Achievable rates for a constrained Gaussian channel.

We consider a continuous-time channel where the input waveform x(t) is constrained to take on but two values, i.e. x(t) = +-square root P, where P is the signal power. The signal is passed through a linear filter and added to white Gaussian noise. With a suitable choice of filter, this channel is a model of the channel corresponding to a magnetic storage medium. We are interested in the channel capacity, C(0), of this channel, and in particular the relation of C(0) to C(p) and C(AV), where C(p) is the capacity of the same channel with the two- level constraint on x(t) replaced by the "peak-power" constraint /x(t)/