CN102164304B - Encrypting identification intercutting-preventing method for broadcasting program based on satellite transmission - Google Patents
Encrypting identification intercutting-preventing method for broadcasting program based on satellite transmission Download PDFInfo
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Abstract
The invention relates to an encrypting identification intercutting-preventing method for broadcasting program based on satellite transmission, and the method comprises the following steps: selecting at least one frequency value, the frequency of which is above 16kHz, as a characteristic frequency; modulating an original characteristic signal onto the characteristic frequency; after performing the pretreatment and amplitude control on an original digital audio frequency signal and the modulated characteristic signal, superposing the signals and broadcasting the signals on an emitting station; performing band-pass digital filter on the received signals by a receiver; extracting the characteristic signal and performing spectrum analysis and demodulation on the characteristic signal; judging the validity of the received signal according to a preset judging system; and controlling whether to supply a broadcasting signal to a downstream device according to the judging result, and supplying the alarm information. By using the method, various malevolent interferences and illegal insert cuts can be efficiently resisted on the premise of causing no obvious influence on a subjective listening effect, the manual monitoring pressure and cost are greatly reduced, and the security system for broadcast safe running is perfected.
Description
Technical field
The present invention relates to a kind of enciphering identifying method of digital transmission system, exactly, relate to a kind of anti-inserting method that is applied to the encryption identification in the satellite transmission broadcast program.
Background technology
Satellite radio television program covers extensively, influence is big, but because host-host protocol and standard are open and clear, makes it vulnerable.In recent years, the safety of broadcast TV program is broadcasted situation great changes has been taken place, and happens occasionally for the malicious interference of radio and television and the case of utilizing broadcast television facility illegally to intercut.At malicious interference, some satellite interference protection measures that now proposed relate generally to following several big class methods.
(1) signal pressure method for making.Namely increase the ascending power of normal program signal, make signal strength signal intensity obviously greater than interference, with the compacting interference signal.Up earth station arranges high-power transmitter and high-gain transmitting antenna, in case satellite is disturbed, automatic or manual increasing connecting station radiofrequency signal power level to strengthen transponder input signal interference ratio, is avoided or reduced the illegal signals interference effect.
(2) space isolation method.Be that up fixedly shaped-beam receives.The fixedly shaped-beam of satellite repeater reception antenna only covers the legal particular locality in various places, does not comprise the area that most possible generation is disturbed, to reach anti-interference purpose.
(3) frequency isolation method.Namely change the upward signal frequency.When the transponder receiver receives interference signal on the satellite, the transponder receiver in time changes receive frequency to reject interference signal according to control signal, and correspondence changes given ground connecting station tranmitting frequency simultaneously, continues to receive and transmit legal upward signal so that transponder receives function.
(4) signal facture.Be the up preceding plus signal processing unit of satellite earth station, satellite ground receives and carries out the authentication of program source legitimacy, to reach the interference effect that suppresses illegal signals.
At present, mainly bear satellites such as No. three, prosperous promise transmitting the home broadcasting TV programme, culminant star 6B and just taking relevant interference protection measures such as space isolation technology, can be to a certain extent the satellite uplink of specific region be disturbed and isolate, but can't take precautions against local malicious interference and illegally intercut.
So far, in the field of broadcast televisions of using satellite-signal as program source, do not have and anti-ly intercut the report that commercial operation research and develop successfully or dropped into to relevant ground installation, prevent that intercutting work is mainly realized by relevant unit's manual monitoring.
Summary of the invention
The purpose of this invention is to provide a kind of broadcast program based on satellite transmission and encrypt the anti-inserting method of identification, effectively resist satellite and local malice is intercutted behavior, effectively avoid broadcast program to suffer malicious interference and illegally intercut.
In order to achieve the above object, the technical scheme that the present invention takes provides a kind of broadcast program based on the satellite transmission and encrypts the anti-inserting method of identification, may further comprise the steps:
(1) cell site is according to original digital audio signals sampling rate to be broadcast with quantize BIT, select frequency be at least one above frequency values of 16kHz as characteristic frequency, generate corresponding carrier wave numeral wave table, and this characteristic frequency be set to each receiving station;
(2) select a primitive character signal, this characteristic signal is modulated to characteristic frequency obtains characteristic signal, and this primitive character signal is set to each receiving station;
(3) the original digital audio signal is carried out energy and calculate, according to the original digital audio signal energy that calculates, the amplitude of control characteristic signal and original digital audio signal;
(4) characteristic signal that step (3) is obtained and original digital audio signal carry out the signal stack, and broadcasting via satellite;
(5) receiving station receives the superposed signal of satellite emission, according to the frequency range at characteristic frequency place superposed signal is with logical digital filtering, extracts characteristic signal;
(6) characteristic signal that extracts is carried out spectrum analysis and obtain its frequency domain distribution, and characteristic signal is carried out demodulation;
(7) signal after the demodulation and primitive character signal are compared, judge the legitimacy that receives signal according to the decision mechanism that sets in advance;
(8) control this superposed signal according to judged result and whether offer upstream device, and warning information is provided.
