Patent ID: 6433531
Filing Date: 2002-08-13
Classification: G01R

Abstract:
A method for measuring the frequency of an input signal occurring in an input band comprised of;a folding down conversion step, wherein the entire input band is folded into a common baseband by mixing the said input band with the harmonics of an LO, and wherein two folding down conversions are performed, a reference down conversion employing the LO harmonics directly and a delayed down conversion employing the LO harmonics after they are delayed in time and wherein each down conversion is a quadrature down conversion, producing two conversion products in quadrature with each another and followed by a phase encoding means configured to provide a digital representation of the phase angle represented by the said quadrature conversion products, and a folding harmonic determination step, wherein the frequency of the LO harmonic, effective in folding the signal into the base band is determined by dividing the difference between the phases encoded from the reference and delayed down conversions and dividing that difference by the product of the product of the said delay and the fundamental frequency of the said folding LO and a baseband frequency measuring step, wherein the frequency of the signal occurring in one of the baseband channels is determined by constructing the rate of change of the measured phase and followed by a numerical combining step, in which the frequency of the LO harmonic effective in folding the signal into the baseband is combined with the measured baseband frequency to form the input signal frequency.