CN100588242C - Digital television signal encryption and modulation method - Google Patents
Digital television signal encryption and modulation method Download PDFInfo
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- CN100588242C CN100588242C CN200510120805A CN200510120805A CN100588242C CN 100588242 C CN100588242 C CN 100588242C CN 200510120805 A CN200510120805 A CN 200510120805A CN 200510120805 A CN200510120805 A CN 200510120805A CN 100588242 C CN100588242 C CN 100588242C
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Abstract
The invention provides an approach of encrypting and modulating digital TV signal, the details are: frame synchronized detecting module and dynamic encrypting module read original digital TV signal; frame synchronized detecting module detects synchronization head and ending code of original digital TV signal, while the detected synchronization head and end code are same with that in memory send asynchronization spring signal to the dynamic encrypting mode; after the encrypting module receiving the spring signal it replaces the original synchronization head and end code by encrypted data to generate frame encrypted digital TV signal; controlling module encodes key and relative replaced synchronization head and end code to produce data signal; modulating module modulates frame encrypted digital TV signal and data signal respectively and combines the done data. The invention is simple, easy, low-cost and reliable.
Description
Technical field
The present invention relates to digital TV field, particularly a kind of encryption of digital television signal and modulator approach.
Background technology
The digital television program of China is just being prepared to go on the air at present, and it has been within sight that Digital Television replaces simulated television, but the programme signal of puzzlement China Digital Television development is encrypted and the technical problem of Conditional Access, never obtains fine solution.
Digital television signal transmits with the form of Frame, the code check of transmission is very high, high definition digital television (HDTV) particularly, code check is up to more than the 20MPS, therefore the encryption of signal generally all needs to realize with high speed data processing device such as RISC-CPU (as: ARM-CPU) that contains the DSP function or SOC or circuit, and uses these devices also to need embedded OS software, middleware and data processing software to support, so, hardware cost is very high, and the software development difficulty is also very big.
Therefore, at shortcomings such as method cost height such as above digital television signal encryption, technological development difficulty are big, be necessary to develop a kind of simple, digital television signal encryption method and corresponding modulator approach thereof that cost is low.
Summary of the invention
Technical problem to be solved by this invention is to overcome above-mentioned the deficiencies in the prior art, and a kind of encryption and modulator approach of simple, digital television signal that cost is low is provided.
The technical scheme that the present invention deals with problems is, a kind of encryption and modulator approach of digital television signal is provided, and comprising:
Frame synchronization detection module and dynamic encryption module read the original figure TV signal;
The frame synchronization detection module detects the synchronous head and the end code of original figure TV signal, when this synchronous head and end code are identical with end code with its synchronous head of storing, sends synchronous triggering signal to the dynamic encryption module;
After the dynamic encryption module receives synchronous triggering signal, replace synchronous head and/or end code in the described original figure TV signal, produce the digital television signal that frame is encrypted with enciphered data;
Control module generates data-signal with synchronous head and/or the end code coding that is replaced in key and the original figure TV signal;
Modulation module is modulated digital television signal and data-signal that frame is encrypted respectively, and digital television signal and data-signal that the frame after will modulating is encrypted merge formation enciphered digital TV signal.
The digital television signal that described modulation module adopts Quadrature Phase Shift Keying modulation, quadrature amplitude modulation or frequency division multiplexing modulation that frame is encrypted is modulated.
The digital television signal that described modulation module is encrypted frame carries out digital modulation, and data-signal is carried out analog-modulated.
Described modulation module adopts the modulation of keying frequency modulation, keyed amplitude modulation modulation or pulse-width modulation that data-signal is modulated.
Described frame synchronization detection module and described dynamic encryption module read the original figure TV signal by shift register respectively.
Described frame synchronization detection module judges with end code and its synchronous head stored and end code whether the two is identical by the synchronous head of bit comparison original figure TV signal by bit comparator.
