Flag semaphore (from the Greek σῆμα, sema, meaning sign and φέρω, phero, meaning to bear; altogether the sign-bearer) is the telegraphy 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 (with hand-held flags replacing the mechanical arms of shutter semaphores) 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.
The current flag semaphore system uses two short poles with square flags, which a signal person holds in different positions to signal letters of the alphabet and numbers. The signalman holds one pole in each hand, and extends each arm in one of eight possible directions. Except for in the rest position, the flags do not overlap. The flags are colored differently based on whether the signals are sent by sea or by land. At sea, the flags are colored red and yellow (the Oscar flag), while on land, they are white and blue (the Papa flag). Flags are not required; their purpose is to make the characters more obvious.
The following 30 semaphore characters are presented as they would appear when facing the signalman:
Error / Attention
Numbers can be signaled by first signaling "Numerals". Letters can be signaled by first signaling "J".
The sender uses the "Attention" signal to request permission to begin a transmission. The receiver uses a "Ready to receive" signal not shown above to grant permission to begin the transmission. The receiver raises both flags vertical overhead and then drops them to the rest position, once only, to grant permission to send. The sender ends the transmission with the "Ready to receive" signal. The receiver can reply with the "Attention" signal. At this point, sender and receiver change places.
The Japanese merchant marine and armed services have adapted the flag semaphore system to the Japanese language. Because their writing system involves a syllabary of about twice the number of characters in the Latin alphabet, most characters take two displays of the flags to complete; others need three and a few only one. The flags are specified as a solid white square for the left hand and a solid red one for the right. The display motions chosen are not like the "rotary dial" system used for the Latin alphabet letters and numbers; rather, the displays represent the angles of the brush strokes used in writing in the katakana syllabary and in the order drawn. For example, the character for "O" [オ], which is drawn first with a horizontal line from left to right, then a vertical one from top to bottom, and finally a slant between the two; follows that form and order of the arm extensions. It is the right arm, holding the red flag, which moves as a pen would, but in mirror image so that the observer sees the pattern normally. As in telegraphy, the katakana syllabary is the one used to write down the messages as they are received. Also, the Japanese system presents the number 0 by moving flags in a circle, and those from 1 through 9 using a sort of the "rotary dial" system, but different from that used for European languages.
Semaphore flags are also sometimes used as means of communication in the mountains where oral or electronic communication is difficult to perform. Although they do not carry flags, the Royal Canadian Mounted Police officers have used hand semaphore in this manner. Some surf-side rescue companies, such as the Ocean City Maryland Beach Patrol, use semaphore flags to communicate between lifeguards. The letters of the flag semaphore are also a common artistic motif. One enduring example is the peace symbol, adopted by the Campaign for Nuclear Disarmament in 1958 from the original logo created by a commercial artist named Gerald Holtom from Twickenham, London. Holtom designed the logo for use on a protest march on the Atomic Weapons Establishment at Aldermaston, near Newbury, England. On 4 April 1958, the march left Trafalgar Square for rural Berkshire, carrying Ban the Bomb placards made by Holtom's children making it the first use of the symbol. Originally, it was purple and white and signified a combination of the semaphoric letters N and D, standing for "nuclear disarmament," circumscribed by a circle.
The album cover for the Beatles' 1965 album Help! was to have portrayed the four band members spelling "help" in semaphore, but the result was deemed aesthetically unpleasing, and their arms were instead positioned in a meaningless but aesthetically pleasing arrangement. Along with Morse code, flag semaphore is currently used by the Navy and also continues to be a subject of study and training for young people of Boy Scouts. In a satirical nod to the flag semaphore's enduring use into the age of the Internet, on April Fools' Day 2007 the Internet Engineering Task Force standards organization outlined the Semaphore Flag Signaling System, a method of transmitting Internet traffic via a chain of flag semaphore operators. The second episode in the second series of Monty Python's Flying Circus depicted famous stories retold using various communication systems, including Wuthering Heights in semaphore.
He [Gerald Holtom] considered using a Christian cross motif but, instead, settled on using letters from the semaphore – or flag-signalling – alphabet, super-imposing N (uclear) on D (isarmament) and placing them within a circle symbolising Earth.