Further, in the described step (1), selecting the frequency values of characteristic frequency is 18kHz ~ 19kHz.
The bandwidth of original characteristic signal is below 0.2kHz in the described step (2), and modulation system is ASK or FSK or DPSK.
Further comprising the steps of between described step (2) and the step (3), according to the frequency range at characteristic frequency place the characteristic signal after modulating is with logical digital filtering, carry out spuious inhibition; And according to the frequency range at characteristic frequency place the original digital audio signal is with the resistance digital filtering.
Be that to be chronomere carry out energy to the original digital audio signal calculates with 1 ~ 10ms in the described step (3).
Span of control limit of control is that to make the original digital audio signal energy be 1 to 10 times of characteristic signal in the described step (3).
Be with characteristic signal and the directly addition in real time of original digital audio signal in the described step (4), and the signal that addition obtains is carried out overflow protection.
Spectrum analysis in the described step (6) and demodulation are to realize by fast Fourier transform (FFT) algorithm.
Decision mechanism in the described step (7) is to adopt the dual thresholding of setting similarity and judgement number of times, judges that the reaction time was less than 2 seconds.
In the described step (8), export complete 0 signal when illegal and replace digital audio and video signals to broadcast when signal is judged as.
According to the acoustic characteristic of human body, people's ear is difficult to differentiate to the sound of frequency more than 16kHz, especially person in middle and old age colony.Based on above characteristic, can be at broadcast program source signal (the real-time continuous high-frequency signal (characteristic signal) of waveform that inserts of 18kHz in 20～20kHz) ~ 19kHz part of satellite earth station upstream ends, and rationally control its amplitude, can not produce obvious influence to subjective audibility, and can resist the MPEG-2 lossy compression method, every technical indicator all can meet the demands, and covers point at frequency modulation and differentiates the broadcast program legitimacy according to inserting signal.
Anti-inserting method of the present invention has significant benefit.
Encryption and the identification of method provided by the invention by characteristic signal, can effectively resist in the satellite uplink stage attack, frequency modulation covers near the temporary erection interference source point and attacks, directly invades the various malicious interference that illegal means such as unmanned transmitter room replacement satellite signal source causes and illegally intercut.Can reduce manual supervisory pressure and cost greatly, improve broadcast safe operational support system.
Description of drawings
Fig. 1 is the flow chart of anti-inserting method one embodiment of the present invention.
Fig. 2 is the flow chart of cell site's end in the anti-inserting method of the present invention.
Fig. 3 is the flow chart of receiving station's end in the anti-inserting method of the present invention.
Embodiment
Further specify essential characteristic and concrete enforcement of the anti-inserting method of the present invention below in conjunction with embodiment.
Referring to Fig. 1 ~ shown in Figure 3, the broadcast program that the present invention is based on the satellite transmission is encrypted the anti-inserting method of identification, may further comprise the steps:
(1) at program according to original digital audio signals sampling rate to be broadcast with quantize BIT, select frequency be at least one above frequency values of 16kHz as characteristic frequency, generate corresponding carrier wave numeral wave table, and this characteristic frequency be set to each receiving station;
(2) select a primitive character signal, this characteristic signal is modulated to characteristic frequency obtains characteristic signal, and this primitive character signal is set to each receiving station;
(3) the original digital audio signal is carried out energy and calculate, according to the original digital audio signal energy that calculates, the amplitude of control characteristic signal and original digital audio signal;
(4) characteristic signal that step (3) is obtained and original digital audio signal carry out the signal stack, and broadcasting via satellite;
(5) receiving station receives the superposed signal of satellite emission, according to the frequency range at characteristic frequency place superposed signal is with logical digital filtering, extracts characteristic signal;
(6) characteristic signal that extracts is carried out spectrum analysis and obtain its frequency domain distribution, and characteristic signal is carried out demodulation;
(7) signal after the demodulation and primitive character signal are compared, judge the legitimacy that receives signal according to the decision mechanism that sets in advance;
(8) control this superposed signal according to judged result and whether offer upstream device, and warning information is provided.
