Signal recognition in an on-frequency repeater
First Claim
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1. 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.
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Abstract
An intelligent gain controller (IGC) for an on-frequency repeater implements a method for identifying a desired narrow band signal within a broadband RF signal. Thus, a candidate narrow band signal within the broadband signal is isolated. The isolated narrow band signal is then processed to detect repeating features of the narrow band signal. The detected repeating features are then analyzed to identify the signal type of the isolated narrow band signal. System gain of the in-frequency repeater can be controlled based on the power level of the identified narrow band signal.
28 Citations
10 Claims
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1. A method for a repeater to identify a desired narrow band signal within a broadband RF signal, the method comprising steps of:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification