64results about How to "Improve anti-intercept performance" patented technology

The invention discloses a self-adaptation frequency hopping pattern generation method. Both parties of communication obtain the same SNR and the same SIR through channel estimation, an adjustment factor Vt of a frequency hopping pattern is generated, an operation is performed on the adjustment factor Vt and a frequency hopping pattern control word rt generated by a pseudorandom sequence generator to obtain a frequency hopping pattern control word t, and the frequency hopping pattern control word t is used for generating the frequency hopping pattern. In the self-adaptation frequency hopping pattern generation method, channel estimation is used for generating the self-adaptation frequency hopping pattern based on channel dynamism, the channel dynamism utilized by the self-adaptation frequency hopping pattern is the special characteristic of the both parties of communication, any third party cannot copy the characteristic, and the interception resisting performance is further improved. More importantly, even if one device is cracked or obtained by the enemy, effective interception and interference cannot be performed.

The invention provides a communication link used for a telemetry and telecontrol communication system. An uplink broadcasing and downlink TDMA (time division multiple access) mode is adopted to solve the measurement and control problems of a single ground station for multiple aircrafts. A downlink adopts hybrid spread spectrum BPSK (binary phase shift keying) with multiple stages of adjustable gain for modulation, an uplink adopts coded spread spectrum QPSK (quadrature phase shift keying) with fixed gain for modulation, so that the anti-interference, anti-interception and anti-capturing capacity of a wireless link is improved, and asymmetry of the uplink and the downlink is considered. Both the uplink and the downlink adopt a single-pulse modulation symbol packet transmission mode, a fixed interval is inserted into every two adjacent symbol pulses, and accordingly, the spread spectrum signal capturing, tracking and synchronizing complication of receivers is reduced. Non-coherent demodulation is adopted, a complicated carrier synchronization problem is avoided, and the design and project realization of the receivers are further simplified. The complicated carrier synchronization problem is avoided, and wireless communication between a single ground station device and multiple telecontrol terminal devices is realized.

The invention discloses a method for resisting interception and inference for signals based on quadrinomial weighted fractional Fourier transform of multiple-path variable parameters, relating to the communication technical field and solving the problems of poor interception resistance and poor interference resistance in the existing transmission resistance process of communication signals. The method comprises the following steps: at a transmitting end: digital signals are modulated by a baseband and then are subjected to spread spectrum encoding and quadrinomial weighted fractional Fourier transform under the control of a dynamic encryption parameter alphai and a dynamic encryption vector Vi, and encryption data synthesized by signals in multiple paths are subjected to digital carrier modulation and then are sent to a channel to transmit after D / A conversion and up-conversion; and at a receiving end: the data after down-conversion and A / D sampling is subjected to digital carrier coherent modulation, is decomposed by the signals in multiple paths, is subjected to quadrinomial weighted fractional Fourier transform for m times under the control of the dynamic encryption parameter alphai and dynamic encryption vector Vi, and is modulated by the baseband. The method is suitable for occasions of communication signal transmission.

The invention provides a cylindrical integrated active phased-array antenna. 96 linear radiation arrays are arranged in parallel to form a cylindrical array phase, each linear radiation array includes 8 radiation units and 8 phase shifters, and wave beam scanning in the pitching surface is realized; and each radiation column is connected with a switch array via a T / R assembly, the switch array divides the 96 linear radiation arrays into four groups, and a power amplifier is connected via an circulator. According to the invention, an independent antenna can be used to realize omnidirectional scanning with neither increase of array planes nor addition of mechanical scanning, the complexity and power consumption of an antenna system are reduced, and problems in heat radiation and the like are solved.

