Analysis of a TASI System Employing Speech Storage

This paper presents a performance analysis of a PLC-1 private line voice concentrator which uses speech interpolation to increase the capacity of transmission facilities. The PLC-1 employs speech storage. As a result it can be applied to relatively small trunk groups where statistics of loading patterns are particularly unfavorable. Speech impairments can be categorized as delay, gap modulation, and clipping. A mathematical model based on queueing theory is presented for the evaluation of the statistics of these impairments. The model can be used to determine obtainable TASI advantage for various system configurations and loading conditions. It is shown that a TASI advantage of two is achievable with 24 transmission facilities. The veracity of the queueing model is established using simulation techniques.     

Unloaded Q of Single Crystal Yttrium-Iron-Garnet Resonator as a Function of Frequency (Correspondence)

The practical feasibility of constructing magnetically tunable broad-tuning range microwave filters using single crystal yttriumiron-garnet resonators was demonstrated in a recent paper. Experimental results were presented on one- and two- resonator filters which can be tuned by varying a dc magnetic field bias over a full waveguide bandwidth and greater, at the same time maintaining an insertion loss performance which is comparable to mechanically-tuned cavity filters. The crucial parameter of the resonant elements in a band-pass filter is the unloaded Q, Q/sub u/. With a spherical single crystal of yttrium-iron-garnet the Q/sub u/ decreases with frequency below X-band frequencies reaching very low values at frequencies around 2000 Mc.     

Efficient FPGA Implementation of a Programmable Architecture for GF(p) Elliptic Curve Crypto Computations

This paper presents a processor architecture for elliptic curve cryptography computations over GF(p). The speed to compute the Elliptic-curve point multiplication over the prime fields GF(p) is increased by using the maximum degree of parallelism, and by carefully selecting the most appropriate coordinates system. The proposed Elliptic Curve processor is implemented using FPGAs. The time, area and throughput results are obtained, analyzed, and compared with previously proposed designs showing interesting performance and features.     

Design and Performance of a DSI Terminal for Domestic Applications

The development of a microprocessor-controlled 96/48 DSI terminal is described. The terminal is intended for domestic use, and is designed so as to maximize compatibility with existing digital carrier systems, it merges four T1 signals into two T1 compatible bit streams for transmission. The terminal is given sufficient excess capacity to accommodate voiceband data, while retaining toll-grade transmission quality for speech. Implementation approaches and considerations in both calculated and measured system characteristics are described.     

C++编译器前端对函数重载的设计研究

针对标准C++语言中的函数重栽机制,提出一种设计方法,解决编译器前端构建中重载函数的解析.文中首先阐述了重栽的概念和解析的基本过程,其次讨论了语法分析器、文法产生式、符号表、抽象语法树四者在处理函数重载时的相互关系.最后详细介绍了重裁函数的存储、名字解析、重栽解析的方法.     

TTT System (50 Mbits/s PCM-TDMA System With Time Preassignment and TASI) and Its Satellite Test Results

An experimental 50 Mbits/s pulse-code modulation-time-division multiple access (PCM-TDMA) system with time preassignment and time-assignment speech interpolation (TASI) features (called the TTT system) was built for use in a satellite test. This system was designed for application in the INTELSAT IV network and has the channel capacity of more than 700 telephone channels. This capacity can be increased up to twice when pulse-code modulation-time-assignment speech interpolation (PCM-TASI) is adopted. The field test was conducted via INTELSAT III in 1970 and satisfactory results were obtained, which encourages the introduction of the TDMA system for commercial use.     

Delay Analysis of TASI with Random Fluctuations in the Number of Voice Calls

In this paper we consider a system where the talkspurts from several voice conversations are buffered and multiplexed over the same transmission channels. A simple mathematical model is given for the case where the number of voice calls may statistically come and go. This model is then used to numerically analyze the system and make comparisons with previously presented results.     

Spreading Resistance as a Function of Frequency

The equivalent circuit applicable to most semiconductor diodes contains a term R/sub s/ called the spreading resistance which is a very critical parameter of any diode. In a mixer diode, R/sub s/ limits the conversion efficiency and increases the noise temperature. In parametric amplifiers, R/sub s/ affects the overall impedance levels and determines the minimum noise figure of which the amplifier is capable. In harmonic generators it drastically affects the conversion efficiency, as it dissipates power not only at the input and output harmonic frequencies but also at every idler frequency for which current may flow through the diode. This paper details more specifically the problems encountered when high frequency operation must be evaluated. The cylindrical capacitor is examined with emphasis on the configuration which applies to the variable-capacitor diode, which is used primarily for harmonic power generation. The point-contact diode configuration is examined and the field equations are derived in terms of the oblate spheroidal coordinates. It is shown that this is the natural coordinate system for such an analysis and that the spreading resistance is quite easily derived in this system.     

