声光频谱分析仪对瞬变信号参数的提取算法研究

声光频谱分析仪利用声光调制技术和空间傅里叶变换原理,实现高带宽信号的频谱测量。本算法通过将被测信号的空域傅里叶变换,数据按瞬态时-空关联输出并进行一定运算处理就可获取信号瞬态时频域全参数信息。仿真结果表明,信号频率还原率在99.5%以上,信号漏检率小于0.2%。     

声光频谱分析仪对瞬变信号参数的提取算法研究

声光频谱分析仪利用声光调制技术和空间傅里叶变换原理,实现高带宽信号的频谱测量。本算法通过将被测信号的空域傅里叶变换,数据按瞬态时 空关联输出并进行一定运算处理就可获取信号瞬态时频域全参数信息。仿真结果表明,信号频率还原率在99.5%以上,信号漏检率小于0.2%。     

自动尿液分析仪系统设计

介绍了基于干化学法的尿液分析仪研制以及系统组成,并对系统误差进行了分析。分析仪利用红、绿、蓝LED灯作为光源对不同的试纸块进行照射,利用光电池和信号调理电路将反射光转换为相对应的电压信号,输出信号与分析仪预存的阈值比较得出检验结果。利用STM32F103ZET6作为分析仪的控制单元,通过D/A转换器输出直流电压作为信号调理电路的直流偏置电压,以补偿环境光和元件所产生的误差。理论分析与实验数据表明,该补偿方式取得了较好的效果。     

DDS自动测试技术研究

重点研究了如何快速又精确地输出DDS的测试值并使测试值符合测试规范.基于NI卡板、信号分析仪、示波器和信号发生器,对DDS的特性参数进行测试研究.信号发生器提供时钟信号与比较器输入;信号分析仪对频域和调制域信号进行测试;示波器对时域信号进行测试;通过IabViEW编程得到DAC数字正弦波和输入数字码并实现测试自动化;最后将结果返回计算机,测试结果符合规范.实验证明,在实际应用中该方法快速精确并具有很好的通用性,可拓展到其他芯片的测试.     

基于热释电型红外气体探测器的原始信号探究

作为采用非色散分光红外吸收光谱(Non-dispersed Infrared, NDIR)原理的红外光谱气体分析仪的一个核心器件,热释电型红外气体探测器输出信号的特征与后级信号处理息息相关。基于PYS3228TC_G1G20热释电红外气体探测器在不同调制频率下对激励源和输出的原始信号的同步跟踪,深入分析了激励源与探测器输出信号之间的关系。通过这些实验,总结并得出了热释电型红外探测器的初始信号特征,为热释电型红外气体分析仪的信号处理提供了重要的理论参考。     

基于STM32F407与PM1158的焦炉煤气氧含量在线分析仪设计

设计了一种基于STM32F407的焦炉煤气氧含量在线分析仪。该分析仪采用数字型磁力机械式氧传感器PM1158进行氧含量的测量,它不仅能够测量常量氧,而且也能够用于微量氧的检测,测量精度高、响应速度快。传感器输出的信号经过信号采集电路及调理电路送入微处理器STM32F407中进行后续处理。实验结果表明,研制的焦炉煤气氧含量在线分析仪抗干扰能力强、稳定性好,完全符合工业现场的需求。     

精确测量1/4波片相位延迟量的新方法

提出了一种精确测量1/4波片相位延迟量的新方法。测量光路由激光器、起偏器、被测1/4波片、光弹调制器、检偏器和光电探测器构成。起偏器和检偏器的透光轴相互垂直。被测1/4波片的快轴与光弹调制器的振动轴平行,且与起偏器和检偏器的透光轴分别成±45°夹角。准直激光束依次经过起偏器、被测1/4波片、光弹调制器和检偏器的探测光强由光电探测器接收。利用探测信号的直流分量与二次谐波分量精确计算出被测1/4波片的相位延迟量。实验验证了这种测量方法的有效性,改变初始光强过程中相位延迟量测量结果的复现性为0.012°,检偏器、被测1/4波片的方位角变化1°的过程中相位延迟量测量结果的复现性为0.008°。     

A new LMS-based Fourier analyzer in the presence of frequency mismatch and applications

