Study of the Intrinsic Recombination Velocity at the Junction of Silicon Solar under Frequency Modulation and Irradiation

In this study, a method for determining the intrinsic recombination velocity at the junction of a silicon solar cell is presented. The expression of intrinsic recombination velocity at the junction was established under irradiation in frequency modulation. Based on this expression, an electrical model of the intrinsic recombination velocity at the junction is presented.

Theoretical analysis of frequency modulation-to-amplitude modulation on the final optics and target of the SG Ⅱ-Up laser facility

Frequency modulation(FM)-to-amplitude modulation(AM) conversion is an important factor that affects the time±power curve of inertial confinement fusion(ICF) high-power laser facilities. This conversion can impact uniform compression and increase the risk of damage to optics. However, the dispersive grating used in the smoothing by spectral dispersion technology will introduce a temporal delay and can spatially smooth the target. The combined effect of the dispersive grating and the focusing lens is equivalent to a Gaussian low-pass filter, which is equivalent to 8 GHz bandwidth and can reduce the intensity modulation on the target to below 5% with 0.3 nm @ 3 GHz + 20 GHz spectrum phase modulation. The results play an important role in the testing and evaluating of the FM-to-AM on the final optics and the target, which is beneficial for comprehensively evaluating the load capacity of the facility and isentropic compression experiment for ICF.

Photonic Vector Signal Generation by Frequency Sextupling for Radio Over Fiber Systems

To generate high-frequency radio frequency(RF) vector signals, a vector signal generation method by optical frequency sextupling using a dual-parallel modulator is proposed. The method modulates vector signal on +3 rd order optical sideband and local oscillator(LO) signal on-3 rd order sideband using the intermodulation process in the DPMZM. After suppressing of the optical carrier and other sidebands through proper adjustment for modulator biases and modulation index, a frequency sextupled millimeter-wave vector signal can be generated after photodetection. The frequency sextupling will lower the bandwidth of the modulator, the local oscillator and the driving circuits. In addition, the phase of generated signal is not distorted after detection, and the power fading after fiber transmission can be avoided. In the simulation, a 500-MSym/s QPSK signal at 60 GHz is generated by 10-GHz drive signal. After travelling over fiber with length of 20/30/40-km, receiver power penalty keeps below 2.5 dB.

基于线性调频连续波的合作式通信辐射源测距

针对加速运动目标参数估计中,离散多项式变换方法无法进行非整数估计的问题,本文提出基于瑞夫算法的离散多项式变换法和基于Chirp-Z变换的离散多项式变换法2种新型离散多项式变换算法,对加速运动目标速度和加速度进行估计,并对2种算法的估计误差和计算量进行了分析比较。结果表明:2种算法在信噪比-20 dB时均方误差开始接近克拉美罗界。基于瑞夫算法的离散多项式变换法与3次迭代基于Chirp-Z变换的离散多项式变换法均可在较低信噪比下可实现任意频率的有效估计且性能接近,二者均可实现低信噪比下速度、加速度的有效估计,但基于瑞夫算法的离散多项式变换法计算量远小于3次迭代基于Chirp-Z变换的离散多项式变换法。

50GHz~110GHz宽带信号下变频技术

矢量信号分析仪作为传统扫频式频谱仪与快速傅里叶变换技术的结合,能够对信号进行数字化处理,分析各种调制信号,同时获得测量信号的幅度和相位信息,对于现代通信意义重大。随着电磁波的应用频率扩展到毫米波乃至太赫兹波段,矢量信号分析仪的测量频率也急需拓展到更高频段,在系统前端搭载下变频器可实现这一目的。基于50GHz~110GHz宽带信号的下变频技术开展研究,研制了变频系统中多个关键器件,包括频分50GHz~110GHz信号的宽带开关、抑制镜频信号的宽阻带波导滤波器以及基于倍频放大模块的本振,同时搭建了50GHz~110GHz宽带信号下变频系统,将50GHz~110GHz宽带信号下变频到4.6GHz~39.6GHz。实验表明,下变频后的信号在任意2GHz内平坦度小于±3.5dB,对镜频信号的抑制大于60dBc,输出杂散抑制度大于40dBc,本振泄漏抑制大于70dBc,满足系统指标要求。

综合处理工艺在西溪湿地清水入城中的应用

针对钱塘江来水含沙量高,水体浑浊、透明度低等特性,以西溪湿地清水入城为例,通过减缓水流流速、投放絮凝剂、底泥疏浚等综合处理工艺,加快悬浮质絮凝沉淀过程、提升来水透明度;并通过耦合来水量、浊度、流速与絮凝剂投放量之间的关系,提出变频投放系统,寻求最经济运行模式。

基于高频开关电源的通信设备整流模块设计与性能优化

文章基于高频开关电源的通信设备整流模块设计与性能优化展开研究,旨在提出一种高效稳定的电源解决方案。设计直流/直流(Direct Current/Direct Current,DC/DC)变换电路,实现对直流电压的变换和稳定输出,并设计多种监控电路,包括配电监控电路、绝缘监控电路、主监控电路,以全面监测和管理整流模块的工作状态,保障系统的安全稳定运行。通过优化调整脉冲宽度调制(Pulse Width Modulation,PWM)频率和占空比,确定最佳参数配置,获得稳定且低纹波的输出电压。这些研究成果为通信设备提供一种可靠的电源解决方案,具有重要的实际应用价值。

