Patent ID: 7405568
Filing Date: 2008-07-29
Classification: G01R

Abstract:
1. A method of digital quadrature lock-in detection for receiving a magnetic resonance signal or electron spin resonance signal by a digital quadrature lock-in detection technique, said method comprising the steps of: digitizing a signal wave; multiplying said digitized signal wave by digitized reference waves of sine and cosine functions to obtain signals of real and imaginary parts which are 90° out of phase; varying the frequencies of the sine and cosine functions according to an observation width; and repeating said multiplying step, wherein high-frequency components are removed from the signal waves, which have been multiplied by the reference waves of said digitized sine and cosine functions, by a low-pass filter, said low-pass filter having a cutoff frequency comparable to or lower than a digital resolution obtained by dividing an observed spectral width by the number of data points.