Primer on Fiber Optic Data Communications for the Premises Environment
ACKNOWLEDGEMENTS
The idea for writing a monograph on the subject of fiber optic data communications was proposed to me
many times by my assistant, Gail Nelson.
The material in this work was derived from my constant perusal of many diverse sources spread over my
years in engineering. I apologize for not providing a precise acknowledgment of every source. However,
it would have led to a clutter of footnotes. I know that this often makes for tedious reading and did not
want to burden the reader. Nonetheless, I would not feel comfortable unless specific credit is given to
those publications listed as 'References.' If, on occasion, I paraphrased any of these works too closely it
should be taken in the most complimentary manner.
Pat O'Hara assisted me in taking a typed manuscript and putting it in final form complete with graphics,
photographs and other illustrations. Pat carries out this task for all of my publications. She never
complains when I come to her with last minute changes. Her cooperation is really appreciated. I can
truthfully say this work would not have been completed without her assistance. Note to Pat, we'll soon
begin another effort.
Thanks to Doug Honikel for having incorporated this onto our website.
Tony Horber and Bob Ravenstein (Bomara, Inc.) checked the work for technical accuracy. This was a
particularly stressful task especially when it led to protracted discussions on certain points. I am
indebted to them for their efforts.
Professor Nicholas DeClaris first introduced me to communications engineering while I was an
undergraduate at Cornell University. Professor DeClaris, now of the University of Maryland, inspired
me with his love for teaching and research. Dr. Irvin Stiglitz later sharpened my communications
engineering and technical writing skills while he was my Group Leader at M.I.T. Lincoln Laboratory.
Needless to say, it is a lot easier to reach Irv's high standards these days with word processing.
Thanks to Lightwave Magazine and MRV Communications for use of the illustration for the cover.
Finally, I would like to thank my wife, Diane, my children Andrew, Jessica and Rachel, my mother and
father, Lillian and Irving Schneider and my, close, life long, friends Seth Stowell, Jamil Sopher and Joel
Goldman. In different ways each gave me encouragement over the years. Without this support I would
have never have reached this point.
*ST is a registered trademark of AT & T
many times by my assistant, Gail Nelson.
The material in this work was derived from my constant perusal of many diverse sources spread over my
years in engineering. I apologize for not providing a precise acknowledgment of every source. However,
it would have led to a clutter of footnotes. I know that this often makes for tedious reading and did not
want to burden the reader. Nonetheless, I would not feel comfortable unless specific credit is given to
those publications listed as 'References.' If, on occasion, I paraphrased any of these works too closely it
should be taken in the most complimentary manner.
Pat O'Hara assisted me in taking a typed manuscript and putting it in final form complete with graphics,
photographs and other illustrations. Pat carries out this task for all of my publications. She never
complains when I come to her with last minute changes. Her cooperation is really appreciated. I can
truthfully say this work would not have been completed without her assistance. Note to Pat, we'll soon
begin another effort.
Thanks to Doug Honikel for having incorporated this onto our website.
Tony Horber and Bob Ravenstein (Bomara, Inc.) checked the work for technical accuracy. This was a
particularly stressful task especially when it led to protracted discussions on certain points. I am
indebted to them for their efforts.
Professor Nicholas DeClaris first introduced me to communications engineering while I was an
undergraduate at Cornell University. Professor DeClaris, now of the University of Maryland, inspired
me with his love for teaching and research. Dr. Irvin Stiglitz later sharpened my communications
engineering and technical writing skills while he was my Group Leader at M.I.T. Lincoln Laboratory.
Needless to say, it is a lot easier to reach Irv's high standards these days with word processing.
Thanks to Lightwave Magazine and MRV Communications for use of the illustration for the cover.
Finally, I would like to thank my wife, Diane, my children Andrew, Jessica and Rachel, my mother and
father, Lillian and Irving Schneider and my, close, life long, friends Seth Stowell, Jamil Sopher and Joel
Goldman. In different ways each gave me encouragement over the years. Without this support I would
have never have reached this point.
