跳频通信技术研究及仿真分析

跳频通信系统具有较强的抗干扰能力,在现代通信中具有广泛的应用.了解跳频通信基本原理及不同干扰样式下抗干扰性能,能在通信对抗中实施更有效的干扰与反干扰.在对跳频通信基本原理进行分析阐述的基础上,采用Matlab/Simulink对跳频通信系统进行了仿真.针对宽度噪声干扰、 部分频带干扰和单音干扰3种特定干扰样式下跳频通信...     

基于Simulink的跳频通信系统抗干扰性能分析

跳频通信方式是军事通信的主要手段,保证跳频通信系统的正常工作十分重要,研究了跳频通信的几种常见干扰样式,用Simulink仿真工具搭建跳频通信系统仿真平台,并模拟几种常见干扰源,包括宽带或部分频带阻塞干扰、梳状阻塞干扰及跟踪干扰。分别在信道注入各种干扰,得到相应的误码率曲线,分析并评价其抗干扰性能。     

水声跳频通信系统抗干扰性能仿真研究

跳频通信系统与常规定频通信系统相比具有较强的抗干扰能力。在介绍水声跳频通信基本原理的基础上,分析了在部分频带干扰下的跳频通信系统的抗干扰性能,并提出利用信号分集技术解决部分频带干扰问题。借助MATLAB仿真工具,得到不同情况下的误码率．信噪比曲线,从而验证了理论分析的结果。     

跳频通信的抗干扰性能仿真检测

干扰与抗干扰是现代化战争中的博弈,实践表明跳频通信技术具有优良的抗干扰性能。通过讲述跳频通信的基本原理,分析其具有良好抗干扰性能的原因,并利用Matlab软件Simulink模块设计出一种计算机仿真检测模块,检测跳频通信系统的抗干扰性能,分析其在宽带干扰、窄带单频干扰、多频连续波干扰下的误码率,并给出了仿真结果,对设计跳频通信系统具有借鉴作用。     

自适应跳频通信系统抗干扰性能分析

部分频带噪声干扰和多音干扰对常规跳频通信系统危害较大,自适应跳频系统能够改善跳频通信系统的抗干扰性能。基于自适应理论,对两个系统的抗干扰性能进行了仿真和比较,结果表明,自适应跳频通信系统对抗这两种干扰性能较强,适用于军事通信和其它易受人为干扰的通信领域。     

短波自适应跳频通信抗干扰技术研究

针对军事无线通信抗干扰和保密性需求，给出了自适应跳频通信系统模型。采用双态信道模型，深入分析了自适应跳频系统的抗干扰性能。分别在部分频带噪声干扰和多音干扰下，对常规跳频系统和自适应跳频系统性能进行了仿真，结果表明自适应跳频系统对上述两种干扰有较好的抗干扰性能。     

跳频系统抗干扰性能研究

对跳频通信系统抗干扰原理进行了分析,研究了跳频系统对抗两种主要干扰:阻塞式干扰和抗单频干扰的性能,给出了跳频通信系统性能和干扰信号的关系,通过仿真验证进行了验证,并给出结论.     

差分跳频通信系统抗部分频带噪声干扰的性能分析

该文介绍了一种新型的短波跳频通信技术差分跳频。频率转移函数设计和信号的检测方法是差分跳频中的关键技术。针对逐符号检测接收和序列检测线性合并接收两种信号检测接收方法,分别就差分跳频通信系统抗部分频带噪声干扰的性能进行了理论分析,同时做出相应的计算机仿真。结果证实,差分跳频通信技术与序列检测线性合并接收方法的相结合,使通信系统的抗部分频带噪声干扰的性能得到了比较显著的提升。     

衰落信道的快速跳频通信系统抗干扰分析

介绍了跳频通信原理,利用Simulink仿真工具,建立快速跳频通信系统仿真模型,在不同干扰模式下进行仿真,分析了抗干扰性能,并在不同信道下完成仿真,接近真实干扰环境。最终得出结论,快速跳频系统具有较强的抗干扰与多径衰落能力,且随着调频速率的增高,该能力也在增强。     

乘积合并接收的差分跳频通信系统在瑞利衰落信道上抗部分频带干扰的性能分析

该文介绍了一种新型短波跳频通信技术差分跳频,频率转移函数设计和信号的检测方法是差分跳频中的关键技术。在瑞利衰落信道上,在有部分频带干扰和加性高斯白噪声共存的条件下,采用乘积合并接收的方法,对差分跳频通信系统的误符号性能进行了理论分析,同时做出相应的计算机仿真。结果证实了,在瑞利衰落信道上差分跳频通信系统采用乘积合并接收的方法要比采用线性合并接收的方法具备更好的抗部分频带干扰的性能。     

Analysis of an antijam FH acquisition scheme

An easily implemented matched filter scheme for acquiring hopping code synchronization of incoming frequency-hopping (FH) signals is analyzed, and its performance is evaluated for two types of jamming: partial-band noise jamming and partial-band multitone jamming. The system is designed to reduce jammer-induced false alarms. The system's matched filter output is compared to an adaptive threshold that is derived from a measurement of the number of acquisition channels being jammed. Example performance calculations are given for the frequency coverage of the jamming either fixed over the entire acquisition period or hopped, that is, changed for each acquisition pulse. It is shown that the jammer's optimum strategy (the worst case) is to maximize the false alarm probability without regard for the effect on detection probability, for both partial-band noise and multitone jamming. It is also shown that a significantly lower probability of false acquisition results from using an adaptive matched filter threshold, demonstrating that the strategy studied here is superior to conventional nonadaptive threshold schemes     

基于Monte Carlo模型的FFH/BFSK合并技术研究

分析了FFH/BFSK接收机的两种合并方式:平方律线性合并和具有自适应增益控制(AGC)的平方律非线性合并;在部分频带噪声干扰下,使用Monte Carlo模型对这两种合并方式进行仿真得到误码率曲线,仿真结果与理论误码率吻合,并得出结论:在热噪声功率受限的情况下,使用AGC合并能有效的抑制部分频带噪声干扰.     

