Patent ID: 7519134

Claim:
A method of obtaining a phase offset for a received analog signal relative to a reference cosine wave by obtaining the arctangent of the quotient of a Quadrature component divided by an In-Phase component; the method comprising: multiplying a series of digitized values of the received analog signal from a remote device against a series of digitized values of the reference cosine wave of a particular frequency using an In-Phase multiplier and accumulating the result as the In-Phase component using an In-Phase accumulator; multiplying a series of digitized values of the received analog signal against a series of digitized values of a reference sine wave of a particular frequency using a Quadrature multiplier and accumulating the result as the Quadrature component using a Quadrature accumulator; determining the phase offset for the received analog signal from the reference cosine wave based upon the accumulated In-Phase component and the accumulated Quadrature component; and comparing the phase offset of the received analog signal with a previously determined phase offset to decode at least one bit of information conveyed by phase shift keying, wherein the process of: determining the phase offset for the received analog signal relative to the reference cosine wave based upon the accumulated In-Phase component and the accumulated Quadrature component includes: comparing an absolute value of the accumulated In-Phase component in the In-Phase accumulator and an absolute value of the accumulated Quadrature component in the Quadrature accumulator with a minimum threshold for the absolute value of each of the accumulators to determine whether a burst is to be declared a valid burst; and scaling the accumulated In-Phase component and the accumulated Quadrature component before using the scaled components in a look-up table by executing IF a sign bit of the In-Phase component equals a most significant bit of the magnitude of the In-Phase component AND a sign bit of the Quadrature component equals a most significant bit of the magnitude of the Quadrature component THEN shifting the bits of the magnitude of the In-Phase component toward the most significant bit AND shifting the bits in the magnitude of the Quadrature component towards the most significant bit ELSE using the current magnitudes and sign bits to determine the phase offset for the received analog signal relative to the reference cosine wave.