State what the term amplitude modulation (AM) of a radio wave means.
An audio signal is used to modulate a radio wave. Fig. 5.1 shows how the amplitude of the modulated wave varies with frequency $f$. Determine (i) the wavelength of the carrier wave, (ii) the bandwidth of the modulated wave, and (iii) the maximum frequency of the audio signal.
Determine the wavelength associated with the carrier wave.
Determine the bandwidth shown by the modulated wave.
Determine the highest frequency of the audio signal.
A radio signal has transmitter power $P_{T}$. At the receiver, the received power $P_{R}$ is given by $P_{R} = \frac{0.082\,P_{T}}{x^{2}}$, where $x$ is the separation, in metres, between the transmitter and the receiver. For this transmission, the attenuation is $73\,\text{dB}$. Determine the distance $x$.