动态频谱抗干扰系统在部分频带干扰下的性能

为了评估动态频谱抗干扰新体制在抗干扰通信中的性能,采用理论分析与仿真相结合的方法,研究了动态频谱抗干扰系统在部分频带干扰下的信道容量及比特误码率,并将其与常规跳频系统在部分频带干扰下的信道容量及比特误码率进行了比较.结果表明:在很宽的部分频带干扰因子取值范围内,动态频谱抗干扰系统的信道容量均大于常规跳频系统的信道容量,...     

Error-correcting codes and nonlinear diversity combining againstworst case partial-band noise jamming of frequency-hopping MFSK systems

Error probability analyses are performed for a coded M-ary frequency-shift keying system (MFSK) using L hops per M-ary word frequency-hopping spread-spectrum waveforms transmitted over a partial-band Gaussian noise jamming channel. The bit error probabilities are obtained for a square-law adaptive gain control receiver with forward-error-control coding under conditions of worst-case partial-band noise jamming. Both thermal noise and jamming noise are included in the analyses. Performance curves are obtained for both block codes and convolutional codes with both binary and M-ary channel modulations. The results show that thermal noise cannot be neglected in the analysis if correct determinations of the optimum order of diversity and the worst-case jamming fraction are to be obtained. It is shown that the combination of nonlinear combining, M -ary modulation, and forward-error-control coding is effective against worst-case partial-band noise jamming     

Probability of Error Analyses of a BFSK Frequency-Hopping System with Diversity Under Partial-Band Jamming Interference--Part II: Performance of Square-Law Nonlinear Combining Soft Decision Receivers

In this paper, error probability analyses are performed for a binary frequency-shift-keying (BFSK) system employingLhop/bit frequency-hopping (FH) spread-spectrum waveforms transmitted over a partial-band Gaussian noise jamming channel. The performance results for two types of square-law nonlinear combining soft decision receivers under worst-case partial-band jamming are presented. The receivers employ, prior to combining, nonlinear weighting strategies of 1) adaptive gain control and 2) soft limiting (clipping) of the detector output of each channel of the dehopped waveform. Both thermal noise and jamming are included in the analyses. It is shown in the paper that a diversity gain for error rate improvement is realizable for nonlinear combining receivers provided that the noncoherent combining loss is less dominant than the jamming power reduction realized by the weighting strategy. Performance comparisons between linear and nonlinear combining receivers are presented.     

Diversity and Coding for FH/MFSK Systems with Fading and Jamming--Part I: Multichannel Diversity

The performance of diversity and/or coding is evaluated for FH/MFSK signaling over Rayleigh fading channels in the presence of jamming. The effects of partial-band tone and partial-band noise jamming on uncoded and coded systems are considered. The results indicate that FH/MFSK signaling with diversity provides satisfactory performance for jammed fading channels. For coded FH/MFSK signaling over fading channels, noise jamming may be more effective than tone jamming. The amount of improvement resulting from the use of diversity in conjunction with coding depends upon many factors, including the nature of the channel, the degree of channel state information available at the decoder, the type of decoding, and the modulation alphabet size.     

On the probability distribution of differential phase perturbed bytone interference and Gaussian noise

This paper presents a novel method for determination of the general probability distribution of a received differential phase corrupted by both continuous tone jamming and Gaussian noise. An alternative and yet simple expression is derived for this general probability distribution. As an example of its application, we analyze the error performance of a general uncoded SFH/DPSK system under partial-band multitone jamming     

Diversity combining in FH/BFSK systems to combat partial bandjamming

A combiner for a frequency-hopped binary frequency-shift keyed (FH/BFSK) system, called the product-combining receiver (PCR), is introduced. The performance of the PCR is evaluated for the cases of an on/off partial-band noise with optimum-jamming fraction, and worst-case, partial-band tone jamming. The performance of PCR is shown to be comparable to that of the clipper receiver. The effect of diversity combining, along with convolutional coding and ratio-threshold technique, is analyzed. Whereas the clipper requires the knowledge of signal-to-noise ratio for threshold adjustments, the PCR does not require this knowledge for this operation     

Limiter-differential detection of a frequency-hopped CPFSKdiversity system in partial-band jamming

The error probability achieved by a differential detector with a bandpass limiter preceding the receiver is analyzed for a slow-frequency-hopped CPFSK diversity waveform transmitted over a partial-band noise jamming channel, and is compared to the system's performance without the bandpass limiter. The system's thermal noise is not neglected in the analysis. In principle, each bit is repeated on L different hops, and for the FH/CPFSK system analyzed, these repetitions are combined to yield a soft decision. The main result is that a diversity gain for error rate improvement in worst-case partial-band jamming is realized with the detector preceded by a limiter, but not without the limiter. This is shown by considering the error probability for L=2 in comparison with that for L=1