What is the modulation type that produces brief bursts of an RF carrier, forming Morse code?

The correct answer is Continuous Wave (CW) Modulation. CW modulation involves the transmission of radio frequency (RF) signals that are turned on and off in a rapid manner, which is ideal for generating Morse code. This technique transmits information through the presence (or absence) of a carrier wave, effectively creating a series of dots (short bursts) and dashes (long bursts) that represent letters and numbers in Morse code.

In contrast, other modulation methods such as Amplitude Modulation (AM) and Frequency Modulation (FM) involve varying the amplitude or frequency of the carrier wave continuously, which is not suitable for producing the discrete bursts characteristic of Morse code. Pulse Width Modulation (PWM) is a technique commonly used in controlling power delivered to devices, like motors, but does not apply to the transmission of Morse code as it does not involve a continuous RF carrier in the same manner. Therefore, Continuous Wave modulation is the preferred and traditional method for Morse code communication due to its simplicity and effectiveness in conveying information through brief bursts of signal.