This paper presents the definition of perfect punctured binary sequence pair and the combinatorial admissible conditions for searching the perfect punctured binary sequence pairs and proves that all of the pseudo-rand...This paper presents the definition of perfect punctured binary sequence pair and the combinatorial admissible conditions for searching the perfect punctured binary sequence pairs and proves that all of the pseudo-random binary sequences satisfy these conditions. Computer calculation verifies that the pseudo-random binary sequences with length up to N=127 can be easily turned into perfect punctured binary sequence pairs.展开更多
Discrete chaotic systems are used for bi-directlonal secure communication. Both sides of communication keep sending signals to achieve their synchronization, and then recover the messages. However, the third side with...Discrete chaotic systems are used for bi-directlonal secure communication. Both sides of communication keep sending signals to achieve their synchronization, and then recover the messages. However, the third side without keys cannot get useful information. Known-plaintext attack is also engaged to analyze this method, and the simulation results show that the proposed method can reach high security performance.展开更多
The satellite navigation anti-interference technique, especially space anti-interference technique, is subjected to many restrictions, such as cost, energy depletion, and so on, and the satellite signal strength is li...The satellite navigation anti-interference technique, especially space anti-interference technique, is subjected to many restrictions, such as cost, energy depletion, and so on, and the satellite signal strength is limited by the International Radio Advisory Committee, the International Telecommunication Union (ITU) and satellite companies. This paper focuses on satellite navigation systems, especially satellite navigation systems adopting direct sequence spread spectrum (DSSS). The notch filter is used to remove some frequencies from the pseudorandom code frequency spectrum making use of its cyclostationarity first, then the filtered pseudorandom code is modulated by the carrier to attain energy suppression, but the pseudorandom code autocorrelation characteristic stays unchanged. The feasibility of this algorithm is verified by simulation results.展开更多
基金Supported by the National Natural Science Foundation of China under Grant 69972042
文摘This paper presents the definition of perfect punctured binary sequence pair and the combinatorial admissible conditions for searching the perfect punctured binary sequence pairs and proves that all of the pseudo-random binary sequences satisfy these conditions. Computer calculation verifies that the pseudo-random binary sequences with length up to N=127 can be easily turned into perfect punctured binary sequence pairs.
文摘Discrete chaotic systems are used for bi-directlonal secure communication. Both sides of communication keep sending signals to achieve their synchronization, and then recover the messages. However, the third side without keys cannot get useful information. Known-plaintext attack is also engaged to analyze this method, and the simulation results show that the proposed method can reach high security performance.
基金Supported by the National Natural Science Foundation of China(No. 60802018)the National Key Basic Research and Development Technology Plan (No. 2007CB815500)
文摘The satellite navigation anti-interference technique, especially space anti-interference technique, is subjected to many restrictions, such as cost, energy depletion, and so on, and the satellite signal strength is limited by the International Radio Advisory Committee, the International Telecommunication Union (ITU) and satellite companies. This paper focuses on satellite navigation systems, especially satellite navigation systems adopting direct sequence spread spectrum (DSSS). The notch filter is used to remove some frequencies from the pseudorandom code frequency spectrum making use of its cyclostationarity first, then the filtered pseudorandom code is modulated by the carrier to attain energy suppression, but the pseudorandom code autocorrelation characteristic stays unchanged. The feasibility of this algorithm is verified by simulation results.
