超高频RFID读写器数字接收机设计

针对超高频无源标签返回信号能量差异显著、数据率偏差大的特点,提出一种超高频无线射频识别(RFID)读写器数字接收机的实现方案。采用包含功率估计、数字锁相环同步和差分解码等模块的接收机方案,实现快速准确的接收。该数字接收机经过Matlab仿真验证,在Xilinx Spartan3E平台上实现并测试通过。与常用的多组相关器接收机方案相比,该数字接收机能以更少的硬件资源消耗实现更高性能的接收效果。     

基于FPGA的低成本GPS信号模拟器设计

本文介绍了一种低成本的GPS信号模拟器的设计;根据GPS信号的数学模型,设计了采用FPGA实现所有基带处理功能的方案。利用码发生器产生GPS各卫星的伪随机码,采用数字延迟滤波器实现信号的延迟处理,采用多级采样率转化器和滤波器串联的方法提高延迟精度,生成的多星基带信号在数字域进行叠加,再通过正交射频调制得到L1频点的GPS信号;该GPS信号模拟器结构简单,成本低,生成的GPS信号精度高,可以满足部分GPS接收机的测试需求。     

基于DDS产生线性调频信号技术研究

本文介绍了一个线性调频信号数字产生系统的设计与实现。首先对线性调频信号的两种主要数字产生方法进行了简要阐述和比较,然后根据直接数字合成（DDS）方法提出了线性调频信号产生方案,对其进行了系统实现研究,并给出了部分测试结果。     

OFDM雷达信号源设计与实现

为了验证正交频分复用(Orthogonal frequency division multiplex,OFDM）信号雷达的可 行性,本 文在研究信号产生原理和波形设计方法的基础上,提出了一种基于现场可编程门阵列技术和 快速傅里叶变换算法的雷达信号实时产生方案。该方案采用数字可编程技术实现正交多载波 调制,信号参数和调制方式具有可重配置的特点,满足多种场合的应用要求。本文针对OFDM 信号产生的关键步骤展开讨论,并给出测试结果。外场试验验证了该方案的可行性。     

AD9857在高频雷达发射系统中的应用研究

设计了一种基于可编程上变频器AD9857实现高频地波雷达数字上变频的方案。该方案采用DSP处理数字基带信号并控制AD9857完成上变频，可实时改变数字基带信号的调制方式和雷达的工作参数。实验证明该设计可以减化雷达体系结构，可实现雷达工作参数的可编程性，满足了武汉大学研制的下一代高频地波海洋监测雷达的需要。     

多波束视频信号模拟器的设计

为模拟雷达回波信号,验证波束形成情况,研究了雷达视频信号模拟器的体系结构、功能,给出了一种可实时模拟多路目标回波的雷达信号模拟器的实现方案。重点介绍了系统的硬件电路及其实现,叙述了多波束模拟的原理。该模拟器应用了DDS(直接式数字合成)和FPGA(现场可编程门阵列)等技术,具有较好的灵活性和通用性。可完成多波束视频信号产生的要求。     

脉冲信号发生~4/比较法的CPLD设计

本文讨论了一种新的脉冲信号的数字设计方法4/比较法,该方法通过对信号频率、占空比、余数的比较来产生频率、占空比均步进可调的脉冲信号。实验表明,该方法是行之有效的。本文着重介绍了其CPLD设计原理和实现方法,同时介绍了以CPLD为数字处理核心、在PC机的控制下实现脉冲信号产生的系统设计方案。     

采用计数器存储权值的人工神经网络的实现

文中提出了一种采用计数器存储权值的人工神经网络的实现方案。数字权值采用计数器存储,突触电路和神经元电路用模拟电路来实现。数字权值经脉冲宽度调制电路转换为脉冲信号作为模拟突触电路的输入信号。因而权值可以长期存储,对权值的修改易于实现,突触神经元电路结构简单,融合了人工神经网络模拟实现和数字实现的优点。对于智能计算机的实现具有重要的意义。     

