(第5空)Although a given waveform may contain frequencies over a very broad range, as a practical matter any transmission system will be able to accommodate only a limited band of ( ) . This, in turn, limits the data rate that can be carried on the transmission ( ) . A square wave has an infinite number of frequency components and hence an infinite ( ). However, the peak amplitude of the Mi frequency component, k_f，is only 1/k, so most of the ( ) in this waveform is in the first few frequency components. In general, any digital waveform will have ( ) bandwidth. If we attempt to transmit this waveform as a signal over any medium, the transmission system will limit the bandwidth that can be transmitteD.