共查询到20条相似文献,搜索用时 937 毫秒
1.
2.
3.
基于时频表示的跳频信号分析 总被引:4,自引:0,他引:4
针对跳频信号的非平稳性,提出了基于时频表示的跳频信号分析方法。该方法能够有效地描绘出跳频信号的频率随时间跳变的规律 (跳频图案 ),具有很高的时间 -频率分辨率,同时能够有效抑制或减小交叉项的干扰,计算时可采用递归算法,运算量较小,因此能够满足跳频系统的快速分析、跟踪、测量等要求。计算机仿真验证了应用时频表示法分析跳频信号的有效性和实用性。 相似文献
4.
DTMF信号具有优良的抗干扰性能和一定的抗多普勒频移的能力,广泛应用于语音信道的低速数据通信。文中分析了地-空短波通信的多普勒频移、基于Goertzel算法的DTMF信号解码基本原理和基本过程;在语音噪声背景下,基于Goertzel算法,解算了16个频点的信号幅值,对地—空短波通信的多普勒频移对DTMF信号解码性能的影响进行了仿真,得出了在语音和多普勒频移干扰的背景下,信噪比高于9dB时,基本可实现DTMF信号的高可靠检测的结论。 相似文献
5.
扩频系统具有抗干扰能力强、保密性能好、信号功率谱密度低、能多址兼容等优点,因而很受人们重视。跳频扩频是扩频系统的一种模式,它是通过信号载波频率在一定范围内的跳跃来实现的。跳跃的规律一般由伪随机码来控制,这个码称为跳频码。在跳频码控制下,载波的周期性变化序列称为跳频图样。而高速跳频系统是指每秒频率跳变在 相似文献
6.
针对传统方法对DS/FH(直接序列扩频/跳频扩频)系统的综合性能测试不够全面有效的问题,提出通过最低性能指标约束法对系统抗干扰性能进行综合分析。以音调干扰、窄带噪声和脉冲干扰3种典型干扰为例,探讨了这3种干扰在不同参数条件下对最低性能指标的影响。并且进一步分析了动态条件下多普勒频偏对DS/FH系统捕获性能的影响。为便于对系统的综合性能进行定量分析,给出最低性能指标约束下的系统综合性能评价指标。最后通过实例分析说明了系统综合性能评估方法的正确性与有效性,该方法对DS/FH这一复杂系统的测试具有指导意义。 相似文献
7.
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. 相似文献
8.
9.
10.
CAN总线是一种多主方式的串行总线.本文设计实现了基于高级RISC处理器(ARM)的CAN协议通信系统,具有高抗干扰性和良好的实时性,应用简单、可靠性高、开发成本低.本文详细介绍了该系统的硬件设计,软件设计,以及通信测试结果. 相似文献
11.
Scholtz R.A. Kappl J.J. Nahi N.E. 《IEEE transactions on aerospace and electronic systems》1976,(2):117-126
Pulse train detection of fluctuating targets whose coherence time is long compared to the time between pulses and short compared to the pulse train duration is compared for two systems: (1) a recursive digital optimal receiver operating in conjunction with a coherent pulse train transmitter, and (2) a good (but not optimal) receiver operating with a block coherent frequency-hopping transmitter. The equivalence of this type of problem to noise-in-noise detection problems is demonstrated, the performance relations for both systems are derived and comparisons are made. 相似文献
12.
13.
14.
