同时传输遥测和伪码测距信号的GMSK技术

介绍了一种同时传输遥测和伪码测距信号的GMSK(高斯最小偏移键控)技术,分析了其调制及解调原理,推导了相关调制、解调及频谱公式,并与UQPSK(非平衡四相相移键控)体制进行了比较。通过对其频谱及误码性能的仿真分析得出,在非线性信道和高码速率下,基于GMSK体制的遥测和伪码测距系统比基于UQPSK体制的系统在包络恒定和频谱利用率方面具有明显优势。     

一种新型交流恒功率负载仿真模型

根据闭环控制的高功率因数(HPF)脉冲宽度调制(PWM)整流器的恒功率工作特性,对交流(AC)恒功率负载(CPL)仿真模型进行了研究。采用输入电流波形跟随电压波形的方法,利用MATLAB建立了交流恒功率负载的仿真模型。在模型两端加载的电压不含谐波和含有谐波的两种情况下,模型均可以自动计算出输入电流有效值(RMS),使得模型输入平均功率保持恒定,并能生成电流波形,反映出电压谐波对电流波形的影响。模型仿真结果与实际高功率因数PWM整流器的输入波形进行了比较,验证了该模型的正确性。     

变换域通信系统及其关键技术

变换域通信系统通过信道估计在变换域设计信号波形避开干扰,它没有采用载波调制,而是用一个类似噪声的基函数进行信息调制。论述了变换域通信系统的基本概念,对变换域通信系统的关键技术——环境干扰估计与检测、基函数序列与波形设计、调制解调与高速率数据传输进行了分析,最后指出了其应用前景。     

基于滑模观测器的永磁同步电机无传感器控制系统的优化研究

为了优化传统基于滑模观测器(SMO)的永磁同步电机(PMSM)无传感器控制系统的性能,分析了传统控制系统中相应模块的数学模型和控制算法存在的问题,建立了优化的基于SMO的PMSM无传感器控制系统模型并进行了仿真。通过分析传统SMO的数学模型,在保证SMO满足Lyapunov稳定条件的前提下,根据电机不同工况对滑模增益进行实时优化,提高了SMO的观测性能。为了提高锁相环(PLL)输出信号的质量,在PLL输入端加上低通滤波器,并对低通滤波环节造成的位置角度偏差进行补偿。通过仿真验证上述所采用优化策略的正确性和可行性,结果表明:优化模型在保证系统动态性能的同时能够获得比传统观察系统质量更高的观测信号。     

旋转捷联惯导系统原理及典型方案分析

旋转捷联惯导系统采用旋转调制误差补偿技术对陀螺仪和加速度计误差进行调制,可以提高系统导航精度。文章借助捷联系统基本误差方程,简要分析了旋转调制误差补偿的机理;通过对几种典型IMU旋转方案的分析和仿真,验证了旋转调制误差补偿技术的有效性并比较了不同旋转方案的特点。     

用于非线性有源天线的耦合锁相环特性分析

为实现非线性有源天线阵波束扫描,研究了互耦锁相环(PLL)的基本特性。通过对互耦PLL的相位动力学方程的稳定性进行分析,建立了具有延时的阵列模型;通过调节环路延时,互耦PLL不同的非线性动力学特性;采用四单元的耦合锁相环阵列实验电路对理论分析进行了验证,从而提出了在设计基于耦合锁相环的非线性有源天线时,必须对环路延时进行控制,防止环路出现振荡和混沌现象。     

300 MVA脉冲发电机组滑差方式起动过程研究

介绍了300 MVA脉冲发电机组的滑差装置。对机组采取滑差方式的起动过程进行了分析和等效建模。根据机组实际起动过程电气波形,利用非线性规划模型,建立了滑差装置液体电阻等效仿真模型,并代入机组参数对起动过程进行仿真,仿真结果和实际波形吻合,验证了模型的正确性。在此基础上,为了使机组的转速达到额定转速,提出在滑差装置液体电阻低位时并入两级固体金属电阻后短接的方案,给出了两级固体金属电阻的阻值等理论参数,并通过仿真验证了方案的可行性。建立的仿真模型可以作为研究不同参数、不同控制策略下的机组起动过程动态特性的重要工具。     

