CambridgeIC’s CTU chips generate a drive waveform that is used to inductively power the resonator inside a target, and detection circuitry to measure the levels of return signals from which coupling factors are determined.

CTU chips use a pulse echo approach, where the drive waveform is applied to power the resonator and is then removed for detection. This approach minimises errors due to direct coupling from the excitation to sensor coils, including any connecting leads that may be used. The sequence of events is illustrated below.
pulse echo measurement sequence
CTU chips detect resonator frequency, and they continuously adjust their operating frequency to match the resonator for optimum signal level.