Described data-signal also comprises user code, program number and expenses standard.
Implement the encryption and the modulator approach thereof of digital television signal of the present invention, only need to adopt ball bearing made using and device etc. can realize that need not to adopt high-speed data processor spare or circuit, cost is low; And the encrypting and decrypting software development do not need the embedded OS platform, so the technological development difficulty is low, the reliability height.
Below in conjunction with drawings and Examples the present invention is done and to describe in further detail.
Description of drawings
Fig. 1 is the basic coding form schematic diagram of digital television signal in transmission course;
Fig. 2 implements the encryption of digital television signal of the present invention and the systematic schematic diagram of modulator approach;
Fig. 3 is the modulation spectrum figure of modulator approach of the present invention;
Fig. 4 implements the encryption of digital television signal of the present invention and the optimum decision system schematic diagram of modulator approach.
Embodiment
Fig. 1 is the basic coding form of digital television signal in transmission course, also is the basic transmission coded format of general digital signal.The digital television signal of this coded format comprises synchronous head, transmits data and three parts of end code, and these three parts constitute a frame of digital television signal.Digital signal is that a frame one frame ground transmits.
Synchronous head and end code are referred to as frame swynchronization code or synchronization bit in the frame of digital television signal.Synchronous head and end code are made up of some bits respectively.Generally, the bit number of frame more more is that the length of frame is long more, and the interval between two consecutive frames is short more, then requires the number of bits of synchronous head and end code also many more.If the interval between two consecutive frames is very long, then synchronous head and end code only need one or two bit promptly enough.The length of frame is mainly decided by the content that transmits data, and the interval of frame and frame is then decided by the data conveying capacity.The amount of information of digital television signal is very big, so frame is very long, and the interval of frame and frame is very short, so require the number of bits of synchronous head and end code a lot.
In transmission process for digital signal, if lost synchronous head and end code, or mistaken synchronous head and end code, and signal just can't transmit data, because this is equivalent to make signal to lose sequential, there is not sequential just can't from signal, data to be separated and decode.
The present invention can be converted to the original figure TV signal enciphered digital TV signal, and it is modulated, wherein digital television signal being encrypted mainly is earlier by the original figure TV signal is carried out dynamic memory, again the data of original figure TV signal are carried out bit comparison, detect the synchronous head and the end code of original figure TV signal, and replace corresponding synchronous bit (synchronous head and/or end code) in the original figure TV signal with new synchronization bit (synchronous head and/or end code).
As shown in Figure 2, be the encryption of enforcement digital television signal of the present invention and the systematic schematic diagram of modulator approach.This system comprises frame synchronization detection module, dynamic encryption module, control module and modulation module.
Wherein the frame synchronization detection module is used to receive the original figure TV signal, this original figure TV signal is carried out frame information to be detected, and the output synchronous triggering signal, it comprises digital signal dynamic memory, bit comparator and the frame synchronization information memory that can store the original figure TV signal.
The dynamic encryption module, be used to receive the original figure TV signal, and the original figure TV signal is encrypted according to the synchronous triggering signal that the frame synchronization detection module sends, with the digital television signal of generation frame encryption, but it comprises the digital signal encrypted memory and the encrypted data store of dynamic memory original figure TV signal.
Control module, send synchronous head in the original figure TV signal and end code, enciphered data respectively, be that the encryption synchronisation bit is to frame synchronization information memory, encrypted data store, and, form digital signal with the coding that the synchronization bit that is replaced in key, the initial data TV signal and other user data are encoded together and formed.Enciphered data and key can be designed as in time and change in the present invention.
Modulation module, be used for the digital television signal after the frame encryption is carried out digital modulation, data-signal is carried out analog-modulated, and the signal after the two modulation is merged, be converted to the enciphered digital TV signal that is fit to transmission, it comprises first modulator, mixer and second modulator.Wherein first modulator is used for the digital television signal that frame is encrypted is carried out digital modulation; Second modulator is used for data-signal is carried out analog-modulated; Mixer be used for signal with the output of first modulator and second modulator close that the road produces can the enciphered digital TV signal.
