10 results about "Random frequency hopping" patented technology

The present application belongs to the technical field of radar imaging, and relates to a kind of dual-base radar cooperative imaging method based on complementary random waveform, it is characterized in that, including the following steps: step 1: establish dual radar cooperative detection echo model, radar 1 and radar 2 all adopt random frequency hopping waveform;Step 2: carry out distance difference compensation, eliminate the phase modulation term of the phase difference of the echo signal received by radar 1 and radar 2, realize distance difference compensation;Step 3: carry out echo motion compensation, eliminate the component related to velocity component in echo, realize echo motion compensation;Step 4: carry out band fusion imaging, rearrange different frequency band random frequency hopping, carry out zero filling processing to echo data on the missing frequency point, and through setting tight constraint condition, make the echo signal of two radar through FFT transformation to realize phase correlation fusion imaging.The imaging method of the present application designs new frequency hopping waveform, realizes efficient motion compensation, and realizes band fusion by using phase correlation processing algorithm.

FIELD: radio engineering.SUBSTANCE: invention can be used in the construction of radar systems (REE) in order to increase their protection against barrage interference. In the method of protection against interference, the allocated range of carrier frequencies of the REE is divided into N sub-ranges, the width of the gap between adjacent sub-ranges is set so that the spectrum of the barrage interference, the central frequency of which corresponds to the average value of the maximum and minimum carrier frequencies of the REE in the entire allocated range, does not fall in whole or in part into any of the sub-ranges, the change in the carrier frequency of the REE signals is carried out after the emission of each signal in the entire allocated range, the interference level is assessed before the emission of each REE signal at its carrier frequency.EFFECT: increased protection of radio electronic equipment operating under pseudo-random frequency hopping from barrage interference.1 cl

This application relates to an improved random frequency hopping radar imaging method, apparatus, computer equipment, and storage medium. The method includes: modulating the original random frequency hopping radar signal with pulse repetition time using a defined sub-pulse repetition time modulation formula to obtain a random frequency hopping signal jointly modulated by pulse repetition time and frequency; detecting a target using the jointly modulated random frequency hopping signal; compensating the nonlinear phase term of each range cell in the target echo mixing signal using a preset kernel function; performing a Fast Fourier Transform (FFT) on the compensated baseband echo signal of each range cell; and outputting the range image in the Doppler channel with the highest energy as the high-resolution range image of the target. This invention eliminates high-order coupling terms between motion and frequency, utilizes kernel function correlation combined with FFT for fast imaging, avoids the target velocity estimation step in the imaging process, reduces computational load, and is beneficial for engineering implementation.

The invention relates to the technical field of frequency hopping communication, and discloses a method for generating an orthogonal pseudo-random frequency hopping sequence by combining time domain synchronization with encryption, which comprises the following steps of: S1, obtaining an initial value: obtaining an N-bit TOD initial value from TOD information; s2, calculating a sequence: carrying out progressive increase operation on the TOD initial value according to a frequency hopping time interval to obtain a TOD sequence value; s3, calculating a ciphertext: taking the TOD sequence value as a plaintext input of an encryptor, and encrypting with a preset key to obtain an N-bit ciphertext; and S4, frequency hopping code division: taking a group of T-bit numerical values from the N-bit ciphertext as frequency hopping codes, wherein T is a preset bit number. The method mainly adopts a method of combining time domain synchronization and AES encryption, has the characteristics of strong interception resistance, high transmission reliability and strong anti-interference capability, avoids a periodic problem or an initial value dependence weakness possibly existing in a traditional pseudo-random sequence, adopts an encryptor to carry out multi-round encryption transformation on a TOD sequence, generates a ciphertext as a basis of a frequency hopping code, and improves the frequency hopping efficiency. And the anti-cracking capability of the sequence is obviously enhanced.

The invention relates to the technical field of wireless communication, and discloses a rapid printing connection method and system suitable for mobile scenes such as e-commerce. According to the rapid printing connection method and system, through double-end collaborative perception and relative time sequence synchronization, clock drifting is avoided, pseudo-random frequency hopping scanning is combined, multi-dimensional channel parameters are rapidly collected and intercommunicated, the perception efficiency is improved, and power consumption is reduced; and the outdoor endurance requirement is met. Priority channels are screened, compliance alternative channels are planned, special control channels and simplified instructions are matched, millisecond-level channel synchronization and second-level link establishment are achieved, the pairing efficiency is improved by more than 70% compared with a traditional method, and the printing preparation time is shortened. And through low-power-consumption monitoring and hundred-millisecond-level seamless switching, the connection stability is improved by matching with the bottom and learning optimization functions. Multi-protocol compatibility is achieved by means of the protocol adaptation layer, hardware does not need to be transformed, replacement cost is reduced, lightweight encryption is additionally arranged to guarantee data safety, multi-class e-commerce mobile scenes are adapted, and mobile office and printing efficiency is improved.

