CN1117691A - interference blanking system and method for TV signal - Google Patents

Abstract

The method involves compressing the carrier amplitude and changing the carrier phase in horizontal blanking period to achieve interference adding for TV signal and data transmission. It uses two varieties of 16 bits pseudorandom code to control the variation of compressed amplitude and data cipher. During interference removing, an identical pseudorandom code is added in the receiving data to restore the TV signal. The method can add interference in image, colour and accompanying sound, and provide a reliable and safe data transmission.

Description

A kind of interference blanking system of TV signal and method

The present invention relates to television signal transmission system, particularly television signal transmission system is carried out safer more economical method for scrambling.

A kind of reliable charged TV system is badly in need of in universal each TV station that makes of cable TV.Carry out scrambling by the charge program to wired network in charged TV system, the user must use a descrambler could normally watch after TV station is authorized.Thereby the security reliability of whole system is most important.But the descrambling end must be with low cost, and a domestic unique system that is tested and appraised at present can't addressing, and TV station can not carry out the control of licensing status by wired network to user side.Go back some method simultaneously: higher as digitlization scrambling cost, the base band scrambling is relatively poor to the index that image recovers, and is only lower to the fail safe of horizontal blanking compression on the radio frequency.

The purpose of this invention is to provide a kind of brand-new interference blanking system and method, used the filter of high conformity the TV signal carrier frequency to be compressed phase shift at row latent period, realize the transmission of scrambling and data simultaneously, more simple with existing interference blanking system alternative route, more economy, safety, the high-performance interference blanking system that is suitable for producing in enormous quantities.

Interference blanking system provided by the invention and method are characterised in that: use three kinds of different qualities filters that carrier frequency is compressed and carrier frequency is carried out phase change at line blanking period, neither compressing the transmission that also not phase shift realizes TV signal is carried out scrambling and data simultaneously At All Other Times, each line blanking period is dynamic change to the suppressed range of carrier frequency, this Changing Pattern is the form existence by the scrambling mode sign indicating number, and this yard is that the one group of number that produces at random leaves in the memory.The rule of data encryption also is stored in the memory with the encrypted code form, and it also produces at random.Carrier frequency is expanded to recover original amplitude to realize the recovery to TV signal at row latent period according to received data during descrambling.

Below in conjunction with accompanying drawing the present invention is described in detail:

Fig. 1 is the theory diagram of scrambling system among the present invention.

Fig. 2 is data structure among the present invention.

Fig. 3 is the theory diagram of descrambling system among the present invention.

Fig. 4 is the definition of data " 0 ", " 1 " among the present invention.

By Fig. 1, video signal source (1) is through intermediate frequency modulator (2) and the filter bank A with different qualities, B links to each other with C, these filters output to electronic switch (6) and are selected wherein 1 the tunnel to output to common port by compound circuit, output after upconverter (7) again, vision signal is also by the isolated row of synchronizing separator circuit (8), field sync signal is delivered in the controller (9) of band microprocessor, the data that data generator produces are after encrypting CRC code generator (10), deliver in the controller (9), go to control the work of compound circuit by the output of controller, this output is included in TV signal line blanking period binary data: the C/A/B pattern wherein obtains binary signal by the carrier frequency phase shift and has comprised all data encrypted; C/B or C/A or C/A/B become for connecting by A, B, C filter according to the form that controller is appointed.

The signal that controller (9) sends is selected to allow CF signal be sent to (7) by coming among A, B, the C by electronic switch (6), filter A, B, C are three filters with different qualities, C is one and neither compresses the also filter of not phase shift, and A is to make vision carrier frequency that fixed phase drift and two different filters of suppressed range be arranged with B, carry out the phase shift compression at line blanking period by filter or to carrier frequency, all the other times are passed through C.Here used the 1st, 2 or 3 kind of scrambling mode scrambled television signal.The 1st kind is to use filter A (3) at line blanking period, uses filter C (5) At All Other Times, is called C/A; The 2nd kind is to use filter B (4) at row latent period, uses filter C (5) At All Other Times, is called the C/B pattern; The 3rd kind is dynamically to control B (4) or A (3) as required at line blanking period, is using C At All Other Times, is called the C/A/B pattern.Utilize the length difference of phase shift time to transmit data, switching circuit (6) selects A, B, C to form multiple scrambling mode.Because scrambling mode is dynamic change, thereby fool proof.

The transmission of data is to realize with the width of line blanking period phase shift, has adopted PSK to transmit data.The every 64bit of these data forms a packet, and Fig. 2 is a binary data structure of the present invention, and the 1st packet #1 is global information.Each user terminal all will be used, it comprises program identification, information such as scrambling mode definition of data encryption, the #2～#4 packet is three groups of independent station address packets, the station address packet comprises the authorization message of program and the key that solves data, and data that these are different and authorization data store in the memory of user terminal together.Data are carried out pulse-width modulation earlier after encrypting, it defines as Fig. 4, goes to control the time span of carrier frequency phase shift thereafter with this signal, and every row transmits the 1bit data.