The performance of the conventional least mean square (LMS) Fourier analyzer may degenerate significantly, if the signal frequencies given to the analyzer are different from the true signal frequencies. This difference is referred to as frequency mismatch (FM). We first analyze the performance of the conventional LMS Fourier analyzer for a single sinusoid in the presence of FM. We derive the dynamics and steady-state properties of this analyzer as well as the optimum step size parameter which minimizes the influence of the FM. Extensive simulations reveal the validity of the analytical results. Next, a new LMS-based Fourier analyzer is proposed which simultaneously estimates the discrete Fourier coefficients (DFCs) and accommodates the FM. This new analyzer can very well compensate for the performance degeneration due to the FM. Applications to estimation/detection of dual-tone multiple frequencies (DTMF) signals and analysis of real-life noise signals generated by a large-scale factory cutting machine are provided to demonstrate the excellent performance of our new Fourier analyzer.     

Y型声表面波器件特性分析

在1280旋转Y切割X传播方向上的L iN bO3基片上设计并研制了Y型声表面波器件。它将输入IDT激发的声表面波轴对称分成两路并由各自的输出IDT检测输出。应用P矩阵法分析了其中一输出IDT检测输出的一次时延信号、三次渡越反射信号和五次渡越反射信号与输入IDT所加的电信号之间的关系式,并应用网络分析仪测量Y型声表面波器件幅度特性,结果表明,理论分析与实验结果基本相符。     

低精度ADC下大规模多输入多输出系统基于三对角迭代法的软输出信号检测

受硬件成本制约,大规模多输入多输出（massive Multiple Input Multiple Output, mMIMO）基站通常配置低精度模数转换器（Analog-to-Digital Converter, ADC）。低精度ADC下,如果多用户mMIMO系统采用最小均方误差（Minimum Mean Square Error, MMSE）检测,将导致过高复杂度。为此,本文基于三对角迭代法（Tridiagonal Iterative Method, TDIM）,结合分块矩阵求逆的初始值确定,提出一种低复杂度的MMSE软输出信号检测算法。数值仿真表明:基于TDIM的软输出信号检测算法经4次迭代即可达到收敛,同时,数值结果验证了ADC量化比特为4时,该算法可取得接近全精度ADC的性能,为低精度ADC下mMIMO系统的上行链路信号检测实现提供了切实可行的方案。      

Selection of signal detection threshold in Doppler spectrum analyzer

It is shown, that for spectrum analyzer noise immunity increase, during processing of optical Doppler location signal with unknown frequency, random appearance time and low signal to noise ratio it is advisable to use methods of false alarm probability decrease, where decision about useful signal presence is made according to two pulses appearance at the matched filter output. These pulses have the same delay times with regard to signal analysis beginning time. This methodology application for signal detection allows to decrease a false alarm probability with regard to one period of analysis in case of the same values of threshold.     

Synthetic instruments extract masked signal parameters

We have reviewed the signal conditioning required to obtain high-quality spectral measurements with an FFT-based spectrum analyzer. The conditioning includes data windowing and extended length. Folded windows are required at the input to the transform, and significant ensemble averaging of power spectrum and cross power spectrum at the output of the FFT is needed. We also commented on the effect of cross coupling between signal and noise terms on the variance of the spectral output terms when the signal contains both spectral lines and additive noise. Finally, we presented techniques based on cross spectra. In particular, the normalized cross spectra known as the coherence function was shown as a technique to separate spectral components traceable to the input signal from those not traceable to the input signal.     

Measurement tools for digital video transmission

An overview of test equipment and applications targeted specifically for digital broadcast signal distribution is given. The vector generator and analyzer evaluate the constellation accuracy, give direct conclusions with regard to the source of impairments, and allow SER (symbol error rate) estimates. Peak power and peak-to-average power ratio, key parameters in digital broadcasting, are monitored with the digital video power analyzer. The power distribution functions of the power analyzer may prove useful as an economic tool for linearity and group delay adjustments. The effects of potential impairments in the transmission path, like reflections, multipath signals, or Doppler effects from antenna sway, can be evaluated with a channel simulator. The bottom line assessment of a total system's transmission quality is delivered by BER (bit error rate) measurements from modulator input to receiver demodulator output     

