基于PM 的多功能超宽带调制技术的研究

基于相位调制器(PM)级联高斯带通滤波器,提出了一种超宽带(UWB)多功能调制方案,可以实现通断键控(OOK)、脉冲极性调制(PBM)和脉冲形状调制(PSM)。该方案结构简单,只需单个光源,利用率较高,仅改变比特序列发生器(BSG)的编码就可实现三种UWB调制格式间的灵活切换;产生的三种信号只包含一个波长,在光纤中传输时无需复杂的非线性控制和色散管理。使用光通信软件Optisystem进行模拟,研究了光源功率、调制速率以及两支路PM和滤波器系统误差的影响,对OOK、PBM和PSM信号的传输性能进行了分析。结果表明,光源功率和调制速率在一定范围内变化时,可以获得性能最佳的UWB调制信号。     

一种基于相位调制器的40 GHz OFDM-ROF系统实验研究

实验研究了一种基于相位调制器(PM)并级联强度调制器(IM)实现40 GHz毫米波传输正交频分复用(OFDM)信号的光纤无线通信(ROF)系统。在中心站,采用20 GHz的射频(RF)信号驱动PM,调节驱动信号的强度,使输出的信号经光纤布拉格光栅(FBG)滤除中心载波后再送入IM。2.5 Gbit/s的OFDM信号直接调制在光毫米波上,经过50 km标准的单模光纤(SSMF)传输到基站。在基站,光调制信号经光电转换器(PD)转换成电调制信号,再与RF信号混频,恢复出基带OFDM信号。实验结果表明,在无色散补偿、误码率(BER)为10-3的条件下,下行链路中2.5 Gbit/s的OFDM信号经光纤传输50 km后,其功率代价小于1 dB,而且信号的星座图依然较好。     

基于半导体放大器实现多功能超宽带调制的研究

基于半导体放大器(SOA)的增益饱和效应,提出了一种简单的实现多功能超宽带(UWB)调制的方案。方案采用一个光源和单个SOA,可以实现脉冲波形调制(PSM)、脉冲幅度调制(PAM)和脉冲极性调制(BPM),因此实现容易、结构简单和成本低。利用OptiSystem软件对方案进行了仿真研究,分析了各参数对调制信号的影响以及信号的传输特性。结果表明,本方案对光源的波长和光源的光功率的变化不敏感,仿真输出的调制信号在单模光纤(SMF)中可传输35km。     

基于光纤光栅的超宽带信号产生与传输

针对现有方法功率利用率低与调制实现困难的问题,采用基于光纤光栅（FBG）的超宽带（UWB）调制信号产生方法,建立了UWB信号产生系统。不仅可以实现UWB信号的调制,而且提高了产生信号的信噪比。实现了二进制相位调制（BPM）、脉冲幅度调制（PAM）和脉冲位置调制（PPM）等UWB信号产生。分析了光纤传输对产生信号的影响,...     

基于FPGA无线光通信PPM调制解调的设计

调制与解调是无线光通信中的一项关键技术。目前的无线光通信系统大多设计为光强度调制/直接检测(IM/DD)系统。开关键控(OOK)作为最早的调制方式由于易于实现而被广泛使用。但OOK调制功率效率和带宽利用率有限,易受大气噪声影响。为了进一步提高数据传输效率,提出了脉冲位置调制(PPM)技术,它具有较高的平均功率效率,较强的抗干扰能力,能够较好地满足信号传输要求。通过使用QuartusII12.0软件,编写Verilog代码并反复调试,实现了4-PPM设计。     

基于单边带调制的直接探测光OFDM-RoF系统研究

研究基于单边带调制(SSB)的直接探测光正交频分复用-光载射频(OFDM-RoF)系统的性能。10Gbit/s的二进制数据信号经过QAM符号映射和OFDM调制后,与10GHz射频信号混频并驱动双电极LiNbO3马赫-曾德尔调制器(LN-MZM)产生SSB-OFDM信号,调制信号通过光纤传输至基站,进行直接探测转换为毫米波电信号后再无线发送到用户端。仿真结果证实,OFDMRoF系统在4QAM和16QAM两种调制格式下的EVM都满足FEC的要求。同时,理论分析并仿真验证存在一个最佳调制指数可以使信号传输性能达到最佳,并且最佳调制指数与光纤长度无关。     

利用微结构光纤进行全光再生的实验研究

利用自相位调制(SPM)效应和窄带滤波器,在高非线性微结构光纤(MF)中实现了全光2R再生,获得了无波长变换的再生信号。实验中,再生前的信号由经过一段普通单模光纤(SMF)和衰减器的10Gb/s脉冲信号获得,两段MF的非线性系数均为36W-1·km-1。通过两级2R再生后,获得了与初波长相同的再生信号,再生效果良好。实验结果表明,高非线性MF在全光再生方面有很大的应用潜力。     

