All Morse Code Prosigns
Click any prosign to open its dedicated page with audio playback, ITU timing reference, and a memory aid.
What Is a Morse Code Prosign?
A prosign — short for procedural signal — is a Morse code symbol sent as a single, unbroken sequence of dots and dashes that represents an instruction rather than a letter. Operators use prosigns to keep transmissions short, clear, and standardized worldwide.
For example, AR (.-.-.) is sent as one continuous character — not as the letters A then R. The lack of a letter gap is what makes it a prosign. Written in text, prosigns usually appear with an overline (AR, SK) or in angle brackets (<AR>, <SK>).
Key rule: A prosign has no inter-letter gap. The two or more letters are run together as a single rhythmic unit. This is the only thing that distinguishes the prosign AR from the letters A + R sent normally.
Why Prosigns Matter
- Brevity — A single prosign replaces a whole phrase ("end of message", "stand by", "I understood").
- Clarity — Standardized worldwide by the ITU and adopted by amateur radio, military, and maritime services.
- Speed — Skilled CW operators recognize prosigns instantly, allowing fast back-and-forth conversations on the air.
- Safety — SOS is universally recognized as the international distress signal.
Prosign Comparison Chart
Quick reference table — every common Morse code prosign at a glance.
| Prosign | Morse Code | Meaning | When To Use |
|---|---|---|---|
| AR | .-.-. |
End of Message | End of message — 'Over to you' or 'message complete'. |
| AS | .-... |
Wait / Stand By | Wait — 'Stand by, I need a moment'. |
| BK | -...-.- |
Break / Back to You | Break — used in conversational CW to swap turns quickly. |
| BT | -...- |
New Paragraph / Pause | New paragraph — pause and continue with the next idea. |
| CL | -.-..-.. |
Clear / Closing Down | Closing down — station is shutting off, no further calls. |
| CT | -.-.- |
Start of Transmission | Start copying — formal message is about to begin. |
| HH | ........ |
Error / Correction | Error — the previous word was wrong, listen for the correction. |
| KN | -.--. |
Invitation to Named Station | Named station only — invitation directed to one operator. |
| SK | ...-.- |
End of Contact | End of contact — 'Thanks for the QSO, 73'. |
| SN | ...-. |
Understood | Understood — 'Roger, copy that'. |
| SOS | ...---... |
International Distress Signal | Emergency distress — life-threatening situation, request immediate help. |
How to Send a Prosign
To send a prosign correctly, transmit the dots and dashes without the normal 3-unit letter gap between the component letters. Treat the entire sequence as one character.
Example: Sending AR (.-.-.)
- Wrong: Send "A" (.- ), pause 3 units, send "R" (.-.) → this is heard as the letters A R.
- Right: Send .-.-. as one continuous string with only 1-unit gaps between each dot/dash.
- This continuous rhythm is what tells the receiver: "this is the prosign AR — end of message."
ITU Timing for Prosigns
| Element | Length | Rule |
|---|---|---|
| Dot (·) | 1 unit | Base unit |
| Dash (−) | 3 units | 3× a dot |
| Gap inside a prosign | 1 unit | Same as inside a single letter |
| Gap between words | 7 units | Standard word gap still applies after the prosign |
Prosigns in Amateur Radio (CW)
In amateur radio, prosigns are the backbone of efficient CW (continuous-wave Morse) conversations. A typical QSO (radio contact) uses prosigns to mark every transition:
CT → start of formal message
BT → new paragraph or pause for thought
AR → end of message, over to you
KN → only the named station should reply
SK → end of contact (final sign-off)
CL → closing the station entirely
Frequently Asked Questions — Morse Code Prosigns
A prosign (procedural signal) is a special Morse code sequence sent as a single character — without the usual letter gap between symbols — to convey a procedural meaning rather than a letter. Common examples include AR (end of message), SK (end of contact), and SOS (distress).
Prosigns are usually written with a bar over the two letters, like AR or SK, to show they are sent as one unit. In plain text they are often shown as
AR (.-.-.) means 'end of this message — over to you' during a conversation. SK (...-.-) means 'end of contact — the QSO is finished'. AR is mid-conversation; SK is the final sign-off.
Yes. SOS (...---...) is the most famous prosign — an internationally recognized distress signal sent as one continuous string with no letter gaps between S, O, and S.
Dozens exist historically, but about 11 prosigns are in common use today: AR, AS, BK, BT, CL, CT (KA), HH, KN, SK (VA), SN (VE), and SOS. Each serves a specific procedural purpose in CW radio communication.
Prosigns are used in amateur radio (ham radio) CW operations, military Morse code, maritime communication, and any context where Morse code is sent. They keep transmissions short and unambiguous.
Continue Learning
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