宽带数字信道化接收机综述

 宽带数字信道化接收机以其高性能在电子战和无线电通信中有着重要的运用.本文基于复杂电磁环境下电子战的运用需求,分析了信道化接收机系统的发展现状和趋势;研究了目前的数字信道化接收机技术的主要系统结构及其发展趋势;重点分析了信道化接收机技术的发展历程和发展趋势.根据目前的信道化接收机系统和数字信道化接收机技术的现状可以看出,数字信道化接收机发展的一个趋势是:宽带数字化(大量子信道)和非均匀信道化接收机及动态信道化接收机.     

多相滤波宽带信道化数字接收机

宽带雷达电子战数字接收机是当前国内外研究的重点,信道化接收机能够处理同时到达的多个信号并有较高的截获概率。多相滤波信道化接收机运算量小且易于实现。为克服因D倍抽取而产生的多相滤波信道化数字接收机的接收盲区,引入了重叠一半的多相滤波信道化数字接收机。利用瞬时自相关接收机,可在消除信道化接收机虚假输出的同时提高信道化接收机的测频精度。文中给出了上述数字接收机的实现方法,并通过仿真实验证明了以上结论的有效性。     

数字接收机中超高速A／D转换电路的PCB设计

随着大规模集成电路和数字信号处理技术的迅速发展，雷达接收机和电子战接收机的数字化已是一种必然趋势，A／D变换器是决定数字接收机性能的关键部件之一，文中结合一种采样率可达1GSPS的A／D转换电路的设计，重点介绍了高速高频PCB设计的一些规则、注意事项和经验。     

Timing with Dirty Templates for Low-Resolution Digital UWB Receivers

As a rapid timing synchronization technique for ultra-wideband (UWB) communications, the timing with dirty templates (TDT) technique effectively collects the multipath energy even when the channel is unknown [7]. In this paper, we investigate TDT algorithms for digital UWB receivers with low-resolution analog-to-digital converters (ADC). Different from the original TDT in [7] for analog UWB receivers, our digital TDT synchronizers here can avoid the ultra-wideband analog delay elements which are difficult to implement at the IC level. Our analysis and simulations show that the (non)data-aided digital TDT algorithms remain operational even when the ADC resolution is very low.     

Interference cancellation with an array processing MLSE receiver

the capacity and transmission quality in cellular systems can be improved by using receivers that mitigate cochannel interference and multipath propagation. In this paper, a class of multichannel maximum likelihood sequence estimation (MLSE) receivers is developed for this purpose. Interference mitigation is accomplished via adaptive antenna arrays, while multipath propagation is combated via MLSE. Practical considerations are included, such as fixed front-end filtering, sampling, and estimation of parameters from received samples. Maximal ratio combining, conventional array processing and metric combining (MC) are shown to be special cases of the proposed receivers. Performance is evaluated for π/4-shift DQPSK, using the parameters and transmission format of the time-division multiple-access (TDMA)-based IS-136 (D-AMPS) digital cellular standard. Semi-analytical performance predictions are developed which confirm simulation trends. The results show that these receivers can operate at significantly lower carrier-to-interferer (C/I) levels than conventional MC receivers     

Applications of magnetostatic wave technology to EW systems — An assessment

Current magnetostatic wave technology applicable to EW systems is assessed. Some of the developments currently underway with dispersive and non-dispersive delay lines, tunable oscillators and bandpass filters are examined and projected performance three years from now is given. Various EW applications are then described based on these projections. This includes compressive receivers, fast call receivers, phased arrays, scanning receivers, and channelizers. In many instances MSW technology can replace SAW provided further improvements materialize.     

