Patent ID: 6931082

Claim:
A method of operating a digital phase locked loop utilized for amplitude demodulation of a modulated signal, the method comprising: (a) receiving an input digital sampled signal representing said modulated signal and divided into a plurality of frames having substantially equal number of samples, wherein a frequency of said input digital signal for each frame ω k of said plurality of frames having a frame number k is represented as a sum of a nominal frequency component ω 0 , which is a common value to said plurality of frames, and a frequency component Δω k , which is an increment depending on the frame number k and having an absolute value substantially smaller than a reversed value of a frame size N multiplied by a sampling time increment Δt; (b) calculating data indicative of values of analytical functions including trigonometric functions depending at least on said nominal frequency component ω 0 for each frame from said plurality of frames; (c) storing the data obtained in step (b); (d) generating an output signal representing sine I and cosine Q branches of said digital phase locked loop by utilizing the data of the analytical functions stored in step (c), values of the component Δω k and the increment Δt for substantially all frames of said plurality of frames; and (e) computing an envelope of said modulated signal and generating a demodulated signal.