CHAPTER 1 COMMUNICATIONS

CHAPTER 1 COMMUNICATIONS As an Aviation Electronics Technician, you will be tasked to operate and maintain many different types of airborne communications equipment. These systems may differ in some respects, but they are similar in many ways. As an example, there are various models of AM radios, yet they all serve the same function and operate on the same basic principles. It is beyond the scope of this manual to discuss each and every model of communication equipment used on naval aircraft; therefore, only representative systems will be discussed. Every effort has been made to use not only systems that are common to many of the different platforms, but also have not been used in the other training manuals. It is the intent of this manual to have systems from each and every type of aircraft in use today. RADIO COMMUNICATIONS Learning Objective: Recognize the various types of radio communications. Identify the various frequency bands and their uses and limitations. In basic terms, communication is defined as the meaningful transfer of information from one location (the sender, source, originator) to another location (the destination or receiver). Electronic communication uses electrical energy to transmit the information to be communicated Since this electrical energy travels at the speed of light, the transfer can occur within a fraction of a second. The information must be converted from its original form of sound, light, or mechanical energy into electrical energy. This electrical energy can then be transmitted via wires or radiated through space to a receiver. The receiver must then convert the electrical energy back into its original form to complete the communication cycle. TYPES OF RADIO COMMUNICATIONS Radio communications has become a highly sophisticated field of electronics. All Navy aircraft have the capability to use the commonly used ship-to-ship, ship-to-air, air-to-air, air-to-ground, and ship-to-shore communication circuits. These operations are accom- plished through the use of compatible and flexible communication systems. Radio is the most important means of com- municating in the Navy today. There are many methods of transmitting in use throughout the world. This manual will discuss three types. They are radiotelegraph, radiotelephone, and teletypewriter. Radiotelegraph Radiotelegraph is commonly called CW (con- tinuous wave) telegraphy. Telegraphy is accomplished by opening and closing a switch to separate a continuously transmitted wave. The resulting “dots” and “dashes” are based on the Morse code. The major disadvantage of this type of communication is the relatively slow speed and the need for experienced operators at both ends. Radiotelephone Radiotelephone is one of the most useful military communication methods. It is used by aircraft, ships, and shore stations because of its directness, con- venience, and ease of use. The equipment used for tactical purposes usually operate on frequencies that are high enough to have line-of-sight characteristics. This cuts down not only on the possibility of the enemy intercepting the messages, but also cuts down on the distance between the transmitter and receiver. Teletypewriter Teletypewriter (TTY) signals may be transmitted by either landlines (wire), cable, or radio. The Navy uses radio teletypewriter (RTTY) for high-speed automatic communications. The keyboard used with a TTY system is similar to that of a typewriter. When the operator strikes a key, a sequence of signals is transmitted. At the receiving station, the signals are translated back into letters, figures, and symbols that are typed onto paper for use. 1-1