through the satellite line 3, and after FM demodulation, is passed through a low-pass filter and a band-pass filter (not shown) to receive a scrambled video signal SD _VD and a scrambled audio signal SD.
After being divided into _AD1 , they are input to the video descramble circuit section 8 and the separation circuit 9, respectively.

The scrambled video signal SD _VD input to the video descramble circuit section 8 includes a data descramble circuit section.
The descrambling process is performed in units of one frame in the order of horizontal scanning lines according to the descrambling data DSA generated based on the scramble data SDA given from 10, and as a result, a video signal _SVD1 is obtained. .

The separating circuit 9 separates the scramble control information SIF from the input scrambled audio signal SD _AD1 and sends it to the authorization judging circuit 11, and sends out the other scrambled audio signal SD _AD2 to the data descramble circuit section 10. .

For example, the authorization judging circuit 11 receives the contract decoder identification number RID input from the decoder identification number storage circuit 12 in the ROM configuration given from the transmitting device 2 side at the time of contract and outputs the contract decoder identification number RID in the scramble control information SIF input from the separation circuit 9 It is determined whether or not the receiving device 4 has been authorized based on whether or not it matches a plurality of decoder identification numbers DID, and only when authorized, the input key data KEY is supplied to the data descrambling circuit unit 10. I do.

As a result, the data descramble circuit 10 descrambles the scrambled audio signal SD _AD2 based on the key data KEY input from the authorization determination circuit 11, and thus receives the digital audio signal D _AD1 consisting of PCM audio data. Output as a signal,
The scramble data SDA included in the independent data portion of the scrambled audio signal SD _AD2 is supplied to the video descramble circuit section 8.

In this manner, in the satellite television broadcasting signal transmission / reception system 1, the video signal
The S _VD0 scrambled in accordance with a predetermined scramble data SDA, the scrambled data SDA with digital audio signal D _AD0, adapted to transmit is further scrambled and thus the video signal S _VD0 at predetermined intervals with a simple configuration By being able to scramble and transmit based on the changing scramble data, confidentiality can be remarkably improved.

(G2) Configuration of Embodiment In the case of this embodiment, the scramble data SDA input from the control circuit of the transmission device 2 is transmitted for a predetermined period (for example, 1
The data scramble circuit section 6 of the transmitting device 2 writes predetermined synchronization signal data at a timing corresponding to one frame of the scramble data SDA. .

In practice, this synchronizing signal data is such that data of an 8-bit structure, which changes every moment, is transmitted twice and continuously for 16 bits. In the video descrambling circuit section 8 of the receiving apparatus 4, FIG. Sync signal detection circuit 20 shown in
Is used to detect this.

That is, in the synchronization signal detection circuit 20, the scramble data SDA composed of serial data is input to the input terminal a of the switch circuit 21.

This switch circuit 21 stores the 8 bits of the scramble data SDA.
The first or second output terminal b or c is switched and controlled for each bit. Thus, the scramble data SDA for 8 bits is successively transmitted through the first and second output terminals b and c, respectively. The signals are input to the first and second shift registers 22 and 23.

The first and second shift registers 22 and 23 is a shift register of 8 bits, each bit output b ₀ ~b ₇ and b ₁₀ ~b ₁₇ corresponding respectively, first to eighth exclusive OR of The signals are input to the circuits 24A to 24H and exclusive OR is calculated.

The first to eighth exclusive OR circuits 24A to 24H
Each operation output c ₀ to c ₇ are input to the AND circuit 25 through an inverter, respectively, thus calculating the output of the AND circuit 25, exclusive OR circuit operation output c ₀ of 24A~24H
.., C ₇ all have the value “1” when they have the value “0”.

In this way, in the synchronization signal detection circuit 20, the scramble data SDA is input in units of 8 bits,
It is possible to detect whether or not each bit of the 8-bit scrambled data SDA matches the immediately preceding 8-bit scrambled data SDA, and reproduce the synchronizing signal S _SYN having the value “1” at the same timing. It has been made like that.