一种新的无人机数据链抗干扰技术研究(英文) 总被引:2,自引:0,他引:2
Huang Wenzhuna * Wang Yongshenga Ye Xiangyangb aSchool of Electronics Information Northwestern Polytechnical University Xi’an China bTelecommunication Engineering Institute Air Force Engineering University Xi’an China 《中国航空学报》2008,21(2):141-148
Based on the M-ary spread spectrum (M-ary-SS), direct sequence spread spectrum (DS-SS), and orthogonal frequency division multiplex (OFDM), a novel anti-jamming scheme, named orthogonal code time division multi-subchannels spread spectrum modulation (OC-TDMSCSSM), is proposed to enhance the anti-jamming ability of the unmanned aerial vehicle (UAV) data link. The anti-jamming system with its mathematical model is presented first, and then the signal formats of transmitter and receiver are derived. The receiver's bit error rate (BER) is demonstrated and anti-jamming performance analysis is carded out in an additive white Ganssian noise (AWGN) channel. Theoretical research and simulation results show the anti-jamming performance of the proposed scheme better than that of the hybrid direct sequence frequency hopping spread spectrum (DS/FH SS) system. The jamming margin of the OC-TDMSCSSM system is 5 dB higher than that of DS/FH SS system under the condition of Rician channel and full-band jamming, and 6 dB higher under the condition of Rician channel environment and partial-band jamming. 相似文献
15.
制导武器系统抗干扰可分解为串联关系的2个过程,即导引头抗干扰过程和控制系统抗干扰过程。本文用贝努力方法计算抗干扰性能的概率及其置信区间,推导出计算方法,用蒙特卡洛方法仿真验证,得出贝努力方法可以有效地估计制导武器系统抗干扰性能置信区间的结论。 相似文献
16.
针对以往雷达网抗干扰效能评估不具有直观性、脱离战场地形环境的缺点,设计了一种基于GIS的雷达网抗干扰效能评估系统,实现了可视化的雷达网抗干扰效能评估。仿真应用表明,此系统具有较高的推广和实际应用价值。 相似文献
17.
针对DS/FH(Direct Sequence/Frequency Hopping,直扩/跳频)混合扩频测控系统抗干扰问题,提出一种效能评价方法.基于任务需求,构建系统抗干扰效能评估指标体系;将三角模糊数、指数标度和层次分析法相结合,提出一种改进的TFN-AHP(Triangular Fuzzy Number-Analytic Hierarchy Process,三角模糊数-层次分析法),提高了较小指标的区分度,剔除了极端数据,最大限度发挥专家的经验知识,实现了指标赋权的客观程度,最后通过AHP对不同设备系统关于指标体系判断矩阵的确定、一致性检验和层次总排序,实现了系统抗干扰效能的评价和选择.分析结果表明,该评价方法能够实现不同设备的抗干扰效能评估,有助于用户对设备的选择. 相似文献
18.
19.
When a pseudo-random frequency-hopping signal is intercepted by a conventional receiver operating within the same frequency band, the interfering signal has the form of a pulse-amplitude modulated signal. Each pulse amplitude is dependent upon the hopping frequency and the selectivity characteristic of the victim receiver. The probability density function for the interfering pulse amplitude prior to demodulation is determined when the probability density function for the hopping frequency is uniform and the victim-receiver characteristic is 1) ideal flat bandpass, 2) single tuned, and 3) Gaussian shaped. It is shown that the average interfering pulse amplitude and interference power decrease as the frequency-hopping bandwidth increases with respect to the victim-receiver bandwidth. Fast Fourier transform computer techniques are used to obtain the probability density function of the interference amplitude in a Gaussian receiver when several (from 2 to 10) pseudo-random frequency-hopping systems are simultaneously using the same frequency band. The probability that the interference exceeds a prescribed threshold value is computed from the derived probability density functions. This probability may be used in signal-to-interference ratio calculations, to describe the capture effect, or to compute the expected number of clicks produced in an FM discriminator. 相似文献
20.
网电空间数据链的认知抗干扰技术 总被引:1,自引:0,他引:1
为了增强复杂电磁环境中网电空间数据链的抗干扰能力,提出了基于发送-感知-接收(T-S-R)工作模式的同时收发认知抗干扰(SCAJ)技术,通过在感知/接收周期内动态分配感知、接收时隙而实现实时抗干扰。针对所提同时收发抗干扰策略,研究了基于能量检测的干扰感知性能,推导出衰落信道下干扰检测概率的闭式表达,并分析了同时收发认知抗干扰系统容量。仿真结果表明,提出的同时收发认知抗干扰技术提升了网电空间数据链的干扰感知能力,且在自干扰较低时能够提高网电空间数据链系统容量。 相似文献