Morse code
| Morse code (CW) | |
|---|---|
| Mode type | On-off keying of a continuous wave |
| Bandwidth | Roughly 100–200 Hz |
| License requirement | None in the US since 2007; optional under ITU rules since 2003 |
| Typical speeds | 5–15 wpm beginners, 20–35 wpm experienced, 40+ contesters |
| Where to find it | |
| HF | Lowest segment of every band, e.g. 7.000–7.125 MHz, 14.000–14.070 MHz |
| VHF | 144.000–144.100 MHz |
| Common abbreviations | Q-codes, CQ, DE, K, 73 |
Morse code, which hams call CW (for continuous wave), sends text as patterns of short and long tones, dits and dahs. It is the oldest mode in radio and, more than a century on, still one of the most used. A CW signal occupies a tiny slice of spectrum and needs only a few watts to cross an ocean, which is why it survives on crowded bands and in emergencies long after fancier modes have failed.
Why hams still use it
- It gets through. A CW signal can be copied by ear when it is barely above the noise, and it is about 15 dB more effective than voice for the same power. Five watts of CW is a serious DX signal.
- Simple equipment. A CW transmitter is the simplest kind to build, and many hams' first home-built rigs are CW-only.
- Narrow bandwidth. Dozens of CW contacts fit in the space of one voice signal.
- It's a skill. Learning the code and copying it in your head is a satisfaction that many hams compare to learning an instrument.
No license anywhere in the US has required Morse since February 2007, and the ITU made the requirement optional in 2003. Activity on the CW segments has not fallen; by some measures it has grown. Clubs devoted to CW help keep it busy: the Straight Key Century Club runs regular sprints for operators using manual keys, CWops holds weekly one-hour CWT sessions, and FISTS pairs experienced operators with newcomers.
The code
Each character is a pattern of dits (·) and dahs (−). A dah is three dits long, characters are separated by three dits of silence, and words by seven.
| A ·− | B −··· | C −·−· | D −·· | E · | F ··−· | G −−· | H ···· | I ·· |
| J ·−−− | K −·− | L ·−·· | M −− | N −· | O −−− | P ·−−· | Q −−·− | R ·−· |
| S ··· | T − | U ··− | V ···− | W ·−− | X −··− | Y −·−− | Z −−·· | |
| 1 ·−−−− | 2 ··−−− | 3 ···−− | 4 ····− | 5 ····· | 6 −···· | 7 −−··· | 8 −−−·· | 9 −−−−· |
| 0 −−−−− | ? ··−−·· | / −··−· | . ·−·−·− | , −−··−− | AR ·−·−· | SK ···−·− | BT −···− |
Learning it
The method that works is to learn the sounds, not the dots and dashes on paper. The Koch method starts with two characters at full speed, say 20 words per minute with extra space between characters, and adds a new one each time you copy 90 percent correctly. Farnsworth spacing keeps characters fast while stretching the gaps, so you never have to "speed up" later. Free apps and websites teach both. Fifteen minutes a day for a couple of months is enough to get on the air.
On the air, a CW contact follows a pattern: call CQ, exchange call signs, then signal report (RST), name and location (QTH), then whatever else, and finish with 73. Q-codes and abbreviations keep it short.
Keys
A straight key is a single lever; you form every dit and dah yourself. A paddle with an electronic keyer makes perfectly timed dits on one side and dahs on the other, and is what most operators use above about 15 words per minute. A bug is a mechanical semi-automatic key from the early 20th century that still has devotees. Many hams also send from a keyboard, and decoding software can copy CW to the screen, though purists would rather use their ears.