Further, in the described step (1), selecting the frequency values of characteristic frequency is 18kHz ~ 19kHz.
The bandwidth of original characteristic signal is below 0.2kHz in the described step (2), and modulation system is ASK or FSK or DPSK, also can adopt other digital signal modulation modes as required.
Further comprising the steps of between described step (2) and the step (3), according to the frequency range at characteristic frequency place the characteristic signal after modulating is with logical digital filtering, carry out spuious inhibition; And according to the frequency range at characteristic frequency place the original digital audio signal is with the resistance digital filtering.
Be that to be chronomere carry out energy to the original digital audio signal calculates with 1 ~ 10ms in the described step (3).
Span of control limit of control is that to make the original digital audio signal energy be 1 to 10 times of characteristic signal in the described step (3).
Be with characteristic signal and the directly addition in real time of original digital audio signal in the described step (4), and the signal that addition obtains is carried out overflow protection.
Spectrum analysis in the described step (6) and demodulation are to realize by fast Fourier transform (FFT) algorithm.
Decision mechanism in the described step (7) is to adopt the dual thresholding of setting similarity and judgement number of times, judges that the reaction time was less than 2 seconds.
In the described step (8), export complete 0 signal when illegal and replace digital audio and video signals to broadcast when signal is judged as.
During real work, in satellite earth station, i.e. program signal upstream ends:
Selecting the original digital audio signal sampling rate for use is 48kHz, and 16BIT quantizes, and selecting frequency is that the sine wave of 18.5625K is carrier wave, it is carried out the 48k sampling after, generate the digital wave table of 256 sampling number certificates.
The primitive character signal is set to fixedly binary sequence 11010110, is sigtnal interval (a corresponding 256*16 carrier data) with 85.3ms, as modulation signal, carries out the 2ASK modulation, adopts the mode (OOK) of on-off keying and carrier wave to merge.
The design sample rate is 48K, and passband is 18-19kHz, adopts 200 rank Direct-Form FIR digital band-pass filter, wherein stopband attenuations of Kai Ze-Bei Saier window
Get 50,
Get 4.5.Characteristic signal after the modulation is sent into this filter carry out spuious filtering.
The design sample rate is 48K, and stopband is 18.4-18.72kHz, adopts 220 rank Direct-Form FIR digital band-reject filter, wherein stopband attenuations of Kai Ze-Bei Saier window
Get 50,
Get 4.5.Will insert the signal of frequency range suppresses characteristic signal in the original digital audio signal.
Be that data block is carried out average energy and calculated to the digital audio and video signals behind the bandreject filtering with 256 sampled points (5.3ms), the result is equally divided into 16 grades, and the characteristic signal of filter being exported according to different grades is that data block multiply by different coefficients with 256 data.
Introduce the FIFO(first in first out) data buffer, the digital audio and video signals of importing is carried out data buffering, guarantee the characteristic signal data block stack of audio data block with its corresponding energy grade of 256 sampled points.
In the characteristic signal additive process after digital audio and video signals and modulation, the generation of counter-rotating situation is overflowed in monitoring.If take place, carry out overflow protection.Because data bit width is 16bit in the present embodiment, namely Dui Ying data area be-32767 ~ 32767, every stack afterwards data greater than 32767 or less than-32767, all protecting is 32767 and-32767.
Cover point, i.e. program signal downstream end at frequency modulation:
Design the 18-19K digital band-pass filter identical with the transmitting terminal parameter, the digital audio and video signals that receives is carried out bandpass filtering.
To extract 18-19kHz frequency range data and carry out real-time 512 FFT conversion.In the present embodiment, the audio data samples rate is 48kHz, and the characteristic signal carrier wave is the sine wave of frequency 18.5625kHz, then need analyze FFT conversion the 198th data point (18.5625K*256/24K=198), carry out the 2ASK demodulation, the reduction characteristic signal sequence is judged the signal legitimacy.
Except aforesaid way, can also adopt characteristic signal sequence is carried out correlation calculations, the coefficient correlation maximum appears at the characteristic signal sequence original position, can realize characteristic signal sequence synchronously and bit synchronization by catching this maximum, the bit data energy is calculated in the back synchronously, be easy to restore sequence content according to decision threshold, thereby judge the signal legitimacy.
