Application of Correctness Preserving Transformations for Deriving Architectural Descriptions of Interactive Systems from User Interface Specifications

A passive transmitter incorporates a parametric device, e.g. a varactor diode. A tuned circuit derives energy received from a source of radiowaves, and is coupled to pump the varactor diode. The varactor diode produces a subharmonic output. Means are coupled to the varactor diode to modulate the subharmonic signal, and the modulated subharmonic output may be transmitted without amplification.