共查询到19条相似文献,搜索用时 218 毫秒
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在分析高斯最小移频键控(GMSK)调制基本原理的基础上,基于直接分解法提出的暂态部分和稳态部分的概念,提出了一种相位累加法实现GMSK调制的方法。给出了采用并行处理的相位累加法实现框图,并对正交调制过程及其频谱和差分解调误码性能进行了仿真分析。仿真结果证明信号具有相位平滑、边缘滚降特性好、带外辐射小、抗干扰能力强等特点,与GMSK信号的各方面特性与理论值相吻合,方案可行。 相似文献
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消除GMSK信号符号间串扰的迭代译码技术 总被引:2,自引:0,他引:2
本文给出了卷积码与GMSK调制器级联系统的一种迭代译码方案.将最大后验概率(MAP)算法应用于GMSK差分相位检测器(DPD)使之能够接收先验信息并给出软输出,实现了解调器与其后的卷积码译码器之间的迭代计算.仿真结果表明,与传统的译码方法相比,新方案对于克服GMSK信号所固有的严重符号间串扰(ISI)有明显的改进. 相似文献
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本文提出了CPM的非相干解调与2状态格状译码的方法,并对GMSK信号进行了误码性能的模拟。结果表明:GMSK的2状态格状译码的比特差错性能,远远优于常规的1比特差分解码的GMSK的比特差错性能。 相似文献
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本文阐述了GMSK调制解调的原理与特点,并对其关键技术进行了分析;介绍了其在FPGA中的硬件实现方案,同时给出了GMSK信号调制解调的仿真图。 相似文献
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GMSK调制信号包络恒定、频谱利用率高,但传统的波形存储正交实现方法在相位路径的计算和存储器地址映射上过于复杂。将高斯滤波器作为独立模块加入MSK调制电路中,得到一种GMSK调制器的简化设计,其具有结构简单、高斯滤波器设计灵活的优点。通过频域和时域仿真验证了GMSK调制器简化设计的有效性。 相似文献
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基于带内扩频技术的无线电台数字通信的设计与实现 总被引:1,自引:0,他引:1
提出了一种采用DS-GMSK体制、基于带内扩频技术的无线电台数字通信方案.分析了伪随机码的设计方法,阐述了扩频及解扩同步、纠错编码、GMSK等部分的实现方法,并给出了实现框图.该方案可方便地给以模拟方式作为语音通信的无线电台增加数据通信及保密通信功能,大大提高了电台的性价比. 相似文献
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为提高现有通信系统中高斯最小频移键控(GMSK)信号的接收性能,提出了一种基于后解码的GMSK相干解调方法.对于接收到的GMSK基带信号,首先完成相位和载波的同步,将信号的初始相位补偿到零相位;然后通过交替抽取GMSK基带信号的虚部与实部幅度采样值完成信息提取;最后通过后续解码处理完成信号解调.仿真表明,在误码率为10-3时,基于后解码的GMSK解调性能仅比预编码GMSK相干解调差0.5 dB,与传统基于维特比迭代处理的GMSK相干解调性能基本相当,但算法实现更为简化,有利于在现有非相干解调GMSK通信系统中的性能提升实现. 相似文献
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一种GSM无源雷达信号模型及模糊函数性质研究 总被引:6,自引:0,他引:6
GSM无源雷达以广泛使用的数字蜂窝通信网GSM基站发射的无线电信号作探测源.本文提出了一种能方便地描述GSM信号的多突发映射模型,建立了GSM信号多突发映射结构图,提供了多突发映射方法,用一个矩阵多次映射可获得多突发的GSM信号数据码.然后在一个突发内,用合成法产生GMSK调制相位,从而得到GSM信号.另外通过观察大量的GSM信号模糊函数,发现GSM信号模糊函数在数据长度较长(多于一帧)时具有单峰性,即这时的GSM信号模糊函数属图钉型.对这个性质进行了多方面探讨说明,并用蒙特卡罗法进行了试验验证. 相似文献
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The absorption and scattering of light in seawater channel cause signal attenuation, and the turbulence of seawater causes signal amplitude fluctuation, both of which will reduce the bit error rate (BER) performance of underwater wireless optical communication (UWOC) system. The effects of the two channel characteristics on the signal performance were considered comprehensively, and a method was proposed to equate the transmission distance and turbulence probability density function to the system signal-to-noise ratio (SNR) and turbulence noise, and then the signal attenuation and turbulence noise were combined into the signal waveform to establish the underwater composite channel signal transmission model. According to the experimental system parameters, the signal transmission waveforms of Gaussian minimum frequency shift keying (GMSK) modulation under composite channel were simulated, and the one-bit difference demodulation algorithm was used to compare the demodulated waveforms with the original waveform, and the influence relationships of composite channel on the system BER performance was analyzed. The simulation experiment results show that, compared with on-off keying modulation (OOK), pulse position modulation (PPM), GMSK system can obtain the SNR gain of 3.3 dB, 4.8 dB respectively only in the attenuation channel with seawater attenuation coefficient of 0.151 m?1. Under the composite channel, GMSK modulation performance is superior to OOK modulation and PPM modulation. When the water attenuation coefficient is 0.151 m?1, and turbulence intensity variance is smaller than 0.16, GMSK modulation system has no error rate limit, the system BER is decided by signal attenuation and turbulence noise and Gaussian noise together, GMSK modulation achieves SNR gain of 4.35 dB compared with PPM modulation. Furthermore, turbulence intensity variance is greater than 0.16, system BER arrives limit, which value is determined by the turbulence intensity, and the limit value of BER increases nonlinearly with the increase of turbulence intensity. 相似文献
