低功耗水声接收机系统设计

为了接收水下目标回波,研究设计了一款低功耗水下接收机。由于信号发射功率和传播过程中强干扰噪声影响,信号发生衰减、畸变、混响等现象,致使接收机输入端信号动态范围较大,直接影响后端数字处理。系统采用硬件电路实现恒Q的多频率接收,并采用AGC实现大动态范围的压缩和相位幅度的一致性。考虑到所处环境,降低元器件功耗以及不工作时DSP处于关机状态,海试结果表明该系统能有效降低功耗,实现动态范围大、灵敏度高、一致性好等优点。     

水声信号自动增益控制及幅值恢复电路设计实现

针对水声信号动态范围大、噪声干扰强的特点,研制了水声信号自动增益控制（AGC）及幅值恢复电路。电路以数控衰减技术完成对大动态范围信号的接收和处理,以功率比较和窄带带通滤波技术屏蔽和滤除噪声对系统的干扰。经水下实验结果表明,该电路具有精度高、抗干扰能力强、工作稳定等优点。     

基于YIG调谐带阻滤波器的低噪声L波段接收前端

L波段接收前端的噪声、频率预选和带内干扰信号的抑制对雷达接收机的灵敏度、动态范围、信号的选择和抗干扰能力等技术指标有着重要影响。采用三阻带YIG调谐带阻滤波器,通过连续可调谐、可分可合控制方法实现了L波段预选滤波器带内多达3个干扰信号的抑制以及单个干扰信号的深度抑制。多阻带抑制、限幅、低噪声系数及前置衰减的动态范围扩展等设计有效提升了L波段接收前端在复杂空间电磁环境中的抗干扰能力。试验样品的测试数据验证了设计方案的可行性和工程实用性。     

Intersil推出最大输入电压为36伏的超高初始精度的精密带隙电压基准芯片

日前,全球高性能模拟混合信号半导体设计和制造领导厂商IntersiI公司（纳斯达克全球交易代码：JSlL）推出具有低噪声、低温度漂移而且低功耗的精密电压基准芯片——ISL21090,用以满足高端和便捷式仪器系统的要求。lSL21090是一种宽输入范围、低噪声的精密带隙基准电压源,其功耗和噪声仅均为同类产     

海洋环境噪声接收机的设计与实现

针对海洋环境噪声的测量,设计了一种低噪声、宽带、高动态范围的水声接收机。采用新一代真有效值转直流芯片AD8436实现噪声信号有效值的实时高精度计算,并通过微控制器调整程控增益放大器的增益码完成自动增益控制,同时自动记录系统增益值。该接收机具有良好的人机交互接口,既可在线传递系统的增益,又可按用户需求设定固定的增益。实验测试表明,该接收机的等效输入自噪声小等于3 μVrms,频率带宽为20 Hz~5.5 kHz,信号输入的动态范围大等于68 dB;且具有精度高、适应性强和电路性能稳定等特点,可较好地满足海洋环境噪声的测量与分析。     

数字卫星电视接收机的选择与安装

数字卫星电视接收机的主要功能是将来自高频头第一中频的弱信号进行低噪声放大,变频和解调处理后,输出全电视基带信号。在卫星电视接收系统中,数字卫星电视接收机由于其结构复杂、设计难度大、功能多,因而直接影响着整个卫星电视的接收性能和成本。     

红外探测器低频噪声长时间监测系统设计

针对锰钴镍氧化物薄膜型红外探测器的结构特点,提出了一种红外探测器低频噪声长时间监测系统设计方案,并进行了测试验证。监测系统采用低噪声偏置电源激发红外探测器的低频噪声,然后将该低频噪声信号通过设计的高性能前置放大器放大,利用基于PC的硬件平台采集放大后的噪声信号,最后通过编写的算法提取噪声信号的各种参量。实际测试结果表明,该监测系统能在10 k Hz的采样率下连续30 d不间断采集探测器的低频噪声,并实时计算噪声信号的峰峰值、均方值、功率谱密度等参数,频率分辨率可达到0.05 Hz。     

