INTERNATIONAL SERIES OF MONOGRAPHS ON ELECTRONICS AND INSTRUMENTATION
GENERAL EDITORS: D. W. Fry and W. HIGINBOTHAM
VOLUME 11
FREQUENCY MODULATION THEORY
APPLICATION TO MICROWAVE LINKSby
Jacques FAGOT
Ingénieur E.S.E., Licencié es-Sciences
Technical Manager at the Compagnie Générale de Télégraphie Sans Fil
Lecturer at E.S.E., Radioand
Philippe MAGNE
Ingénieur E.S.E., Radio
Laboratory Head at the Compagnie Générale de TélCgraphie Sans Fil
Professor at I.S.E.P.
Foreword by
Roger AUBERT
Ingénieur E.S.E.
General Technical Manager at the Compagnie Générale de Télégraphie Sans Fil
Past President of the Societe des Radioelectriciens
PERGAMON PRESS
NEW YORK OXFORD LONDON
SOCIETE FRANCAISE
DE DOCUMENTATION ELECTRONIQUE
PARISCopyright © 1961
PERGAMON PRESS Ltd. and SOFRADEL (FRANCE)
First published in English 1961
Library of Congress Card Number 60-14939
It bears markings from the library of the
Naval Research Laboratory in Washington, D.C.Here are the Contents and Introduction, to give you the idea:
CONTENTS
FOREWORD
INTRODUCTION
1. PROPAGATION - ENERGY TRANSFER
1.1 Definition of the transmission equivalent
1.2 Propagation of the carrier wave in free space - Calculation of the
T ransmission equivalent between aerials
1.3 Propagation in the atmosphere and near the ground
1.4 Atmospheric absorption
1.5 Atmospheric refraction
1.6 Fresnel ellipsoid
1.7 Profile representation
1.8 Ground reflections
1.9 Attenuation by a hill-crest of the "knife edge type
1.10 Conclusions regarding the installation of radio links over an optical path
1.11 Tropospheric propagation beyond the horizonReferences
2. DISTORTION AND NOISE IN FREQUENCY MODULATION
2.1 Principle of frequency modulation
2.2 Spectrum of a sinusoidally frequency-modulated oscillation
2.3 Non-linear distortions in frequency modulation
2.4 Analysis of amplitude distortion
2.5 Analysis of phase distortion
2.6 Application of general network laws for the evaluation of phase distortion in amplifiers
2.7 Phase distortion in an amplifier consisting of a series of triplets
2.8 Noise in frequency modulation
2.9 Method of direct calculation of non-linear distortion in frequency modulationReferences
3. PROPAGATION DISTORTION
3.1 Signal expressed by the Fourier integral
3.2 Localization of the information by the stationary phase principle
3.3 Phase velocity and group velocity of a travelling wave
3.4 Wave propagation along a double path
3.5 Distortion in frequency modulation for the double path case
3.6 .Transmission on a mismatched feeder
3.7 Frequency modulation distortion in a mismatched feeder
3.8 Direct calculation of frequency modulation distortion over a double pathReferences
4. TRANSMISSION OF THE OVERALL INFORMATION
4.1 General
4.2 Frequency distribution in carrier current multiplex
4.3 Problem of levels in carrier current multiplex
4.4 Application of multiplex signals to frequency modulation radio equipment
4.5 Formulae related to thermal noise
4.6 Overall cross-talk power in amplitude modulation
4.7 Intermodulation distribution in the base-band
4.8 Combination of intermodulation in the various elements of a microwave link
4.9 The multiplex signal considered as a stationary random function- Application to the calculation of the intermodulation spectrum
4.10 Intermodulation in frequency modulation equipment
4.11 Propagation crosstalk
4.12 Transmission conditions for television signals
4.13 Principal technical problems raised by the transmission of television on microwave linksReferences
5. EQUIPMENT
5.1 Design of radio link equipment
5.2 Structure of microwave links
5.3 Highly linear modulation and demodulation-General remarks
5.4 Frequency modulation of the U.H.F. band
5.5 Frequency modulators operating in the "intermediate frequency band
5.6 Demodulation
5.7 Amplification technique-General remarks
5.8 Noise figure
5.9 Amplifier pass-band and gain
5.10 Impedance breaks between elements of an amplifier chain
5.11 Phase distortion correction - Group propagation time equalizers
5.12 Frequency changing-Mixers
5.13 Frequency stabilization
5.14 Filters for hyper-frequencies
5.15 Aerials
5.16 Ferrite unidirectional attenuator (isolator)
5.17 MeasurementsReferences
NOTATIONS
ABBREVIATIONS
INDEX
FOREWORD
OUR ancestors signalled their victories or important news by means of fires lit on elevated ground. But the amount of information which could be transmitted in this way was small. So, in the Middle Ages, when communication routes became safer and better means of travel were available, this mode of communication was abandoned and substituted by the despatch of messengers bearing a much greater amount of information. Hill-tops were then abandoned. Yet, though there was a gain in the quantity of information, there was a substantial loss in speed of transmission. Hence, in the eighteenth century there was an endeavour to increase that speed, while retaining the possibility of transmitting a large amount of information.It was Chappe who, with his semaphore telegraph, solved the problem. His line from Paris to Lille was opened in March 1794. Fifty years later, the French network consisted of 500 stations, which, once more, used the hill-tops.
It should be noted that speed of transmission was higher than might be supposed, since only 2 mm were required to transmit an elementary signal from Paris to Lille, and only 20 mm for the transmission of the same signal from Paris to Toulon, through 116 relay stations.
However, in the nineteenth century the Chappe telegraph was dropped for the Morse telegraph, the group propagation velocity and transmission capacity of which were substantially greater.
Hill-tops were once more abandoned and, according to the perpetual evolution of technique, it was only about a century later that the introduction of microwave links once more drew attention to these high points for the installation of the various relay stations which, as in the case of the Chappe telegraph, must in practice possess an optical path.
The French microwave link system counts at the present day over 3000 miles of line and close on one hundred relay stations. It is still under development, while in the French Union, and more particularly in the Sahara, tropospheric and direct line-of-sight beams are beginning to be developed in order to exploit these regions.
In accordance with a technique which has become quite general, all these beams use frequency modulation and transmit either television signals, or numerous telephone channels, multiplexed on the carder-current technique. These beams are a useful complement to the national and international Systems, in association with which they are to be considered more as complelfleutary than as competitive. Also, their transmission quality has been constantly improving and they now satisfy the same criteria as the international cable telephony circuits.
MM. Fagot and Magne's book first sets out the theoretical principles on which such beams are based: propagation of the waves used, frequency modulation, noise and sundry distortions liable to arise either in the course of propagation or in the equipment, and in the methods used for the transmission of the information; it then goes on to describe the various devices used: modulators, amplifiers, mixers, regulators, aerials, multiplexing circuits for the various channels, and measuring and maintenance gear. None were better suited than the authors to write about this subject, since both of them for more than 10 years have effectively designed or supervised the design of much radio link equipment built by the group of the Compagnie Générale de Télégraphie Sans Fil.
Their book, particularly noteworthy for its clear exposition, has the advantage of containing not only the theoretical principles, but also many practical details relative to equipment in service. At every point the reader will be happy to find current numerical values, difficulties usually met with, and means applied for overcoming them.
This book is written not only for the student and the young engineer who wishes to become familiar with microwave beam technique, but also for the specialized engineer who will find within its pages a large amount of valuable information. It is sure to secure a favourable reception from the public, which it fully deserves.
ROGER AUBERT
