I’ve been thinking about writing on this topic for quite a while. There is a lot of interest in learning Morse code and communicating via CW (continuous wave). And just like the amount of interest in Morse, there’s no shortage of methods to learn it. By the way, CW, or continuous wave, simply means turning your transceiver’s transmitted RF (radio frequency) signal on and off by using a key or paddle (Photo A).1 A short pulse of RF (CW) is sent over the air. The combination of frequency pulses and time between pulses is the method used to transmit and to receive Morse code via radio. In February 2007, the FCC (Federal Communications Commission) removed the Morse Code requirement for a ham radio license. Some pundits at the time predicted that it wouldn’t be long before CW all but vanished from the ham radio bands. Only the Morse code die-hards would remain as relics to a distant past, they said. Contrary to their predictions, CW didn’t vanish. Instead, CW is flourishing!
CW & Weak Signal Copy
There are several reasons why CW is flourishing. Besides being fun, it is perfect for weak signal communications. What do I mean by weak signal communications? Turn on your transceiver and listen to the static. That is your transceiver’s “noise floor.” Some days have more static than others. Sometimes, when the static levels are very high, it seems like nothing will punch through the noise. Often a CW signal, even a weak one, can punch through QRN (static) to be successfully copied. It may be a struggle on both ends of the radio, but it can be done.
Bandwidth
The amount of RF spectrum a modulated signal occupies is called its bandwidth. It is measured in Hertz (Hz). For example, a typical single sideband (SSB) signal is around 2.8 kilohertz (kHz) wide, whereas a CW signal is around 150 Hz.