*ST is a registered trademark of AT & T
The Fundamental Problem of Communications
The subject of interest in this book is premises data communications using fiber optic cable as the
transmission medium. This is at once a very specific yet very extensive topic. It is an important topic
both within the context of data communications today and into the future. All, or almost all, aspects of
this subject will be explored. However, it seems rather forbidding just to jump into this topic.
Rather, it is more appropriate to take a step back to the very beginning and talk about the nature of
communications first. This will allow some needed terminology to be introduced. It will also lead us in a
natural way to the subject of fiber optic cable as a transmission medium and to why it is attractive for
premises data links.
Of course, the reader, well versed in data communications, may choose to skip past this introduction and
suffer no real penalty.
The subject of communications really begins with the situation shown in Figure 1-1. Here is an entity
called the Source and one called the User- located remotely from the Source. The Source generates
Information and the User desires to learn what this Information is.
transmission medium. This is at once a very specific yet very extensive topic. It is an important topic
both within the context of data communications today and into the future. All, or almost all, aspects of
this subject will be explored. However, it seems rather forbidding just to jump into this topic.
Rather, it is more appropriate to take a step back to the very beginning and talk about the nature of
communications first. This will allow some needed terminology to be introduced. It will also lead us in a
natural way to the subject of fiber optic cable as a transmission medium and to why it is attractive for
premises data links.
Of course, the reader, well versed in data communications, may choose to skip past this introduction and
suffer no real penalty.
The subject of communications really begins with the situation shown in Figure 1-1. Here is an entity
called the Source and one called the User- located remotely from the Source. The Source generates
Information and the User desires to learn what this Information is.
It is absolutely impossible in the real world for the User to obtain the Information without the chance of
error. These may be caused by a variety of deleterious effects that shall be discussed in the sequel.
This means that the User wanting to learn the Information- the binary sequence- must be content in
learning it to within a given fidelity. The fidelity measure usually employed is the Bit Error Rate (BER).
This is just the probability that a specific generated binary digit at the Source, a bit, is received in error,
opposite to what it is, at the User.
There are some real questions as to how appropriate this fidelity measure is in certain applications.
Nonetheless, it is so widely employed in practice, at this point, that further discussion is not warranted.
The question then arises as to how to send the binary data stream from Source to User. A Transmission
Medium is employed to transport the Information from Source to User. What is a Transmission
Medium?
A Transmission Medium is some physical entity. As shown in Figure 1-4 it is located between the
Source and the User and it is accessible to both. The Transmission Medium has a set of properties
described by physical parameters. The set of properties exists in a quiescent state. However, at least one
of these properties can be stressed or disturbed at the Source end. This is accomplished by somehow
imparting energy in order to stress the property. This disturbance does not stay still, but affects the parts
of the Transmission Medium around it. This disturbance then travels from the Source end to the User
end. Consequently, energy imparted in creating the disturbance is thereby transferred from the Source
end to the User end. Finally, this disturbance or stressed property, can be sensed at the User end. It can
be measured.
to download this course click here
error. These may be caused by a variety of deleterious effects that shall be discussed in the sequel.
This means that the User wanting to learn the Information- the binary sequence- must be content in
learning it to within a given fidelity. The fidelity measure usually employed is the Bit Error Rate (BER).
This is just the probability that a specific generated binary digit at the Source, a bit, is received in error,
opposite to what it is, at the User.
There are some real questions as to how appropriate this fidelity measure is in certain applications.
Nonetheless, it is so widely employed in practice, at this point, that further discussion is not warranted.
The question then arises as to how to send the binary data stream from Source to User. A Transmission
Medium is employed to transport the Information from Source to User. What is a Transmission
Medium?
A Transmission Medium is some physical entity. As shown in Figure 1-4 it is located between the
Source and the User and it is accessible to both. The Transmission Medium has a set of properties
described by physical parameters. The set of properties exists in a quiescent state. However, at least one
of these properties can be stressed or disturbed at the Source end. This is accomplished by somehow
imparting energy in order to stress the property. This disturbance does not stay still, but affects the parts
of the Transmission Medium around it. This disturbance then travels from the Source end to the User
end. Consequently, energy imparted in creating the disturbance is thereby transferred from the Source
end to the User end. Finally, this disturbance or stressed property, can be sensed at the User end. It can
be measured.
to download this course click here
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