On the efficient use of computer simulated digital signals toevaluate performance parameters

The design of symbol sequences to be used in quasi-analytical simulation to estimate performance parameters of digital transmission systems is considered. An efficient method is presented for including the effects of external interfering signals in the evaluation of error probabilities. It consists of using simulated signals to obtain the moments of interference samples and applying the Gauss quadrature rule to calculate error probabilities. Several results are presented that confirm both the accuracy and efficiency of this procedure in the simulation of some interference environments     

The digital computer as a creative medium

Digital computers are now being used to produce musical sounds and to generate artistic visual images. The artist or composer interacts directly with the computer through a console. This article explores the possibilities of the computer as an artistic medium and makes some predictions about the art of the future.     

Passively Q-switched spaser as a terahertz clock oscillator for plasmon computer

The interaction of plasmons in spaser with saturable absorber leads to pulse generation under passive Q-switching. A distributed scheme of spaser that represents a groove on metal surface filled with active medium is considered. The Maxwell–Bloch equations are used to describe generation of 1D plasmons in such a distributed spaser. The operation of the system as a terahertz clock oscillator is demonstrated with the aid of numerical experiment.     

A new approach to the use of a digital computer in circuit design

In the presently available C.A.D. systems the extent to which the computer can assist in the design of a circuit is fundamentally limited by the fact that the potential user generally has to perform the initial d.C. and a.c. design of the circuit before such a system can be used. This paper discusses a new approach whereby the systematic hy-hand design procedure is automated so that the circuit designer is able to use the computer throughout the whole design phase. The problem of selecting the optimum set of preferred values is discussed, although at the time of writing an efficient algorithm to solve this nun-linear optimization problem has yet to be developed.     

Implementation of linear programming with a digital stochastic computer

The problem of online computation of linear-programming problems with digital-stochastic-computing structures is considered. Such techniques are shown to provide very economical and fast online computations. The simple logic-circuits used for the realisation of the stochastic operators are ideally suited for large-scale integrated-circuit fabrication. Experimental results are presented for the stochastic computation of linear programming with an algorithm based on steepest-descent techniques.     

适用于数字电源的新型温度自校准片上振荡器的设计

设计了一种应用于数字电源的新型温度自校准高精度片上振荡器。该振荡器利用片内集成的环形振荡器作为"温度传感器",环形振荡器的偏置电流设计成与热力学温度成正比,输出时钟信号频率对温度变化高度敏感,以此作为温度校准的参考信号,经过数字自校准算法产生控制RC振荡器充电电流大小的信号,校准RC振荡器输出时钟频率,从而完成片上实时温度自校准的功能。采用双比较器加SR触发器对称结构,降低比较器延迟误差。电路基于0.18μm BCD工艺模型,采用Cadence和Hspice进行仿真。仿真结果表明,在–55~+155℃温度范围内,振荡器输出中心频率为10.1 MHz,振荡器的频率随温度变化的偏移量在±0.6%以内。     

On the design of a series-feedback network in a transistornegative-resistance oscillator

This paper presents a review and exposition to the design of the series-feedback network commonly used in a negative-resistance transistor oscillator. An appropriate selection of the feedback network can significantly increase the negative resistance of the two-port network and is, therefore, an important design step. Three methods, the third being a CAD method, are given for the design of the series-feedback network with examples that help illustrate the procedures used in each method. Furthermore, the examples show the agreement amongst the three methods     

Multihysteresis block as a polyphase square-wave oscillator

This paper introduces an apparently new circuit component, the multihysteresis block. It consists of several hysteresis elements having the same input signal. It is shown that this component could simplify the circuit of polyphase square-wave oscillators. Only one integrator is requested for any number of phase generations     

Simulation of dynamic physical systems using a digital process-control computer

A digital computer designed for process control can be used for the simulation of complex continuous systems. The program is to contain facilities for the inclusion of items of operating equipment within the simulation study.     

Increasing the locking bandwidth of a waveguide-cavity oscillator through the use of a double-tuned circuit

The experimental 6 GHz Gunn oscillator consists of a TE101 waveguide cavity and a coupling slot, both being mechanically tunable in frequency. Fractional-bandwidth?voltage-gain products of approximately 0.2, corresponding to Qext = 10, were obtained. Comparison is made with other broadband injection-locked solid-state oscillators.     

