Implementation of a kind of FPGA-based binary phase coded radar signal processor architecture

A flexible field programmable gate array based radar signal processor is presented. The radar signal processor mainly consists of five functional modules： radar system timer, binary phase coded pulse compression（PC）, moving target detection （MTD）, constant false alarm rate （CFAR） and target dots processing. Preliminary target dots information is obtained in PC, MTD, and CFAR modules and Nios I! CPU is used for target dots combination and false sidelobe target removing. Sys- tem on programmable chip （SOPC） technique is adopted in the system in which SDRAM is used to cache data. Finally, a FPGA-based binary phase coded radar signal processor is realized and simula- tion result is given.

Polyphase coded signal design for MIMO radar using MO-MicPSO

A novel modified optimization technique known as the multi-objective micro particle swarm optimization（MO-MicPSO） is proposed for polyphase coded signal design.The proposed MO-MicPSO requires only a small population size compared with the standard particle swarm optimization that uses a larger population size.This new method is guided by an elite archive to finish the multi-objective optimization.The orthogonal polyphase coded signal（OPCS） can fundamentally improve the multiple input multiple output（MIMO） radar system performance,with which the radar system has high resolution and abundant signal channels.Simulation results on the polyphase coded signal design show that the MO-MicPSO can perform quite well for this high-dimensional multi-objective optimized problem.Compared with particle swarm optimization or genetic algorithm,the proposed MO-MicPSO has a better optimized efficiency and less time consumption.

Novel non-coherent integration method using binary phase-coded radar signal

The m series with 511 bits is taken as an example being applied in non-coherent integra- tion algorithm. A method to choose the bi-phase code is presented, which is 15 kinds of codes are picked out of 511 kinds of m series to do non-coherent integration. It is indicated that the power in- creasing times of larger target sidelobe is less than the power increasing times of smaller target main- lobe because of the larger target＇ s pseudo-randomness. Smaller target is integrated from larger tar- get sidelobe, which strengthens the detection capability of radar for smaller targets. According to the sidelobes distributing characteristic, a method is presented in this paper to remove the estimated sidelobes mean value for signal detection after non-coherent integration. Simulation results present that the SNR of small target can be improved approximately 6. 5 dB by the proposed method.

THE MINIMUM SQUARED EUCLIDEAN DISTANCE OF MULTI-h PHASE CODES

The minimum squared Euclidean distance(MSED) of binary multi-h phase codes is presented. The signal segregation degree(SSD) has been put forward to determine MSED of multi-h phase codes. In order to maximize MSED, SSD should be as large as possible. The necessary and sufficient conditions of maximizing SSD are derived. Finally, SSD and the exact formulae for MSED of binary 2-h phase codes are also presented.

对瞬时测频干扰机理的研究

瞬时测频(instantaneous frequency measurement,IFM)接收机是电子侦察中非常重要的测频资源,其结构简单、灵敏度高、侦察频带宽、分辨率高,可以快速测定被测信号的频率,在现代电子战中得到广泛应用。基于IFM微波鉴相器在某一瞬间只能响应一个信号的特性,结合IFM工作原理,研究了一种新的(超过2个信号)对IFM干扰策略,并分析了干扰机理,通过模拟仿真对IFM的干扰效果进行了评估。仿真结果表明:多信号交叠可以对IFM系统产生明显的干扰效果,可以使得其无法测得正确频率,并错误地输出同时到达信号指示。

基于相位编码波形和非匹配滤波器设计的间歇采样转发干扰抑制方法

间歇采样转发干扰(ISRJ)利用信号欠采样原理和匹配滤波特点,在雷达信号距离维上产生多个数量可控的虚假目标点。根据ISRJ采样函数特点,本文提出一种针对ISRJ的相位编码波形和非匹配滤波器设计方法。在雷达发射信号前,根据干扰的脉冲宽度和重复频率参数,设计适用于抑制ISRJ的非匹配滤波的相位编码信号。在接收到带有干扰的回波后,根据ISRJ采样函数与发射前设计的编码信号,构建抑制ISRJ的非匹配滤波器,降低干扰能量。仿真结果表明,与传统未经处理的相位编码信号相比,所提方法优化设计的信号表现出更好的抗干扰能力。

