A method for detecting an object, comprising: providing a pulsed signal to a charging circuit (1302, 306), wherein each pulse in the pulsed signal comprises a plurality of cycles of a clock signal that has a frequency greater or less than a nominal resonant frequency of the charging circuit; characterised by: detecting a change in resonance of the charging circuit; the method is characterised by further comprising: wherein the change in resonance of the charging circuit includes a decrease in Q factor of the charging circuit, based on a difference in response of the charging circuit to a first pulse in the pulsed signal with respect to a corresponding response of the charging circuit to a second pulse previously transmitted in the pulsed signal; and determining that a chargeable device has been placed in proximity to a coil of the charging circuit based on the difference in response, wherein detecting the change in resonance of the charging circuit includes: receiving a measurement signal representative of Q factor of the charging circuit; filtering the measurement signal to obtain a filtered version of the measurement signal that changes at a slower rate than the measurement signal; and generating an indication of change in resonance in a detection signal that switches when a difference between the measurement signal and the filtered version of the measurement signal exceeds a threshold level. providing a pulsed signal to a charging circuit (1302, 306), wherein each pulse in the pulsed signal comprises a plurality of cycles of a clock signal that has a frequency greater or less than a nominal resonant frequency of the charging circuit; characterised by: detecting a change in resonance of the charging circuit; the method is characterised by further comprising: wherein the change in resonance of the charging circuit includes a decrease in Q factor of the charging circuit, based on a difference in response of the charging circuit to a first pulse in the pulsed signal with respect to a corresponding response of the charging circuit to a second pulse previously transmitted in the pulsed signal; and determining that a chargeable device has been placed in proximity to a coil of the charging circuit based on the difference in response, wherein detecting the change in resonance of the charging circuit includes: receiving a measurement signal representative of Q factor of the charging circuit; filtering the measurement signal to obtain a filtered version of the measurement signal that changes at a slower rate than the measurement signal; and generating an indication of change in resonance in a detection signal that switches when a difference between the measurement signal and the filtered version of the measurement signal exceeds a threshold level. detecting a change in resonance of the charging circuit; the method is characterised by further comprising: wherein the change in resonance of the charging circuit includes a decrease in Q factor of the charging circuit, based on a difference in response of the charging circuit to a first pulse in the pulsed signal with respect to a corresponding response of the charging circuit to a second pulse previously transmitted in the pulsed signal; and determining that a chargeable device has been placed in proximity to a coil of the charging circuit based on the difference in response, wherein detecting the change in resonance of the charging circuit includes: receiving a measurement signal representative of Q factor of the charging circuit; filtering the measurement signal to obtain a filtered version of the measurement signal that changes at a slower rate than the measurement signal; and generating an indication of change in resonance in a detection signal that switches when a difference between the measurement signal and the filtered version of the measurement signal exceeds a threshold level. receiving a measurement signal representative of Q factor of the charging circuit; filtering the measurement signal to obtain a filtered version of the measurement signal that changes at a slower rate than the measurement signal; and generating an indication of change in resonance in a detection signal that switches when a difference between the measurement signal and the filtered version of the measurement signal exceeds a threshold level.