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.
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. Aside from military and Amateur radio use, one other remaining specialized radio message format is the airline industry Airline Teletype System, which still uses the IATA Teletype message format (though not always via radio) for worldwide air traffic communications
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
Military organizations have historically used radiograms for transmitting messages. One notable example is the notification of the air raid on Pearl Harbor that brought the United States into World War II.
The standard military radiogram format (in NATO allied nations) is known as the 16-line message format, for the manner in which a paper message form is transcribed through voice, Morse code, or TTY transmission formats. Each format line contains pre-defined content.
When sent as an ACP-126 message over teletype, a 16-line format radiogram would appear similar to this:
RFHT DE RFG NR 114 R 151412Z MAR FM CG FIFTH CORPS TO CG THIRD INFDIV WD GRNC BT UNCLAS PLAINDRESS SINGLE ADDRESS MESSAGES WILL BE TRANSMITTED OVER TELETIPEWRITER CIRCUITS AS INDICATED IN THIS EXAMPLE BT C WA OVER TELETYPEWRITER NNNN
Some of the format lines in the above example have been omitted for efficiency. The translation of this abbreviate format follows:
|Format Line||Message Text||Explanation|
|Line 2||RFHT||Station being called, which will receive the message|
|Line 3||DE RFG NR 114||Sent by radio station having the callsign RFG, station serial number 114|
|Line 5||R 151412Z MAR||Routine precedence, March 15, 2:12pm UTC in Date-time group format|
|Line 6||FM CG FIFTH CORPS||The message is from CG FIFTH CORPS|
|Line 7||TO CG THIRD INFDIV||The message is to CG THIRD INFDIV|
|Line 10||WD GRNC||Accounting symbol (WD); word groups have not been counted (GRNC)|
|Line 11||BT||Section separator between heading and text|
PLAINDRESS SINGLE ADDRESS
MESSAGES WILL BE TRANSMITTED
OVER TELETYPEWRITER CIRCUITS
AS INDICATED IN THIS EXAMPLE
|Message content is unclassified, and the message is...|
|Line 13||BT||Section separator between text and the ending|
|Line 15||C WA OVER TELETYPEWRITER||corrects (C) word after (WA) "OVER" to "TELETYPEWRITER"|
|Line 16||NNNN||end-of-message indicator|
This radiotelegraph message format (also "radio teletype message format", "teletypewriter message format", and "radiotelephone message format") and transmission procedures have been documented in numerous military standards, including the WWII-era U.S. Army Manuals TM 11-454 (The Radio Operator), FM 24-5 (Basic Field Manual, Signal Communication), FM 24-6 (Radio Operator's Manual), TM 1-460 (Radiotelephone Procedure), FM 24-18 (Radio Communication), FM-24-19 (Radio Operator's Handbook), FM 101-5-2 (U.S. Army Report and Message Formats), TM 11-380, FM 11-490-7 (Military Affiliate Radio System), AR 105-75, Navy Department Communication Instructions 1929, and their modern decedents in the Allied Communications Procedures, including ACP 124 (messages relayed by telegraphy), ACP 125 (messages relayed by voice), ACP 126 (messages relayed by radio teletype), ACP 127 (messages relayed by automated tape), AR 25-6, U.S. Navy Signalman training courses and others.
At one point before WWII, the U.S. FCC defined (at least for domestic police radio traffic) a station serial number as a sequential message number that was reset at the beginning of each calendar month.
The Communications Standard Dictionary defines radiotelegraph message format as "The prescribed arrangement of the parts of a message that has been prepared for radiotelegraph transmission."
This example of an USMTF message contains a good summary of the message creation and handling rules.
The Military Affiliate Radio System uses radiograms, or MARSgrams, to transmit health & welfare message between military members and their families, and also for emergency communications. Some MARS radio procedure documents include instructions on how to exchange ARRL NTS Radiograms over a MARS radio net. Both formats include a procedure for counting the number of word groups (words in NTS, groups in the ACP/MARS format), but differ in how word groups are counted, for instance, so the counting method must be resolved when converting messages between formats.
U.S. Department of State ACP-127 radiograms
The U.S. Department of State uses the military's automated message delivery version of the 16-line format, known as ACP-127, with its own structured definitions of the format lines.
Police radiograms had their own format, likely derived from the commercial radiogram format.
Example radiogram from A National Training Manual and Procedural Guide for Police and Public Safety Radio Communications Personnel, 1968.
15 SHRF LEE COUNTY ILL 12-20-66 (A. Preamble) PD CARBONDALE ILL (B. Address) DATA AND DISPOSITION RED 62 CHEVROLET (C. Text) 4 DOOR ILL LL1948 VIN 21723T58723 ABANDONED DIXON ILLINOIS THREE DAYS HELD ANDREWS GARAGE FRONT END DAMAGED NOT DRIVEABLE NO APPREHENSIONS WILL BE RELEASED TO OWNER ON PROOF OF OWNERSHIP SHERIFF LEE COUNTY ILLINOIS JRM 1530 CST (D. Signature)
Section A6.6 Message Form
From the above training manual:
A formal message is one constructed, transmitted and recorded according to a standard prescribed form (see Sec. 4). A formal message should contain the following essential P A R T S:
- Preamble - message number, point of origin or agency identifier, date.
- Address - to whom the message is directed.
- Reference - to previous message, if any.
- Text - the message.
- Signature or Authority - department requesting the message.
It is a plaintext message, along with relevant metadata (headers), that is placed into a traffic net by an amateur radio operator. Each radiogram is relayed, possibly through one or more other amateur radio operators, to a radio operator who volunteers to deliver the radiogram content to its destination.
- "International Telegraph Conference (London, 1903)" (PDF). Retrieved 26 April 2015.
- "International Telegraph Conference (Paris, 1925)" (PDF). Retrieved 26 April 2015.
- "Rec. ITU-R M.1171" (PDF).
- "Radiogram reporting the Pearl Harbor attack, December 7, 1941".
- "FM 24-5 (Basic Field Manual, Signal Communication)" (PDF).
- "FM 24-6 (Radio Operator's Manual)" (PDF).
- "FM 11-490-7 (Military Affiliate Radio System)" (PDF).
- "U.S. Navy Signalman training course" (PDF).
- "U.S. Navy Signalman training course" (PDF).
- "The APCO Bulletin, 1938" (PDF).
- "Communications Standard Dictionary". Retrieved 19 April 2015.
- "MARS Radiogram" (PDF).
- "5 FAH-2 H-320 ACP-127 FORMAT LINES" (PDF).
- "A National Training Manual and Procedural Guide for Police and Public Safety Radio Communications Personnel". Retrieved 27 April 2015.