D (named dee ) is the fourth letter of the modern English alphabet and the ISO basic Latin alphabet.E
E (named e , plural ees) is the fifth letter and the second vowel in the modern English alphabet and the ISO basic Latin alphabet. It is the most commonly used letter in many languages, including Czech, Danish, Dutch, English, French, German, Hungarian, Latin, Latvian, Norwegian, Spanish, and Swedish.Flag signals
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.Flagging dance
The art of flagging dance, often called flag spinning, flag dancing, or rag spinning, but more commonly referred to as flagging, is the undulation, spinning and waving of flags in a rhythmic fashion to music. Practitioners of this form of performance art and dance are usually referred to as "flaggers" and "flag dancers", though until the 1990s this mostly referred to those waving flags to aid transportation professions (flag semaphore).Florence Violet McKenzie
Florence Violet McKenzie OBE (née Granville; 28 September 1890 or 1892 – 23 May 1982), affectionately known as "Mrs Mac", was Australia's first female electrical engineer, founder of the Women's Emergency Signalling Corps (WESC) and lifelong promoter for technical education for women. She campaigned successfully to have some of her female trainees accepted into the all-male Navy, thereby originating the Women's Royal Australian Naval Service (WRANS). Some 12,000 servicemen passed through her signal instruction school in Sydney, acquiring skill in Morse code and visual signalling (flag semaphore and International Code of Signals).She set up her own electrical contracting business in 1918, and apprenticed herself to it, in order to meet the requirements of the Diploma in Electrical Engineering at Sydney Technical College and in 1922 she was the first Australian woman to take out an amateur radio operator's license. Through the 1920s and 1930s, her "Wireless Shop" in Sydney's Royal Arcade was renowned amongst Sydney radio experimenters and hobbyists. She founded The Wireless Weekly in 1922, established the Electrical Association for Women in 1934, and wrote the first "all-electric cookbook" in 1936. She also corresponded with Albert Einstein in the postwar years.I
I (named i , plural ies) is the ninth letter and the third vowel in the modern English alphabet and the ISO basic Latin alphabet.International Code of Signals
The International Code of Signals (ICS) is an international system of signals and codes for use by vessels to communicate important messages regarding safety of navigation and related matters. Signals can be sent by flaghoist, signal lamp ("blinker"), flag semaphore, radiotelegraphy, and radiotelephony. The International Code is the most recent evolution of a wide variety of maritime flag signalling systems.Llanfaethlu
Llanfaethlu is a village in the north west of Anglesey, in north-west Wales. The community population taken at the 2011 Census was 553. The village takes its name from the Church of Saint Maethlu.M
M (named em ) is the thirteenth letter of the modern English alphabet and the ISO basic Latin alphabet.Manual communication
Manual communication systems use articulation of the hands (hand signs, gestures) to mediate a message between persons. Being expressed manually, they are received visually, and sometimes tactually (see tactile signing). Manual communication, when it is a primary form of communication, may be enhanced by body language and facial expressions and other forms of communication.
Manual communication is employed in sign languages and in systems that are codes for oral languages (see Manually Coded Language).
Other, simpler forms of manual communication have also been developed. They are neither natural languages nor even a code that can fully render one. They communicate with a very limited set of signals about an even smaller set of topics and have been developed for situations where speech is not practical or permitted, or secrecy is desired.N
N (named en ) is the fourteenth letter in the modern English alphabet and the ISO basic Latin alphabet.O
O (named o , plural oes) is the 15th letter and the fourth vowel in the modern English alphabet and the ISO basic Latin alphabet.Optical communication
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.
An optical communication system uses a transmitter, which encodes a message into an optical signal, a channel, which carries the signal to its destination, and a receiver, which reproduces the message from the received optical signal. When electronic equipment is not employed the 'receiver' is a person visually observing and interpreting a signal, which may be either simple (such as the presence of a beacon fire) or complex (such as lights using color codes or flashed in a Morse code sequence).
Free-space optical communication has been deployed in space, while terrestrial forms are naturally limited by geography, weather and the availability of light. This article provides a basic introduction to different forms of optical communication.P
P (named pee ) is the 16th letter of the modern English alphabet and the ISO basic Latin alphabet.PACE - Communication Plan
PACE is an acronym and methodology used to build a communication plan. PACE stands for Primary, Alternate, Contingency, and Emergency means (i.e. technologies or systems) of communication. The method requires the author to determine the different parties that need to communicate and then determine, if possible, the best four forms of communication between each of those parties. PACE also designates the order in which an element will move through available communications systems until contact can be established with the desired distant element(s). Ideally each method will be completely separate and independent of the other systems of communication. For each method, the receiver must first sense which one the sender is using and then respond.
A PACE-based Communication Plan exists for a specific mission or task, not a specific unit, because the plan must consider both intra- and inter-unit sharing of information. An organization may have multiple plans for different situations, activities, and/or partners.
Per the US Army, a PACE Comm plan "designates the order in which an element will move through available communications systems until contact can be established with the desired distant element."A PACE plan is not a frequency plan (which details frequency allocation and radio spectrum characteristics) or band plan (to avoid interference) or channel plan (which details which channels users listen/talk upon) or deployment plan (which details the users' radios types and locations).
Primary = the best and intended method of communication between parties.
Alternate = another common but less-optimal method of accomplishing the task. Often monitored concurrently with primary means.
Contingency = method will not be as fast/easy/inexpensive/convenient as the first two methods but is capable of accomplishing the task. Often (but undesirably) the receiver rarely monitors this method.
Emergency = method of last resort and typically has significant delays, costs, and/or impacts. Often only monitored when the others means fail.
A few examples.
