This paper presents a novel scheme of high efficiency spreading spectrum modulation using double orthogonal complex sequences （DoCS）. In this scheme, input data bit-stream is split into many groups with length M. Ea...This paper presents a novel scheme of high efficiency spreading spectrum modulation using double orthogonal complex sequences （DoCS）. In this scheme, input data bit-stream is split into many groups with length M. Each group is then mapped into a word of width M and then utihzed to select one sequence from 2u-2 DoCS sequences each with length L. After that, the selected sequence is modulated on carrier in quadrature phase shift keying （QPSK） mode. In addition, a new method named forward phase correction （FPC） is put forward for carrier recovery. Theoretical analysis and bit-error-ratio（BER） experiment results indicate that the proposed scheme has better performance than the conventional direct sequence spread spectrum（DSSS） scheme both in bandwidth efficiency and processing gain of the receiver.展开更多
The technology for phase detection of liquid crystal optical device is a difficult research in current domestic and overseas. However, for the existing liquid crystal optical device, aiming at the poor anti-vibration ...The technology for phase detection of liquid crystal optical device is a difficult research in current domestic and overseas. However, for the existing liquid crystal optical device, aiming at the poor anti-vibration capability and poor versatile of phase detection, the complexity of phase retrieval algorithm, we propose a new phase measurement principle and experimental methods of liquid crystal optical device. It is a phase measurement method based on the combination of phase- shifting interferometer and phase conjugation technology. The deflection characteristics of the liquid crystal device means the device can implement phase modulation to only one direction of polarized light while is completely transparent to orthogonal polarized light. We put forward the phase shift of the orthogonal polarization phase shift interferometer method, using phase shifting interference as well as the combination of phase conjugate means to achieve its phase measurement. So we can retrieves devices modulation phase simply and efficiently combines with phase- shifting interferometer technology.展开更多
针对雷达通信一体化信号雷达、通信性能无法兼顾的问题,提出了OFDM-CPM-LFM雷达通信一体化信号.首先,通过连续相位调制(Continuous Phase Modulation,CPM)对线性调频信号(Linear Frequency Modulation,LFM)进行调制,降低信号模糊函数旁...针对雷达通信一体化信号雷达、通信性能无法兼顾的问题,提出了OFDM-CPM-LFM雷达通信一体化信号.首先,通过连续相位调制(Continuous Phase Modulation,CPM)对线性调频信号(Linear Frequency Modulation,LFM)进行调制,降低信号模糊函数旁瓣提高雷达探测能力,在动态调制指数下均衡一体化信号性能;然后结合正交频分复用技术(Orthogonal Frequency Division Multiplexing,OFDM)提高通信传输速率,通过增加循环前、后缀降低干扰影响保证通信性能;最后,利用模糊函数与误码率分析一体化信号性能.仿真结果表明,所提一体化信号在保证雷达探测性能同时,能够实现高效通信,且误码率在信噪比10 dB时可达到10−5以下.展开更多
针对混沌序列单一调频或调相波形存在波形复杂度低,限制了混沌信号可预测的概率、雷达的截获概率和抗干扰性能的问题,提出了基于混沌序列将频率和相位联合调制用于波形设计的方法。首先,对雷达信号进行混沌频率编码,即将一个脉冲分成一...针对混沌序列单一调频或调相波形存在波形复杂度低,限制了混沌信号可预测的概率、雷达的截获概率和抗干扰性能的问题,提出了基于混沌序列将频率和相位联合调制用于波形设计的方法。首先,对雷达信号进行混沌频率编码,即将一个脉冲分成一系列子脉冲,对不同子脉冲进行不同的频率调制。同时,在每个频率编码子脉冲内对波形的每个周期使用随机产生的初始相位。仿真结果表明,联合调频调相混沌雷达信号的自相关旁瓣峰值最大值达到-24.71 d B,相比调频混沌信号或调相混沌信号,其相关性性能有所提高。实验结果表明,联合调频调相混沌雷达波形结合调相和调频的优点,既具有调相信号的功率谱平坦的特性,又具有调频信号抗噪声干扰特性,为非常理想的探测信号。展开更多
基金Union Innovation Found of Jiangsu Province(No. BY2009149)
文摘This paper presents a novel scheme of high efficiency spreading spectrum modulation using double orthogonal complex sequences （DoCS）. In this scheme, input data bit-stream is split into many groups with length M. Each group is then mapped into a word of width M and then utihzed to select one sequence from 2u-2 DoCS sequences each with length L. After that, the selected sequence is modulated on carrier in quadrature phase shift keying （QPSK） mode. In addition, a new method named forward phase correction （FPC） is put forward for carrier recovery. Theoretical analysis and bit-error-ratio（BER） experiment results indicate that the proposed scheme has better performance than the conventional direct sequence spread spectrum（DSSS） scheme both in bandwidth efficiency and processing gain of the receiver.
文摘The technology for phase detection of liquid crystal optical device is a difficult research in current domestic and overseas. However, for the existing liquid crystal optical device, aiming at the poor anti-vibration capability and poor versatile of phase detection, the complexity of phase retrieval algorithm, we propose a new phase measurement principle and experimental methods of liquid crystal optical device. It is a phase measurement method based on the combination of phase- shifting interferometer and phase conjugation technology. The deflection characteristics of the liquid crystal device means the device can implement phase modulation to only one direction of polarized light while is completely transparent to orthogonal polarized light. We put forward the phase shift of the orthogonal polarization phase shift interferometer method, using phase shifting interference as well as the combination of phase conjugate means to achieve its phase measurement. So we can retrieves devices modulation phase simply and efficiently combines with phase- shifting interferometer technology.
文摘针对雷达通信一体化信号雷达、通信性能无法兼顾的问题,提出了OFDM-CPM-LFM雷达通信一体化信号.首先,通过连续相位调制(Continuous Phase Modulation,CPM)对线性调频信号(Linear Frequency Modulation,LFM)进行调制,降低信号模糊函数旁瓣提高雷达探测能力,在动态调制指数下均衡一体化信号性能;然后结合正交频分复用技术(Orthogonal Frequency Division Multiplexing,OFDM)提高通信传输速率,通过增加循环前、后缀降低干扰影响保证通信性能;最后,利用模糊函数与误码率分析一体化信号性能.仿真结果表明,所提一体化信号在保证雷达探测性能同时,能够实现高效通信,且误码率在信噪比10 dB时可达到10−5以下.
文摘针对混沌序列单一调频或调相波形存在波形复杂度低,限制了混沌信号可预测的概率、雷达的截获概率和抗干扰性能的问题,提出了基于混沌序列将频率和相位联合调制用于波形设计的方法。首先,对雷达信号进行混沌频率编码,即将一个脉冲分成一系列子脉冲,对不同子脉冲进行不同的频率调制。同时,在每个频率编码子脉冲内对波形的每个周期使用随机产生的初始相位。仿真结果表明,联合调频调相混沌雷达信号的自相关旁瓣峰值最大值达到-24.71 d B,相比调频混沌信号或调相混沌信号,其相关性性能有所提高。实验结果表明,联合调频调相混沌雷达波形结合调相和调频的优点,既具有调相信号的功率谱平坦的特性,又具有调频信号抗噪声干扰特性,为非常理想的探测信号。