A self-interference communication method and system belong to the technical field of communication. The sender converts the useful sequence to be sent into a specific format and modulates it to generate a self-interference signal, linearly superimposes the useful signal and the self-interference signal into a mixed signal, and sends it on the same channel. According to the known self-interference signal generation format, the cooperative receiver estimates the channel parameters of the self-interference signal for the received mixed signal, reconstructs the self-interference signal, and then subtracts the reconstructed self-interference signal from the received mixed signal Demodulate to get the useful sequence. In the whole communication process from the transmitting party to the cooperating receiving party in the present invention, part of the transmission is a mixed signal, which has great anti-interception performance. Since the non-cooperating party does not know the format of the self-jamming signal and cannot reconstruct the self-jamming signal, there is no way to extract useful information from the mixed signal and ensure the information security of communication. Compared with the PCMA technology, the invention can enhance the security of the whole communication process and widen the application scope.

The invention provides a double side band frequency diversity array radar system and an object positioning method thereof and belongs to the technical field of radar signal processing. The double side band frequency diversity array radar system consists of N array elements that are linearly and uniformly arranged at an interval, N is a positive integer, and each array element comprises an emitting part and a receiving part. The emitting part comprises a modulation signal generator, a double side band modulator and an emitting antenna, wherein an output end of the modulation signal generator is connected with an input end of the double side band modulator, and an output end of the double side band modulator is connected with the emitting antenna. The receiving part comprises a receiving antenna, a filter group and a positioning calculation unit, wherein the filter group consists of two narrow band filters that are different in frequency, the receiving antenna is connected with input ends of the two narrow band filters, and output ends of the two narrow band filters are connected with an input end of the positioning calculation unit.

The invention relates to a depth spread spectrum capture and interference suppression method based on sparse Fourier transform and belongs to the technical field of spread spectrum communication signal processing. The method includes: adopting the depth spread spectrum technology to improve concealment and intercept resistance of a user side; adopting the interference suppression algorithm to further improve interference margin of a system and guarantee communication reliability; jointly processing the capture technology and the interference suppression algorithm and reducing complexity of spaceborne signal processing; adopting the sparse Fourier transform to reduce algorithm complexity, wherein in-band interference of a spread spectrum receiver is sparse in a frequency domain.

The invention provides a code-hopping direct spread communication method and system based on OVSF codes. According to data rate requirements of different users, the OVSF codes of different spreading factors serve as a spreading code block, and a code-hopping pattern is generated under the spreading factors to control hopping of spreading codes, namely, code-hopping direct spread of user data is carried out on the basis of the spreading code block. The method and system meet the rate requirements of different users by the adoption of the OVSF code spreading factors, meanwhile carry out spreading on data signals under the same spreading factor by means of code-hopping, and greatly improve anti-interference performance and an-intercept performance of code-hopping direct spread communication.

The invention relates to the field of optical signal processing in optical communication systems and discloses a method for encoding and decoding optical signals on a raster and structures of an optical encoder and an optical decoder to solve the safety problem of eavesdropping existing in an existing optical communication system. The method and the structures are characterized in that according to the technology, the optical signals are encoded and decoded on the raster based on a wavelength selective switch (WSS) and by combining an optical fiber delay line network, and code word dynamic reconstitution of optical encoding and optical decoding can be achieved. The method and the structures have the advantages that the outstanding advantages that the code word dynamic reconstitution amount of optical encoding and decoding is large, the dynamic change range is large, remote software controllability can be achieved, mobile parts do not exist, reliability is high, the insertion loss is low and the power consumption is low are achieved, so that the interception resisting capability of the optical communication system is greatly improved, and the safe transmission of the optical signals is ensured. The technology can be widely applied to optical information safe transmission in the field of optical communication (optical fiber communication and wireless optical communication).

