Patent ID: 6232878
Filing Date: 2001-05-15
Classification: G08B

Abstract:
An apparatus for measuring electrical characteristics of a resonant circuit without physically contacting the resonant circuit comprising:a numerically controlled oscillator for generating an alternating electric signal, the frequency of the alternating electric signal varying in accordance with a numerical frequency control signal;a transmitting antenna connected to the numerically controlled oscillator for establishing an electromagnetic field within a measurement zone;a receiving antenna for sensing disturbances to the electromagnetic field due to a presence of the resonant circuit within the measurement zone;a receiver for receiving signals from the receiving antenna representative of the disturbances to the electromagnetic field and for determining a Q and a center frequency of the resonant circuit; anda clock having a substantially fixed frequency connected to the numerically controlled oscillator for providing a frequency reference to the numerically controlled oscillator, wherein the frequency of the alternating electric signal is restricted to being an integer multiple of an integer sub-multiple of the clock frequency.