基于SOA和EAM的全光超宽带脉冲波形调制

提出了一种基于半导体光放大器(SOA)和电吸收调制器(EAM)实现超宽带(UWB)脉冲波形调制(PSM)的方案,利用SOA的交叉增益调制(XGM)和增益饱和效应产生高斯单边带(monocycle)信号,利用EAM的交叉吸收调制(XAM)效应控制泵浦光与monocycle信号的叠加,进而实现UWB PSM。与其它方案相比,本文方案具有结构简单、易于控制和色散管理相对简单的优势。利用OptiSystem7.0软件进行了仿真研究,分析了输入信号功率、调制速率和光源波长对UWB PSM信号的影响,研究了UWB PSM信号在光纤中的传输特性。结果表明,本文方案对输入信号波长不敏感。给出了输入信号功率和调制速率的优化范围。     

基于LDPC-OFDM编码调制的无源光网络

在无源光接入网中,利用高编码增益的前向纠错编码和先进的调制技术可以降低系统对发射功率的要求,提升网络性能。本文将低密度奇偶校验(LDPC)码和正交频分复用(OFDM)调制技术引入无源光网络(PON),构建基于LDPC-OFDM编码调制的无源接入网系统,在20km单模光纤(SMF)上实现10Gbit/s LDPC-OFDM编码调制信号的下行传输,2Gbit/s编码OOK信号的上行传输。误码率(BER)均为10-3时,在下行链路LDPC-OFDM编码调制较未采用编码调制系统性能提升了3.9dB;在上行链路,LDPC编码信号性能较RS(255,223)和RS(255,239)分别有1.8dB和2.3dB的提升。     

光纤声光调制器的高频驱动器

光纤声光调制器驱动器作为光纤激光器的重要组成部分,其性能参数对激光品质具有重要影响。该文设计了高频、高功率驱动器方案。该方案通过20²00kHz脉冲信号控制模拟开关实现脉冲信号和150 MHz载波信号的二进制幅度键控(2ASK)调制,调制信号经功率放大器放大,进行阻抗匹配后输出到声光调制器,驱动声光调制器工作。驱动信号的频率为20200kHz脉冲信号控制模拟开关实现脉冲信号和150 MHz载波信号的二进制幅度键控(2ASK)调制,调制信号经功率放大器放大,进行阻抗匹配后输出到声光调制器,驱动声光调制器工作。驱动信号的频率为20²00kHz,功率为3 W。     

Effects of phase noise on subcarrier modulation performance over Malaga turbulence channel

The performance of wireless optical system employing subcarrier phase-shift keying modulation was researched,which was influenced by phase noise of system demodulator under on Malaga atmospheric turbulence channel.Combined Fourier series and MeijerG function properties,the probability density function of instantaneous signal to noise ratio in the Malaga turbulence model was got.The Fourier series of receiving signal phase and the closed form expression of symbol error probability were derived,which were in the wireless optical subcarrier shift keying modulation system.Under different modulation order and light intensity fluctuation variance,the influence of phase noise on the system symbol error rate was analyzed.The numeric results present that the system symbol error rate increases with the light intensity fluctuation variance when the phase noise is lower.When the phase noise is larger,the influence of modulation order is greater than of turbulence intensity to the error-rate floor appearing.And with the increasing of modulation order,the corresponding average signal to noise is lower when symbol error-rate floor appears.     

新型副载波调制EDFA远程在线监控技术的原理论证

从理论和实验上论证了一种用于掺铒光纤放大器 (EDFA)远程在线监控和判断级连EDFA系统级间断点位置的技术方案。该方案利用频移键控 频分复用 (FSK FDM)技术进行声频副载波调制 ,通过光强度调制实现远程在线EDFA监控信息随主信号的传输。实验测得在副载波调制度为 3 %和 15 %时 ,10Gbit s波分复用 (WDM)光传输系统的功率代价分别为 0 16dB和 0 86dB。采用锁相技术 ,成功进行了 3 %调制度的监控信息解调。说明该方案可以实现对 5级EDFA系统的监控     

A Novel Direct Detection Microwave Photonic Vector Modulation Scheme for Radio-Over-Fiber System

This letter demonstrates the feasibility of a novel direct detection microwave photonic vector modulation scheme for the radio-over-fiber (RoF) system. Unlike the traditional double-sideband with optical carrier suppression modulation scheme, which can carry only the on-off keying data format, the proposed scheme encodes the electrical vector signal on either the upper sideband (USB) or the lower sideband (LSB) only and a pure optical subcarrier on the other sideband. Therefore, phase and amplitude information will be preserved after direct detection. A frequency doubling scheme is employed to reduce the cost of RoF systems. Additionally, the relative intensity between USB and LSB can be easily tuned by adjusting the individual power of electrical driving signals to optimize the performance of the optical radio-frequency signals. A proof-of-concept experiment is conducted by using a 1.25 Gb/s BPSK signal at a carrier frequency of 20 GHz. After transmission over 50-km single-mode fiber, the receiver sensitivity penalty is less than 0.5 dB.     