采样时钟抖动在弱光信号检测中的影响分析

信号采样是弱光信号检测的关键技术环节,由于采样时钟抖动引起的采样信号的输出误差会影响后续的信号检测和处理。为此,分析了输入光信号为近高斯分布波形时由时钟抖动引起的采样误差,推导出了采样输出的信噪比损失公式,讨论了采样带宽、输入信噪比以及信号脉宽对输出信噪比损失的影响,最后以取样积分检测技术为对象,计算了在不同累积次数的条件下采样抖动对取样积分检测性能的影响,对弱光信号检测中的采样时钟选取具有一定的指导意义。     

Large-signal characterization of dual-gate field effect transistorsusing load-pull measurements

An automated injected signal load-pull measurement system has been designed to operate from 8 to 12 GHz, with a range of injected signal power extending to 4 W. The system has been shown to be as accurate as the HP8510 network analyzer. The large signal intrinsic drain-to-source resistance of an 1800 μm dual-gate FET was measured on the load-pull system, and subsequently a variable power amplifier was designed using the load-pull data. The output phase variation of the variable power amplifier was 10° when operating at 31.3 dBm     

高灵敏加速度计微弱信号提取电路设计与测试

介绍了一种压阻式高灵敏加速度传感器微弱信号提取电路。该信号提取电路采用两级信号放大设计,两级之间设计有二阶巴特沃兹低通滤波器。本设计电路通过电路仿真软件进行仿真和外接加速度计测试。测试结果表明,该微弱信号检测提取电路可以很好地对高灵敏MEMS加速度计输出的信号进行放大,具体表现为可将传感器输出信号从毫伏级放大到伏级。采用这种电路设计的MEMS高灵敏加速度计输出信号具有良好的低频特性,可以满足高灵敏传感器宽频带测试的需要。     

Joint data detection and channel estimation for coded and uncoded continuous phase modulation signals

The performance of decision‐directed approach for joint data detection and channel estimation for continuous phase modulation (CPM) signal is limited because of an inevitable decision delay, which results in a trade‐off between data detection and channel estimation. In this paper, a novel hard output demodulation that solves the conflict requirement on the decision delay by predicting the channel coefficients over a given observation interval through a Kalman filter is proposed for uncoded CPM signal. The prediction guarantees high channel tracking capability and meanwhile maintains the accuracy of data detection. The proposed hard output demodulator is further extended to design a soft‐input soft‐output demodulator for serially concatenated CPM signal, which allows iterative processing. The convergence behavior of the proposed iterative receiver is presented. Simulation results show that the proposed demodulators provide improved performance in terms of bit error rate over some existing algorithms. Copyright © 2014 John Wiley & Sons, Ltd.     

ASE Analysis and Correction for EDFA Automatic Control

A theoretical model is described that can be used for calculating the amplified spontaneous emission (ASE) at the output of an optical amplifier. The technique can be used to determine the usable optical signal power at the output of an erbium-doped fiber amplifier (EDFA) operating in the constant-output-power control mode. The model was experimentally verified by automating an EDFA to operate in the constant-signal-power control mode using an ASE correction based on our model. Calculated signal-output powers were then compared to the measured values that were obtained using an optical spectrum analyzer.     

一种低噪声微弱信号调理电路设计

水下主动声纳探测系统是通过发射换能器发射主动声信号,水听器检测回波信号完成目标探测和方位估计等任务。由于水听器输出信号微弱,易被复杂的海洋环境噪声干扰不能直接用于后续采集电路,要求信号调理电路具有高增益并且自噪声远低于水听器输出信号。而且主动声呐工作在近距离时,水听器接收到的混响信号远高于目标的回波信号,水听器接收到的信号动态范围大。本文提出的一种低噪声微弱信号调理电路,是一种低噪声、高增益、大动态范围、高一致性的信号调理电路。     

Optical Microwave and Millimeter Generation by Using Birefringent Fiber FP Cavity with Pulse Laser Injection

A novel optical microwave and millimeter generation by using single mode fiber FP cavity (SMFFPC) with pulse laser injection is proposed and experimentally demonstrated. The frequency of output signal is determined by the birefringence degree of the SMFFPC, a general relationship between output signal frequency of SMFFPC and birefringence degree of single mode fiber is derived. The proof of concept device consists of a light source, a polarizer controller, a modulator, a RF generator, a single mode fiber Fabry-Perot cavity, a strain inspector, an erbium doped fiber amplifier, a filter, a polarizer, and a digital communication analyzer. The results demonstrate the new concept of optical microwave and millimeter generation and the technical feasibility.