The invention relates to a physical layer security enhancement method for a free space optical network. The physical layer security enhancement method for the free space optical network comprises thefollowing steps: S1, a sender legitimate user Alice sends a data signal, and an interference module sends an interference signal according to channel state estimation; S2, signal modulation is performed on the data signal and the interference signal according to different data symbols by means of a modulator; S3, the modulated optical signals of the data signal and the interference signal are encoded by using different encoders; S4, the encoded data signal and interference signal are coupled to an atmospheric turbulence channel for transmission by using a coupler; S5, a receiving end legitimate user Bob uses a decoder to perform corresponding matching decoding on the received optical signals; S6, a photo-detector APD is used to perform photoelectric detection on the signals; S7, the legitimate user demodulates the signals which are performed the photoelectric detection by using a demodulator to obtain the data signal sent by the sender Alice. Therefore, the security of the FSO transmission system is improved.

The invention provides a method for reducing synchronization time of frequency-hopping communication. With the method, the synchronous performance of the frequency-hopping signal can be improved obviously. According to the technical scheme, the method comprises: with a frequency-hopping synchronization circuit, after a frequency band where a frequency-hopping signal is located is determined, channel division is carried out on a frequency band covered by the frequency-hopping signal based on a frequency-hopping pattern and a frequency-hopping frequency point, times of occurrence of signals in all channels are recorded, recorded frequency-hopping points are mapped into a sequence generating a frequency-hopping pattern, and the sequence correlates with a generated periodic sequence generating a frequency-hopping pattern and a position of a received signal in the frequency-hopping pattern is found out; and after the position of the signal in the frequency-hopping pattern is found out, an occurrence frequency point and occurrence time are determined by combining a local counter and a frequency point and time of occurrence of a next signal are determined, so that coarse synchronization is completed. After de hopping and demodulation are carried out on the signal after coarse synchronization, a precise frequency-hopping frequency point switching time is obtained, thereby realizing precise synchronization and tracking of the frequency-hopping signal.

The invention provides a digital random multi-frequency-point frequency hopping and time hopping signal transmission method and system. The method comprises the steps of sampling N-bit signals, building an N-point FFT module, building a frequency hopping pattern generation module, building a data cache module, building a subcarrier mapping module and building an IFFT module. Aiming at the problemsthat the dimension of a frequency hopping set is small and the like, an OFDM (Orthogonal Frequency Division Multiplexing)-based digital frequency hopping communication technology is adopted, the dimension of the frequency hopping set is improved in a mode of caching data before subcarrier mapping and then remapping, and the purpose of enhancing the anti-interception performance of a frequency hopping system is achieved.

The invention relates to a difference frequency hopping communication method based on the correlation capture of an m sequence, belonging to the field of digital communication and comprising the following steps: setting m sequence data, deserializing, carrying out G functional mapping, generating a baseband frequency wave form, and carrying out intermediate frequency filtering and emission processing in the launch flow; receiving and processing signals, generating the baseband frequency wave form, carrying discrete acquisition, carrying out time / frequency signal transformation, decoding, carrying out correlation processing, judging capture, separating data, carrying out serial conversion processing, and outputting in the receiving flow. The invention has the characteristics of effective capture probability enhancement, false alarm rate reduction, capture time shortening, effective intercept resistance and anti-interference performance enhancement of a system and the like because the invention firstly transmits the m sequence data inserted with random numbers in a uniformly spaced mode and carrying out the G functional mapping processing of the m sequence data and serial Bit data on a transmitting terminal, and eliminates the random numbers through Viterbi decoding and carries out the correlation capture processing on the m sequence after time / frequency signal conversion on a receiving terminal.

The invention discloses a long-short code joint spread spectrum system unmanned aerial vehicle data link transmitter. It adopts the two-way signal orthogonal modulation system of short code direct spread signal and long code direct spread signal. The short code modulation information is the time synchronization information guiding the long code acquisition mode, and the long code modulation information is user data information. Compared with the data link of the short-period direct-spread system, the patent of the present invention adopts the long-period pseudo-random sequence spread spectrum, which significantly improves the anti-intercept ability of the UAV link, and also has high degree of digitization, small size, easy debugging, With the advantages of stable and reliable performance, it is suitable for information transmission in a complex electromagnetic environment that requires a high degree of command information security.

