带通信号采样定理和全数字式正交检波器的设计

带通信号采样定理是全数字式正交检波器设计的理论基础，目前国内外相关文献关于带通信号采样定理的表述有多种形式，这将直接影响到全数字式正交检波器设计的优点。本文首先讨论带通信号采样定理，然后在此基础上研究全数字式正交检波器的优化设计。     

数字式中频正交检波器

介绍了数字式中频检波器的原理、组成及关键技术、相对于模拟式中频正交检波器的优点及通信号的采样定理。     

带通信号的数字正交采样定理及优化设计

在数字正交采样中,带通信号存在频谱迁移问题,虽然满足带通信号的采样定理,仍可能产生频谱混叠。该文证明了带通信号的数字正交采样定理,并讨论了这种采样系统的优化设计。     

带通信号采样定理的教学浅析

现有＂信号与系统＂及＂信号处理＂两门课程的教材对带通信号的采样定理未给出详细讨论,在一定程度上影响了学生对带通信号采样定理的理解。笔者根据多年的教学体会,从带通信号采样定理的引入、推导及举例等几个基本环节,对带通信号采样定理作简要描述,供读者参考。     

带通信号的直接采样与重构

本文指出目前带通信号直接采样和重构定理是不充分和不完整的,基于Shannon采样定理的频谱褶叠概念,本文提出了带通信号离散化后频谱的二类混淆现象,即叠加混淆和错位混淆的概念,给出和证明了带通信号直接采样和重构定理.同时,本文说明Shannon采样定理是本文提出定理的一个特例。     

DBF系统的数字正交相干检波设计

结合某具体工程实例讨论了带通信号采样定理,在此基础上研究了数字正交相干检波技术的优化设计.计算机仿真和性能分析表明,该设计对其他工程具有一定的参考价值.     

带通采样定理与中频采集数字正交检波

结合对带通采样定理的理解，讨论了直接中频带通信号采样正交检波的基本原理，重点探讨正交混频低通滤波法和希尔伯特变换频移法。利用对带通采样定理的理解，扩展其应用范围，给出了适用条件、原理框图以及信号流图。最后用仿真实例验证了扩展方法的可行性，对工程实际有一定的参考意义。     

带通采样在多载波数字中频接收机中的应用

在全面论述带通信号的采样定理,并对带通采样后的频谱结构仔细分析的基础上,从工程应用的角度出发,提出一种中频频率、采样频率联合优化的方法。将此方法应用于cdma2000多载波数字中频接收机的设计中,验证了它的可行性和实用性。     

一种新的带通信号采样方法

本文提出一种新的带通信号采样方法,实现对带通信号的“等效”低通信号采样。带通信号实际采样率仅为输出端所获同相分量和正交分量采样率的两倍,可以直接确定采样频率和设计低通抗混叠滤波器。该采样方法使用滤波器的多相结构实现,这种实现方法特别适合于线性相移FIR滤波器。     

非理想中频信号带通采样及数字正交检波器设计

信号中频的非理想给带通采样有着不利影响,并影响正交变换的性能.文中分析了非理想带通采样情况下正交检波器的设计以及性能,对正交变换中最重要的低通滤波器的性能以及参数选择进行了仿真,并给出了低通滤波器的设计方法和该数字正交检波器在FPGA中的实现方法.     

An optimum generalized cross-spectrum symbol-rate detector

The optimal design of a precorrelation filtering system for use in cross-spectrum symbol-rate detectors in the presence of additive Gaussian noise is described. This approach generalizes practical cross-spectrum symbol-rate detectors, and derives a necessary condition which achieves the maximum processed signal-to-noise ratio at an integer multiple of the symbol rate. The resultant optimum condition depends on the transfer functions of precorrelation filters and fixed signal model parameters. As a by-product, a performance measure applicable to any quadrature amplitude modulation format and including the effects of self-noise and intersymbol interference is derived. An algorithm for constructing physically realizable precorrelation filters that satisfy the optimum condition is given to complete the design process     

Mean-Square Error Optimization of Quadrature Receivers for CPM with Modulation Index 1/2

Detection of continuous phase modulation (CPM) signals can be accomplished using quadrature coherent detectors which include a pair of linear and time-invariant postdetection filters. Performance of the quadrature detectors is highly sensitive to the postdetection filters response. This paper presents a rigorous derivation of an optimum postdetection filter response. The derivation is based on minimizing the mean-square interference subject, to the constraint that the filter noise bandwidth is held constant. The amount of computations involved is fairly small and increases linearly with the receiver observation interval. Performance analysis results for several modulation techniques are presented.     

基于多相滤波法的中频信号正交解调的CPLD实现

正交相干检波可以将复包络的所有信息进行保留,所以在数字信号处理中得到广泛应用。该文讨论了数字信号正交相干检波的多相滤波实现方法,并且给出了基于 CPLD 的 IC 实现。计算机仿真结果表明,多相滤波方法可以提高信噪比,实现高性能数字信号处理的要求。     

基于多相滤波简化结构的数字正交相干检波

针对传统正交相干检波方法存在镜频抑制比、数据吞吐率小以及硬件设计资源消耗大的不足，提出了一种基于多相滤波和简化加法器图结构的数字正交相干检波方法，此方法在有效改善系统正交相干检波性能的同时，提高了数据吞吐率，节省了系统实现的硬件资源。理论仿真结果和实际工程应用都验证了所提方法的有效性。     

Penalties of Sample-and-Sum and Weighted Partial Decision Detectors in Gaussian Noise

The deterioration in performance, measured in the probability of error sense, of sample-and-sum and weighted partial decision detectors are analyzed for arbitrary signal-to-noise ratios. These suboptimal detectors have more modest computational requirements than the optimal digital matched filter making them amenable to simple digital implementations. The effects on the penalties of the signaling waveform employed, the number of samples processed, and the signal-to-noise ratio are considered in detail. Included are the penalties for the optimum weighted partial decision detector. The optimum weighted partial decision detector is the optimum detector, in the minimum probability of error sense, for hard-limited samples. The penalty of the optimum weighted partial decision detector relative to the digital matched filter detector represents the fundamental loss in signal detectability due to hard-limiting in a sampled system.     

一种多模式合成孔径雷达数字接收机

针对一种多模式极化合成孔径雷达（SAR）,给出了中频数字接收机工作参数选择,混频滤波方法,实现了三种带宽信号的数字正交解调。通过分析同相、正交通道误差对正交解调性能的影响,确定了滤波器最佳设计准则。最后给出了基于FPGA的实现结构,仿真试验结果表明中频数字接收机性能比一般模拟接收机有显著提高。     

Distributed signal detection under the Neyman-Pearson criterion

A procedure for finding the Neyman-Pearson optimum distributed sensor detectors for cases with statistically dependent observations is described. This is the first valid procedure we have seen for this case. This procedure is based on a theorem proven in this paper. These results clarify and correct a number of possibly misleading discussions in the existing literature. Cases with networks of sensors in fairly general configurations are considered along with cases where the sensor detectors make multiple bit sensor decisions