The encryption of digital television signal of the present invention and modulator approach are sent it into the digital signal dynamic memory of frame synchronization detection module and the digital signal encrypted memory of dynamic encryption module after system reads the original figure TV signal.The bit comparator of frame synchronization detection module reads the synchronous head and the end code of the original figure TV signal in the digital signal dynamic memory, and deposit this synchronous head and end code and control module in the synchronous head of frame synchronization information memory and end code relatively, when the two is consistent, the output synchronous triggering signal is to encrypted data store, then the encryption synchronisation bit (enciphered data) that deposits in control module of this encryption output storage is replaced corresponding synchronous bit in the original figure TV signal that the digital signal encrypted memory received, the original figure TV signal is encrypted the digital television signal that delta frame is encrypted.The digital television signal that this frame is encrypted is exported to first modulator of modulation module by the digital signal encrypted memory.
Simultaneously, control module is replaced the key of its generation in the initial data TV signal the synchronization bit generation data-signal of encoding, and this data-signal is delivered to second modulator of modulation module.If the user data that also have to need sends is as user code, program number, expenses standard etc., the generation data-signal of then corresponding synchronous bit and these user data in key, the initial data TV signal being encoded together.
First modulator of modulation module and second modulator are modulated it respectively after receiving the digital television signal and data-signal of frame encryption.Because digital television signal and data-signal are two kinds of signals of different nature, the digital television signal amount of information is very big, and it is very high to require to transmit code check; And the data-signal amount of information is very little, it is not high to require to transmit code check, therefore first modulator can adopt the very high Quadrature Phase Shift Keying of modulation efficiency (QPSK), quadrature amplitude modulation (qam) or frequency division multiplexing modulator approaches such as (OFDM) that the digital television signal of frame encryption is modulated, as select the QAM-64 modulating mode for use, then the highest code check that frame enciphered digital TV signal can 36MPS transmits; Second modulator can adopt the lower keying frequency modulation (FSK) of modulation efficiency, keyed amplitude modulation (ASK) or pulse-width modulation modulator approaches such as (PWM) that data-signal is modulated, as select FSK or ASK modulating mode for use, then the highest code check that data-signal can 500KPS transmits.Two paths of signals is merged into the enciphered digital TV signal by mixer again after modulation, can be on TV broadcast channel through high frequency modulated, and by the output of high-frequency signal transmitting apparatus, the spectrum distribution of its carrier frequency can be as shown in Figure 3, f
DBe the centre frequency of data-signal high-frequency modulation signal (secondary modulation), it generally is positioned at the edge of channel bandwidth, f
PCentre frequency (tv channel frequency) for digital television signal high frequency carrier (secondary modulation).
As shown in Figure 4, be to implement the encryption of digital television signal of the present invention and the optimum decision system schematic diagram of modulator approach.The digital signal dynamic memory corresponding displaced register 1 of frame synchronization detection module, frame synchronization information memory corresponding stored device 1 among this embodiment; The digital signal encrypted memory corresponding displaced register 2 of dynamic encryption module, encrypted data store corresponding stored device 2; Control module is by computer realization, and this computer deposits the synchronous head and the end code of initial data TV signal in memory 1 by data interface circuit, is that the encryption synchronisation bit deposits memory 2 in enciphered data.Shift register 1 and shift register 2 all are connected to analog switch K, can select to export the digital television signal of not encrypted or frame encryption by this analog switch.
After the original figure TV signal enters this system, be divided into two paths of signals, one the tunnel sends into shift register 1, be used for the frame data or the frame synchronizing signal of original figure TV signal are detected, shift memory 2 is sent on another road, is used for the original figure TV signal is encrypted and the initial data TV signal that frame is encrypted is exported.
