数字光信号源：—光纤通信系统的一种新型配套仪器

本文叙述了数字光信号源的主要用途、性能参数、工作原理和电路设计原理及原理图。     

New methods of radar performances analysis

Original methods for radar detection performance analysis are derived for a fluctuating or non-fluctuating target embedded in additive and a priori unknown noise. This kind of noise can be, for example, the sea or ground clutter encountered in surface-based radar for the detection of low grazing angle targets and/or in high-resolution radar. In these cases, the spiky clutter tends to have a statistic which strongly differs from the Gaussian assumption. Therefore, the detection theory is no longer appropriate since the nature of statistics has to be known. The new methods proposed here are based on the parametric modelling of the moment generating function of the noise envelope by Padé approximation, and lead to a powerful estimation of its probability density function. They allow to evaluate the radar detection performances of targets embedded in arbitrary noise without knowledge of the closed form of its statistic and in the same way to take into account any possible fluctuation of the target. These methods have been tested successfully on synthetic signals and used on experimental signals such as ground clutter.     

SIP和PSTN语音网关的设计与实现

文章基于SIP协议，提出了一个PSTN小型语音网关的设计与实现方案．使IP网络上的SIPUA可以与PSTN的电话进行语音互通。同时，对网关的安全性进行了探讨与实现。     

若干信号处理的总体设计思路

信号处理是目前电子战技术发展的一个关键技术。不能单纯从信号处理本身来考虑如何实现信号处理 ,必须从系统角度设计信号处理 ,同时结合工作实践对信号处理提出一些建议。     

An FFT-based signal identification approach for obtaining the propagation constants of the leaky modes in layered media

We propose to find the propagation constants of modes in layered media by means of signal identification methods. To this effect we employ Cauchy's theorem, conformal mapping and Fast Fourier Transform (FFT) techniques to generate relevant Hankel moments, afterwards to be processed with selected signal identification algorithms. The method, terminated by a few Newton steps, provides a batch of highly accurate roots in appropriate disks or half-disks.     

光纤综合业务局域网

本文扼要地介绍了把光通信技术和计算机技术组合应用,以光纤为传输介质,组成一个以一根光纤同时传输图象信息、话音信息、文字真迹信息和数据信息等不同业务的综合业务局域网。并叙述了网络的拓扑形式、功能、用途及光端机的构成,计算机的作用等。     

TMS 32020单片信号处理器在测控系统中的应用

在卫星地面测控系统中,要求在低信噪比(如-20分贝)条件下提取目标的多普勒频率信息,以引导接收机锁相环捕获信号并锁定。模拟式频率引导采用经典的晶体滤波器组,其数量大、成本高、重量体积大。数字式频率引导采用对接收信号采样序列进行FFT运算处理实现对目标的频率捕获,具有显著的优越性。作者等人以8086微机实现的数字频率引导设备已成功地应用于同步通讯卫星测控站中。为了进一步提高处理速度,采用了TMS32020单片信号处理器研制出频率引导快速处理机,使频率引导处理时间提高15倍以上。该成果的硬件设备可适应不同的实时数字信号处理要求,应用于雷达、通讯、遥控、仪器、语音、智能等各种场合。     

Signal suppression effects in an ideal hard-limiter for the many-carrier case

An analytical expression, previously derived in a companion paper published in Volume 7, Issue No. 1 of the International Journal of Satellite Communications (pp. 3–6), was used to generate signal suppression data for 3, 5, 10, 20, 40 and 55 input signal scenarios in the presence of Gaussian noise assuming an ideal hard-limiter for a wide range of input signal ratios. Additionally, the signal suppression effect has been quantified for up to 200 input signals with input SNRs of ∞, 6 dB and 0 dB for the case in which a single higher-power input signal exists in the presence of lower, equal-powered signals. The data support the argument that the signal suppression effect is significantly reduced as the number of input signals is increased for the scenarios investigated. Also, the generated data show that the signal suppression effect decreases asymptotically to a value less than 1 dB for the case of a single higher-power signal in the presence of varying degrees of input Gaussian noise and up to 200 total signals. Finally, a Gaussian approximation of the input signal ensemble was verified for the full range of input signal sets investigated.