脉冲信号发生-比较法的CPLD设计

本文讨论了一种新的脉冲信号的数字设计方法-比较法，该方法通过对信号频率、占空比、余数的比较来产生频率、占空比均步进可调的脉冲信号。实验表明，该方法是行之有效的。本文着重介绍了其CPLD设计原理和实现方法，同时介绍了以CPLD为数字处理核心、在PC机的控制下实现脉冲信号产生的系统设计方案。     

多路电视信号发生器R＆SCLG

罗德与施瓦茨公司在业界推出基于单机的多路信号发生方案：多路信号发生器R＆SCLG。该产品可以仿真模拟实际的有线电视网络，支持所有的频道，支持模拟电视和数字电视信号混合。尽管CLG只有19英寸宽和1U高度，它可以完全替代以往需要用整个机柜才能实现的功能。该产品可支持47～1002MHz频率范围，实现160路信号，并实现数字和模拟的任意组合。     

Enhanced process activation method to remove harmonics and input nonlinearity

A new closed-loop process activation method is proposed to reduce the harmonics and obtain more accurate frequency data compared with the previous methods. It has another advantage that the effect of the input nonlinearity can be removed by the proposed method combined with disturbance rejection techniques. The proposed method combines 10 pulses to generate one period of the relay signal. The 10 pulses are combined in an optimal way by solving a constrained nonlinear optimization problem to reduce the harmonics as much as possible. In the implementation step, this study uses the obtained optimal solution without continuing to solve the optimization problem. So, the implementation is almost as simple as that of the previous methods. The proposed method shows significantly smaller harmonics compared with the conventional relay feedback method. The previous approaches, which use a sinusoidal signal, multi-step signal, saturation-relay signal or preload relay signal to reduce the harmonics, cannot manipulate the input nonlinearity. However, the proposed method can estimate the frequency data set of the process effectively for the case where the process has an input nonlinearity because the proposed method uses pulse signals.     

基于瞬时相位分析的时钟抖动检测方法

针对时钟信号抖动的测量问题,提出了一种通过分析信号瞬时相位来测量信号抖动的新方法.该方法利用基于双窗函数频域法实现的希尔伯特变换来构造待测时钟信号的解析信号,再由该解析信号提取出待测信号各个时刻的瞬时相位,最后通过分析相位的抖动计算出时钟信号的抖动.用该方法对实例含抖动时钟信号进行了仿真实验,结果表明所测抖动与在待测时钟信号中加入的抖动一致;在窗函数的对比实验中,该方法表现出了更好的测量精度.     

A 2~n scaling scheme for signed RNS integers and its VLSI implementation

High effcient implementation of scaling in residue number system (RNS) is one of the critical issues for the applications of RNS in digital signal processing (DSP) systems. In this paper, an effcient scaling algorithm for signed integers in RNS is proposed firstly through introducing a correction constant in negative integers scaling procedure. Based on the proposed scaling algorithm, an effcient RNS 2n scaling implementation method is presented, in which Chinese remainder theorem (CRT) and a redundant modu...     

Design and implementation of a realtime co-processor for denoising Fiber Optic Gyroscope signal

The amount of noise present in the Fiber Optic Gyroscope (FOG) signal limits its applications and has a negative impact on navigation system. Existing algorithms such as Discrete Wavelet Transform (DWT), Kalman Filter (KF) denoise the FOG signal under static environment, however denoising fails in dynamic environment. Therefore in this paper an Adaptive Moving Average Dual Mode Kalman Filter (AMADMKF) is developed for denoising the FOG signal under both the static and dynamic environments. Performance of the proposed algorithm is compared with DWT and KF techniques. Further, a hardware Intellectual Property (IP) of the algorithm is developed for System on Chip (SoC) implementation using Xilinx Virtex-5 Field Programmable Gate Array (Virtex-5FX70T-1136). The developed IP is interfaced as a Co-processor/ Auxiliary Processing Unit (APU) with the PowerPC (PPC440) embedded processor of the FPGA. It is proved that the proposed system is an efficient solution for denoising the FOG signal in real-time environment. Hardware acceleration of developed Co-processor is 65× with respect to its equivalent software implementation of AMADMKF algorithm in the PPC440 embedded processor.     

