Patent ID: 7106064

Claim:
A method for quadrature detection comprising: setting a reference frequency to be ω 0 ; using an analog-to-digital converting device to convert an analog input signal into a digital signal f 1 (t); using a first delaying device to delay the signal f 1 (t) by a sampling time τ to form a signal f 2 (t); using a second delaying device to delay a reference signal sin ω 0 t by the sampling time τ to form a delay reference signal sin ω 0 (t−τ); using a third delaying device to delay a reference signal cos ω 0 t by the sampling time τ to form a delay reference signal cos w 0 (t−τ); using a first multiplying device to multiply the signal f 2 (t) by the reference signal sin ω 0 t; using a second multiplying device to multiply the signal f 1 (t) by the delayed reference signal sin ω 0 (t−τ); using a third multiplying device to multiply the signal f 2 (t) by the reference signal cos ω 0 t; using a fourth multiplying device to multiply the signal f 1 (t) by the delayed reference signal cos ω 0 (t−τ); using a first subtracting device to determine a difference between the output signal of said first multiplying device and the output signal of said second multiplying device; using a second subtracting device to determine a difference between the output signal of said third multiplying device and the output signal of said fourth multiplying device; using a fifth multiplying device to multiply the output signal of said first subtracting device by a predetermined coefficient; and using a sixth multiplying device to multiply the output signal of said second subtracting device by a predetermined coefficient; and wherein the I- and Q-components in quadrature detection are determined by: I={f 2( t )*sin ω 0 t−f 1( t )*sin ω 0 ( t−τ)}/sin ω 0 τ Q={f 2( t )*cos ω 0 t−f 1( t )*cos ω 0 ( t−τ)}/sin ω 0 τ.