Digital microwave receiver technology

This paper reports the impact of digital signal processing on microwave receiver technology. The majority of modern receiver designs are based on digital technology. Wide-and narrow-band receivers are presented. The wide-band receivers cover approximately 1-GHz instantaneous bandwidth and are used to intercept radar pulses. Current narrow-band receivers cover up to 50-MHz instantaneous bandwidth and are primarily used for receiving communication signals. Two approaches for wide-band receiver design are discussed. One is the conventional digital receiver. The other one is called the monobit receiver, which has slightly inferior performance in some respects, but can be built on a single chip. Narrow-band receivers are best implemented in software because they can more adapt to changes. Two types of receivers are discussed. One is the software Global Positioning System receiver. The other one is called a transform-domain communication system. The object of this system is to avoid interference in a hostile communication environment     

舰载无源综合脉冲/孔径雷达及其若干关键问题

本文根据综合脉冲/孔径雷达采用多个天线同时向全空域辐射多个载频信号,而在接收端通过信号处理获得发射方向图的特点,提出一种新的雷达体制——舰载无源综合脉冲/孔径雷达.该雷达既利用在岸上发射、在舰船上接收而构成岸-舰双/多基地"广播式"雷达,又由于在接收站不发射信号而相当于无源定位.本文介绍该雷达的基本组成、工作原理及其特点;分析其性能;讨论该雷达需解决的关键问题.     

Investigation into the interference potential of spread-spectrum clock generation to broadband digital communications

Since its inception, spread-spectrum clocks have been a valuable technology for the purposes of EMI reduction and EMC compliance. This study evaluates the interference potential of spread spectrum clocks to broadband digital communications such as high definition television (HDTV). This is accomplished by comparing the spread spectrum clock interference susceptibility of digital television (DTV) receivers to the interference susceptibility of analog television receivers. This study shows that DTV receivers are more immune to the same level of interference than existing analog television receivers by 16 dB. Since industry has shown that analog television has had negligible interference from information technology equipment, including spread spectrum clocks, then the digital systems should have even less.     

High two-signal dynamic range and accurate frequency measurement for close frequency separation wideband digital receiver using adaptive gain control and adaptive thresholding

In electronic-warfare (EW) receiver applications, real-time measurement of the radar signals' carrier frequencies is mandatory and considered to be one of the most important radar parameters. Accurate frequency detection can be used to sort and deinterleave signals in a dense signal environment where multiple signals arrive simultaneously presenting severe problems unless they can be differentiated appropriately. Researchers and engineers are actively looking for new algorithms for high resolution wideband receivers with easier implementation. This paper presents an adaptive gain control and dynamic thresholding wideband digital receiver to accurately detect two simultaneous high dynamic range signals, even when their signal frequencies are very close. The proposed fast Fourier transform (FFT) based receiver examines incoming signal characteristics and provides real-time accomplishment of these tasks, by way of using an adaptive gain-control amplifier, a squarer, two analog-to-digital converters, and two FFT's. The wideband receiver offers high probability of intercept over wide instantaneous RF bandwidths, high dynamic ranges and sensitivity. Two simultaneous signal accommodations and their characteristics are provided to demonstrate the improvements over presently used receivers in this field.     

Sequence estimation techniques for digital subscriber looptransmission with crosstalk interference

The use of reduced-state sequence estimation techniques in a digital subscriber loop receiver is discussed. These techniques offer a potential performance improvement over conventional equalization techniques such as decision feedback equalization (DFE). Stationary and cyclostationary NEXT noise models are described. The theoretical performance obtainable from a Viterbi algorithm receiver with stationary white Gaussian noise, stationary NEXT, and cyclostationary NEXT noise models is estimated, and the reduced-state decision feedback sequence estimation and M algorithms are reviewed. It is shown that the improvement can be especially significant in the presence of cyclostationary crosstalk because of the freedom that sequence estimation receivers afford in the choice of receiver sampling phase. This advantage is evaluated for Viterbi algorithm receivers. By simulation of two practical reduced-state sequence estimation receivers, it is demonstrated that, in the presence of cyclostationary crosstalk, a substantial increase in maximum loop range (or equivalently, maximum bit rate) may be achievable compared to conventional DFE equalization     

