Question 6A415

Radiotelegraphy (CW) involves rapidly turning a radio carrier on and off. When a signal is switched on and off, it's not a perfectly smooth transition, but rather a series of pulses. These rapid changes in the signal envelope generate sidebands around the carrier frequency. The faster the code speed, the more rapid these on/off transitions become. From a theoretical standpoint (Fourier analysis), sharper, faster changes in a waveform require a wider range of frequencies (i.e., more numerous and stronger sidebands) to accurately represent the pulsed signal. Therefore, increasing the code speed directly increases the bandwidth occupied by the radiotelegraph emission. * **A) Correct:** As explained, faster keying creates more rapid spectral changes, demanding greater bandwidth. * **B) Incorrect:** This statement is the opposite of the fundamental principle. Slower changes (lower code speed) would result in *less* bandwidth. * **C) Incorrect:** Code speed relates to how quickly information is transmitted, not the power output of the transmitter. Signal strength is determined by transmit power, antenna gain, and path loss, independent of keying speed. * **D) Incorrect:** Since C is incorrect, D is also incorrect.