telephone systems

Telephone Circuits - Two-way operation is essential for satisfactory telephone service, and many of the problems of the industry arise from this fact. A simplified circuit for obtaining two-way operation is shown in the below figure. This is called a local-battery system..

The transmission lines used in telephony are of two kinds: open- wire and cable. The open-wire lines are gradually being superseded by cable construction, either overhead or underground, for two principal reasons. In the first place, many more circuits can be accommodated-there is a standard cable ..

A modem (a modulator/demodulator) lets you connect your computer to a standard telephone line so that you can transmit and receive electronically transmitted data. It is the key that unlocks the world of the Internet and its World Wide Web, commercial online services, electronic mail (E-..

. In 1960, Theodore Maiman of Hughes Research Laboratory operated the first laser. In 1962, the first semiconductor laser was in its infanc..

The disadvantages associate with digital communication systems include (i) Increased transmission (ii) Increased system complexity Although digital communication is becoming increasingly attractive for practical use, it is a fact that analog communication systems are ..

Introduction - We are already familiar with set theory and mathematical logic from earlier classes. It has already been seen that there is a similarity between the laws stated in set theory and the mathematical logic. The operations 'union', 'intersection' and 'complement' on sets are comparable wi..

.e., facsimile of printed matter or pictures) use a similar mechanism. In the case of intercontinental telecommunication, two or more satellites are linked together. High frequency radio and submarine cable systems have been widely used for long- distance overseas telecommunications. The ..

. Telephone and telegraph wires; audio, video, and radio cables; and the myriad nerve fibers in our bodies are all transmission lines. The interconnections of all electric circuits are transmission lines, and in a broad sense waveguides and optical fibers, and even radio links maybe regar..