Applications of Multipath Transform-Domain Charge-Sampling Wide-Band Receivers

Transform-domain (TD) receivers expand the received signal over a basis set, and then operate on the basis coefficients. An analog computation of the basis coefficients efficiently parallelizes the signal for digital processing, relaxing the sampling requirements and enabling parallel digital processing at a much lower rate. Frequency-domain (FD) sampling, as a special case of TD sampling, has been proposed to parallelize the sampling process in broad-band communication receivers. The flexibility and scalability of TD receivers allow for the design of receivers that can cope with a large range of narrow-band and broad-band communications standards. A theoretical TD receiver design example is provided which is capable of processing GSM, Bluetooth, IEEE802.11g, Wimax, and UWB in just one configurable front-end. An example of spectrum sensing in cognitive radio is also provided.     

Broadcasting

Three major allocation issues involving the broadcasting and broadcasting-satellite services that will be discussed at the 1992 World Administrative Radio Conference (WARC-92) are examined. They are expansion of frequencies for conventional high-frequency (shortwave) broadcasting, new frequencies for both satellite and terrestrial digital audio (radio) broadcasting to handheld and automobile receivers, and new frequencies for studio-quality high-definition television broadcasting from satellites. The bands that are viable candidates for these services are discussed     

海战场电子战的发展和对策

简述海战场电子战在现代海战中的作用,分析海战场电子战的发展水平和面临的挑战,提出海战场电子战的发展趋势和对策。     

电子战接收机的发展历程及其面临的挑战

回顾了电子战接收机特别是电子战数字接收机的发展历程,在此基础上指出宽带数字接收机是电子战接收机的发展趋势,并提出了宽带数字接收机必须要克服的主要技术难题。     

A survey of the communication theory literature: 1968-1973

This paper surveys the literature on communication theory from 1968 to 1973. A large part of this literature, and of this paper, deals with digital communication through linear dispersive channels. Error rate bounds for pulse-amplitude modulation systems, the optimization of linear transmitters and receivers, and adaptive equalization are topics discussed initially. Important results from the literature on non-linear receivers are described next, including decision feedback, maximum-likelihood, and Viterbi algorithm approaches. New results on the conventional digital modulation formats of amplitude, phase, and frequency-shift keying are summarized. The paper concludes with sections describing the literature from this period on nonlinear and non-Gaussian problems, analog communication, and feedback communication.     

新型卫星电视门限扩展解调器—FPLL

FPLL是一种新型卫星电视门限扩展解调器。与常规PLL门限扩展解调器相比,它具有捕获范围宽,捕获时间短,门限改善量显著等优点。本文首先介绍FPLL的工作原理,然后对FPLL进行初步理论分析。     

Locally optimum Bayes detection (LOBD) in signal-dependent noise

The locally optimum Bayes detection (LOBD) framework for nonadditive non-Gaussian noise is applied to a particular additive and signal-dependent noise model where the noise components are correlated. Under the proposed observation model, the performance of the LOB detectors is compared with that of well-known conventional receivers     

Convergence analyses and comparisons of Markov chain Monte Carloalgorithms in digital communications

Markov chain Monte Carlo (MCMC) methods have been applied to the design of blind Bayesian receivers in a number of digital communications applications. The salient features of these MCMC receivers include the following: (a) they are optimal in the sense of achieving minimum symbol error rate; (b) they do not require knowledge of the channel states, nor do they explicitly estimate the channel by employing training signals or decision-feedback; and (c) they are well suited for iterative (turbo) processing in coded systems. We investigate the convergence behavior of several MCMC algorithms (both existing and new ones) in digital communication applications. The geometric convergence property of these algorithms is established by considering only the chains or the marginal chains corresponding to the transmitted digital symbols, which take values from a finite discrete set. We then focus on three specific applications, namely, the MCMC decoders in AWGN channels, ISI channels, and CDMA channels. The convergence rates for these algorithms are computed for small simulated datasets. Different convergence behaviors are observed. It is seen that differential encoding, parameter constraining, collapsing, and grouping are efficient ways of accelerating the convergence of the MCMC algorithms, especially in the presence of channel phase ambiguity