无人机高速DS/FH混合扩频通信系统关键模块设计

针对UAV(Unmanned Aerial Vehicle,无人机)测控链路高抗干扰需求,给出了实现跳频速率20 000次/s的扩跳混合无人机测控数据链系统实现方案.系统采用跳频频率并行捕获模式.跳频源设计采用直接频率合成、DDS(Direct Digital Synthesis,直接数字频率合成)和PLL (Phase-Locked Loop,锁相环)相结合的混合频率合成技术.利用相位响应滤波器,通过正交调制技术完成MSK(Minimum Shift Keying,最小频移键控)、GMSK (GaussianMinimum Shift Keying,高斯最小频移键控)调制.通过推导得出2 bit差分解调输出与载波频率选择有关,且为四分之数据率的整数倍关系.然后通过实例分析给出了跳频频率间隔选取方法,即跳频间隔应当将临近跳频的主瓣分开,同时跳频载波频率应当设在其他跳频频谱的零点处.最后总结了高速扩跳频系统参数设计一般步骤.     

一种基于自适应滤波器的潜艇辐射噪声仿真方法

文章提出了一种基于自适应滤波器的潜艇辐射噪声仿真方法。在对潜艇辐射噪声连续谱、线谱和调制谱的数学模型进行研究的基础上,利用Ecs型功率谱模型,基于自适应滤波器,通过傅里叶反变换对潜艇辐射噪声连续谱进行了仿真,分别叠加了线谱信号和调制谱信号之后,得到潜艇辐射噪声的仿真结果。通过对仿真结果的分析和利用仿真结果与实装进行对接测试,表明仿真的辐射噪声逼真度较高。     

基于PNFM-LFM复合调制的探测干扰共享波形设计

针对雷达-电子战一体化共享信号波形的设计需求,提出一种伪码噪声调频与线性调频复合调制的探测干扰共享波形。在伪码序列的伪随机性和规律性上,通过理论推导和仿真实验,分析并验证了该探测干扰共享波形具有良好的模糊函数以及线性可控的频谱特征,有效通带内干扰功率利用率平均可达38%;通过探测干扰共享信号的相关信号处理,本地接收机能够成功地对信噪比不低于-27 dB的回波信号进行检测,且改善因子可达30 dB。     

A Semi-Empirical Approach to the PLL Threshold

This correspondence considers the response of the PLL near threshold to an input consisting of a modulated carrier and white, Gaussian noise. For high input signal-to-noise power ratios ?, the output noise power is Gaussian with a parabolic spectrum. As ? is decreased, the PLL tends to lose lock which gives rise to impulses or ?spikes? in the output with a resulting white power spectrum. The additional output noise due to these ?spikes? causes a threshold in the output signal-to-noise ratio. Unfortunately the loss of lock rate in the PLL depends on the modulation as well as the noise power. A semiempirical approximate expression for the loss of lock rate as a function of the noise and sinusoidal frequency modulation is presented and is used to determine the optimum design procedure for PLL's to demodulate FM signals of varying modulation indexes, ?.     

双绕组感应发电机静止励磁调节器的锁相环研究

双绕组感应发电机具有随负载变化调节励磁磁场、保持负载电压恒定不变的优点,通过静止励磁调节器输出的有功电流控制母线电压、无功电流控制负载电压,两者经过坐标变换形成反馈电流,实现系统的闭环控制。锁相环(PLL)为坐标变换提供相位信息,选用合适的PLL可以提高坐标变换的动静态性能,为控制系统提供快速准确的反馈信息。分析了双绕组感应发电机励磁电压的特点,分析了双dq变换PLL、延时信号对消PLL、基于延时信号对消的滑动平均滤波PLL的各自工作特点,最后优选了基于延时信号对消的滑动平均PLL检测励磁电压相位。     

一种用于深空测距的数字化锁相环设计

在深空测距中，扩大锁相环捕获范围与提高锁相环对微弱信号检测能力是一对矛盾。为解决这一矛盾，本文提出一种基于频率引导与二次混频的数字化锁相环结构，并对其性能进行理论分析和计算机仿真。仿真结果表明，该锁相环可以很好地在较大范围内实现对微弱测距信号的捕获锁定。该结构已在实际测距接收机中使用。     

PAM approach to weak CPM and its application to flight termination receivers

A method for computing the PAM representation for weak continuous phase modulation (CPM) is presented and applied to the modulation defined in the enhanced flight termination system (EFTS) standard. The pulse-amplitude modulation (PAM) representation was used to formulate a reduced-complexity detector whose performance is within 0.7 dB of maximum likelihood detection and 5.6 dB better than limiter-discriminator detection in the additive white Gaussian noise (AWGN) environment. The complexity of the reduced-complexity detector is less than 25% that of the maximum likelihood detector but, unlike the limiter-discriminator detector, requires a carrier phase PLL. In the presence of phase noise, the reduced-complexity detector outperforms limiter-discriminator detection when the RMS frequency deviation due to phase noise is less than 10% of the bit rate.     