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Wallace R.E. Zaky S.G. Balmain K.G. 《Electromagnetic Compatibility, IEEE Transactions on》1995,37(1):75-80
Human electrostatic discharge (ESD) produces a transient current pulse with a very fast risetime, which can be a source of electromagnetic interference in digital devices. The focus of this paper is the radiated susceptibility of D-type flip-flops implemented in various CMOS and TTL logic technologies. A transient impulse was used to simulate the radiated field produced during an ESD event. A synchronized-disturbance testing methodology is developed that allows accurate control of the instant at which the disturbing signal is applied to the data input lines during an operational cycle of the circuit. The study reveals that these devices are susceptible only during certain time intervals during an operational cycle. The particular interval during which a flip-flop is susceptible is dependent on the logic state of the data input line, the implementation technology of the flip-flop, and the amplitude of the disturbing signal. The total width of the susceptibility intervals is a device parameter that can be used to determine the probability that the flip-flop will fail in the presence of random transient interference pulses 相似文献
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This paper proposes a new two-branch amplification architecture that combines baseband signal decomposition with RF front-end optimization. In the proposed architecture, the filtered modulated signals are separated into two components that are then amplified independently and combined to regenerate an amplified version of the original signal. A branch with an efficient amplifier transmits a low-varying envelope signal that contains the main part of the information. Another branch amplifies the residual portion of the signal. The baseband decomposition and parameters of the RF part are optimized to find the configuration that gives the best power efficiency and linearity. For M-ary quadrature amplitude modulation (M-QAM) signals, this technique is limited in terms of power efficiency. However, for filtered continuous phase modulation (CPM) signals, especially for minimum shift keying (MSK) and Gaussian MSK (GMSK) signals, high power efficiency can be achieved with no significant impact on the overall linearity. The results show that this technique gives better performance than the single-ended ctass-B amplifier. 相似文献
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本文提出基于GA-LS指数衰减正弦信号的参数估计方法,根据系统模型特性将待估计参数分成两类,非线性类和线性类,将遗传算法和最小二乘法估计结合起来对参数进行估计。在观察与分析信号的频域特征后,确定各非线性部分的参数范围,采用遗传算法在参数空间里搜索,再用当下最优的非线性类参数,通过最小线性二乘法确定线性类参数。通过缩小了遗传算法的搜索空间维数,考虑了系统的线性部分参数间的约束关系,达到提高参数的搜索效率,提高参数的估计精度。大量仿真实验表明算法收敛速度优于标准遗传算法,精度高。用于估计冲击实验的采集信号满足实际需要。 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》1980,26(2):234-238
A generalized minimum shift keying (GMSK) signal is defined, and its equivalence to a modified offset quadrature shift keying signal is shown. A simple formula for the spectrum of a GMSK signal is presented and the spectrum and out-of-band power are computed for two examples. 相似文献