3R■测量系统的高精度新型应答机设计

介绍了一种基于3R■测量系统的三通道高精度新型应答机,该应答机采用一路相参、两路非相参的方案。比较了中频调制转发(中转调)和中频混频转发(中转发)两种方案的特点,并对特殊环路设计、多路信道带宽设计和强弱信号增益线性设计等关键技术进行了详细论述。     

3RR测量系统的高精度新型应答机设计

介绍了一种基于3RR应测量系统的三通道高精度新型应答机,该应答机采用一路相参、两路非相参的方案。比较了中频调制转发（中转调）和中频混频转发（中转发）两种方案的特点,并对特殊环路设计、多路信道带宽设计和强弱信号增益线性设计等关键技术进行了详细论述。     

脉冲应答机距离零值误差补偿

本文叙述了在雷达链工作条件下,非相参脉冲应答机采用对数接收方式时,接收信号电平对应答机距离零值的影响。提出了减小这种距离零值误差的办法,并给出了实验结果。     

游标测距技术在脉冲雷达中的应用及精度分析

游标测距技术是根据脉冲雷达接收信号的相位导出径向距离测量值,也就是在雷达起始距离基础上加上相位增量对应的距离。采用游标测距技术的脉冲测量雷达可以提高雷达径向距离的测量精度,以及提高雷达探测目标的能力。文中结合游标测距原理,建模仿真,分析游标测距精度的影响因素,并通过跟踪机载应答机信号及空间目标实际验证游标测距技术在脉冲雷达平台上应用。     

一种测量非相干扩频应答机时钟准确度的新方法

简要介绍了扩频测控系统中非相干扩频测距的原理,针对在轨飞行器非相干扩频应答机频率准确度难以准确测量的问题,提出了一种基于星地帧周期固定差统计的卫星时钟准确度的测量方法,编制了下行测量帧解析工具,对卫星实时下传的测量帧数据进行解算,并结合实测距离进行分析处理,推算出应答机实时频率准确度,一定程度上实现了对在轨飞行器时钟系统的健康诊断。     

固定目标的运动单站被动测距

分析了角度和角度变化率被动测距系统的基本原理,研究了空间固定目标的单站被动测距方法,并提出光学成像系统中角度及角度变化率测量方法。利用Monte Carlo模拟验证了被动测距的数学模型,角度及角度变化率的测量误差是影响距离测量精度的主要因素,为了克服误差的影响,研究了基于推广卡耳曼滤波(EKF)距离估算方法。实验结果表明,对于含有零均值高斯噪声的角度和角度变化率的测量数据,利用推广卡耳曼滤波可以提高距离估算的稳定性和精度。     

测速应答机相位误差分析及精度提升方法

针对测速应答机中信号转发的相位误差问题,提出一种在计算相参转发频率的过程中增加计算变量位宽,从而降低信号相位误差的方法,同时对转发性能进行了分析,数字中频处理过程中环路振荡器频率、DDS输出频率以及转发比量化误差为影响测速应答机相位误差的主要因素.仿真验证及试验结果表明,在满足产品设计指标的条件下,可适当提高该变量的计...     

一种DVB系统数字中频发射机的计算机仿真测量方法

为提高DVB数字中频调制系统的性能,避免因基带和中频数字信号处理环节潜在的设计隐患而影响系统调制质量,提出一种基于矢量信号分析的数字中频发射机仿真测量方法,可对发射机中频和基带各主要数字信号处理环节进行系统级仿真测量分析,可对多种测量域内的性能指标进行仿真测量和评估.通过与实测结果分析比对,证明该仿真测量方法有效,能够对实际系统起到系统级性能评估、参数修正和故障诊断等方面的设计指导作用.     

测控雷达距离零值校准方法研究

距离值是测控系统外测数据中的重要一项,某船载测控系统的测距系统采用的纯侧音测距体制是距离值测量的一种常用方法。在介绍了传统距离校零方法的基础上,分析了该测控系统的地面零值分离方法,且对任务中距离零值的装订方法进行了说明。实践证明,该方法准确有效,历次任务分离的地面零值比较稳定。     

星载数字化TDRSS/USB双模应答机设计与试验

介绍了跟踪与数据中继星系统(TFDRSS)中用户星TDRSS/USB双模应答机的功能和组成,在传统USB应答机和扩频应答机的基础上设计了一种数字化的星载TDRSS/USB双模应答机,具有TT&C和TDR两种工作模式.接收机采用了中频数字化的载波跟踪和解扩解调、伪码快速捕获和精确跟踪方法;发射机的相干载波产生和PM调制采用直接数字频率合成(DDS)方法;两种模式下共用了收发通道和部分FPGA.资源.新的设计方法使应答机的调试难度、稳定性、载波和伪码捕获速度、跟踪精度、测距时延误差、功耗、重量等指标均有改善.     

Contactless radiation pattern measurement method for UHF RFID transponders

A contactless method of measuring the radiation pattern of a UHF RFID transponder is presented. The novel technique does not require any special transponder IC or measurement equipment. The measurement method also enables radiation pattern determination in the end-use application. The measurement setup and some example results are presented.     

Remotely powered addressable UHF RFID integrated system

This paper presents a fully integrated remotely powered and addressable radio frequency identification (RFID) transponder working at 2.45 GHz. The achieved operating range at 4 W effective isotropically radiated power (EIRP) base-station transmit power is 12 m. The integrated circuit (IC) is implemented in a 0.5 /spl mu/m silicon-on-sapphire technology. A state-of-the-art rectifier design achieving 37% of global efficiency is embedded to supply energy to the transponder. The necessary input power to operate the transponder is about 2.7 /spl mu/W. Reader to transponder communication is obtained using on-off keying (OOK) modulation while transponder to reader communication is ensured using the amplitude shift keying (ASK) backscattering modulation technique. Inductive matching between the antenna and the transponder IC is used to further optimize the operating range.     

