Time-division Principles Research Articles

A Novel Multi-Channel MAC Protocol for Cluster Based Wireless Multimedia Sensor Networks

An energy efficient, scalable and collision free MAC protocol, DTFMM, is presented in this paper, which combines frequency and time division principles for medium sharing. It is based on clustered network topology, and the protocol employs a distributed local coordinate algorithm for assigning channels among clusters to enable simultaneous non-interfering data collection. Intra-cluster transmissions are scheduled by cluster head (CH) based on time slot. CHs aggregate the gathered data and forward it over inter-CH paths to the base-station based on minimum spanning tree routing. Distinct channels are adopted by the independent branches of the inter-CH routing tree. Data transmission on a branch is further scheduled in depth-first ordering. DTFMM allows nodes to stay in sleeping mode for the longest duration and thus it minimizes energy consumption. Simulation demonstrated superiority of DTFMM in terms of convergent rate, throughput and delay performance when compared with well-known protocol MMSN.

Integration of quantum cryptography into fiber-optic telecommunication systems

The prototype of a new quantum cryptosystem is described. Such a cryptosystem is naturally called time-shift quantum cryptography. It realizes all basic quantum-cryptography protocols [BB84, B92, BB84(4+2)] in a common fiber-optic system. This scheme does not involve Mach-Zehnder interferometers, which enables one to naturally realize the multiplex mode of secure key distribution and to naturally integrate this quantum-cryptography scheme into traditional fiber-optic telecommunication systems. The proposed time coding method in quantum cryptography makes it possible to significantly simplify experimental schemes and to exclude the finest fiber-optic part, the interferometer. In essence, the fundamental difference of the time coding method from the phase coding method is that the part using phase relations in superposition between “parts” of a quantum state is eliminated from the phase-coding method, and only the part using the time division principle is retained. The time division principle is common for both methods and is minimally necessary, in contrast to the phasecoding method, which can be excluded altogether. The proposed scheme is briefly compared with the two most developed phase-coding schemes (without self-compensation and with passive self-compensation).

Switched-capacitor function generators

This paper presents new function generators (non-linear converters) with improved performance. It is shown that non-linear converters such as multiplier-dividers, generalized integrators and universal piecewise-linear function generators can be realized by using time-division principles and switched-capacitor (SC) techniques. In order to design such converters unified stray-insensitive, offset-compensated CMOS SC subcircuits (macrocells) are used as basic building blocks. The proposed structures have been constructed, experimentally tested and applied to solve some problems with accurate results.

Systematic error of time-division wattmeters when voltage and/or current are distorted

The mathematical models of three different electronic wattmeters based on time-division principles are derived. By using these models the systematic errors of such electronic wattmeters can be calculated for both sinusoidal and distorted voltage and/or current waveforms. It is emphasized that the systematic errors are a function of the ratio of the input and the internal converter frequency. The behavior of several wattmeters is analyzed theoretically and experimentally for a few practical situations. The conclusion is reached that time-division wattmeters can be used for high-precision power measurement when voltage and current are not distorted and also, with certain precautions, when they are distorted.

MOS SC microsystem for generating trigonometrical functions and their inverses

A new switched-capacitor (SC) circuit arrangement is proposed for the simultaneous generation of trigonometrical functions (sin x, cos x, tan x) and their inverses (sin-1 x, cos-1 x, tan-1 x) in analogue form, where x(t) is the input voltage. The method is based on the sample-and-hold and time-division principles. The system possesses some attractive features, e.g. simplicity and low cost, and can be easily implemented in monolithic (IC) form using MOS technology. The performance of the system is illustrated by experimental results.

Development of a Time-Division Switching Network Usable in a Very Large Range of Capacities

Well adapted to medium size systems, the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</tex> switching networks fully proved the operational value of the time division principles. For higher capacities, the more usual realizations are now STS and mainly TST networks. These are attractive as the growth of the equipment proportional to the square of the number of subscribers is limited to the intermediate stage (or stages). Drastic improvements in semiconductor technology, particularly in the memory field, allow another step: mixing in the same I.C. can, the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</tex> stages. In this concept, staggering or even functional discrimination of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</tex> appears to be useless and artificial. The resulting matrix circuit has quite symmetrical input-outputs and the multiple incoming bit positions are distributed to the output in whatever time and space arrangement that is needed. This paper describes the networks based on this concept.