Shift register 1 strictness monitors the synchronous head of corresponding every frame data TV signal and the moment of end code, and the synchronous head and the end code of every frame signal are imported bit comparator.Because of shift register 2 in parallel with shift register 1, so when just in time storing a full frame signal in the shift register 1, also just in time store a full frame signal in the shift register 2.
Whether the synchronous head of every frame signal is consistent with end code with the synchronous head in the memory 1 with end code in the bit comparator monitoring shift register 1, when both are consistent, export a synchronous triggering signal to memory 2, shift register 2 is read and delivered to the encryption synchronisation bit of memory 2, this encryption synchronisation bit is the encryption synchronisation head in the present embodiment, with the synchronous head of the every frame initial data TV signal in the displacement shift register 2, the digital television signal that delta frame is encrypted.The digital television signal that shift register 2 is encrypted this frame is delivered to first modulator from the 2-3 port of analog switch K and modulates.
Simultaneously, computer is modulated by second modulator by data-signal to the first modulator of data interface circuit output with synchronous head in key, the initial data TV signal and the generation of other user data coding.
Behind digital television signal and data-signal that the frame of first modulator and second modulators modulate is encrypted, after merging, obtain the enciphered digital TV signal through mixer.
Claims (7)
1, a kind of encryption of digital television signal and modulator approach is characterized in that: comprising:
Frame synchronization detection module and dynamic encryption module read the original figure TV signal;
The frame synchronization detection module detects the synchronous head and the end code of original figure TV signal, when this synchronous head and end code are identical with end code with its synchronous head of storing, sends synchronous triggering signal to the dynamic encryption module;
After the dynamic encryption module receives synchronous triggering signal, replace synchronous head and/or end code in the described original figure TV signal, produce the digital television signal that frame is encrypted with enciphered data;
Control module generates data-signal with synchronous head and/or the end code coding that is replaced in key and the described original figure TV signal;
Modulation module is modulated digital television signal and data-signal that frame is encrypted respectively, and digital television signal and data-signal that the frame after will modulating is encrypted merge formation enciphered digital TV signal.
2, encryption according to claim 1 and modulator approach is characterized in that: the digital television signal that described modulation module is encrypted frame carries out digital modulation, and data-signal is carried out analog-modulated.
3, encryption according to claim 1 and 2 and modulator approach is characterized in that: the digital television signal that described modulation module adopts Quadrature Phase Shift Keying modulation, quadrature amplitude modulation or frequency division multiplexing modulation that frame is encrypted is modulated.
4, encryption according to claim 1 and 2 and modulator approach is characterized in that: described modulation module adopts the modulation of keying frequency modulation, keyed amplitude modulation modulation or pulse-width modulation that data-signal is modulated.
5, encryption according to claim 1 and 2 and modulator approach is characterized in that: described frame synchronization detection module and described dynamic encryption module read the original figure TV signal by shift register respectively.
6, encryption according to claim 1 and 2 and modulator approach is characterized in that: described frame synchronization detection module judges with end code and its synchronous head stored and end code whether the two is identical by the synchronous head of bit comparison original figure TV signal by bit comparator.
7, encryption according to claim 1 and 2 and modulator approach is characterized in that: described data-signal also comprises user code, program number and expenses standard.
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| Application Number | Priority Date | Filing Date | Title |
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| CN200510120805A CN100588242C (en) | 2005-12-12 | 2005-12-12 | Digital television signal encryption and modulation method |
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| CN200510120805A CN100588242C (en) | 2005-12-12 | 2005-12-12 | Digital television signal encryption and modulation method |
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| CN1937760A CN1937760A (en) | 2007-03-28 |
| CN100588242C true CN100588242C (en) | 2010-02-03 |
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| EP3528490B1 (en) * | 2016-10-31 | 2021-07-07 | Huawei Technologies Co., Ltd. | Image data frame synchronization method and terminal |
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