What type of radio communication uses a continuous wave (CW)?

Continuous wave (CW) refers to a basic form of radio transmission in which the signal is represented as a continuous electromagnetic wave. This method is primarily associated with Morse code transmissions, which utilize a series of dots (short signals) and dashes (long signals) to convey alphanumeric information. In CW operation, the sender transmits the established signal continuously and turns it on and off to create the distinct Morse code symbols.

Morse code is particularly suited for continuous wave transmission as it allows operators to communicate efficiently even over weak radio signals, making it a staple in amateur and maritime radio communications. The simplicity and effectiveness of CW for transmitting Morse code distinguish it from other types of radio communication, which may rely on more complex modulation techniques or encoding methods.

In contrast, speech transmissions typically involve modulated audio signals, data packets are formatted collections of binary information, and digital modulation encompasses various techniques for representing information through changes in carrier wave properties, all of which do not utilize the straightforward ON/OFF signaling characteristic of CW. Thus, Morse code transmissions stand out as the direct application of continuous wave radio communication.