Electronic Three-Phase Four-Wire Power-Frequency Converter With High Accuracy Over a Wide Range of Use

This paper describes a new type of power-frequency converter with an electronic measuring device. It is of the three-phase four-wire type and was developed in the Physikalisch-Technische Bundesanstalt (PTB) especially for the precision measuring of electrical energy in high-voltage circuits. It has an accuracy of 10-3 over a current range of 1: 100. The measuring elements use the time-division principle. The wide current range is achieved by commutating the charging current for the integrating circuit. The running (indication) of the instrument with no load is eliminated. The specifications are much better than those of a high-precision rotor-type meter of class 0.5 (Recommendations of the International Electrotechnical Commission-IEC).

Adjusting resistors in an electronic way

In this paper a method is described for adjusting electronically the value of a resistor. The method is based on the time-division principle. Switching a resistor << onand << offhigh-frequency the effective mean value of the conductivity is proportional to the relative << on -time. There are several possibilities of application for these electronic resistors. Here we will discuss the realization of the coefficients of an operational amplifier by means of electronic resistors. In this investigation the usual d.c. high gain amplifier of an operational amplifier has been replaced by an electronic comparator. This has been done to enable the use of the two-level output signal of the operational amplifier or a signal obtained from it by some logic operation for controlling one or more electronic resistors. For some examples we will show that one-and more-dimensional non-linear functions can be generated in this way.

Considerations for a New Military Radio Relay System

PRIOR to World War II, the Armed Forces' need for multitelephone channel trunk circuits was satisfied by the use of metallic wire circuits. Early in the war, it was demonstrated that the fluidity of movement which accompanied blitz-type warfare required a more rapid means of providing multichannel trunk facilities than could be had with wire circuits. As a result, military radio relay equipment operating in the very-high-frequency range was developed early in 1942, capable of providing rapidly installable transmission facilities for four frequency-division multiplexed voice channels. This equipment was used successfully in all theaters of operation throughout World War II, conclusively demonstrating the tactical advantages of this type of transmission facility. In addition, 8-channel microwave equipment, using time-division principles of multiplexing, was developed for use at high echelons of command.

Considerations for a new military radio relay system

PRIOR to World War II, the Armed Forces' need for multitelephone channel trunk circuits was satisfied by the use of metallic wire circuits. Early in the war, it was demonstrated that the fluidity of movement which accompanied blitz-type warfare required a more rapid means of providing multichannel trunk facilities than could be had with wire circuits. As a result, military radio relay equipment operating in the very-high-frequency range was developed early in 1942, capable of providing rapidly installable transmission facilities for four frequency-division multiplexed voice channels. This equipment was used successfully in all theaters of operation throughout World War II, conclusively demonstrating the tactical advantages of this type of transmission facility. In addition, 8-channel microwave equipment, using time-division principles of multiplexing, was developed for use at high echelons of command.

Relay Time-Division Multiplier

This paper describes the theory and design of a new low-cost analog multiplier suitable for use with the dc analog computers now widely applied as differential analyzers and equation solvers. The new multiplier comprises a simple relay circuit utilizing the time-division principle. The multiplier accepts input voltages of both signs and is capable of multiplication to within an accuracy of 3.5 percent of full scale at zero frequency and 7 percent of full scale through the frequency range between 0 and 10 cycles per second. Greater accuracy is possible through sacrifices in the useful frequency range. The dynamic range of input and output voltages is −80 volt to +80 volts. The multiplier circuit proper contains no vacuum tubes, servomechanisms, or power supplies but utilizes one of the operational amplifiers of the dc analog computer with which it is used.

Analysis of distortion in pulse-code modulation systems

After a short introduction about the time division principle (horizontal quantization) an investigation is made of the distortion caused by quantization of the amplitude of the input signal (vertical quantization) in a pulse-code modulation system. A general analysis is given, independent of the way in which a quantization level is chosen and for arbitrary values of sampling frequency versus signal frequency. The method used may be useful for the solution of similar problems.