Patent ID: 7552810
Filing Date: 2009-06-30
Classification: G07D

Abstract:
1. A sensor assembly for determining an authenticity of coins, comprising: an excitation device configured to receive an excitation signal having multiple fixed excitation frequency components and to produce a magnetic field over a coin path, said magnetic field coupling to said coins to induce eddy currents within said coin; a reception device configured to receive first and second reception signals corresponding to said eddy currents, the voltage difference of said first and second reception signals being termed a detection signal, said detection signal having the same multiple fixed frequency components as said excitation signal; and first logic circuitry coupled to analog-to-digital (ADC) circuitry, said ADC circuitry coupled to said reception device, said first logic circuitry configured to produce a coin signature representing at least one of amplitudes and phase angles of said multiple fixed frequency components of said detection signal by application of a Fast Fourier Transform (FFT) to digital samples representing said detection signal, wherein said ADC circuitry is configured to sample said detection signal at a sampling frequency greater than a highest frequency of said multiple fixed excitation frequency components to produce digital samples representative of said detection signal.