Performances of BPSK, balanced quaternary modulation, dual quaternary modulation and complex quaternary modulation in direct sequence spectrum spread (DS SS) system are discussed in this paper. Based on the crit...Performances of BPSK, balanced quaternary modulation, dual quaternary modulation and complex quaternary modulation in direct sequence spectrum spread (DS SS) system are discussed in this paper. Based on the criterion the power of original signal is the same, it is shown that complex quaternary modulation has the best performance, and dual quaternary modulation degrades 2dB. Moreover, the frequency efficient of the two modulations is 2bit/Hz. Balanced quaternary has the same performance as BPSK with frequency efficient 1bit/Hz.展开更多
A novel monolithic digitalized random carrier frequency modulation spread-spectrum clock generator （RCF-SSCG） is proposed.In this design,the output frequency of the proposed RCF-SSCG changes with the intensity of th...A novel monolithic digitalized random carrier frequency modulation spread-spectrum clock generator （RCF-SSCG） is proposed.In this design,the output frequency of the proposed RCF-SSCG changes with the intensity of the capacitive charge and discharge current.Its analytical model is induced and the effect of the modulation parameters on the spread spectrum is numerically simulated and discussed.Compared with other works,this design has the advantages of small size,low power consumption and good robustness.The circuit has been fabricated in a 0.5μm CMOS process and applied to a class D amplifier in which the proposed RCF-SSCG occupies an area of 0.112 mm^2 and consumes 9 mW.The experimental results confirm the theoretical analyses.展开更多
根据上扫频和下扫频线性调频(LFM)信号的特性,针对传统的超宽带无线通信系统中线性调频扩频技术存在的调制效率低、误码率性能低、实现复杂高等问题,结合线性调频(Chirp)扩频以及循环移位编码(CCSK)扩频,提出了一种基于线性调频信号的...根据上扫频和下扫频线性调频(LFM)信号的特性,针对传统的超宽带无线通信系统中线性调频扩频技术存在的调制效率低、误码率性能低、实现复杂高等问题,结合线性调频(Chirp)扩频以及循环移位编码(CCSK)扩频,提出了一种基于线性调频信号的循环移位线性调频扩频技术(CSCSS)。首先,将输入数据映射在循环移位因子(CSF)上;然后,根据CSF数值对基带所产生的Chirp信号进行循环移位达到调制的目的;最后,在解调端经过加窗处理、快速傅里叶变换(FFT)得到与发射端对应的CSF,从而得到发送的数据。误符号率的仿真结果与理论推导公式相吻合,从调制效率和误码率性能上讲,该方案相比线性调频二进制正交键控(Chirp BOK)系统具有超过10 d B的误码率性能。因此,该方案具有更好的误码率性能、更高的调制效率及实现更低的复杂度。展开更多
针对无人机数据链系统中下行宽带信号的隐蔽性和抗截获性不足的问题,提出宽带多进制正交扩频方案,结合宽带多进制正交扩频调制器的要求,设计了基于多相结构的FIR成形滤波器及高中频数字调制器。阐述了成形滤波的基本原理,高速FIR成形滤...针对无人机数据链系统中下行宽带信号的隐蔽性和抗截获性不足的问题,提出宽带多进制正交扩频方案,结合宽带多进制正交扩频调制器的要求,设计了基于多相结构的FIR成形滤波器及高中频数字调制器。阐述了成形滤波的基本原理,高速FIR成形滤波器的多相结构,运用Matlab和Quartus Ⅱ软件设计了多相成形滤波器,并且采用并行直接数字频率合成(Direct Digital Synthesis,DDS)和高速DA实现了宽带扩频数据高中频数字调制。结果表明,采用该设计方法的调制器具有良好的频谱特性。展开更多
基金ThisprojectwassupportedbytheKeyProjectoftheNaturalScienceFoundationofChina (No .6 98310 30 )
文摘Performances of BPSK, balanced quaternary modulation, dual quaternary modulation and complex quaternary modulation in direct sequence spectrum spread (DS SS) system are discussed in this paper. Based on the criterion the power of original signal is the same, it is shown that complex quaternary modulation has the best performance, and dual quaternary modulation degrades 2dB. Moreover, the frequency efficient of the two modulations is 2bit/Hz. Balanced quaternary has the same performance as BPSK with frequency efficient 1bit/Hz.
基金Project supported by the National Natural Science Foundation of China(No.60436030).
文摘A novel monolithic digitalized random carrier frequency modulation spread-spectrum clock generator （RCF-SSCG） is proposed.In this design,the output frequency of the proposed RCF-SSCG changes with the intensity of the capacitive charge and discharge current.Its analytical model is induced and the effect of the modulation parameters on the spread spectrum is numerically simulated and discussed.Compared with other works,this design has the advantages of small size,low power consumption and good robustness.The circuit has been fabricated in a 0.5μm CMOS process and applied to a class D amplifier in which the proposed RCF-SSCG occupies an area of 0.112 mm^2 and consumes 9 mW.The experimental results confirm the theoretical analyses.
文摘根据上扫频和下扫频线性调频(LFM)信号的特性,针对传统的超宽带无线通信系统中线性调频扩频技术存在的调制效率低、误码率性能低、实现复杂高等问题,结合线性调频(Chirp)扩频以及循环移位编码(CCSK)扩频,提出了一种基于线性调频信号的循环移位线性调频扩频技术(CSCSS)。首先,将输入数据映射在循环移位因子(CSF)上;然后,根据CSF数值对基带所产生的Chirp信号进行循环移位达到调制的目的;最后,在解调端经过加窗处理、快速傅里叶变换(FFT)得到与发射端对应的CSF,从而得到发送的数据。误符号率的仿真结果与理论推导公式相吻合,从调制效率和误码率性能上讲,该方案相比线性调频二进制正交键控(Chirp BOK)系统具有超过10 d B的误码率性能。因此,该方案具有更好的误码率性能、更高的调制效率及实现更低的复杂度。
文摘针对无人机数据链系统中下行宽带信号的隐蔽性和抗截获性不足的问题,提出宽带多进制正交扩频方案,结合宽带多进制正交扩频调制器的要求,设计了基于多相结构的FIR成形滤波器及高中频数字调制器。阐述了成形滤波的基本原理,高速FIR成形滤波器的多相结构,运用Matlab和Quartus Ⅱ软件设计了多相成形滤波器,并且采用并行直接数字频率合成(Direct Digital Synthesis,DDS)和高速DA实现了宽带扩频数据高中频数字调制。结果表明,采用该设计方法的调制器具有良好的频谱特性。
