Signals intelligence (SIGINT) is the act and field of intelligence-gathering by interception of signals, whether communications between people or from electronic signals not directly used in communication. Signals intelligence is a subset of intelligence collection management. As classified and sensitive information is usually encrypted, signals intelligence may necessarily involve cryptanalysis. Traffic analysis—the study of who is signaling to whom and in what quantity—is also used to integrate information, and it may complement cryptanalysis.
A message is a discrete unit of communication intended by the source for consumption by some recipient or group of recipients. A message may be delivered by various means, including courier, telegraphy, carrier pigeon and electronic bus. A message can be the content of a broadcast. An interactive exchange of messages forms a conversation.
Tactical communications are military communications in which information of any kind, especially orders and military intelligence, are conveyed from one command, person, or place to another upon a battlefield, particularly during the conduct of combat. It includes any kind of delivery of information, whether verbal, written, visual or auditory, and can be sent in a variety of ways. In modern times, this is usually done by electronic means. Tactical communications do not include communications provided to tactical forces by the Defense Communications System to non-tactical military commands, to tactical forces by civil organizations, nor does it include strategic communication.
The Allied military phonetic spelling alphabets prescribed the words that are used to represent each letter of the alphabet, when spelling other words out loud, letter-by-letter, and how the spelling words should be pronounced for use by the Allies of World War II. They are not a "phonetic alphabet" in the sense in which that term is used in phonetics, i.e. they are not a system for transcribing speech sounds.
Optical communication, also known as optical telecommunication, is communication at a distance using light to carry information. It can be performed visually or by using electronic devices. The earliest basic forms of optical communication date back several millennia, while the earliest electrical device created to do so was the photophone, invented in 1880.
The Royal Corps of Signals is one of the combat support arms of the British Army. Signals units are among the first into action, providing the battlefield communications and information systems essential to all operations. Royal Signals units provide the full telecommunications infrastructure for the Army wherever they operate in the world. The Corps has its own engineers, logistics experts and systems operators to run radio and area networks in the field. It is responsible for installing, maintaining and operating all types of telecommunications equipment and information systems, providing command support to commanders and their headquarters, and conducting electronic warfare against enemy communications.
Traffic analysis is the process of intercepting and examining messages in order to deduce information from patterns in communication. It can be performed even when the messages are encrypted. In general, the greater the number of messages observed, the greater information be inferred. Traffic analysis can be performed in the context of military intelligence, counter-intelligence, or pattern-of-life analysis, and is also a concern in computer security.
The National Security Agency took over responsibility for all U.S. Government encryption systems when it was formed in 1952. The technical details of most NSA-approved systems are still classified, but much more about its early systems have become known and its most modern systems share at least some features with commercial products.
Flag signals can mean any of various methods of using flags or pennants to send signals. Flags may have individual significance as signals, or two or more flags may be manipulated so that their relative positions convey symbols. Flag signals allowed communication at a distance before the invention of radio and are still used especially in connection with ships.
A secret broadcast is, simply put, a broadcast that is not for the consumption of the general public. The invention of the wireless was initially greeted as a boon by armies and navies. Units could now be coordinated by nearly instant communications. An adversary could glean valuable and sometimes decisive intelligence from intercepted radio signals:
A signaller, signalman, colloquially referred to as a radioman or signaleer in the armed forces is a specialist soldier, sailor or airman responsible for military communications. Signallers, a.k.a. Combat Signallers or signalmen or women, are commonly employed as radio or telephone operators, relaying messages for field commanders at the front line, through a chain of command which includes field headquarters. Messages are transmitted and received via a communications infrastructure comprising fixed and mobile installations.
The United States Army Signal Corps (USASC) is a branch of the United States Army that creates and manages communications and information systems for the command and control of combined arms forces. It was established in 1860, the brainchild of Major Albert J. Myer, and had an important role in the American Civil War. Over its history, it had the initial responsibility for portfolios and new technologies that were eventually transferred to other U.S. government entities. Such responsibilities included military intelligence, weather forecasting, and aviation.
The Royal Australian Corps of Signals (RASigs) is one of the 'arms' of the Australian Army. It is responsible for installing, maintaining, and operating all types of telecommunications equipment and information systems. The motto of the Signals Corps is Certa Cito and is translated as 'Swift and Sure', signifying the aim of the signal service – that communication be carried out with maximum speed and certainty. Like their British counterparts, the Royal Australian Corps of Signals' flag and hat badge feature Mercury, the winged messenger of the gods, affectionately referred to by members of the corps as "Jimmy".
The Communications and Electronics Branch is a personnel branch of the Canadian Armed Forces (CAF). The army component of the branch is designated the Royal Canadian Corps of Signals.
Signalman was a U.S. Navy rating for sailors that specialized in visual communication. See Signaller for more about the roles of Signalmen.
Flag semaphore is a semaphore system conveying information at a distance by means of visual signals with hand-held flags, rods, disks, paddles, or occasionally bare or gloved hands. Information is encoded by the position of the flags; it is read when the flag is in a fixed position. Semaphores were adopted and widely used in the maritime world in the 19th century. It is still used during underway replenishment at sea and is acceptable for emergency communication in daylight or using lighted wands instead of flags, at night.
Underwater acoustic communication is a technique of sending and receiving messages in water. There are several ways of employing such communication but the most common is by using hydrophones. Underwater communication is difficult due to factors such as multi-path propagation, time variations of the channel, small available bandwidth and strong signal attenuation, especially over long ranges. Compared to terrestrial communication, underwater communication has low data rates because it uses acoustic waves instead of electromagnetic waves.
The Royal Signals trades are the employment specialisations of the Royal Corps of Signals in the British Army. Every soldier in the Corps is trained both as a field soldier and a tradesman. There are currently six different trades, all of which is open to both men and women:
Information systems technician (IT) is a rating for United States Navy and United States Coast Guard enlisted personnel, specializing in communications technology. Information systems technician submarines (ITS) is a rating for U.S. Navy submariners. The Information systems technician (IT) rating corresponds to the new Navy Occupational Specialty (NOS) code B460 while the information systems technician submarines (ITS) rating corresponds to Navy Occupational Specialty (NOS) code C260.
The Russian Signal Troops , also known as the Signal Communications Troops, is a Combat Arm of the Russian Ground Forces, responsible for military communications.
