Electrical telegraphs were point-to-point text messaging systems, primarily used from the 1840s until the late 20th century. It was the first electrical telecommunications system and the most widely used of a number of early messaging systems called telegraphs, that were devised to communicate text messages more quickly than physical transportation. Electrical telegraphy can be considered to be the first example of electrical engineering.
Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called dots and dashes, or dits and dahs. Morse code is named after Samuel Morse, one of the early developers of the system adopted for electrical telegraphy.
Telegraphy is the long-distance transmission of 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, so such systems are thus not true telegraphs.
A teleprinter is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations.
Wireless telegraphy or radiotelegraphy is transmission of text messages by radio waves, analogous to electrical telegraphy using cables. Before about 1910, the term wireless telegraphy was also used for other experimental technologies for transmitting telegraph signals without wires. In radiotelegraphy, information is transmitted by pulses of radio waves of two different lengths called "dots" and "dashes", which spell out text messages, usually in Morse code. In a manual system, the sending operator taps on a switch called a telegraph key which turns the transmitter on and off, producing the pulses of radio waves. At the receiver the pulses are audible in the receiver's speaker as beeps, which are translated back to text by an operator who knows Morse code.
The Q-code is a standardised collection of three-letter codes that each start with the letter "Q". It is an operating signal initially developed for commercial radiotelegraph communication and later adopted by other radio services, especially amateur radio. To distinguish the use of a Q-code transmitted as a question from the same Q-code transmitted as a statement, operators either prefixed it with the military network question marker "INT" or suffixed it with the standard Morse question mark UD.
SOS is a Morse code distress signal, used internationally, originally established for maritime use. In formal notation SOS is written with an overscore line, to indicate that the Morse code equivalents for the individual letters of "SOS" are transmitted as an unbroken sequence of three dots / three dashes / three dots, with no spaces between the letters. In International Morse Code three dots form the letter "S" and three dashes make the letter "O", so "S O S" became a common way to remember the order of the dots and dashes. IWB, VZE, 3B, and V7 form equivalent sequences, but traditionally SOS is the easiest to remember.
The R-S-T system is used by amateur radio operators, shortwave listeners, and other radio hobbyists to exchange information about the quality of a radio signal being received. The code is a three digit number, with one digit each for conveying an assessment of the signal's readability, strength, and tone. The code was developed in 1934 by Amateur radio operator Arthur W. Braaten, W2BSR, and was similar to that codified in the ITU Radio Regulations, Cairo, 1938.
A signal strength and readability report is a standardized format for reporting the strength of the radio signal and the readability (quality) of the radiotelephone (voice) or radiotelegraph signal transmitted by another station as received at the reporting station's location and by their radio station equipment. These report formats are usually designed for only one communications mode or the other, although a few are used for both telegraph and voice communications. All but one of these signal report formats involve the transmission of numbers.
Radiotelephony procedure includes various techniques used to clarify, simplify and standardize spoken communications over two-way radios, in use by the armed forces, in civil aviation, police and fire dispatching systems, citizens' band radio (CB), and amateur radio.
A Radio code is any code that is commonly used over a telecommunication system such as Morse code, brevity codes and procedure words.
Procedural signs or prosigns are shorthand signals used in Morse code telegraphy, for the purpose of simplifying and standardizing procedural protocols for landline and radio communication. The procedural signs are distinct from conventional Morse code abbreviations, which consist mainly of brevity codes that convey messages to other parties with greater speed and accuracy. However, some codes are used both as prosigns and as single letters or punctuation marks, and for those, the distinction between a prosign and abbreviation is ambiguous, even in context.
Morse code abbreviations are used to speed up Morse communications by foreshortening textual words and phrases. Morse abbreviations are short forms, representing normal textual words and phrases formed from some (fewer) characters taken from the word or phrase being abbreviated. Many are typical English abbreviations, or short acronyms for often-used phrases.
A radiogram is a formal written message transmitted by radio. Also known as a radio telegram or radio telegraphic message, radiograms use a standardized message format, form and radiotelephone and/or radiotelegraph transmission procedures. These procedures typically provide a means of transmitting the content of the messages without including the names of the various headers and message sections, so as to minimize the time needed to transmit messages over limited and/or congested radio channels. Various formats have been used historically by maritime radio services, military organizations, and Amateur Radio organizations.
Procedure words are words or phrases limited to radio telephone procedure used to facilitate communication by conveying information in a condensed standard verbal format. Prowords are voice versions of the much older procedural signs for Morse code which were first developed in the 1860s for Morse telegraphy, and their meaning is identical.
APRS Calling is a manual procedure for calling stations on the Automatic Packet Reporting System (APRS) to initiate communications on another frequency, or possibly by other means. It is inspired by Digital Selective Calling, a part of the Global Maritime Distress Safety System. It also builds on existing digital procedures inherited from morse code and radioteletype operation. ITU Q codes are used in conjunction with APRS text messages to implement APRS calling. APRS calling is intended to complement monitoring voice calling frequencies.
A plain-language radio check is the means of requesting and giving a signal strength and readability report for radiotelephony (voice) communications, and is the direct equivalent to the QSA and QRK code used to give the same report in radiotelegraph communications. SINPEMFO code is the voice signal reporting format developed by the ITU in 1959, but sees little use outside of shortwave listeners.
16-line message format, or Basic Message Format, is the standard military radiogram format for the manner in which a paper message form is transcribed through voice, Morse code, or TTY transmission formats. The overall structure of the message has three parts: HEADING, TEXT, and ENDING. This heading is further divided into procedure, preamble, address, and prefix. Each format line contains pre-defined content. An actual message may have fewer than 16 actual lines, or far more than 16, because some lines are skipped in some delivery methods, and a long message may have a TEXT portion that is longer than 16 lines by itself.
In CW Morse code operations, QSK or full break-in operation describes an operating mode in which the transmitting station can detect signals from other stations between the elements or letters of the Morse transmission. This allows other stations to interrupt the transmitting station between individual coding elements, and such allows for a conversational style of communication.
The QSA code and QRK code are interrelated and complementary signal reporting codes for use in wireless telegraphy. An enhanced format, SINPO code, was published in the ITU Radio Regulations, Geneva, 1959, but is longer and unwieldy for use in the fast pace of Morse code communications.