Transmission of SDH signals through future satellite channels usinghigh-level modulation techniques

The authors discuss the possibility of transmitting synchronous digital hierarchy (SDH) signals through two-link nonlinear satellite channels. Transmitting such high bit rate signals through a standard 54 MHz or 36 MHz transponder bandwidth requires the use of high-level modulation schemes. The techniques and technologies needed to make the use of 16-ary quadrature amplitude modulation (QAM) and 64-ary QAM transmissions feasible for future satellite communication systems are examined. It is shown that it is possible to transmit a synchronous transport module-level 1 (STM-1) signal through a standard 54 or 36 MHz transponder bandwidth using 16-ary QAM or 64-ary QAM transmission, respectively, for the 6/4 GHz band. However, for higher frequency bands, due to high fade margins needed to achieve the high availability and performance for SDH systems, is not practical to transmit the STM-1 signal through such standard transponder bandwidths     

采用光干涉技术的保偏光纤拍长测量方法

简要介绍了采用光干涉技术的保偏光纤拍长测量方法,并给出了测量实例.与外调制测量法相比,该方法具有更高的测量重复性,测量原理也更为直观清晰.     

Exponential Time Differencing Algorithm for Debye Medium in FDTD

The exponential time differencing (ETD) formultion is proposed for Debye medium using finite-difference time-domain (FDTD) method. The schemes of the auxiliary differential equation (ADE) and ETD algorithms are presented. The algorithms are validated by comparing the simulation results with analytical values. The ETD method costs the same memory as the ADE method, and the numerical results indicate that the ETD technique is more accurate than the ADE method.     

Measurement accuracy of chromatic dispersion by the modulation phase technique

A simple measuring method for the chromatic dispersion measurement is described. This technique uses group delay measurement by modulation phase of laser diodes with different wavelengths. An experiment showed that this technique is capable of measuring the chromatic dispersion of a 42.3-km single-mode fiber. The accuracy of measurement is discussed in view of fiber length, modulation frequency, and the number of employed laser diodes. The accuracy is improved when a higher modulation frequency is used and a longer fiber is measured since the detected phase fluctuation depends little on the modulation frequency and very little on the fiber length. The estimated measurement error of chromatic dispersion was 0.1 ps/km/nm for a four-laser diode system.     

基于脉冲宽度调制技术的水浊度探测研究

介绍了水浊度常用的测量方法-散射法、透射法及比值法的原理,在此基础上结合脉冲宽度调制(PWM)解调技术,提出了采用调制光强测量浊度的方法,并详细介绍了实验系统的组成和调制解调实现电路.采用该实验系统对福尔马肼标准液进行测量,列出了测量数据,并绘出三种方法所测浊度的拟合曲线.对实验结果的分析和比较表明使用PWM调制结合比值法能最有效地排除背景光的干扰,在保证精度的前提下提高水浊度的测量范围.     

BPSK and QPSK non‐linear satellite communication system performance in the presence of cochannel interference

Taking the uplink and downlink cochannel interference and noise into account, the analytical expressions are derived for determining the bit error probability in detecting a binary phase‐shift‐keying (BPSK) and a quaternary phase‐shift‐keying (QPSK) Gray coded signal, transmitted over a satellite system exhibiting amplitude modulation‐to‐amplitude modulation (AM/AM) conversion effects and amplitude modulation‐to‐phase modulation (AM/PM) conversion effects. On the basis on the derived theoretic formulae, using real‐life system parameters, numerical results are obtained and presented. We point out the explicit comparisons of satellite communication system performance obtained when a satellite transponder amplifier is modelled by a hard‐limiter and those obtained when both AM/AM and AM/PM non‐linearities of the satellite transponder amplifier are taken into consideration. Copyright © 2003 John Wiley & Sons, Ltd.     

高精度双干涉光路调频连续波激光绝对测距系统

调频连续波激光测距具有无盲区、非接触测量和绝对测距等优点,但是由于可调谐激光器光频率调制非线性对其测量精度的影响,限制了调频连续波激光测距在精密测量领域中的应用。针对调频连续波激光测距中测距精度受到激光器光频率调制非线性的影响,提出了双干涉光路调频连续波激光测距方法,利用两个干涉系统得到的干涉条纹数量的比值计算得到被测目标的距离,消除了激光器光频率调制非线性对测距精度的影响,实现了65 m的测量分辨率和15 m的重复测量精度。该方法无需对激光的波长进行测量,也无需对激光器进行锁频,系统组成简单,在工业大尺寸测量、空间技术、测绘等领域有着广阔的应用前景。     

利用帧头消除测距时标整周期滑动的方法

在弹载扩频脉冲应答式测距系统中,应答机直接利用捕获脉冲作为时标信号进行测距。此法在高信噪比时测距精度较高,但在低信噪比时,伪码同步脉冲的抖动较大,同时捕获脉冲会产生整数个伪码周期地滑动,导致测距误差较大。为了提高测距精度,提出了一种利用帧头消除脉冲应答式测距时标整周期滑动并降低时钟抖动的方法。在获得伪码捕获脉冲并检测到帧头后,应答机才启动应答信号,可有效降低低信噪比时的测距误差。