Principles of Synchronous Digital Hierarchy

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Introduction to Optical Transport Networks

With the advent of optical ber technology, the telecommunication ser-

vices not only improved immensely in quality but also became much more

affordable. In fact, the cost of making a long-distance call today is a very

small fraction of the cost 30 years back. In India, until a few decades ago,

it was cheaper to travel to the intended long-distance destination by train

and come back, as compared with making a telephone call to the place last-

ing for 10 minutes. As the affordability improved, the demand increased,

which further boosted the volume of production of equipment and cables,

making t ...