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ITU-R M.1677-1 & ARRL Procedural Signals

Morse Code Prosigns (Procedural Signals)

Master the essential procedural commands (AR, BT, SK, KN, AS, BK) used in radiotelegraphy traffic. Explore family-wise classifications, alternate ASCII punctuation mappings, and an annotated step-by-step CW QSO example.

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Written by Waleed Akram
â€ĸ Published July 29, 2026 â€ĸ Last Updated July 29, 2026 â€ĸ 6 Min Read
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Prosign Audio Synthesizer Settings

Adjust transmission speed & tone pitch before playing prosigns below.

Speed (WPM): 20 WPM
Tone Frequency: 600 Hz
đŸ§Ŧ Functional Taxonomy

Prosigns Grouped by Operational Family

In radiotelegraphy, prosigns perform distinct operational roles ranging from traffic handoff to error recovery and emergency priority.

📡

Transmission & Handover

Controls who transmits next and signals message boundaries.

AR (End of Message) ASCII: +
.-.-.
BT (Break / Separation) ASCII: =
-...-
SK / VA (End of Work) ASCII: Final Sign-off
...-.-
K (Invite Any Station) Open turn-over
-.-
KN (Invite Named Station) ASCII: (
-.--.
đŸ“ĸ

Calling & Identification

Establishes contact and identifies transmitting stations.

CQ (General Call) Call to any listening station
-.-. --.-
DE (From) Precedes callsign
-.. .
BK (Break-in Interrupt) Interject into ongoing QSO
-...-.-
QRZ? (Who is calling?) Query identifying station
--.- .-. --.. ..--..
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Pause, Error & Ack

Handles timing delays, errors, and receipt confirmations.

AS (Wait / Standby) ASCII: &
.-...
HH / 8 Dits (Error) Erase previous word
........
R (Received Solid) Roger / Acknowledged
.-.
VE (Verified / Understood) ASCII: Message verified
...-.
📄

Message Structure

Paging, line breaks, and heading markers for formal telegrams.

AA (New Line / Line Break) ASCII: \n
.-.-
INT (Query / Interrogative) Prepended to Q-code
..--.
KA / PACT (Start of Message) Attention pre-amble
-.-.-
🆘

Emergency & Distress

Highest priority radio signals taking immediate precedence.

SOS (Distress Signal) International Mayday
...---...
XXX (Urgency Signal) Pan-Pan Equivalent
-..- -..- -..-
TTT (Safety Warning) Securite Navigation
- - -
🔒

Station Status & Closure

Shutting down operations or declaring no further messages.

CL (Closing Station) Going off the air
-.-. .-..
NIL (Nothing Follows) No further traffic
-. .. .-..
73 (Best Regards) Friendly sign-off code
--... ...--
📊 Definitive Reference

Complete Morse Code Prosigns Chart

Filter by family or search any prosign, ASCII alternate punctuation, or sound pattern.

Prosign Symbol Concatenated Code Dit-Dah Rhythm Alternate Punctuation / ASCII Operational Meaning Audio
AR <AR> .-.-. di-dah-di-dah-dit + (Plus) End of Message / Out Appended at end of transmission or formal message telegram.
BT <BT> -...- dah-di-di-di-dah = (Equal Sign) Break / New Paragraph Separates thoughts or sections within a continuous text transmission.
SK / VA ...-.- di-di-di-dah-di-dah End of Contact End of Work / Silent Key Final sign-off terminating contact between stations entirely.
K -.- dah-di-dah Over (Open) Invitation to Transmit (Open) Signals any listening station that you are yielding the frequency.
KN -.--. dah-di-dah-dah-dit ( (Left Paren) Invite Named Station ONLY Strict invitation to transmit aimed ONLY at the specified station.
AS .-... di-dah-di-di-dit & (Ampersand) Wait / Standby Requests receiving station to wait for a moment (e.g. AS 2 MIN).
BK -...-.- dah-di-di-di-dah-di-dah Break-In Break-in Interruption Used in full break-in QSK mode to instantly interrupt or request quick reply.
CQ -.-. --.- dah-di-dah-dit dah-dah-di-dah General Call General Call to All Stations Call to any listening station inviting a reply to establish contact.
DE -.. . dah-di-dit dit From / This Is From Station / This Is Precedes callsign to identify the transmitting station.
QRZ? --.- .-. --.. ..--.. dah-dah-di-dah di-dah-dit dah-dah-di-dit di-di-dah-dah-di-dit Who is calling? Who Is Calling Me? Queries the identity of a station that just called.
HH ........ 8 dits continuous Error / Backspace Error Signal (8 Dits) Signals that the preceding word was sent in error and will be re-transmitted.
R .-. di-dah-dit Roger / Solid Received Solid / Roger Confirms that the last transmission was received completely and understood.
VE ...-. di-di-di-dah-dit Verified Verified / Understood Confirms formal telegram message verification and comprehension.
AA .-.- di-dah-di-dah \n (New Line) New Line / All After Used to force line feed or request text repeat after a word.
INT ..--. di-di-dah-dah-dit ? (Interrogative) Interrogative / Query Prepended to a Q-code to convert an assertion into a question.
KA / PACT -.-.- dah-di-dah-di-dah Attention / Preamble Start of Message / Attention Attention preamble transmitted before the start of a formal message.
SOS ...---... di-di-di-dah-dah-dah-di-di-dit Distress International Distress Signal Concatenated SOS signal requesting immediate maritime or life-safety aid.
XXX -..- -..- -..- dah-di-di-dah dah-di-di-dah dah-di-di-dah Urgency / Pan-Pan Urgency Signal (Pan-Pan) Transmitted three times to signal an urgent safety message concerning a vessel or person.
TTT - - - dah dah dah Safety Warning Safety Warning (Securite) Transmitted three times to introduce a navigational or meteorological safety warning.
CL -.-. .-.. dah-di-dah-dit di-dah-di-dit Closing Station Closing Station / Off Air Signals that the station is shutting down and going off the air.
NIL -. .. .-.. dah-dit di-dit di-dah-di-dit Nothing Follows Nothing Follows / No Traffic Indicates that the station has no further messages or traffic to transmit.
73 --... ...-- dah-dah-di-di-dit di-di-di-dah-dah Best Regards Best Regards / Friendly Sign-off Traditional friendly closing greeting between operators at the end of a contact.
📖 Educational Guide