机载低轨卫星通信发展及关键技术综述

卫星通信是保障机载平台远程飞行的主要通信手段。低轨卫星通信具有传输损耗小、传输时延短、卫星发射灵活、能全球覆盖等优点,已成为机载卫星通信领域的研究热点。梳理了国内外机载低轨卫星通信技术发展历程,开展了机载低轨卫星通信应用分析,重点从相控阵天线、信号同步、编码调制、接入与切换等方面阐述了机载低轨卫星通信需要解决的关键技术,探讨了机载低轨卫星通信发展趋势,可为机载低轨卫星通信系统建设应用提供借鉴。

Impact of GPS Almanac Broadcast Strategy on the Signal Acquisition Time

This paper investigates the problem of almanac affecting the signal acquisition time with two constraints: different age of data and multi-sets of almanac. The contributions made in this paper include: 1) the exploiting of signal acquisition concept to extend well-known almanac function of predicting visible satellite and initializing signal acquisition to minimizing the signal acquisition time; 2) a model based on code phase and Doppler frequency to reflect the impact of multi-sets of almanac on the signal acquisition time; 3) the evaluation of the existing GPS almanac with different broadcast strategy. The theoretical analyses and simulations conducted on three sets of almanac show that the model proposed in this paper is general and efficient for almanac design and application.

Research of Hybrid Modulation Radar Signal

Based on the advantage of phase coded signal and stepped frequency signal,a new hybrid modulation signal is introduced in this paper. It combines phase code modulation during the pulse with stepped frequency modulation between the pulses, which is named as phase-coded stepped-frequency ( PCSF ) signal. By analyzing its waveform and ambiguity function,the comparison between Stepped-Frequency ( SF) signal and PCSF signal is given,which shows that the PCSF signal is better than SF signal. Finally,the signal processing method with two stage compressed processing is presented. The simulation results show that this new hybrid modulation radar signal can get a higher stepped frequency than ordinary SF signal,realize the same equivalent bandwidth with less pulse number,and solve the conflict among the stepped frequency,the number of pulse, and transmit average power. Under the premises of a certain range resolution,this new hybrid modulation radar signal not only raises the data rate of radar system,but also reduces Doppler sensitivity with a good prospect, and the effect of one-dimensional range profile is much better than that of traditional SF signal. Therefore,this new hybrid modulation radar signal can be widely used in application.

STUDY ON AUDIO INFORMATION HIDING METHOD BASED ON MODIFIED PHASE PARTITION

Hiding efficiency of traditional audio information hiding methods is always low since the sentience similarity cannot be guaranteed. A new audio information hiding method is proposed in this letter which can impose the insensitivity with the audio phase for auditory and realize the information hiding through specific algorithm in order to modify local phase within the auditory perception. The algorithm is to introduce the operation of "set 1" and "set 0" for every phase vectors, then the phases must lie on the boundary of a phase area after modified. If it lies on "1" boundary, it comes by set 1 operation. If it lies on "0" boundary, it comes by set 0 operation. The results show that, compared with the legacy method, the proposed method has better auditory similarity, larger information embedding capacity and lower code error rate. As a kind of blind detect method, it fits for application scenario without channel interference.

Phase-domain blind estimation of symbol duration based on Haar wavelet transform

A phase-domain blind estimator of symbol duration based on Haar wavelet transform（HWT） is proposed.It can estimate the symbol duration of phase modulated signals,such as M-ary phase-shift keying（MPSK） signals and polyphase coded signals.The closed form of the spectrum of HWT is derived.Theoretical analysis shows the frequency of the first spectral peak is equal to the symbol rate,which is the reciprocal of symbol duration.Thus the symbol duration can be extracted from the spectrum.Subsequently,the optimum wavelet scale is determined according to the maximum output signal to noise ratio（OSNR） criterion.MAT-LAB simulations show that this algorithm can blindly estimate the symbol duration without any prior knowledge.This estimator need not estimate the carrier frequency and has the characteristics of low computation complexity and high accuracy.

