An apparatus and method for separating animal waste from litter are provided. A model stores steady state values of mass flux and enthalpy change related to rotational speed, inlet pressure and temperature and outlet pressure. The semiconductor device includes contact pads disposed on a surface thereof and an insulating material disposed over the contact pads. The system controller assembly is operatively coupled to chiller controller, wherein the system controller assembly is configured to transmit to the chiller controller one of a start signal to start chiller operations or a stop signal to stop chiller operations. The method includes injecting a test signal into the electronic signal path an injection point, receiving a combined signal from the electronic signal path at the injection point, determining an autocorrelation of the combined signal, and estimating a characteristic of the electronic signal path from the autocorrelation. For example, in accordance with one embodiment of the present invention, a multiple-pitch grating is employed to receive one or more laser beams and provide an output laser beam encoded with position information of the grating.