Prosigns
| Prosigns | |
|---|---|
| Full name | Procedural signals |
| Used in | Morse code (CW) |
| How sent | Two or more letters run together as one character, with no gap between them |
| How written | With a bar over the letters, or in angle brackets such as <AR> |
| Most common | |
| End of message | AR |
| End of contact | SK |
| Go ahead, named station only | KN |
| Distress | SOS |
Prosigns, short for procedural signals, are special Morse code characters that control the flow of a CW contact. They tell the other station when a message is finished, when it is their turn, when to wait and when the conversation is over. Most prosigns are written as two letters, but they are sent as a single character: the letters are run together with no space between them, so that, for example, AR sounds like one long pattern rather than A followed by R. In print they are usually shown with a bar over the letters or in angle brackets, as in <SK>.
Prosigns are not abbreviations. CW also uses many abbreviations, such as those described under Ham radio slang and Q-codes, but those are sent as ordinary letters with normal spacing.
The common prosigns
| Prosign | Morse | Meaning |
|---|---|---|
| AR | ·−·−· | End of message. Sent at the end of a transmission, often just before the call signs, and at the end of a CQ. |
| SK | ···−·− | End of contact. Sent with the final transmission of a QSO; the station is finished with this contact. |
| KN | −·−−· | Go ahead, but only the station named. Others should not break in. |
| K | −·− | Go ahead; any station may reply. A single letter, not strictly a prosign, but used the same way. |
| BT | −···− | Break or pause; separates parts of a message, much like a new paragraph. Written as "=". |
| AS | ·−··· | Wait; stand by. |
| CT or KA | −·−·− | Attention; start of transmission. Mostly used in formal message handling. |
| SN or VE | ···−· | Understood. |
| HH | ········ | Error; disregard the last word. Many operators simply send a string of dits, or "EEEEEEEE". |
| SOS | ···−−−··· | Distress. Sent as one unbroken character. |
Two other signals often listed with the prosigns are normally sent as separate letters. BK (break) is used to hand the frequency back quickly without call signs, and CL (closing) means the station is going off the air and will not answer further calls.
Some prosigns share their patterns with punctuation marks: AR is the same as the plus sign, BT the equals sign, KN the open parenthesis and AS the ampersand. The listener tells them apart by context.
Prosigns in a contact
A typical exchange shows how they fit together:
- A station calling CQ ends with K, inviting anyone: CQ CQ CQ DE W1ABC W1ABC K.
- Once a contact is under way, each transmission ends with KN, so that others know the frequency is in use: ... W1ABC DE K2XYZ KN.
- Partway through a long transmission, BT separates subjects, such as moving from a signal report to a description of the station.
- At the end, the station signing off sends 73 SK, and often a final "dit dit". The other station usually answers with its own SK and "dit dit".
AR and SK are easy to confuse. AR marks the end of one transmission or message, while SK marks the end of the whole contact. Some operators combine the two, sending AR before the call signs and SK after the final 73.
Message handling
Prosigns have a more formal role in traffic handling, where operators pass written messages called radiograms. There, BT separates the parts of a message, such as the address, text and signature, and AR marks the end of the message. Using the prosigns correctly lets the receiving operator know exactly where each part begins and ends, which matters when a message is relayed through several stations.
SOS
SOS is the international Morse distress signal, adopted in the early 20th century. It was chosen because its pattern is simple and unmistakable, not because the letters stand for anything; phrases such as "save our souls" were invented later. It is sent as a continuous character, three dits, three dahs and three dits, with no letter spacing. It must be used only when life or property is in immediate danger. The voice equivalent is "Mayday". Any station that hears a distress call should listen carefully, note the details and help if it can; Emergency communications covers the procedures.