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. Radiograms are typically employed for conducting record communications, which provides a message transmission and delivery audit trail. Sometimes these records are kept for proprietary purposes internal to the organization sending them, but are also sometimes legally defined as public records. For example, maritime Mayday/SOS messages transmitted by radio are defined by international agreements as public records.
Historical development From 1850 to the mid 20th century industrial countries used the electric telegraph as a long distance person-to-person text message service. A telegraph system consisted of two or more geographically separated stations linked by wire supported on telegraph poles. A message was sent by an operator in one station tapping on a telegraph key, which sent pulses of current from a battery or generator down the wire to the receiving station, spelling out the text message in Morse code. At the receiving station the current would activate a telegraph sounder which would produce a series of audible clicks, and a receiving operator who knew Morse code would translate the clicks to text and write down the message. By the 1870s, most industrial nations had nationwide telegraph networks with telegraph offices in most towns, allowing citizens to send a message called a telegram for a fee to any person in the country. Submarine telegraph cables allowed intercontinental messages called cablegrams. The invention of radiotelegraphy (wireless telegraphy) communication around 1900 allowed telegraph signals to be sent by radio. An operator at a radio transmitter would tap on a telegraph key, turning the transmitter on and off, sending pulses of radio waves through the air, and at the receiving station a radio receiver would receive the pulses and make them audible as a sequence of beeps in the earphone, and the receiving operator would translate the Morse code to text and write it down. High speed systems used paper tape to send and record the message. Guglielmo Marconi's demonstration of transatlantic radiotelegraphy transmission in 1901 showed that the wireless telegraph could be a useful long-distance communication technology which didn't require the costly installation of a telegraph wire. Around 1906 industrial nations began building powerful transoceanic radiotelegraphy stations to communicate with other countries and their overseas colonies. By World War I these were integrated with landline telegraph networks, so citizens could go to a telegraph office and send a person-to-person telegraph message by radio to another country. This was written down on a standardized form called a radiogram. International radiotelegraphy was expensive so radiograms were mostly used for business and commercial communication. The concept of the standard message format originated in the wired telegraph services. Each telegraph company likely had its own format, but soon after radio telegraph services began, some elements of the message exchange format were codified in international conventions (such as the International Radiotelegraph Convention, Washington, 1927), and these were then often duplicated in domestic radio communications regulations (such as the FCC in the U.S.) and in military procedure documentation. Military organizations independently developed their own procedures, and in addition to differing from the international procedures, they sometimes differed between different branches of the military within the same country. For example, the publication "Communication Instructions, 1929", from the U.S. Navy Department, includes:
One procedure for messages transmitted "in naval form over nonnaval systems" (Part II: Radio, Chapter 15) One procedure for exchanging messages with commercial radio stations (Part II: Radio, Chapter 16, pages 36–37 for examples; see also Part I: Chapter 7) One procedure for messages transmitted within the Navy (Part IV: Procedure and Examples, Chapter 32, especially pages 21 & 22 for the format) One format for exchanging messages between the Army and Navy (Part IV: Appendix A), called the "Joint Army and Navy Radiotelegraph Procedure", with the format shown on page 70. Notable characteristics of radiograms include headers that include information such as the from and to addresses, date and time filed, and precedence (e.g. emergency, priority, or routine), so that the radio operators can determine which messages need to be delivered first during times of congestion.
Chronology of the commercial radiogram format International Telegraph Conference (London, 1903; including Order of transmission beginning on page 40) International Telegraph Conference (Paris, 1925) International Radiotelegraph Convention (Washington, 1927) International Radiotelegraph Conference (Madrid, 1932) was redrafted to include general principles common to telegraph, telephone and radio services.
Maritime radio service radiotelegrams The message format for communications transmitted to sea-going vessels is defined in Rec. ITU-R M.1171, § 28:
radiotelegram begins: from . . . (name of ship or aircraft); number . . . (serial number of radiotelegram); number of words . . . ; date . . . ; time . . . (time radiotelegram was handed in aboard ship or aircraft); service indicators (if any); address . . . ; text . . . ; signature . . . (if any); radiotelegram ends, over
Airline Teletype Message The international airline industry continues to use a radioteletype message format originally designed for transmission to Teleprinters, Airline Teletype System, which is now disseminated via e-mail and other modern electronic formats. However, the relationship of the IATA Type B message to other radio telegram message formats is clearly visible in a typical message:
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