A system for use in inductive sensing, for processing electromagnetic signals returned from a body responsive to application of electromagnetic excitation signals to said body, the system arranged to receive a signal input indicative of said sensed returned signals, the returned signals corresponding to signals sensed at a loop antenna of a resonator circuit based on detecting variations in electrical characteristics of the resonator circuit as the circuit is driven to generate the excitation signals; wherein the system is configured to implement a signal extraction procedure in which the system is configured to: detect from the sensed return signals a first input signal, the first input signal based on a frequency of the sensed returned signal, detect from the sensed return signals a second input signal, the second input signal based on a sensed amplitude of the sensed returned signal, apply a signal generation procedure comprising generating a plurality of candidate signals, each candidate signal formed from a different linear combination of the first and second input signals, and apply a signal selection procedure for selecting one of the candidate signals, the selection procedure based on pre-defined criteria relating to one of more signal characteristics of the input signals, the criteria configured for isolating a signal pertaining to a particular physiological source in the body, the selected signal forming an output signal. the system arranged to receive a signal input indicative of said sensed returned signals, the returned signals corresponding to signals sensed at a loop antenna of a resonator circuit based on detecting variations in electrical characteristics of the resonator circuit as the circuit is driven to generate the excitation signals; wherein the system is configured to implement a signal extraction procedure in which the system is configured to: detect from the sensed return signals a first input signal, the first input signal based on a frequency of the sensed returned signal, detect from the sensed return signals a second input signal, the second input signal based on a sensed amplitude of the sensed returned signal, apply a signal generation procedure comprising generating a plurality of candidate signals, each candidate signal formed from a different linear combination of the first and second input signals, and apply a signal selection procedure for selecting one of the candidate signals, the selection procedure based on pre-defined criteria relating to one of more signal characteristics of the input signals, the criteria configured for isolating a signal pertaining to a particular physiological source in the body, the selected signal forming an output signal. detect from the sensed return signals a first input signal, the first input signal based on a frequency of the sensed returned signal, detect from the sensed return signals a second input signal, the second input signal based on a sensed amplitude of the sensed returned signal, apply a signal generation procedure comprising generating a plurality of candidate signals, each candidate signal formed from a different linear combination of the first and second input signals, and apply a signal selection procedure for selecting one of the candidate signals, the selection procedure based on pre-defined criteria relating to one of more signal characteristics of the input signals, the criteria configured for isolating a signal pertaining to a particular physiological source in the body, the selected signal forming an output signal.