The invention discloses a wireless ad hoc network random frequency hopping system and a modeling method, and the method comprises the steps: obtaining network node distribution, communication and random frequency hopping parameters, deducing an equivalent communication radius based on communication parameters, constructing a susceptible node set of potential new infection nodes, introducing an epidemic theory, and building an annular infection model. Key parameters such as success infection rate, annular infection rate and equivalent communication radius are solved, a message propagation process equation is obtained, and the evolution rule of the number of infected nodes and susceptible nodes along with time is described. The system comprises a parameter acquisition module, an annular infection model construction module, a parameter solving module and a time-varying rule derivation module, and is used for executing the wireless ad hoc network random frequency hopping system modeling method. According to the method, quantitative analysis of the random frequency hopping multi-hop broadcast process is realized, the diffusion range and speed of the message in the network can be accurately reflected, a theoretical basis is provided for performance evaluation of a random frequency hopping system and design and optimization of key parameters, and the method has good engineering application value.

The application discloses an intelligent interference method based on cooperative Q learning. The method is as follows: in the interference scene of multi-agent confrontation, the communication user communicates through cooperation by adopting a fixed sequence frequency hopping mode or a random frequency hopping mode, the intelligent jammer can acquire the user spectrum state information in real time, and establishes and maintains two Q value tables of independent Q value table and joint Q value table; the jammer takes the perceived user spectrum state as the state input, selects the joint action according to the epsilon-greedy strategy, evaluates the current communication effect and calculates the reward value after executing the action, and perceives and obtains the spectrum state at the next moment; the update of the independent Q value table and the joint Q value table is completed according to the obtained interference reward value, and the optimization of the interference strategy in the multi-agent confrontation scene is completed through the cycle. The application considers the coordination of the internal decision of the jammer, and effectively improves the interference effect in the multi-agent confrontation scene.

The invention belongs to but is not limited to the technical field of optical communication, and particularly relates to a method and a system for integrating radio frequency hopping communication and chaotic encryption over fiber. At a transmitting end, a chaotic signal and a true random frequency hopping code are generated by utilizing endogenous high-randomness quantization noise in a DSM (Digital Subscriber Modulation) process; dual security enhancement of waveform disturbance and frequency hopping of plaintext signals is realized, and noise-like chaotic encryption signals are converted into low-order digital signals for transmission. At a receiving end, quantization noise is reconstructed from a received signal, chaotic synchronization and frequency hopping code regeneration are achieved, and frequency hopping and chaotic decryption are completed. The problem of high-quality chaos synchronization is fundamentally solved, the performance bottleneck of true random frequency hopping in a high-speed scene is broken through, nanosecond ultrafast frequency hopping and chaos encryption are realized, only a single low-order digital signal needs to be transmitted, the method is perfectly compatible with an existing communication system, and the method is suitable for large-scale popularization and application. And an efficient and feasible physical layer security solution is provided for a high-speed and high-security radio over fiber access network.

The present disclosure provides a carrier suppression-based optical frequency hopping communication system, characterized in that comprising: a transmitter, configured to carrier suppression modulate a laser signal to generate two frequency signals with different frequencies, output the two frequency signals on two links alternately based on a frequency hopping sequence to generate two carrier signals, modulate two user data on the two carrier signals respectively to generate two modulated carrier signals, and couple the two modulated carrier signals as a transmission signal for transmission; and a receiver, configured to receive the transmission signal, separate the two frequency signals based on different frequencies, output the two frequency signals on two links alternately based on the frequency hopping sequence to recover the two modulated carrier signals, and demodulate the two modulated carrier signals respectively to obtain the two user data. By loading user data on carrier signals with random frequency hopping, the data is effectively hidden to prevent eavesdropping by illegal third parties.

The application discloses a microwave correlation forward-looking imaging method based on random frequency modulation, which comprises the following steps: S1, arranging multiple frequency hopping radar antennas in a specific distribution to form a frequency hopping radar array, and setting a target imaging area; S2, constructing a space-time random radiation field by independently transmitting random frequency hopping signals and receiving antenna random sampling through each frequency hopping radar antenna, and sampling echoes at random time intervals after the target is sighted; S3, judging the randomness of the space-time random radiation field, and processing the space-time random radiation field by using a least square method if the randomness of the space-time random radiation field is insufficient; and S4, performing compression correlation processing on the echoes obtained by the sight and the space-time random radiation field, and realizing target imaging. The application has good azimuth resolution and anti-interference performance, is simple to realize, and has strong engineering application potential.