ELECTRICAL

1-2 The fleets of our modern Navy travel faster and are spread over greater areas of ocean than any seagoing force of the past. Commanders and their subordinates throughout the Department of the Navy use the facilities of naval communications as a primary method of communicating. Naval communications relies on top performance from all of its assigned personnel. Reliable, secure, and timely transmission and receipt of information, based on wartime requirements, is the ultimate goal. Previous modules have discussed electronic components or circuitry in individual units. In this chapter we will tie up some loose ends for you and discuss radio-frequency communications. We will cover the considerations involved in receiving or transmitting a radio-frequency signal between two or more geographic locations. Let's start by defining telecommunications. TELECOMMUNICATIONS refers to communications over a distance and includes any transmission, emission, or reception of signs, signals, writings, images, or sounds. Intelligence produced by visual means, oral means, wire, radio, or other electromagnetic systems are also included. Electrical, visual, and sound telecommunications are all used in the Navy. In this chapter we will talk only about electrical types of telecommunications. ELECTRICAL The types of electrical communications are radio and wire. Radio uses electromagnetic waves to transmit and receive intelligence. The waves are not guided by a physical path between sender and receiver. Wire uses conductors to carry these waves. Radio is the most important method the Navy has of communicating between widely separated forces. The transmission methods we will be discussing are radiotelegraph, radiotelephone, teletypewriter, and facsimile. Radiotelegraph Radiotelegraph transmissions are referred to as continuous wave (cw) telegraphy. Cw is a manual or automatic system of transmitting signals using a wave of radio-frequency (rf) energy. The radio operator separates a continuously transmitted wave into dots and dashes based on the Morse code. This is accomplished by opening and closing a telegraphic hand key. Radiotelegraphy was the first means of radio communications that had military and commercial importance. Radiotelegraph still is used as a means of communication to, from, and among widely separated units of the Navy. Relative slow speed of transmission and the requirement for experienced operators are the major disadvantages of radiotelegraph. The main advantage is reliability. A thinking person at both sending and receiving stations provides a capability of being understood not present in automated systems. Radiotelephone Radiotelephone is one of the most useful military communications methods. Because of its directness, convenience, and ease of operation, radiotelephone is used by ships, aircraft, and shore stations. It has many applications and is used for ship-to-shore, shore-to-ship, ship-to-ship, air-to-ship, ship-to-air, air-to-ground, and ground-to-air communications. Modern means of operation make it possible to communicate around the world by radiotelephone. One of the most important uses of radiotelephone is short-range tactical communications. This method permits tactical commanders to communicate directly with other ships. Little delay results while a message is prepared for transmission, and acknowledgments can be returned instantly. Radiotelephone equipment for tactical use usually is operated on frequencies that are high enough to have line-of-sight characteristics; that is, the waves do not