City of Light: The Story of Fiber Optics

INTRODUCTION 7
channels sometimes brought other irritations. I recall many one-way conversations,
when London could hear me but I couldn’t hear them, or vice versa.
Sometimes silence, or a hum or whine from presumably unhappy electronics,
suddenly replaced the British voices. Other times echoes of my words would
return a second after I spoke them, often louder than the voice on the other
end. ‘‘Sorry,’’ I would say, ‘‘let’s try again,’’ and one of us would call back
to try to get a better line.
The fiber cable gave a new alternative. The bad lines and the satellites
were still there, but TAT-8 added 40,000 good circuits through echo-free
cable—a thousand times more than the first transatlantic telephone cable
carried in 1956. Since then, more fiber cables have crossed the Atlantic, and
poor connections to Britain are as rare as within North America. Even Egypt,
Israel, Hong Kong, and Australia come in loud and clear. When something
goes wrong with the phone line, it’s almost always in the few miles of aged
copper wire that connect my house to the nearest fibers in the telephone
network.
Wires, cables, fibers, and other transmission media are not the whole story
of the revolution in communications. Telephone calls must be routed from
point to point, by switches that make temporary connections in the global
lattice of fibers, wires, and radio signals. At the start of the century, telephone
switching was by hand, with ranks of operators plugging wires into sockets
in the sort of big black switchboards that survive only in old movies. Later
clattering banks of electromechanical switches replaced them, which flipped,
flopped, and stepped from point to point, making and breaking connections
in response to control pulses that originated in telephone dials. Sometimes
you could hear the mechanical switches clicking on their way to making
connections on the line, just as you could hear the pulses as a telephone dial
rotated. Later came transistorized electronic switches, special-purpose computers
designed to send signals along complex routes. Without them, phone
calls could never weave their ways through the maze of big-city networks.
But they’re another story, to be told another day.
How Fiber Optics Changed Communications
What is so good about fiber optics? Looking at the telephone network will
help you understand. The old wires running to my house are both its strength
and weakness—new equipment has to work with the same wires used for
decades. With a screwdriver and very little ingenuity, I can hook up a massive
45-year-old dial phone in Western Electric basic black. Someone dropped it a
few years back and broke a corner off the case, but it still works. So do my
modem, answering machine, and fax machine. It’s a simple, versatile system
of information pipes that is standard throughout North America.
Phone companies laid the wires to provide what they call ‘‘POTS,’’ plain
old telephone service. They designed the network to carry electrical signals
that replicate sound waves at the frequencies we must hear to understand