How is Morse code sent, and what can go wrong?
CW
Continuous wave (CW) is Morse code, transmitted by on-off keying (OOK) of an RF signal.
On-off keying means switching the RF signal on to make a mark (a dot or dash) and off to make a space.
The emission type for international Morse code telegraphy is CW. Standard CW does not use FSK or AFSK (frequency-shift keying), because CW uses on-off keying.
Key clicks
Key clicks are clicking noises caused by an excessively square CW keyed waveform, meaning the RF is switched on and off too abruptly.
To eliminate key clicks, use a key-click filter. It rounds the edges of the keyed waveform.
Chirp
Chirp is a slight shift in oscillator frequency each time a CW transmitter is keyed. It makes the note sound like a bird chirp.
To avoid chirp, regulate the power supply output voltages of the CW transmitter. A poorly regulated supply causes frequency instability, which is chirp.
You now know
- CW is Morse code sent by on-off keying; FSK and AFSK are not used for standard CW.
- Key clicks come from a too-square keyed waveform and are cured by a key-click filter.
- Chirp is a slight frequency shift each time you key, and is avoided by regulating the power supply voltages.