Avoid erroneous judgement for the accuracy that improves judgement, the dual thresholding of similarity and judgement number of times can be set in decision mechanism.In the present embodiment, adopt after the protection of three forward directions and four times to protection mechanism: namely before the lock-in feature signal, the continuous characteristic signal sequence of catching for three times is just thought acquisition success, so effectively filtering void scape; Behind the lock-in feature signal, continue the monitoring feature signal, have only the continuous characteristic signal sequence of catching for four times illegal, think that just characteristic signal loses, cut off and export.Can effectively resist the signal output cut-out that natural cause brings the unstable phenomenon of signal transient or other reason to cause like this.
Simultaneously, decision mechanism must be taken into account simultaneously and avoid erroneous judgement and reaction time, and both are contradiction, therefore, should be set to less than 2 seconds to the illegal judgement reaction time from signal is legal.
The output of determining digital audio and video signals according to the court verdict of decision mechanism whether.When being judged to be when illegal, exporting complete 0 signal substituted audio signal but not cut off, to keep the integrality of link.Simultaneously, send warning information.
Claims (1)
1. encrypt the anti-inserting method of identification based on the broadcast program of satellite transmission, it is characterized in that, may further comprise the steps:
(1) cell site is according to original digital audio signals sampling rate to be broadcast with quantize BIT, select frequency be the frequency values of 18kHz～19kHz as characteristic frequency, generate corresponding carrier wave numeral wave table, and this characteristic frequency be set to each receiving station;
(2) select the primitive character signal of a bandwidth below 0.2kHz, this primitive character signal is modulated to characteristic frequency obtains characteristic signal, and this primitive character signal is set to each receiving station;
(3) be that chronomere carries out energy calculating to the original digital audio signal with 1～10ms, according to the original digital audio signal energy that calculates, the amplitude of control characteristic signal and original digital audio signal, making the original digital audio signal energy is 1 to 10 times of characteristic signal;
(4) characteristic signal that step (3) is obtained and original digital audio signal carry out the signal stack, obtain superposed signal and broadcast via satellite;
(5) receiving station receives the superposed signal of satellite emission, according to the frequency range at characteristic frequency place superposed signal is with logical digital filtering, extracts characteristic signal;
(6) characteristic signal that extracts is carried out spectrum analysis by fast fourier transform algorithm and obtain frequency domain distribution, and characteristic signal is carried out demodulation;
(7) signal after the demodulation and primitive character signal are compared, judge the legitimacy that receives signal, the dual thresholding of similarity and judgement number of times is set in decision mechanism, adopt after the protection of three forward directions and four times to protection mechanism: namely before the lock-in feature signal, the continuous characteristic signal sequence of catching for three times is just thought acquisition success, behind the lock-in feature signal, continue the monitoring feature signal, have only the continuous characteristic signal sequence of catching for four times illegal, think that just characteristic signal loses, cut off output;
(8) whether the superposed signal that control receives according to judged result offers upstream device, and warning information is provided.
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| CN 201110043493 CN102164304B (en) | 2011-02-23 | 2011-02-23 | Encrypting identification intercutting-preventing method for broadcasting program based on satellite transmission |
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| WO2013173943A1 (en) * | 2012-05-25 | 2013-11-28 | Chang Chen-Fei | Modem for cable tv system |
| CN109005450B (en) * | 2018-07-16 | 2021-05-18 | 广州辉群智能科技有限公司 | Broadcast control method and device of broadcast equipment |
| CN112446341A (en) * | 2020-12-07 | 2021-03-05 | 北京明略软件系统有限公司 | Alarm event identification method, system, electronic equipment and storage medium |
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| US5442704A (en) * | 1994-01-14 | 1995-08-15 | Bull Nh Information Systems Inc. | Secure memory card with programmed controlled security access control |
| FI20002607A (en) * | 2000-11-28 | 2002-05-29 | Nokia Corp | Maintaining from terminal to terminal synchronization with a telecommunications connection |
| CN100442838C (en) * | 2001-08-08 | 2008-12-10 | 梁光海 | Cable TV control technology added with de-interference |
| CN1219401C (en) * | 2003-02-14 | 2005-09-14 | 清华大学 | A method for preventing illegal broadcasting in cable digital TV broadcasting |
| CN1901669B (en) * | 2005-07-21 | 2010-08-04 | 康佳集团股份有限公司 | Encrypting and de-encrypting for program of digital TV system and user cut-in managing method |
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