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Excerpt from Operation of the Modulator Tube in Radio Telephone Sets The function of a modulating device in radio communication is to vary the output current of a radio generator at a frequency or at frequencies lower than the radio frequency involved. In' a certain sense practically all radio communication using single wave-length signals is by a modulation method. In continuous wave transmission, the keying by which the signals are conveyed constitutes a dot-and-dash modulation of the antenna current. In the operation of spark and other tone transmitters, the radio frequency wave trains are sent out at more or less regular inter vals at an audio frequency, so that an audible note is heard upon rectification with a detecting device. In addition to this audio modulation, a second order of dot-and - dash modulation is required for conveying the telegraph signal. In radio telephony the mes sage which is conveyed depends upon the first order modulation itself. The antenna current is made to vary, not at a single tone frequency, but with frequencies and in degrees corresponding 'to the pitches and intensities of the sound waves produced by the voice of the speaker. In consequence, upon rectification of the received radio signals, there are produced in the receiving tele phones electrical currents which are of precisely the same nature as would be produced by communication by wire telephony. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.