  A tunable, multi-degree-of-freedom, parametrically excited amplifier is
introduced as an apparatus capable of shifting slow, weak signals to higher
frequencies, by exploiting the amplifier natural resonances via controlled
parametric excitation and nonlinear feedback. This device can find use as a
signal amplifier and as a spectrum control device. A tuned dual-frequency
signal is created to parametrically excite (pump) the system and produce the
desired energy shift. The pump signal is applied by a controlled
electromechanical actuator, and is modified in-situ according to the slow
frequency signal and the desired response. A three DOF model is introduced, and
the governing nonlinear EOM are derived and solved analytically via asymptotic
methods and verified with numerical simulations. A parametric design of an
experimental rig was carried out, and the importance of experimental
calibration and system identification is emphasized. Some preliminary
experimental results are provided with favorable agreement with the theory.
