Excerpt from Principles of Radiotelegraphy: Prepared in the Extension Division of the University of Wisconsin
The transmission of messages by radio signals is to many a mysterious process. The mystery, however, is not inherent in the transmission of intelligence by ether waves for almost every light-house is a radio transmitter which sends out signals by long and short groups of waves, and by waves of different lengths, that is, white and colored light. This is never considered mysterious for the simple reason that nature has furnished man with a sense organ by means of which these light waves are detected. If human beings were blind, like the fish of Mammoth Cave, the detection of light signals would become a very difficult and mysterious process. No light signals could be detected unless some means were devised for translating or converting light phenomena into phenomena capable of detection by some one of the other senses.
The mystery and difficulty of radio communication is primarily due to the fact that nature has not provided man with a sense organ which is capable of detecting electromagnetic waves immediately, but these waves must first be translated into other phenomena. It is undoubtedly true that space is filled with phenomena of which we are wholly unconscious, or in other words to which we are totally blind. This was true of electromagnetic waves until means of detecting these waves were devised. In reality they are no more mysterious than light.
Since radiotelegraphy is an electromagnetic phenomenon, and electric and magnetic apparatus is employed in the generation and detection of electromagnetic waves, a goodly portion of this book is devoted to a discussion of electromagnetic theory and apparatus, for without an understanding of these the student cannot understand the principles of the operation of radiotelegraphic apparatus. He may learn to operate it, but such operation will be merely a mechanical and not an intelligent process.
Although the treatment cannot be called nonmathematical, the use of mathematical expressions is limited and only the more elementary mathematics is used.
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