基于深度强化学习的干扰探测共享信号设计

针对当前雷达电子战越来越向着智能化的方向发展、传统干扰机无法适应环境变化、极大地降低了作战效果等问题,考虑将探测信号隐藏在干扰信号中,实现干扰探测共享信号,使侦察干扰机设备发射的干扰信号兼具探测的效果;针对当前干扰探测共享信号中存在的复杂度低、频谱宽度较窄等问题,设计了一种基于多载频多相位编码(multi-carrier phase code,MCPC)的干扰探测共享信号,其具有良好的类噪声宽频谱特性以及较好的距离探测能力和速度探测能力,可以在对目标雷达实现压制干扰的同时对目标信号及周围环境进行隐蔽探测;为了使共享信号能够适应对战场环境的感知与博弈,进一步引入深度强化学习算法对MCPC干扰探测共享信号进行优化;首先在竞争深度Q学习网络(dueling deep Q-learning network,Du DQN)的基础上对Q值进行正则化,解决了Du DQN中易出现的由过估计导致的局部最优问题;其次,在奖励值中引入状态价值函数形成复合奖励值,将其称为复合奖励值竞争深度正则化Q学习网络(composite reward-dueling deep Q-learning network based on regularization,CR-Du DQNReg),使MCPC共享信号对奖励值的敏感度随自身状态调整,自适应优化相位编码初值,达到更好的干扰和隐蔽探测的效果.实验仿真结果表明:经CR-DuDQNReg算法优化后的MCPC共享信号频谱最高幅度提升17.48%,脉压最高幅度提升17.25%,多普勒模糊函数第1旁瓣幅度降低12.69%,且与传统深度强化学习算法相比,CR-Du DQNReg算法的优化效果更好.

EPC-MIMO雷达主瓣距离欺骗式干扰抑制方法

主瓣距离欺骗式干扰对真实目标的估计精度以及目标跟踪的准确性都会产生极大的影响。针对主瓣距离欺骗式干扰抑制问题,基于脉冲编码-多输入多输出(element pulse coding-multiple input multiple output,EPC-MIMO)雷达,针对主瓣距离欺骗式干扰的脉冲重复频率(pulse repetition frequency,PRF)大于等于两个发射脉冲重频情况,提出了一种抑制主瓣距离欺骗式干扰的算法。在EPC-MIMO雷达主瓣距离式干扰抑制算法中,首先利用线性调频信号对雷达系统中雷达发射-接收通道的信号进行幅相误差校正;其次通过分析雷达回波中真、假目标的脉冲信号差异,对EPC-MIMO雷达的回波进行匹配分离,从而获得转发式干扰的规律;最后对雷达回波的筛选达到抑制假目标的目的。通过对雷达实测数据的分析,验证了该方法能够有效解决主瓣距离欺骗式干扰抑制问题,提升雷达在复杂电磁环境的抗干扰性能。

基于粒子群优化算法的相位编码雷达干扰波形优化

间歇采样转发干扰是一种针对相位编码雷达的有效干扰方法,但存在假目标分布滞后的不足,文中在对间歇采样转发干扰研究的基础上,从波形优化角度出发,提出一种基于粒子群优化(PSO)算法的间歇采样转发干扰优化方法。通过对间歇采样脉冲进行相位序列调制的方式,改变干扰信号脉压后的假目标统计特性,然后利用PSO算法对相位调制序列进行优化求解,形成近似压制性效果。结合仿真实验,围绕不同参数条件下的干扰效果进行了对比,验证了该方法的有效性。

