Patent ID: 7522556

Claim:
A method for a repeater to identify a desired narrow band signal within a broadband RF signal, the method comprising steps of: isolating a candidate narrow band signal within the broadband signal; detecting a predetermined signal element within the narrow band signal; analyzing the detected element to identify the signal type of the isolated narrow band signal; wherein the step of detecting the predetermined signal element within the narrow band signal in the repeater comprises steps of: digitizing the narrow band signal to generate a corresponding n-bit digital signal; and digitally processing the digital signal; wherein predetermined signal element comprises a repeating feature of the narrow band signal, and wherein the step of processing the digital signal comprises a step of autocorrelating the digital signal with at least one delayed version of itself; wherein the step of autocorrelating the digital signal comprises cascaded autocorrelation; and wherein the cascaded autocorrelation comprises steps of: in a first stage, computing a product of the digital signal and a delayed version of the digital signal which has been subject to a delay corresponding to a one frame, wherein a length of the frame is based on an expected repetition rate of repeating features of the narrow band signal; and in each successive stage, computing a product of the product computed by the previous stage and a further delayed version of the digital signal which has been subject to an additional delay corresponding to a one frame.