Combined adaptive up-and-down method for equivalent time signal transformation

A combined adaptive up-and-down method for comparator type equivalent time transformation is proposed. The method uses the signal increment at the preceding phase point of the signal as well as the data for the current signal phase. The efficiency of the proposed method is compared to those of other comparator type equivalent time methods. The method is investigated for implementation in UWB radars.     

A new implementation of discrete bionic wavelet transform: Adaptive tiling

Bionic wavelet transform (BWT) is a biomodel-based adaptive time–frequency analysis technique. Due to its nonlinearity, it is difficult to realize the inverse BWT. To solve this problem, this paper introduces a new implementation for the discrete BWT (DBWT). The T-function from BWT is used to split the dyadic tiling map of DWT to obtain an adaptive DBWT tiling of the time–frequency plane. Quadrature-mirror filters, organized as the DBWT tiling map, are then employed to decompose the signal. This DBWT implementation makes the distortionless signal reconstruction possible. DBWT was used to decompose both simulated signal and actual nonstationary signals. Results show that DBWT performs better than discrete wavelet transform in demonstrating a more concentrated coefficient distribution in time–frequency plane. This proposed DBWT implementation will make BWT more applicable for the future nonstationary signal analysis.     

一种雷达回波实时仿真的软件实现方法研究

为了便于将雷达回波仿真应用于实践,提出一种雷达回波实时仿真的软件实现设计方法。按照雷达信号接收处理的工作原理,对雷达工作方式和战场环境分别建模并作适当简化,利用软件编程实现雷达回波仿真。利用软件实现的便捷性特点,在仿真中设计了一些交互接口,可接收对雷达工作状态的调整指令以及对模拟战场环境的修改信息。这样可实时更新生成不同环境下的动态回波信号,提高仿真应用的灵活性与通用性。仿真结果验证了该方法的可用性和有效性。     

三阶累积量在语音信号端点检测中的应用

语音信号的三阶累积量通常不等于零,因而可以用来检测噪声环境中语音的起始点和终止点。提出一种采用累积量矩阵的最大奇异值来实现语音端点检测的方法,并引入一种自适应的实现方法。仿真实验表明,所提方法在很大程度上降低了传统端点检测方法的错误率。     

Time-space transform: A novel signal processing approach for an acoustic vector-sensor

A new signal processing method using a single vector hydrophone is proposed for solving the problem of azimuth angle estimation for multiple targets based on a small aperture underwater platform.The method extends the aperture from a single vector hydrophone into a half wavelength distance uniform linear array by decomposing the time-domain sample data from different channels of the hydrophone.The extended array has a narrower space beam pattern than a single vector hydrophone.The azimuths of spatial multiple targets are estimated by using the appended array snapshots under the condition of broadband or narrow band signals.The new method is robust because there is no need to correct the array manifold.Theoretical analysis and computer simulations show that,the new algorithm has the ability to distinguish two incoherent targets with either narrow band or broadband signals in an isotropic noise field.The algorithm provides a non-biased estimate with a high signal-to-noise ratio.     

基于RapidIO的宽带实时频谱分析

研究了宽带实时频谱分析技术的实现方法,详述了硬件实现的两项关键技术:采用RapidIO互连技术解决了高速数据传输和大容量的数据缓存;采用并行流水线结构的实时信号处理器实现了有限硬件资源及处理能力下的实时高精度频谱分析。经测试,系统能够实现分析带宽80 MHz、捕获数据容量为512 MB的高精度实时频谱分析,主要性能指标接近国外最新仪器的水平,并已在部分型号的雷达和通信设备中得到了应用。