According to the above configuration, the transmitting device 2 transmits the 8-bit length synchronization signal twice in the scrambled data SDA twice in succession, and the synchronization signal detecting circuit 20 included in the video descramble circuit portion 8 of the receiving device 4 scrambles. 8 data SDA
Scramble data SDA received and input in bit units
8 bits and scramble data SD input immediately before
By detecting the coincidence of A with 8 bits, the timing of the synchronization signal included in the scrambled data SDA can be reliably obtained. Thus, even if the data pattern of the synchronization signal is changed every moment, the synchronization can be achieved. Satellite television broadcast signal transmission / reception system 1 capable of significantly improving confidentiality by being able to transmit signal timings correctly
Can be realized.

(G3) Other Embodiments (1) In the above-described embodiment, when the coincidence between the eight bits of the input scrambled data SDA and the eight bits of the scrambled data SDA input immediately before is detected, the corresponding processing is performed. Although the case where each bit is compared has been described, the detection of coincidence is not limited to this, and it may be possible to detect whether or not each bit that has been arbitrarily corresponded matches or not. , The confidentiality can be further improved.

(2) In the above-described embodiment, a case has been described where an 8-bit synchronization signal is continuously transmitted twice in the scrambled data. However, the present invention is not limited to this. For example, an 8-bit synchronization signal may be used. The signal may be continuously transmitted three times or more, and is also widely applicable and suitable for transmitting a synchronization signal of 7 bits or less or 9 bits or more.

(3) In the above-described embodiment, the case where the synchronization signal included in the scrambled data is encrypted and transmitted has been described. However, the present invention is not limited to this. For example, the key data used when the audio signal is scrambled, This is widely applicable to a case where other reference data is encrypted and transmitted.

In such a case, the operation outputs c _{0 to} c ₇ of the exclusive OR circuits 24A to 24H of the synchronization signal detection circuit 20 may be used as the predetermined data DT _SYN .

(4) In the above-described embodiment, the case where the present invention is applied to the transmitting apparatus and the receiving apparatus for satellite television broadcasting has been described. It is suitable for wide application to data transmission devices requiring other confidentiality such as communication.

As described above, according to the present invention, reference data having a predetermined pattern and having an N-bit length in the digital data is transmitted at least twice consecutively from the data transmission system, and the digital data is converted into N-bit data by the data reception system. By detecting the coincidence between the received N-bit data and the immediately preceding received N-bit data in units, even if the pattern of the reference data is changed every moment, the timing of the reference data can be reliably detected. Thus, it is possible to realize a data transmission device that can greatly improve confidentiality with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of a satellite television broadcasting signal transmission / reception system according to one embodiment of the present invention.
FIG. 2 is a connection diagram showing a synchronization signal detection circuit according to the present invention. 1. Satellite TV broadcasting signal transmission and reception system 2.
... Transmission device, 3 ... Satellite line, 4 ... Reception device, 5 ...
Video scramble circuit section, 6 Data scramble circuit section, 7 Multiplex circuit, 8 Video descramble circuit section, 9 Demultiplexer circuit, 10 Data descramble circuit section, 11 Authorization determination circuit , 12... Decoder identification number storage circuit, 20... Synchronization signal detection circuit, 21.
Switch circuits, 22, 23 ... shift registers, 24A to 24H ...
... Exclusive or circuit, 25 ... and circuit.

Claims (1)

(57) [Claims] 1. A data transmission apparatus for transmitting, in digital data, reference data having an N-bit length consisting of a predetermined pattern appearing periodically, and transmitting said reference data of said predetermined pattern at least twice continuously. A data transmission system, receiving the digital data in units of the N bits of the reference data, detecting whether or not the received N bit data matches the immediately preceding received N bit data, and based on the detection result, A data transmission device, comprising: a data receiving system that obtains timing of reference data.