An ion implantation apparatus with multiple operating modes is disclosed. The MDACs are each configured to provide variable attenuation in a plurality of discrete steps. A rotor configured to rotate in a horizontal plane is positioned between the stators. The tip pad holder has a conical surface that seats upon a mating conical surface of the tip ferrule. Alternately, if the error value is greater than the threshold error value, then the method adaptively calculates updated despreading weights at the base station from the first spread signal and calculates updated spreading weights as the current spreading weights from the updated despreading weights to apply to the outgoing data signal.