S1240交换机的网络话务控制功能

论述了网络话务控制管理的概念、意义以及各项控制功能和使用的方法。     

Computation of the Hecken Impedauce Function (Letters)

The Dolph-Chebyshev impedance function derived by Klopfenstein has discontinuities at the taper ends which introduce unwanted effects in certain applications. The Hecken impedance function is not optimum in the Dolph-Chebyshev sense, but achieves matching without impedance steps. For any bandwidth and maximum magnitude of reflection coefficient in the passband, the Hecken taper is only slightly longer than the optimum taper. Hecken's near-optimum taper is therefore an attractive alternative to the optimum taper when impedance discontinuities are undesirable.     

MPLS-TE流量工程系统设计(2)

介绍了MPLS和MPLS—TE的一些基本概念和技术原理,特别是对MPLS—TE的主要应用,如隧道(Tunnel)和链路保护(FRR)等进行了详细阐述。通过MPLS—TE在广东省IP骨干网络实施方案的介绍,给出了一些MPLS—TE在实际应用中的典型配置。     

MPLS-TE流量工程系统设计(1)

介绍了MPLS和MPLS-TE的一些基本概念和技术原理,特别是对MPLS-TE的主要应用,如隧道(Tunnel)和链路保护(FRR)等进行了详细阐述。通过MPLS-TE在广东省IP骨干网络实施方案的介绍,给出了一些MPLS-TE在实际应用中的典型配置。     

新型多功能交通灯控制系统的设计

介绍了一种新型多功能交通灯控制系统，重点介绍了应用新型在系统可编程器件（ISP）来实现多功能交通灯控制系统的设计方法。     

Application of a Property of the Airy Function to Fiber Optics (Short Papers)

The integral of the square of the Airy function from one of its zeros to infinity is equal to the square of the first derivative of the Airy function at the zero considered. Two important applications of this result to fiber optics are discussed.     

Listening Comprehension as a Function of Word Rate

Twelve comparable groups of Ss heard a listening selection that differed, from group to group, with respect to word rate. Word rate was varied, in increments of 25 wpm (words per minute), from 125 to 400 wpm, by means of the sampling method for compressing or expanding recorded speech. After listening to the selection, Ss were tested for comprehension by a multiple choice test. Comprehension was not seriously affected by increasing word rate from 125 to 250 wpm, but it declined rapidly thereafter. The suggested explanation of these results is that time is required for the perception of words, and that as word rate is increased beyond a certain point, the perception time available to the listener becomes inadequate, and a rapid deterioration of listening comprehension commences.     

浅谈移动通信话务网管系统基本结构与功能

介绍中国移动通信网及网管系统的现状和发展方向以及其省级话务网网管的组网结构、软件结构和基本功能的描述。     

具有GPS功能的集群系统中业务容量的分析

集群系统中引入GPS功能后,由于GPS数据传输的较高优先级,使得已经建立的话音链路有可能被强行拆线,造成话音通信的呼损量的增加。提出了一种计算方法,用来获得按照某种给定呼损量要求和总信道数情况下的各类型信道的最佳分配方案。     

The Performance of the Adaptive Aggregation Mechanism (AAM) Under Mixed Traffic Loads

The adaptive packet aggregation algorithm (AAM) has been shown to have a superior performance over the first-in first-out (FIFO) algorithm in terms of the throughput and delay (Deng and Davis in International conference on wireless communications and signal processing 2013 (WCSP2013), Hangzhou, China, pp 449–504, 2013; 20th IEEE symposium on communications and vehicular technology in the Benelux 2013 (IEEE SCVT 2013), Namur, 2013). In this paper, we will show that when compared with the FIFO and smallest-size first-served algorithms, the AAM algorithm has the best performances in terms of the trade-off between the overhead saving and the average delay under mixed traffic loads in wireless LANs. The simulation results show that the AAM algorithm produces the largest average aggregate packet size.     

Electromagnetic Near Fields as a Function of Electrical Size

The near fields of a radiating rectangular plate placed over and normal to an infinite horizontal ground plane have been analyzed as a function of the electrical size of the plate. Both vertical and horizontal currents are taken into account. Two different methods are used to compute the near fields. The variation of the electric field along the normal to the plate is studied in detail as a function of the electrical length L/? of the plate. The electric-field magnitude decreases as distance r increases until an oscillatory region is encountered about one wavelength from the plate. Oscillations continue until distance is equal to L2 /4?, or one-eighth of the usual far-field distance. The location of various minima and maxima can be predicted by a consideration of Fresnel theory. Comparison is made with the near fields of a circular aperture.