A.C. Recombination Velocity as Applied to Determine n⁺/p/p⁺Silicon Solar Cell Base Optimum Thickness

This work deals with determining the optimum thickness of the base of an n+/p/p+ silicon solar cell under monochromatic illumination in frequency modulation. The continuity equation for the density of minority carriers generated in the base, by a monochromatic wavelength illumination (λ), with boundary conditions that impose recombination velocities (Sf) and (Sb) respectively at the junction and back surface, is resolved. The ac photocurrent is deduced and studied according to the recombination velocity at the junction, to extract the mathematical expressions of recombination velocity (Sb). By the graphic technique of comparing the two expressions obtained, depending on the thickness (H) of the base, for each frequency, the optimum thickness (Hopt) is obtained. It is then modeled according to the frequency, at the long wavelengths of the incident light. Thus, Hopt decreases due to the low relaxation time of minority carriers, when the frequency of modulation of incident light increases.

FSK Modulation Scheme for High-Speed Optical Transmission

In this paper, we describe the generation, detection, and performance of frequency-shift keying （FSK） for high-speed optical transmission and label switching. A non-return-to-zero （NRZ） FSK signal is generated by using two continuous-wave （CW） lasers, one Mach-Zehnder modulator （MZM）, and one Mach-Zehnder delay interferometer （MZDI）. An RZ-FSK signal is generated by cascading a dual-arm MZM, which is driven by a sinusoidal voltage at half the bit rate. Demodulation can be achieved on 1 bit rate through one MZDI or an array waveguide grating （AWG） demultiplexer with balanced detection. We perform numerical simulation on two types of frequency modulation schemes using MZM or PM, and we determine the effect of frequency tone spacing （FTS） on the generated FSK signal. In the proposed scheme, a novel frequency modulation format has transmission advantages compared with traditional modulation formats such as RZ and differential phase-shift keying （DPSK）, under varying dispersion management. The performance of an RZ-FSK signal in a 4 x 40 Gb/s WDM transmission system is discussed. We experiment on transparent wavelength conversion based on four-wave mixing （FWM） in a semiconductor optical amplifier （SOA） and in a highly nonlinear dispersion shifted fiber （HNDSF） for a 40 Gb/s RZ-FSK signal. The feasibility of all-optical signal processing of a high-speed RZ-FSK signal is confirmed. We also determine the receiver power penalty for the RZ-FSK signal after a 100 km standard single-mode fiber （SMF） transmission link with matching dispersion compensating fiber （DCF）, under the post-compensation management scheme. Because the frequency modulation format is orthogonal to intensity modulation and vector modulation （polarization shift keying）, it can be used in the context of the combined modulation format to decrease the data rate or enhance the symbol rate. It can also be used in orthogonal label-switching as the modulation format for the payload or the label. As an example, we propose a simple orthogonal optical label switching technique based on 40 Gb/s FSK payload and 2.5 Gb/s intensity modulated （IM） label.

Analytic approach to the small-signal frequency response of saturated semiconductor optical amplifiers using multisection model

An analytic solution derived by multisection model to the small-signal frequency response （SSFR） of wavelength conversion based on cross-gain modulation （XGM） in semiconductor optical amplifiers （SOAs） is presented. The result contains details that can affect the characteristics of SSFR significantly more than previous ones.

V型啁啾调频单脉冲激光测速测距方法与实现

为实现雷达远距离动目标实时跟踪探测,单脉冲线性调频脉冲压缩算法和V型啁啾调频脉冲压缩算法为快速获得运动目标的距离速度信息提供算法基础。结合脉冲压缩算法优势以及两种波形脉压算法的弊端,利用V型啁啾调频脉冲发射波形,提出采用三角调频滤波处理方法,以解决目标的距离、径向速度值及速度方向信息同时获取的难题,为单脉冲实现速度矢量信息的隐蔽探测提供解决方案。通过搭建脉冲激光相干测量实验平台,在接收镜头后连接17.618 km延迟光纤以延长目标往返距离,对转速从−3.67~3.67 m/s的转盘进行速度距离测量。在40 MHz调制带宽,4.096μs调制脉宽,2.5 GS/s采样率条件下成功实现单脉冲距离速度多维信息获取,并对测速准确性进行评估,距离测量精度达到0.33 m,速度测量精度为0.061 m/s。

矿用电机车变频调速系统研究

为了扩宽矿用电机车的调速范围,优化调速性能,实现企业节能减排的发展目标,将先进的变频调速技术用于电机车调速系统。该系统由主电路、控制电路等部分组成,介绍了部分电路的设计思路。变频调速系统的应用提高了电机车的调速性能,节省了企业支出。

