An exemplary mounting apparatus for an expansion card with an end plate includes a mounting bracket, and a retaining member slidably attached to the bracket. The cooling fan is located on the axial line of the twisting motor so that cooling air effectively flows along the surface of the twisting motor and through within the twisting motor. The receiver circuit includes one or more comb filters, each corresponding to a possible guard interval size, each receiving a series of locations at which the correlation function exceeds a predetermined threshold, and each producing an output that provides information about the guard interval size andor position.