A method of filtering frequency encoded imaging signals includes receiving the frequency encoded imaging signals in the time domain and demodulating the frequency encoded imaging signals. One method includes receiving a request to activate a component having an object class ID and a partition ID and detecting if the object class ID is contained within a default partition corresponding to the partition ID. The differential image is binarized using a predetermined binarization threshold value and the bianrization threshold value is changed until a noise level of a bianrized image becomes not greater than a predetermined value and based on a binarization threshold value at which the noise level becomes not greater than the predetermined value, an intruding object is detected. The frame element can comprise a barrel mount that is configured to selectively engage a side of a crossbow barrel, such as on one or more sides of the crossbow barrel.