The invention discloses signal modulation and demodulation methods and phase hopping modulation and demodulation units. The signal modulation method comprises the steps of 1, generating a phase hopping sequence via a phase hopping sequence generator under the control of a clock reference; and 2, performing corresponding phase shifting on the waveform of each chip in a signal to be modulated underthe control of the phase hopping sequence to acquire a modulated signal, wherein the phase hopping modulation unit comprises a phase shifter and a phase hopping sequence generator; the input end of the phase hopping sequence generator is used for being connected with the clock reference, and used for generating the phase hopping sequence under the control of the clock reference; the input end of the phase shifter is used for receiving the signal to be modulated; the control end of the phase shifter is connected with the output end of the phase hopping sequence generator; and after the phase shifter performs corresponding phase shifting on the waveform of each chip in the signal to be modulated under the control of the phase hopping sequence, the output end of the phase shifter outputs themodulated signal. According to the modulation method provided by the invention, the signal is equivalently subjected to twice PSK modulations, so that the modulated signal is close to noise characteristics, and the anti-detection performance of the signal can be improved.

The invention discloses a high-density differential frequency hopping communication method, which belongs to communication technology. The high-density differential frequency hopping communication method comprises an emitting process and a receiving process, wherein the emitting process comprises serial-to-parallel conversion, the mapping treatment of a differential frequency hopping bit frequency point, the generation of a secondary frequency control word, the generation of a high-density differential frequency hopping frequency control word, and emitting; and the receiving process comprisesreceiving, discrete sampling, the recovery of the secondary frequency control word, frequency-domain waveform output, soft decision, synchronous decision, the serial-to-parallel conversion and data output. In the invention, on the basis of the initial primary secondary word, the secondary frequency word is added to increase the frequency point set density of transmission signals; while a receiving end performs frequency-shifting alignment treatment on the discrete data to remove secondary frequency signals, recover primary frequency signals and restore into the frequency point density of the traditional differential frequency hopping system. Thus, the high-density differential frequency hopping communication method has the characteristics that: the information transmission is safe and reliable; decoding is difficult; the confidentiality and anti-interception capability are high; the frequency point density can be adapted to a system security level according to requirements; and the like.

The present invention provides a target remote positioning system, which belongs to the technical field of radar signal processing, wherein the target remote positioning system is composed of N array elements arranged linearly at equal intervals, wherein N is a positive integer; each array element includes a transmitter part and receiving part. The transmitting part includes a modulated signal generator, a double sideband modulator and a transmitting antenna; the output end of the modulated signal generator is connected with the input end of the double sideband modulator, and the output end of the double sideband modulator is connected with the transmitting antenna. The receiving part includes a receiving antenna, a filter bank and a positioning calculation unit; the filter bank is composed of two narrow-band filters with different passing frequencies; the receiving antenna is connected to the input ends of the two narrow-band filters at the same time, and the two narrow-band filters The output end is simultaneously connected with the input end of the positioning solving unit.

The invention relates to a physical layer anti-interception secure communication method and system. The method is characterized in that modulation and coding for anti-interception security are carriedout on an original information bit stream in a physical layer, and then a plurality of symbol code elements are generated and sent, on one hand, a plurality of symbol code elements have a rateless characteristic in the aspect of encoding, so transmission efficiency of the original information bit stream can be improved, transmission can be carried out close to the capacity of a preset channel between a legal transmitting end and a legal receiving end, and decoding difficulty of an illegal receiving end, namely an illegal eavesdropper, is increased while transmission efficiency is ensured, onthe other hand, as a plurality of symbol code elements are in Gaussian distribution, ultra-Gaussian distribution or sub-Gaussian distribution, an illegal eavesdropper cannot extract specific distribution of a plurality of symbol code elements by using a blind detection method based on a high-order cumulant and the like, so interception resistance and security of a physical layer of a communicationsystem are further improved.

