Satellite Signal Propagation, Impairments and Mitigation

Rajat Acharya

• Publisher: Academic Press
• Year: 2017
• Print ISBN: 9780128097328
• eBook ISBN: 9780128097335
• Topic: Technology & Engineering
• Subtopic: Aeronautic & Astronautic Engineering
• Index: Technology & Engineering

Satellite Signal Propagation, Impairments and Mitigation covers issues related to satellite link design. The book develops every concept from elementary physics, covering the basics of signal propagation from Maxwell's equations and then gradually developing the physical reasons for impairments.It emphasizes the unique concepts for each involved process, based on their physics, and explains how they form the determining factors for the related suitable engineering technique for mitigation. Every basic principle is followed by mathematical substantiation with an explanation of the physics behind the equations.- Covers the basics of signal propagation, starting from Maxwell's equations and then gradually developing the physical reasons for the impairments- Includes different important propagation experiments conducted and detailed in the Appendix- Employs the power of MATLAB® as both a visualization and problem-solving tool- Provides MATLAB scripts for simulation exercises

Chapter 1

Introduction

Abstract

This chapter provides an introduction to the basic concepts of satellite signals, propagation and the propagation effects. After defining the requisite terms pertaining to propagation, this chapter explains the relation of the parameters quantifying the received signal quality in a satellite system to the elements in the propagation channel. The atmosphere is the prime candidate to influence the signals. Therefore, in an attempt to explain it more systematically, the atmospheric structure is categorized on different basis and the prime features of each category are mentioned. Finally, how these atmospheric elements modify the signal parameters is stated. A brief section about how to use the book most efficiently and the details of different chapters of the book is also added at the end.

Keywords

Communication; Satellite; Signals; Parameters; Atmosphere; Propagation

Communication is essentially the exchange of information between two entities. It is probably the oldest of the technologies that is continuing from the early ages of mankind. However, the art of communication predated the advent of mankind. Even before human race evolved, the primitive kinds of the life forms also conveyed their minds by their own means.

Almost every introductory book on telecommunication portrays a brief history of the subject, describing the means by which early men used to communicate with others over distance. They tell us about how the fire signs or smoke puff signals were used for sending information to a distant observer or how the beats of the drums used to carry meaningful messages. We all read them with great amazement. However, in early days, communication over a large distance was not at all an easy task. There were impediments in every facet of such activities. How did those primitive men use the fire signal when it was raining? Were the smoke plumes correctly interpreted during heavy winds or fog? Were the message-bearing drum beats heard really loud enough to be intelligible to the listener even amid other noises? Did they have any alternative methods for communication in such trying situations? Someone asking such questions may sound weird and perhaps none would be interested today to find the answers. Yet, one must realize that the difficulties that men used to face in such conditions were enormous. Today, it is even more difficult to perceive the difficulties to their precise extent. Even Fig. 1.1 understates the grim of the situation.

Fig. 1.1 Early forms of telecommunication and their impairments.

Incidentally, the means and the techniques of communications have changed over the ages, but the problems have not. Rains, fogs, noise, etc. still put hindrances in today's communication systems. Therefore, it is equally interesting to understand, even today, what marring effects the signals face while propagating through different media, why such problems arise and how they are eliminated, moderated or appropriately taken care of. My professional ‘experience’, fortunately, falls in line with this topic. Although it is very aptly said that, ‘Experience is the name wise men give to their mistakes’ (William Wordsworth), yet that is what has made me eligible to write this book. So, in this book we shall delve into the foundations of physics and the aspects of engineering behind the simple propagation of the satellite signals and their apparently challenging impairments.

At the outset, we shall discuss as a prerequisite, the preliminary ideas in this chapter, which will form the basis for understanding many of the subsequent discussions presented in this book.

1.1 Introduction to Electronic Communication

Modern electronic telecommunication, in general, is the technique of sending and receiving any information between two distant points using electromagnetic waves. The information is converted into discrete codes, the units of which are called Bits. Bits are transmitted over the medium ridden over a sinusoidal ‘Carrier’ wave, in which every different kind of bit is represented by a predefined state of the carrier amplitude, phase or frequency. When this is done, the carrier is said to be ‘Modulated’ by the bits. The information bearing carrier is basically an electromagnetic wave ...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Dedication
• Preface
• Acknowledgement
• Chapter 1: Introduction
• Chapter 2: Maxwell's equation and EM waves
• Chapter 3: Interaction of waves with medium
• Chapter 4: Ionosphere and ionospheric impairments
• Chapter 5: Ionospheric impairments: Measurement and mitigation
• Chapter 6: Tropospheric propagation and impairments
• Chapter 7: Tropospheric impairments: Measurements and mitigation
• Chapter 8: Noise, multipath and interference
• Chapter 9: Satellite link performance
• Index