• With alternate mark inversion (AMI) , a voltage of 0 is used to represent a zero, and a rectangular pulse is used to represent a one. However, the sign of the pulse changes with each successive one. So, for example, to represent the message 101100101, the pulse train shown below is transmitted. Assuming that zeros and ones are equally likely to be transmitted, and each message bit is independent of the others, find the power spectral density of the pulse train corresponding to an infinite-length sequence of message bits. Give a mathematical expression for the PSD, and provide an accurate sketch.