The present invention uses discrete multicarrier spread spectrum, direct sequential spread spectrum and inverse dicrete Fourier transformation to form a two-dimensional spread spectrum module, and the two-dimensional spread spectrum module, frequency hopping and time hopping spread spectrum are used to form the emission part of the united extending spectrum communication method. The inverse discrete multicarrier, direct sequential despreading spectrum and discrete Fourier transformation are used to form a two-dimensional despreading spectrum module and two-dimensional despreading spectrum module, time dehopping and frequency dehopping unit are used to form the receiving part of the united extending spectrum communication method.

The invention relates to the field of optical signal processing in optical communication systems and discloses a method for encoding and decoding optical signals on a raster and structures of an optical encoder and an optical decoder to solve the safety problem of eavesdropping existing in an existing optical communication system. The method and the structures are characterized in that according to the technology, the optical signals are encoded and decoded on the raster based on a wavelength selective switch (WSS) and by combining an optical fiber delay line network, and code word dynamic reconstitution of optical encoding and optical decoding can be achieved. The method and the structures have the advantages that the outstanding advantages that the code word dynamic reconstitution amount of optical encoding and decoding is large, the dynamic change range is large, remote software controllability can be achieved, mobile parts do not exist, reliability is high, the insertion loss is low and the power consumption is low are achieved, so that the interception resisting capability of the optical communication system is greatly improved, and the safe transmission of the optical signals is ensured. The technology can be widely applied to optical information safe transmission in the field of optical communication (optical fiber communication and wireless optical communication).

The invention relates to a method for enhancing physical layer security of a free space optical network, comprising: S1, sending a data signal by a legitimate user Alice of the sender, and an interference module sending an interference signal according to channel state estimation; S2, interfering with the data signal and the interference according to different data symbols The signal is modulated by a modulator; S3, using different encoders to encode the modulated data signal and the optical signal of the interference signal; S4, using a coupler to couple the encoded data signal and interference signal to the atmospheric turbulence channel Transmission; S5. The legal user Bob at the receiving end uses the decoder to perform matching decoding on the received optical signal; S6. Uses the photoelectric detector APD to perform photoelectric detection on the signal; S7. The legal user uses the demodulator to perform photoelectric detection on the signal Perform demodulation to obtain the data signal sent by the sender Alice. Therefore, the safety of the FSO transmission system is improved.

The invention discloses an outboard device of a submarine radar. The outboard device mainly solves the problems that an existing outboard device of the submarine radar is prone to seawater leakage, large in working noise, complex in signal transmission system, high in erection requirement and failure rate and poor in interception resistance. An antenna unit (1), a transmitting-receiving unit (2), a driving unit (3) and a watertight cable assembly (4) which are all provided with water-pressure-resistant sealing shells are sequentially connected in a sealed mode to form a water-pressure-resistant sealing body. The antenna unit can simultaneously transmit and receive radar electromagnetic waves; the transceiving unit is used for generating a microwave signal, transmitting the microwave signal to the antenna unit and performing down-conversion processing on the received microwave signal; the driving unit is electrically driven, is filled with an insulating medium and is additionally provided with a pressure balance compensation device; the watertight cable assembly is used for being electrically connected with inboard equipment. The system has the advantages of capability of avoiding seawater leakage, low working noise and erection requirements, simple system structure, low failure rate and better anti-interception performance, and can be used for continuous wave transceiver system radar equipment.

The invention discloses a waveform diversified secure transmission method and system based on extended weighted score Fourier transform, and belongs to the technical field of wireless communication. According to the invention, the problem of poor anti-interception performance caused by poor waveform diversity due to limitation of parameter dimensions in the existing hybrid carrier safety communication method is solved. The waveform diversified secure transmission method is designed for an existing security system, and an extended hybrid carrier signal with high parameter dimension and design flexibility can be obtained by performing extended weighted fractional Fourier transform on the signal. Due to the expansion of the transformation form, the signal waveform has strong diversity, so that the calculation complexity of realizing correct inverse transformation through cracking is greatly improved, the probability that an eavesdropper intercepts a signal is effectively reduced, the physical layer security performance of the system is enhanced, and the communication confidentiality is guaranteed. Meanwhile, the method has good compatibility with an existing security method. The method can be applied to the technical field of wireless communication.