Phase-Lock Loop Jump Phenomenon in the Presence of Two Signals

Jump phenomena are known to exist in many non-linear systems [I], [2], [3]. The non-linear analysis presented in this paper explains and predicts the conditions for the jump phenomenon that is observed in a phase-locked loop (PLL) preceded by an automatic gain control (AGC). The jump phenomenon occurs when the frequency separation AM of two sinusoids at the input to the AGC is greater than the bandwidth B of the linearized PLL. If the loop is initially locked to the stronger signal, the weaker signal will frequency-modulate the PLL voltage-controlled oscillator (VCO) with a modulation frequency AI. The amplitude S2 of the weaker signal al can be increased until it becomes greater than the amplitude Si of the signal being tracked, without causing the loop to lose lock; i. e., the VCO continues to track the original signal. However, if the ratio of the amplitudes S2 S1 = R is increased above some critical value RC > 1, the loop will lose lock on the original signal, and jump to track the interfering signal. If the frequency separation is at least twice the PLL bandwidth, a good approximation for this critical ratio is Rc ? ?w/B.     

基于DDS+PLL的光源调制与功率稳定控制方法CSCD

量子传感器是基于量子操控技术的研究成果,一般具有高精度、小体积等优势。激光器是量子传感器的核心部件,有抽运和检测功能,激光器的稳定性对量子传感器具有重要的意义。提出了一种直接数字合成法(DDS)与锁相回路(PLL)相结合的方法,对激光器进行调制并抑制调制噪声,实现了激光器的稳定输出。基于现有小型量子传感器装置,在DDS生成4kHz参考信号的情况下实现了激光器电流8kHz调制,抑制了调制时调制电流信号噪声约8dB,并提高了激光器输出光功率的稳定性。     

Analysis of interference effects on monopulse radars

The complete numerical analysis of angle-tracking performance of a coherent amplitude-comparison monopulse radar system in a two-target situation is described. This system, equipped with automatic gain control (AGC) and phase-locked loop (PLL), was originally invented for improving the target-tracking performance in multiple-target situation. The general behavior depends on Doppler separation of the targets relative to the bandwidths of AGC and PLL. The performance of this system has previously been roughly analyzed by using linear approximation for four extreme cases: wideband and narrowband AGC in combination with wideband and narrowband PLL. In this study, the author performs nonlinear analysis of the same system for all bandwidths of AGC and PLL, because Doppler separation varies over a wide range in actual tracker, and therefore it is indispensable to know the total system behavior. A special numerical technique called the Galerkin method is used. As a result of this analysis, the extensive target-tracking performance for all intermediate bandwidths of AGC and PLL has been clarified. The result is useful for actual target tracker design     

Optimum Acquisition of the Idling First-Order Phase-Locked Loop

Acquisition of the idling first-order phase-locked loop (PLL) is investigated. An analytical solution for the Fokker-Planck equation is found if the noise term is neglected. Furthermore, the modulation signal that optimizes the acquisition is obtained by use of phase-plane techniques and Pontryagin's minimum principle.     

主字母体制调制系数的选择

针对靶场安全控制系统主字母体制中主字母信号的调制系数选取范围问题,对主字母信号经FM (Fre-quency Modulation,调频)调制后的功率进行理论分析,选取一组频率组成主字母信号调制到中频.通过仿真得到数据曲线.同时将仿真参数移植到与工程设备相似的实验设备上,使用频谱仪进行实际测试,以测试数据拟合出曲线,该曲线符合理论分析及仿真曲线,即理论分析、仿真与设备测试结果一致.可以得出结论,在主字母体制信号可解调的条件下,调制系数与主字母信号经FM调制后的功率的关系函数为对数函数,从而可为工程参数的选择提供参考范围,有利于工程应用.