continuous wave (CW)

Continuous Wave(CW) means as much as uniform wave. What is meant is an electromagnetic wave with a constant frequency and amplitude. The term Continuous Wave is used as a keying for the transmission of individual characters and texts and is therefore also referred to as radio telegraphy.

In CW transmission, an unmodulated electromagnetic wave is sent from the transmitting station to the receiving equipment. For character transmission, the carrier wave is switched on in time, similar to on-off keying. Included in the duration and frequency of the on cycle is the encoding of the characters.

In wireless telegraphy, as used in classical maritime radio and amateur radio, the duty cycles are assigned to Morse code, in which each letter consists of one, two, three, or four duty cycles, depending on how frequently the letter occurs in the German language. Thus, the coding for the letter "E" consists of one short duty cycle, while the letter "H" consists of four short duty cycles. The bandwidths for telegraphy are between 10 Hz and 150 Hz, depending on the telegraphy speed.