一种利用小波降噪的卫星导航信号并行捕获算法

针对全球定位系统(Global Positioning System,GPS)接收机传统捕获算法计算复杂度高、捕获灵敏度低等缺点,提出了一种可降噪的简化并行码相位捕获(Noise Reduction for Simplified Parallel Code Phase Acquisition,NR-SPCA)算法。该算法通过对信号降采样,利用小波变换对二次采样信号作降噪处理,提高了捕获灵敏度;利用GPS信号和C/A码互相关的稀疏性,并行计算降噪后的信号的相关值,提高了运算效率。仿真结果表明,在90%概率捕获成功的前提下,NR-SPCA算法比传统的PCA算法信噪比低1 dB,运算效率提升了100%。该算法还可应用于航天探测、自动驾驶等领域。

基于伪码调相线性调频复合体制测距的优化算法

为了更精确快速地从复杂回波信号中提取出目标信号且使系统具备一定的抗干扰能力,提出了一种基于伪码调相线性调频复合体测距(PRBC)的优化算法——量化-二次相关法,从计算步骤和计算结构两个方面优化,更快速准确得到目标距离信息。算法采用了线性调频(LFM)体制和伪码调相体制,对包含有目标的回波信号进行算法优化后的信号处理,从而得到目标的距离信息。对伪码调相线性调频复合体制雷达的回波信号进行仿真并做优化算法后的信号处理,结果表明了优化算法的有效性,从而为目标测距和干扰抑制提供了一种有价值的方案。

低信噪比下相位编码信号识别技术

为解决低信噪比情况下相位编码信号识别率低的问题,给出了一种基于两级信道化结构和小波变换的调相信号检测方法。采用两级信道化结构进行信号处理提高增益。使用信道化后子信道内的零中频数据进行小波变换,避免了使用小波变换模值检测相位跳变时的小波尺度盲区。仿真结果表明,该方法提高了信号检测的灵敏度,实现了低信噪比环境下相位编码信号的正确检测。

基于相位编码信号的多目标参数测量方法

多目标的高精度参数测量是跟踪雷达的一个难点。由于线性调频信号存在距离-多普勒耦合,在多目标跟踪时需要对每个目标速度进行补偿,而多个目标的速度补偿存在难以匹配的问题。本文提出了一种基于legendre序列的相位编码信号处理方法,可同时实现对多目标的距离和速度测量。该方法利用距离开窗的有限长度在时域进行搜索,相对于传统的频域搜索,实现简单、便于并行处理,且能够提高速度的测量精度。仿真结果验证了该方法的可行性和有效性。

基于矢量信号源的雷达信号产生系统设计

为了满足雷达告警设备的检测需求,设计并实现了一种雷达信号产生系统。该系统硬件基于矢量信号发生器,软件利用Matlab生成基带信号I/Q数据,通过仪器控制工具箱将数据发送到矢量信号发生器,通过TCP/IP通信协议上基于文本的SCPI命令实现系统的总体控制。最后通过生成线性调频脉冲压缩雷达信号具体实例展示该雷达信号产生系统的应用。该设计与通常的雷达信号产生系统相比更具通用性,具有很强的应用和实用价值。

Stimulated-Brillouin-scattering-based arbitrarily phase coded microwave waveform transmitter with anti-dispersion transmission

We focus on photonic generation and transmission of microwave signals in this work.Based on dual-pumped stimulated Brillouin scattering,a single-sideband(SSB)optical signal with high sideband rejection ratio is obtained.Combined with a phase-modulated optical carrier,an arbitrarily phase coded microwave signal is generated after photoelectric conversion.The SSB modulation can eliminate the fiber-dispersion-induced power dispersion naturally,and the phase modulation of the optical carrier can achieve arbitrary phase encoding and suppress background noise.The proposed scheme can achieve both generation and anti-dispersion transmission of arbitrarily phase coded signals simultaneously,which is suitable for one-to-multi long-distance radar networking.