低噪声放大器在非入户串户排查装置中的运用

为提升电网服务质量、维护客户合法权益,研发了一种基于不同频率PLC信号的多表位串户排查系统。通过电力线载波方式,主机将信号送入客户家中,从机从客户门外接收信号,形成一个完整的载波信号从发出到接收的闭环系统。为提高系统灵敏度,电路加装低噪声放大器提取信号。     

激光雷达回波信号及处理方法分析

本文研究的主要内容是用数字信号处理的方法来处理和分析用于大气探测的激光雷达的信号。激光雷达的回波信号有很多种,例如：大气扰动噪声、电噪声以及背景噪声等,本文就是通过对这些大气探测的激光信号进行分析研究,并提出了一定的降噪方案,用来在一定程度上抑制部分噪声。利用距离校正的方法来获得探测距离。消除物理噪声采用的是MTI的方法。设计合适的滤波器,选择适当的截止频率,从而去除接收系统的各器件导致的高频的电噪声。     

三毫米单片集成电路噪声系数测量技术

采用双平衡混频器和本振信号源,把3 mm频段的噪声信号下变频至噪声系数分析仪的频率范围内,配探针台作在片噪声系数测量。为了减小本振源相位噪声和系统元件损耗的影响,在混频器前加低噪声放大器,使系统更加稳定,重复性好、准确度高。该系统具有频率范围宽可扩展至75～110 GHz、结构简单、成本低的特点。     

基于EMD-TFPF算法的电力线通信噪声消除技术研究

针对电力线通信系统中,发射端与接收端之间存在大量噪声严重影响通信质量的情况,引用时频峰值滤波算法(T i m e-F r e q u e n c y P e a k F i l t e r i n g,T F P F)作为噪声消除技术。考虑时频峰值滤波算法中窗长选择的严格限制,引用经验模态分解(E m p i r i c a l M o d e D e c o m p o s i t i o n,E M D)方法对T F P F进行改进。将信号分解为不同模态,在不同模态采用不同窗长进行T F P F滤波,以在信号保真和噪声压制方面得到更好的权衡。实验证明,相对原始T F P F,该方法具有更好的信号保真和噪声压制作用,可以有效地消除电力线通信系统噪声,降低误码率(B E R),提高通信质量。     

动态车辆称重系统的算法研究

汽车动态称重系统的算法研究是动态称重系统研究中的难点。为了提高动态称重系统的测量精度,对传感器在车辆非停车状态下所得短历程信号进行分析,利用巴特沃斯低通滤波器滤除噪声信号中的高频分量后;采用Levenberg Marquardt优化算法进行最小二乘法拟合,有效的抑制了低频周期随机干扰,实现了载荷的分离;通过载荷分离计算出车辆重量。实验表明,该算法能够提高动态称重系统的测量精度。     

Flexible Spectrum and Power Allocation for OFDM Unlicensed Wireless Systems

Future generations of communication systems will benefit from cognitive radio technology, which significantly improves the efficient usage of the finite radio spectrum resource. In this paper we present a wireless unlicensed system that successfully coexists with the licensed systems in the same spectrum range. The proposed unlicensed system determines the level of signals and noise in each frequency band and properly adjusts the spectrum and power allocations subject to rate constraints. It employs orthogonal frequency-division multiplexing (OFDM) modulation and distributes each transmitted bit energy over all the bands using a novel concept of bit spectrum patterns. A distributed optimization problem is formulated as a dynamic selection of spectrum patterns and power allocations that are better suited to the available spectrum range without degrading the licensed system performance. Bit spectrum patterns are designed based on a normalized gradient approach and the transmission powers are minimized for a predefined quality of service (QoS). At the optimal equilibrium point, the receiver that employs a conventional correlation operation with the replica of the transmitted signal will have the same efficiency as the minimum mean-squared error (MMSE) receiver in the presence of noise and licensed systems. Additionally, the proposed approach maximizes the unlicensed system capacity for the optimal spectrum and power allocations. The performance of the proposed algorithm is verified through simulations.      