Analysis of an oscillator consisting of digital integrated circuits

The authors present the theoretical and experimental investigations of an oscillator consisting of digital integrated circuits that act as nonlinear active elements. The circuit equation for this oscillator is derived from the inverse tangent approximation to the input-output characteristic of the digital IC. Using the perturbation method, the approximate solutions of this equation are obtained. The propriety of the inverse tangent approximation is ascertained by comparing the calculated and experimental value of the limit cycles.     

On the use of look-up tables in the microprocessor implementation of digital filters

A simple method is proposed, which results in a 60% reduction in the time taken to obtain a product from a look-up table. This corresponds to increased bandwidths of digital filters implemented using a microprocessor.     

On the use of repetition coding with binary digital modulations onmobile channels

Repetition, diversity, and single-error-correcting codes are examined for use with binary modulation techniques over a mobile communication fading channel. Both bit-error performance and bandwidth efficiency are considered for phase-shift keyed, differential phase-shift keyed, and frequency-shift keyed modulations. The error-correction capability of repetition coding is considered, and optimum repetition is found. M-tuple diversity with maximum-ratio-combining is then compared with repetition coding both with a single-error-correcting code and without coding. It is found that a minimum of a 10 dB signal-to-noise power ratio is required for an improved performance with repetition code or diversity. The repetition code is about 3 dB inferior to optimal diversity. An optimized design of moderate complexity and bandwidth expansion can be reached with twofold diversity and three repetitions as an inner layer of coding concatenated with an outer single-error-correcting code     

应用于数字锁相环的NCO设计

本文鉴于数字锁相环在实际应用中对信号频率的准确度和稳定度有较为严格的要求,设计一种应用于数字锁相环的数控振荡器(NCO,Number Controlled Oscillator)。基于直接数字频率合成(DDS)技术,介绍NCO工作原理,基于FPGA实现NCO,关键是相位累加器与波形存储器两个模块的设计,并利用QUARTUS对设计结果进行编译仿真。对NCO杂散信号进行频谱分析,并提出解决方法。该设计有效抑制杂散,修改灵活,便于调试,在数字锁相环设计中可有广泛应用。     

Gunn oscillator used as a phased-array aerial element

This letter describes an investigation into the feasibility of using the bias voltage as the phase-varying parameter in an array of synchronised Gunn oscillators to steer an antenna. The variation in bias changes the frequency of an unsynchronised oscillator, which, when locked, becomes a change in phase while it is oscillating at the pilot frequency. A simple experiment is described in which the interference pattern from two horns is made to sweep through a fringe wavelength with a voltage variation of 400mV in the bias of one oscillator.     

A survey of digital computer memory systems

Many types of storage and memory systems have been proposed for use in digital computing systems. This survey paper discusses only the various systems whose reaction time is faster than human reaction time, employing a historical approach to the subject. Criteria for evaluation are discussed, and comparisons given among the different systems as to general applicability, ease of construction and use, speed of operation, latency time, memory span, and economy     

Symbolic solution of networks by digital computer

The letter briefly discusses the problem of finding the symbolic expression of a network function (in particular, a driving-point or a transfer impedance). After dividing the problem into two subsequent steps, some methods for the solution of the first step, already presented in the technical literature, are discussed. A method for the solution of the second step is then proposed.     

New digital compensation technique for the design of amicrocomputer compensated crystal oscillator

The study of the stability of frequency sources is a matter of major interest due to the evolution of communication and instrumentation systems resulting in increasing the number of channels in a limited spectrum, and reducing size and power consumption. The paper relates laboratory experiences that explain the behavior versus temperature of thickness-mode quartz crystal resonators (AT- and SC-cut crystals) that are applied to the control of frequency sources, and the performance of digital compensation techniques. Prototypes of microcomputer-compensated crystal oscillators (MCXO's) have been developed to compare the compensation performance using the resonator as the temperature sensor against the use of an external sensor and verify the reduction of compensation errors due to thermal lags and hysteresis. The design of a CMOS integrated circuit for the MCXO is also included. A frequency correction method that does not modify the crystal resonance has been implemented in the circuit. This allows sensing of the temperature by means of the crystal and improving its long-term stability (aging). A new frequency comparator is also introduced. Its aim is to obtain the difference between two very close frequencies at its output, without being affected by the phase variations that the new frequency correction method and the digital circuit introduce. This detector has been implemented to get a high-resolution thermometric frequency and to realize a frequency-locked loop that includes a crystal controlled local oscillator, allowing the use of the MCXO as a good short-term stability source