When the bandwidth of a channel is too small compared to the input symbol rate, "intersymbol interference" occurs. The case known as the "1+D channel" consists of a discrete-time channel in which each output voltage consists of the sum of the amplitudes of the last two input pulses.
a. Describe this channel with binary inputs using a trellis, and describe the demodulator as a procedure for searching a trellis.
b. For this channel construct your own example of a binary input sequence and a corresponding output sequence. Show how the Viterbi algorithm can be used for recovering the input sequence from a noisy version of the output sequence.