The invention discloses a two-way frequency hopping and probability simultaneous co-frequency full-duplex combined communication method, which solves the problems of low frequency spectrum utilizationrate and not high co-frequency full-duplex interference resistance in a frequency hopping system in the prior art. The method comprises the following specific steps: firstly, a terminal node adopts aquadrature phase shift keying QPSK method to modulate a signal; secondly, two-time fast and slow frequency hopping is carried out on the modulated signal; thirdly, the probability of simultaneous co-frequency full-duplex transmission is calculated by a terminal node; finally, self-interference elimination is carried out on the signal needing to be subjected to self-interference elimination by theterminal node, and then, de-hopping and demodulation are carried out to obtain a transmitted signal. The method in the invention is applicable to mutual communication of transmitting and receiving signals at the same time and at the same frequency, and the frequency utilization rate and the anti-interference performance of a cooperative communication system are improved.

The invention discloses a carrier synchronization method based on bit field superposition training sequence. The present invention proposes a carrier synchronization method with strong anti-interference ability aiming at the signal design method of the superposition of the sparse code word and the pseudo-random sequence. In this method, the hidden pseudo-random sequence is used to estimate the frequency offset at the receiving end, and the combination of coarse synchronization and fine synchronization is used to improve the estimation accuracy. Finally, sparse decoding and channel decoding are performed on the restored sequence. The carrier synchronization method proposed by the present invention based on the superposition of sparse coding codewords and pseudo-random sequences can ensure accurate estimation of carrier frequency offset without occupying additional bandwidth resources, and realize reliable transmission of information in combination with channel coding; In addition, the superposition of pseudo-random sequences can enhance the anti-interception ability of burst signals; when there is a fragment loss in the data frame, the remaining hidden pseudo-random sequences can still be used to estimate the frequency offset.

The invention belongs to the technical field of wireless communication, and in particular relates to a group index OFDM communication method based on the combination of message and random sequence. The principle of packet SIM-OFDM communication technology based on the combination of random sequence and message is to use the combination of message drive and random sequence drive to activate some subcarriers of each carrier block in each OFDM symbol to transmit modulation symbols, and other subcarriers remain silent. State, the group index OFDM communication technology based on the combination of message and random sequence uses the randomness of a PN sequence to cause the relationship between index bits and active carrier distribution to also change randomly, making the index bit information more concealed. In the joint driving mode of PN sequence and index bit, without sacrificing the spectral efficiency of the system, the anti-interception performance of the system is greatly improved without reducing the anti-interference performance.

The invention relates to a difference frequency hopping communication method based on the correlation capture of an m sequence, belonging to the field of digital communication and comprising the following steps: setting m sequence data, deserializing, carrying out G functional mapping, generating a baseband frequency wave form, and carrying out intermediate frequency filtering and emission processing in the launch flow; receiving and processing signals, generating the baseband frequency wave form, carrying discrete acquisition, carrying out time / frequency signal transformation, decoding, carrying out correlation processing, judging capture, separating data, carrying out serial conversion processing, and outputting in the receiving flow. The invention has the characteristics of effective capture probability enhancement, false alarm rate reduction, capture time shortening, effective intercept resistance and anti-interference performance enhancement of a system and the like because the invention firstly transmits the m sequence data inserted with random numbers in a uniformly spaced mode and carrying out the G functional mapping processing of the m sequence data and serial Bit data on a transmitting terminal, and eliminates the random numbers through Viterbi decoding and carries out the correlation capture processing on the m sequence after time / frequency signal conversion on a receiving terminal.