What is the approximate bandwidth required to transmit a CW signal?

Continuous Wave (CW), commonly known as Morse code, is the simplest form of modulation. It consists simply of turning an unmodulated carrier wave on and off to form dots and dashes. Because it carries no complex audio information like voice or music, it requires the narrowest bandwidth of any common operating mode. A typical CW signal only requires about 150 Hz of bandwidth to be clearly distinguishable by a receiving station. In contrast, Single Sideband (SSB) voice requires about 2.4 kHz (2400 Hz), AM voice requires about 6 kHz, and standard FM voice requires between 10 to 15 kHz. Therefore, 150 Hz is the correct approximate bandwidth for CW.