A power‐area‐efficient, 3‐band, 2‐RX MIMO,TD‐LTE receiver with direct‐coupled ADC

In this work, a power‐area‐efficient, 3‐band, 2‐RX MIMO, and TD‐LTE (backward compatible with the HSPA+, HSUPA, HSDPA, and TD‐SCDMA) CMOS receiver is presented and implemented in 0.13‐μm CMOS technology. The continuous‐time delta‐sigma A/D converters (CT ?Σ ADCs) are directly coupled to the outputs of the transimpedance amplifiers, eliminating the need of analog anti‐aliasing filters between RX front‐end and ADCs in conventional structures. The strong adjacent channel interference without low‐pass filter attenuation is handled by proper gain control. A low‐power small‐area solution for excess loop delay compensation is implemented in the CT ?Σ ADC. At 20 MHz bandwidth, the CT ?Σ ADC achieves 66 dB dynamic range and 3.5 dB RX chip noise figure is measured. A maximum of 2.4 dB signal‐to‐noise ratio degradation is measured in all the adjacent channel selectivity (ACS) and blocking tests, demonstrating the effectiveness of the strategy against the low‐pass filter removal from the conventional architecture. The receiver dissipates a maximum of 171 mW at 2‐RX MIMO mode. To our best knowledge, it is the first research paper on the design of fully integrated commercial TD‐LTE receiver. Copyright © 2014 John Wiley & Sons, Ltd.     

Noise performance and nonlinear distortion of semiconductor laser under two‐tone modulation for use in analog CATV systems

We introduce numerical modeling of noise performance and distortion of semiconductor lasers subject to two‐tone modulation according to the National Television Standards Committee NTSC plan for the cable television (CATV) signal transport. The waveform of the laser signal is simulated over wide ranges of the modulation index and placements of the modulation channel. The power and frequency spectra of the relative intensity noise (RIN) are characterized, and the associated second‐order harmonic distortion (2HD), and the second‐order (IMD2) and third‐order intermodulation distortions (IMD3) are calculated. The calculated data are used to predict the measures of the CATV system performance. The dynamic range of linearity of the laser is evaluated in terms of the spurious‐free dynamic range SFDR. We show that under weak modulation, the low‐frequency RIN is constant at −168 dB/Hz regardless the modulation frequency. Within this accepted noise level, IMD2 is 4 dBm higher than 2HD and 10 dBm higher than IMD3. When the modulation index exceeds 25%, the laser emits clipped signals associated with large values of signal distortions. Accepted values of the carrier to noise ratio and distortions correspond to lower modulation index and/or channel frequency. Copyright © 2015 John Wiley & Sons, Ltd.     

窄带干扰对导航信号等效载噪比影响分析

等效载噪比是衡量导航信号捕获阈值确定、跟踪环路设计及理论定位精度计算等的重要参数,为了分析窄带干扰对导航信号等效载噪比的影响,在建立导航接收系统模型的基础上,对几种窄带干扰样式对等效载噪比的影响进行了数学仿真,仿真结果表明,等效载噪比与导航信号、干扰的功率以及导航信号调制样式等因素有关。     

An analog spread-spectrum interface for power-line data communication in home networking

Communication using power line as a medium of signal transmission offers a convenient and inexpensive solution for multimedia signal transmission and control applications in smart home networking. This work presents a novel analog spread-spectrum (SS) scheme for physical-layer interface in home networking. The proposed communication scheme uses a chaotic system to modulate the information signal for wideband transmission. The wideband spectral property of the transmitted chaotic signal adds robustness to the proposed scheme against the hostile power-line environment that is characterized by non-Gaussian noise and multipath propagation. By exploiting the ergodic property of chaotic signals, a simple noncoherent receiver is developed here. Not only does the proposed analog scheme demonstrate satisfactory communication performance, but it can also be implemented with simple hardware and low manufacturing cost, which is an important consideration for cost-effective home networking. The proposed noncoherent SS system does not involve quantization and complex synchronization process and, hence, it is more efficient in transmitting analog multimedia signals compared to the conventional SS system. Performance analyses illustrate the superior communication performance of the proposed analog SS system over the conventional SS scheme for multimedia signal transmission in a power-line home networking environment.