PACE for the public radio station WYSO to share local news with a citywide audience might be Primary: FM radio, Alternate: streaming over the Internet, Contingency: local newspaper articles, and Emergency: direct mailing newsletters
PACE would not use a different FM transmitter, antenna, and/or frequency. Those are described as redundant Primary means.
PACE for an Army convoy to talk internally might be Primary: secure military radio, Alternate: secure satellite telephone, Contingency: cellular phones, and Emergency: courier.
PACE would not be changing channels, encryption, location, or power levels on the military radio. All of those still use the Primary means.
PACE for two suburban American families who live blocks apart might be Primary: text messaging via smartphones, Alternate: web-based email, Contingency: landline telephone, and Emergency: driving/biking/walking.
PACE for two Boy Scout patrols across a lake might be Primary: flag semaphore, Alternate: Morse code using clapping wood boards, Contingency: Morse code using a mirror, and Emergency: sending a boat across.Semaphore (disambiguation)
Semaphore usually refers to flag semaphore. It may also refer to;
Semaphore line, a system of long-distance communication based on towers with moving arms
Railway semaphore signal for railway traffic controlOtherTraffic semaphore, another name for automotive traffic lights based on their early resemblance to railway semaphores
Turning semaphore or trafficators, retractable arms to indicate turns on automobiles from the 1920s to 1950s
Semaphore (programming), in computer science, a mechanism for supporting mutual exclusion in concurrent programs
Semaphore, South Australia, a historic seaside suburb of Adelaide
Semaphore railway line, Adelaide, a closed railway line in South Australia
Semaphore (album), a 1998 album by Fridge
Semaphore (song), the 2004 7" single by the New Zealand post-rock band Jakob
Semaphore, fictional professor in Cubitus comic strips or Wowser cartoonsSemaphore telegraph
A semaphore telegraph is an early system of conveying information by means of visual signals, using towers with pivoting shutters, also known as blades or paddles. Information is encoded by the position of the mechanical elements; it is read when the shutter is in a fixed position. The most widely used system was invented in 1792 in France by Claude Chappe, and was popular in the late eighteenth to early nineteenth centuries. Lines of relay towers with a semaphore rig at the top were built within line-of-sight of each other, at separations of 5–20 miles (8.0–32.2 km). Operators at each tower would watch the neighboring tower through a spyglass, and when the semaphore arms began to move spelling out a message, they would pass the message on to the next tower. This system was much faster than post riders for conveying a message over long distances, and also had cheaper long-term operating costs, once constructed. Semaphore lines were a precursor of the electrical telegraph, which would replace them half a century later, and would also be cheaper, faster, and more private. The line-of-sight distance between relay stations was limited by geography and weather, and prevented the optical telegraph from crossing wide expanses of water, unless a convenient island could be used for a relay station. Modern derivatives of the semaphore system include flag semaphore (a flag relay system) and the heliograph (optical telegraphy using mirror-directed sunlight reflections).Signal station
A signal station is a form of Aids to Navigation that is defined by the IHO simply as "A signal station is a place on shore from which signals are made to ships at sea". While this broad definition would include coastal radio stations and fog signal stations, the term is most often used for shore installation that use visual signals to communicate with ships at sea.Telegraphy
Telegraphy is the long-distance transmission of textual messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas pigeon post is not. Ancient signalling systems, although sometimes quite extensive and sophisticated as in China, were generally not capable of transmitting arbitrary text messages. Possible messages were fixed and predetermined and such systems are thus not true telegraphs.
The earliest true telegraph put into widespread use was the optical telegraph of Claude Chappe, invented in the late eighteenth century. The system was extensively used in France, and European countries controlled by France, during the Napoleonic era. The electric telegraph started to replace the optical telegraph in the mid-nineteenth century. It was first taken up in Britain in the form of the Cooke and Wheatstone telegraph, initally used mostly as an aid to railway signalling. This was quickly followed by a different system developed in the United States by Samuel Morse. The electric telegraph was slower to develop in France due to the established optical telegraph system, but an electrical telegraph was put into use with a code compatible with the Chappe optical telegraph. The Morse system was adopted as the international standard in 1865, using a modified Morse code developed in Germany.
The heliograph is a telegraph system using reflected sunlight for signalling. It was mainly used in areas where the electrical telegraph had not been established and generally uses the same code. The most extensive heliograph network established was in Arizona and New Mexico during the Apache Wars. The heliograph was standard military equipment as late as World War II. Wireless telegraphy developed in the early twentieth century. Wireless telegraphy became important for maritime use, and was a competitor to electrical telegraphy using submarine telegraph cables in international communications.
Telegrams became a popular means of sending messages once telegraph prices had fallen sufficiently. Traffic was became high enough to spur the development of automated systems – teleprinters and punched tape transmission. These systems led to new telegraph codes, starting with the Baudot code. However, telegrams were never able to compete with the letter post on price, and competition from the telephone, which removed their speed advantage, drove the telegraph into decline from 1920 onwards. The few remaining telegraph applications were largely taken over by alternatives on the internet towards the end of the twentieth century.