Patent ID: 7639821
Filing Date: 2009-12-29
Classification: H03D,H04B

Abstract:
1. A method operable to detect an amplitude modulated (AM) signal, comprising: receiving a radio frequency (RF) signal containing the AM signal modulated about a carrier frequency (f downconverting the RF signal to baseband with a first local oscillator having a frequency f producing an in-phase (I-channel) signal and a quadrature (Q-channel) signal; forming a frequency information output from the I-channel signal having I-channel signal frequency information: sending the frequency information output to a second and a third local oscillator; forming a phase information output from the I-channel signal having I-channel signal phase information: sending the phase information output to the second and third local oscillator: determining a relationship between f forming an output from the second oscillator based on the frequency and phase information output; forming an output from the third oscillator based on the frequency and phase information output; mixing the output from the second oscillator with the I-channel signal to form a rotated I-channel signal; mixing the output from the third oscillator with the Q-channel signal to form a rotated Q-channel signal; and producing a demodulated AM signal by combining the rotated I-channel and Q-channel signals based on the phase difference.