多普勒模糊下的FMCWMIMO雷达目标参数估计方法

近年来,随着智能驾驶技术的不断发展,毫米波雷达作为汽车安全控制系统的核心组件受到了广泛关注。时分复用(TDM)多输入多输出(MIMO)调频连续波(FMCW)雷达因具有低硬件成本和高角度分辨率的优势而被广泛应用于汽车雷达,但TDMMIMO在实际应用中还存在对运动目标检测易出现速度模糊和角度模糊问题,导致检测误差变大,对于自动驾驶场景存在一定的安全隐患。为解决上述TDM MIMO FMCW雷达存在检测误差高的问题,提出了在多普勒模糊下的FMCW MIMO雷达目标参数估计方法,在不增加额外硬件开销的前提下,可确保算法在低复杂度下提升监测的时效性,解决了速度模糊和相位偏移问题;利用加Kaiser窗FFT波束形成方法对目标角度进行测量,从而得到更精准的目标信息。仿真和实验结果验证了所提方法的有效性。

基于色散管理的自相位调制光谱展宽滤波技术

自相位调制光谱滤波技术能够产生波长可调谐的飞秒脉冲,有望取代传统复杂的光参量振荡器而受到关注.然而,光纤中的正色散会导致光谱旁瓣调制深度减小,同时光波分裂现象阻碍了光谱的展宽.为了解决这两个问题,本文提出了一种基于色散管理的双通光谱滤波技术,在脉冲演化过程中通过引入负色散来优化脉冲的前后沿形状,并压缩脉冲宽度以提升脉冲的峰值功率,所产生的光谱不仅旁瓣更加清晰,而且调制深度更深.使用2 cm LMA-8光纤,利用该技术获得了脉冲能量为6 nJ、中心波长在920 nm的113 fs脉冲.

超宽带变频组件虚假抑制特性研究

大瞬时中频带宽超宽带变频组件的虚假电平抑制特性涉及的影响因素较多,难以快速准确评估。文章介绍了一款工作频率覆盖0.38~18 GHz瞬时带宽BW1/BW2的超宽带变频组件,从目标信号和非目标信号2个角度对虚假抑制特性做了全面的分析讨论,总结了一些设计原则。文章研究可以降低对变频组件虚假抑制需求的快速准确评估难度,提高变频组件的设计效率和虚假抑制水平。实测结果验证了对超宽带变频组件虚假抑制特性研究的准确性和有效性。

一种宽负载高效率Buck转换器设计

本文提出了一种双模式调制技术,以提高宽负载范围内降压型DC-DC转换器的转换效率。采用自适应导通时间电路(AOT)和斜坡信号VRAMP产生电路来维持转换器连续导通时间(CCM)工作模式下开关频率基本稳定;利用过零检测电路来检测电感电流,当电感电流过零时,能及时关断续流管,降低开关损耗,进一步提升轻载转换效率。该DC-DC基于SMIC 0.18 um BCD工艺进行电路仿真验证,该电路可在0~3A宽负载范围内正常工作,在输入电压3~5V范围内,PFM模式下输出电压纹波小于5.2mV,1m A负载下转换效率为87.37%。在PWM模式下输出电压纹波小于2.8mV,3A负载下最低转换效率为84.24%。峰值效率可达94.91%,全负载范围内转换效率大于84%。

数字调制中波广播发射机的改频工程研究

新时期,我国广播电视发射设备逐渐向数字化、固态化方向发展,中波广播发射机不断被完善,并融入数字调制技术。其中,在发射机运行阶段,采用微功耗数字集成电路,可使发射机体积有效降低,有效节省运营成本。因此,本文围绕发射机展开深入研究,重点阐述了数字调制中波广播发射机的改频工程要点,并简单论述了数字调制的方法和特点,希望对相关工作人员有所帮助。

时间位相调制对高强度三次谐波转换的影响

在惯性约束聚变研究中 ,为了利用光谱色散进行光束匀滑以及抑制KDP晶体等大口径光学元件中的横向受激布里渊散射 ,通常需要对激光脉冲进行时间位相调制 详细讨论了高功率条件下KDP晶体Ⅰ /Ⅱ角度失谐三倍频方案中 ,时间位相调制对三次谐波转换效率和脉冲频谱的影响 研究结果表明 。

变频调速技术在风机节能中的应用

分析了变频调速控制的节能原理,以及风机节能计算方法,通过某化工厂的风机变频调速应用实例,结果表明:风机采用变频调速控制运行,能够获得显著的节能效果和经济效益。

电力机车励磁涌流消除系统的研究

针对电力机车过分相区时合闸励磁涌流对电力机车及牵引网的电能质量造成的影响,提出了一种基于大功率电力电子技术的电力机车励磁涌流消除系统原理,并提出了同相调幅法和变频移相法两种PWM调制电压算法。该系统通过控制新型大功率电力电子电路整流、逆变、变频模式及机车变压器不同时刻励磁电压,实现电力机车无冲击平滑换相通过分相区,在出分相区合闸瞬间不产生冲击性励磁涌流。利用所提方法建立了该电力机车变压器分区换相系统的仿真模型。通过仿真分析表明,所提出的两种电压调制算法,均能有效抑制合闸励磁涌流的产生,验证了所提方法的可行性。