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.
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 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 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