Patent ID: 7446704

Claim:
A method for dual frequency reception, comprising: obtaining a receive signal that contains a first signal with a first center frequency f 1 and a second signal with a second center frequency f 2 ; processing said receive signal to generate an output signal, wherein at least two types of output signals can be generated, wherein a first type of said output signal is proportional to the sum of said first signal frequency-converted to a third center frequency f 3 and said second signal frequency-converted to said third center frequency f 3 , wherein a second type of said output signal is substantially one of said first signal frequency-converted to said third center frequency f 3 , and said second signal frequency-converted to said third center frequency f 3 , and wherein said processing to generate said second type of said output signal comprises multiplying said receive signal with a first sinusoid that has a fourth center frequency f 4 to obtain a first mixed signal, multiplying said receive signal with a second sinusoid to obtain a second mixed signal, wherein said second sinusoid has the same center frequency f 4 as said first sinusoid and differs from said first sinusoid by a first phase shift; phase shifting one of said first and second mixed signals with a second phase shift to obtain a phase-shifted mixed signal; and combining said phase-shifted mixed signal and said other mixed signal to obtain said second type of said output signal, wherein said combining comprises one of addition and subtraction, and wherein a switching between said two signals of said second type is performed by switching between addition and subtraction.