But, in any case, the frequency wo, must be higher than the upper frequency of the message to be transmitted. The process of controlling one or several parameters of a high frequency signal is called modulation. The individual signals to be transmitted are modulated with different carrier frequencies. The modulated signals are then summed and transmitted simultaneously over the same communication channel. Through this process the individual input signals are allocated distinct segments of the frequency band.
Band pass filtering to extract the modulated signal corresponding to a specific channel.
It is followed by a demodulation process to recover the original signal. Modulation is extensively used in communication systems. Angle modulation have a number of advantages over amplitude modulation, for example, the modulated signal has a constant peak amplitude and thus allows the transmitter to operated at peak power always. For these reasons, in public broadcasting and a variety of other contexts, FM reception is typically better than AM reception. FM however, requires greater bandwidth than AM does.