基于FP-LD实现副载波信号产生

采用一种基于法布里-珀罗腔激光二极管(FP-LD)的副载波信号的产生方案,此方案主要包括一个FP-LD和一个电光相位调制器(PM)。首先利用可调谐激光器、电光PM及微波源产生光正弦相位调制信号,将该信号注入到FP-LD中,通过FP-LD的注入锁定将该信号转换为副载波信号。在实验中,分别以2、3、4和5 GHz的调制频率注入到FP-LD中,相应得到22、21、24和25 GHz的副载波信号。     

基于子空间的无线光通信副载波盲均衡算法研究

文中基于Gamma-Gamma光强起伏分布大气湍流信道模型,对无线光副载波相移键控调制系统进行了子空间盲均衡算法的研究。对比分析了经过大气湍流信道盲均衡前后的副载波调制信号星座图聚敛性,给出了均衡后不同光强起伏方差下的误码率曲线,当R2=0.1,信噪比为20 dB时,误码率从4.710-1降低到1.5610-3,均衡后误码率明显改善。同时采用两种典型实测天气数据(阴、中雨)模拟大气信道进行了子空间盲均衡实验,均衡后调制信号星座图聚敛性与相位可识别性明显优于均衡前。仿真结果表明,子空间盲均衡算法对大气湍流信道下的副载波调制信号有良好的均衡效果。     

FM subcarrier fiber optical transmission system design and itsapplication in next-generation wireless access

This paper presents a design method of optical frequency modulation (FM) subcarrier (with super carrier) transmission modem. The nonideal link characteristics, including laser chirping, fiber dispersion, voltage controlled oscillator (VCO) phase noise, relative intensity noise (RIN), and equivalent network model of laser diode of such a system that may bring about signal distortion are discussed first. We then propose a hierarchical methods to establish the system equivalent model. Finally this FM modem is applied to a GSM wireless system, in which multichannel signals are transmitted over fiber between radio port and basestation, and system performance is appraised by its dynamic range. It is found that optical FM subcarrier (with super carrier) transmission technique can improve the system dynamic range, compared with the intensity modulated direct detection (IMDD) method, and this is a economical and efficient method     

正交叉积副载波调制与导航信号复用

针对卫星导航现代化条件下的导航信号复用问题,在对正交叉积正弦副载波调制信号和正交叉积方波副载波调制信号的调制方法进行详细分析的基础上,提出了一种新的基于正弦波采样的正交叉积副载波调制方法.应用周期信号的傅立叶级数展开方法,给出了以上三种调制信号的调制表达式和功率效率,并根据这些结果比较了三种副载波调制信号的性能.分析和仿真结果表明:正交叉积正弦副载波调制和正交叉积方波副载波调制都是正交叉积抽样正弦副载波调制的特例,而当抽样指数大于16时,正交叉积抽样正弦副载波调制信号在性能上与正交叉积正弦副载波调制信号接近,但实现方式却比较简单.     

无线光外差检测系统影响因素及关键技术研究

光外差检测能提高无线激光通信系统的光电检测灵敏度,可以增大通信距离,并且能够采用多种调制方式。提出了一种基于副载波调制的无线光外差检测系统,重点对大气信道对外差系统的影响因素进行了分析。着重研究了偏振状态和波前修正联合控制、载波恢复、同态滤波等关键技术,以克服大气散射和大气湍流对外差检测系统的影响。最后介绍了无线光外差检测的实验系统,为无线激光通信外差检测技术提供理论依据和实验基础。     

A wireless infrared system using a dual-band receiver and a pulse width on–off keying modulation scheme

In this paper, we propose a dual-band infrared receiver and a pulse width on–off keying (PWOOK) modulation scheme for wireless systems. The dual-band receiver recovers the signal from two different subcarrier waves: 37.9 kHz for the conventional remote control systems and 113.7 kHz for the human interface device (HID) applications which require relatively fast data-transfer-rate and high infrared noise immunity under various optical environments. The PWOOK modulation scheme is a combined form of the pulse width modulation (PWM) and the on–off keying (OOK) using the subcarrier intensity-modulated (SIM) infrared signal. This paper also describes a wireless infrared system that is designed with the proposed dual-band infrared receiver and the PWOOK modulation scheme to demonstrate practical use of them. The dual-band infrared receiver is fabricated in a 0.5 μm CMOS process and the PWOOK modulation scheme transfers data at average bit-transfer-rate of 2.75 kbit/s through the wireless infrared link.