In one aspect, embodiments of the present disclosure can comprise a non-contact signal detection system for detecting movement associated with a subject. The system can comprise a carrier source configured to generate a first carrier signal in phase coherence with a second carrier signal. Additionally, the system may incorporate a phase-locked loop including noise pre-cancellation system for suppressing the noise associated with a beat signal and a controlled oscillation system. The noise pre-cancellation system can be configured to phase-lock the beat signal to a first reference signal in order to stabilize the phase of the beat signal and pre-cancel the noise associated with the beat signal. The controlled oscillation system can include a propagation pathway on which a transmission signal is phase-modulated with a vibratory signal of the subject. Once acquired, the vibratory signal can have suppressed noise.
