The present invention, generally speaking, provides methods and apparatus for producing an amplitude modulated communications signal, in which a constant-envelope carrier signal is modified in response to a power control signal to produce a modified constant-envelope carrier signal. The sensor system includes a second sensor disposed within a second portion of the steering wheel separate from the first portion to detect contact with a front right surface of the steering wheel. The electric field has an intensity satisfying a lower limit of a specification value of a carrier capturing efficiency and an upper limit of a specification value of a dark current density.