Understanding Concatenated Prosigns

What makes a procedural signal fundamentally different from ordinary words or standard punctuation?

The Rule of Inter-Character Spacing

When sending normal text in Morse code, ITU-R M.1677-1 dictates a mandatory 3-dot unit pause between individual letters. For example, transmitting the letters A and R as separate words sounds like:

A (.-) + [3 dits pause] + R (.-.) = Separate Letters A and R

In contrast, a prosign is formed by running the constituent letters together with ZERO inter-character pause (1 dit element space between dits and dahs):

A (.-) + R (.-.) = .-.-. (Concatenated as single symbol AR)

Overbar Notation & ASCII Equivalents

Because keyboard software and printed logs need a way to distinguish run-together signals from normal character sequences, two universal conventions were created:

  • Overbar Notation (AR, BT, SK): Used in formal paper logbooks and official ITU manuals.
  • Angle Brackets (<AR>, <BT>): Used in computer telegraphy decoders and loggers.
  • ASCII Punctuation Mapping (+, =, &): Keyboards map .-.-. to + and -...- to = for rapid typing.
đŸ“ģ Practical Real-World Example

Annotated Typical Amateur Radio CW QSO

Examine a complete step-by-step Morse code conversation between Station A (W1AW) and Station B (K2GXT), highlighting every prosign and procedural signal in action.

STEP 1: GENERAL CALL OUT (CALLING CQ) Station W1AW
CQ CQ CQ DE W1AW W1AW W1AW K
CQ: Calling any station listening on frequency
DE: From (identifying transmitting station)
K: Open invitation to ANY station to respond
STEP 2: ANSWERING THE CALL Station K2GXT
W1AW DE K2GXT K2GXT K

Station K2GXT calls W1AW twice to ensure clarity over noise, ending with K to hand over control.

STEP 3: FIRST EXCHANGE (SIGNAL REPORT, LOCATION, NAME) Station W1AW
K2GXT DE W1AW = TNX FER CALL = UR RST 599 599 = QTH BOSTON MA = NAME IS BOB BOB = HW ? K2GXT DE W1AW KN
= (BT): Paragraph separation break
RST 599: Readability 5, Signal 9, Tone 9
QTH: Station location (Boston, MA)
KN: Strict invite to K2GXT only!
STEP 4: SECOND EXCHANGE (REPLY & STATION RIG) Station K2GXT
W1AW DE K2GXT = R TNX BOB UR 589 IN NY = RIG IS 100W DIPOLE = WX SUNNY 22C = W1AW DE K2GXT KN

Station K2GXT starts with R (Roger / solid copy), uses = (BT) between sections, and ends with KN.

STEP 5: FINAL SIGN-OFF (END OF WORK) Station W1AW & K2GXT
K2GXT DE W1AW = TNX FER FB QSO = 73 ES GOOD DX = K2GXT DE W1AW SK
W1AW DE K2GXT = 73 SK (followed by two dits: . .)

Both stations append SK (...-.-) to indicate final termination of the QSO contact.

❓ Frequently Asked Questions

Prosigns & CW Signals FAQ

What is the difference between a Prosign and a Q-Code?

A prosign is a single concatenated Morse character (like AR or BT) with zero internal character pauses. A Q-code (like QTH, QSL, QRZ) consists of three standard Morse letters transmitted with normal inter-letter spacing.

Why is K different from KN?

K (-.-) is an open invitation to transmit meant for any station listening on frequency. KN (-.--.) is a strict invitation directed exclusively at the named station, instructing third-party stations not to break in.

How do I send an error signal in Morse code?

If you make a mistake while transmitting, send 8 rapid dits (........) continuous. This instructs the receiving operator to disregard the preceding word and wait for the re-transmission.

Where do the ASCII mappings (+ and =) come from?

In computerized teletype networks and modern amateur radio software (such as FLdigi or N1MM), + generates AR (.-.-.) and = generates BT (-...-), allowing touch-typists to execute prosigns without manual code entry.

Want to translate secret messages, practice Morse code, or check technical ITU standards? Explore our interactive tools and reference guides: