Patent ID: 6011401
Filing Date: 2000-01-04
Classification: G01R

Abstract:
A method for characterizing a unit under test, comprising the steps of:stimulating a unit under test to output a periodic electrical signal; andprocessing the periodic electrical signal to obtain an indication of a magnitude of a desired periodic signal component of the electrical signal, the step of processing including the steps of:sampling the periodic electrical signal to generate, for each sample, a corresponding digital equivalent value of the periodic electrical signal;specifying a reference period setting value as a function of a sampling frequency and a period of the periodic electrical signal;generating a digital equivalent of a periodic reference signal having a specified period and phase;multiplying the digital equivalent of the periodic electrical signal times the digital equivalent of the periodic reference signal to generate a product signal;low pass filtering the product signal; andadjusting the phase of the digital equivalent of the periodic reference signal in accordance with the low pass filtered product signal and the specified reference period setting value so as to maximize a magnitude of the desired periodic signal component of the periodic electrical signal.