RF Communication

INTRODUCTION TO RF COMMUNICATIONS IN NAVAL TELECOMMUNICATIONS

When the wireless (radiotelegraph) was invented, the Navy saw a possible use for it. It could be used for communications from shore stations to ships along the coast. In 1899, the first official naval radio message was sent from ship to shore. It only traveled a distance of 20 miles but that was a start.

The next advance was in 1916 when the Navy first used radiotelephone between ships. Three years later the first airborne radio was used to communicate with a ground station. In the early years, RF communication was not the best because of poor tuning techniques. Receivers often did not pick up the signal. This problem was almost eliminated in 1931 when the first superheterodyne receivers were installed in the fleet.

In 1944, another important event took place. The first successful radio teletypewriter transmissions between ships were completed. The first successful use of radiophoto (facsimile) occurred in 1945 with the transmission of the surrender document signing that ended World War II. Naval communications has grown tremendously in size and complexity since then.

The fleets of a modern Navy travel faster and are spread over greater areas of ocean than any seagoing forces of the past. Commanders and their subordinates throughout their particular departments 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.

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 rf communication 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 modern Navy.

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 rf communication 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 follow the curvature of the earth.

As you know, these characteristics limit the usual range of radiotelephone from 20 to 25 miles. This is important because it reduces the chances of the enemy intercepting the message. Radiotelephone procedures can be learned easily by persons with no other training in communications.

Radiotelephone has some disadvantages. You may find transmissions unreadable because of static, enemy interference, or high local noise level caused by shouts, gunfire, and bomb or shell bursts. Wave propagation characteristics of radiotelephone frequencies sometimes are unpredictable, and tactical transmissions may be heard from great distances. Most radiotelephone messages are in plain language, and if information is to be kept from the enemy, users must keep their messages short, stick to the proper procedures, and be careful of what they say.

The Teletypewriter

System introduction to RF Communications

Radio Transmitting Set

Frequency Band Use

High Frequency Communications

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