As Fig. 3, after each user side station selector (12) receives TV signal, output is phase discriminator (17) and filter A ' then, B ', C ', A ', B ', C ' is and A, B, corresponding three filters of C are thereafter by electronic switch (16), common port is followed general television set (21), it can be the phase discriminator of any type of phase shift of reflecting out that data are differentiated, pulse width signal through phase discriminator output obtains data " 0 " and " 1 " through width discriminating circuit again, these data are decrypted through back, CRC electrical verification road (19) data of deciphering, data after the deciphering are sent in the controller (20) of band microprocessor, microcontroller can be according to the information that is received, the decision signal is by A ', B ' is C ' still, uses and the corresponding C ' of scrambling system/A ', C '/B ', C '/A '/B '.Obviously the control switch of filter will synchronously could correct descrambling with the scrambling end.

Descrambling mode-definition sign indicating number is stored in the memory of microprocessor, under the correct situation about receiving of global data, each all is updated the content of memory, and preserve the mode-definition sign indicating number address receive, be 100 mode-definition sign indicating number for example using the address sometime, this yard is 1 16 random number, this yard is exactly the rule of the selected switch A ' of every row, B ', C ' in the whole audience, for prior receiving-transmitting sides agreement leaves in the memory, have 65536 kinds of agreements, every kind of corresponding a kind of rule of agreement.Therefore if can not know agreement, illegal user terminal promptly enables correctly also can't be correctly to the TV signal descrambling to the data deciphering, and the randomness of this scrambling mode has strengthened the fail safe of native system.The transfer of data of this system is encrypted, and the pattern of its encryption is as scrambling mode, and agreement leaves in the memory in advance, and the outside can't be read.Thereby the disabled user can't correctly receive data, increased fail safe equally, and is reliable for increasing data because data are to be subject to noise jamming, increased CRC (cyclic redundancy check) circuit, increases the reliability of data.

The present invention has following advantage: scrambling mode and encryption mode all are that both sides are in advance about 16 fixed binary codes leave in the internal memory, according to the ground of giving in the global data bag Corresponding data are taken out in location (key) just can carry out correct deciphering and descrambling. This ground The location is at random, and two kind of 16 bit code also produces at random, even thereby expert Will native system is deciphered and made illegal user side is extremely difficult, unless obtain This agreement content, and the data of this agreement only leave the memory of processor inside in In, the outside can't be read, thereby Security of the system is very high. Have in the data transmission CRC check makes the descrambling end can receive correct data, on method for scrambling because Only line blanking period is carried out scrambling, do not destroy picture signal, so after the image recovery In principle undistorted, and because the row latent period compression, the carrier frequency phase shift makes synchronous envelope Phase shift, sound accompaniment are also destroyed, and the normal tv machine can't normally be watched and listen to. Its knot Fruit is that the row field all can't be synchronous, and the chaotic sound of color is unclear, to image, color, companion Sound is all realized scrambling, and the scrambling effect is splendid, owing to adopted the extraordinary filter of uniformity The ripple device, whole digital circuit is integrated among a slice ASIC, and analog circuit has adopted Thick film technology, so that system is safer, circuit is simpler and be easy to produce in enormous quantities, Reduced production cost.

Claims (3)

1. A kind of interference blanking system of TV signal and method comprise the scrambling end to the TV signal scrambling, and the descrambling end recovers TV signal, it is characterized in that:

   1, at line blanking period the carrier frequency amplitude is compressed simultaneously carrier frequency is carried out phase shift, in neither also not phase shift of compression At All Other Times, to realize scrambling to TV signal; The method that the data of system transmit is the method that a kind of employing PSK of encryption transmits data, carries out pulse-width modulation after data are at first encrypted earlier, and every row send 1bit data, with this width-pulse control row latent period carrier frequency phase shift time span; Obtain pulse width signal (also being line synchronizing signal) by phase discriminator during descrambling, and then this width signal is handled to obtain data.Receiving terminal is realized the TV signal of scrambling is carried out descrambling by the mode-definition sign indicating number of agreement.
2. 2, interference blanking system according to claim 1 and method is characterized in that dynamically having used the 1st, 2 or 3 kind of scrambling mode scrambled television signal, and the 1st kind is to use filter A (3) at line blanking period, uses filter C (5) At All Other Times, is called C/A; The 2nd kind is to use filter B (4) at line blanking period, uses filter C (5) At All Other Times, is called the C/B pattern; The 3rd kind is dynamically to control B (4) or A (3) as required at line blanking period, is using C At All Other Times, is called the C/A/B pattern.The use of scrambling mode is dynamic change, the rule that the every row of this control is selected A, B, C be with 1 16 be that the mode-definition sign indicating number leaves in the memory of receiving-transmitting sides at random, have 65536 kinds of agreements, every kind of corresponding a kind of rule of agreement.
3. 3, interference blanking system according to claim 1 and method, it is characterized in that using filter A, B, C that TV signal is carried out scrambling and data transmission, use A ', B ', C ' to carry out descrambling, A is two with B makes vision carrier frequency fixed phase drift be arranged and the different filter of suppressed range, C is the filter that neither compresses also not phase shift, and A ', B ', C ' are the filters complementary mutually with A, B, C.

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