Method of detecting a predetermined sequence in an RF signal using a combination of correlation and FFT
First Claim
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1. A method of recognizing a predetermined sequence within a radio frequency signal received on a Doppler faded radio frequency channel, such method comprising:
- correlating a reference sequence with a sequence of elements of the radio frequency signal received on the Doppler faded radio frequency channel; and
detecting the predetermined sequence within the received signal when an equivalent power level of subsequences of the correlated sequence exceeds a predetermined equivalent power spectrum threshold.
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Abstract
A method and apparatus are provided for recognizing a predetermined sequence within a radio frequency signal received on a Doppler faded radio frequency channel. The method includes the steps of correlating a reference sequence with a sequence of elements of the radio frequency signal received on the Doppler faded radio frequency channel and detecting the predetermined sequence within the received signal when a cumulative power level of subsequences of the correlated sequence exceeds a predetermined power level threshold.
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Citations
26 Claims
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1. A method of recognizing a predetermined sequence within a radio frequency signal received on a Doppler faded radio frequency channel, such method comprising:
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correlating a reference sequence with a sequence of elements of the radio frequency signal received on the Doppler faded radio frequency channel; and
detecting the predetermined sequence within the received signal when an equivalent power level of subsequences of the correlated sequence exceeds a predetermined equivalent power spectrum threshold. - View Dependent Claims (2, 7, 8, 9)
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- 3. The method of recognizing the predetermined sequence as in claim 3 further comprising determining a corresponding frequency domain representation of each correlated subsequence.
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10. An apparatus for recognizing a predetermined sequence within a radio frequency signal received on a Doppler faded radio frequency channel, apparatus comprising:
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means for correlating a reference sequence with a sequence of elements of the radio frequency signal received on the Doppler faded radio frequency channel;
means for detecting the predetermined sequence within the received signal when an equivalent power spectrum of subsequences of the correlated sequence exceeds a predetermined threshold. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. An apparatus for recognizing a predetermined sequence within a radio frequency signal received on a Doppler faded radio frequency channel, the apparatus comprising:
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a plurality of multipliers that provides a correlated sequence by correlating elements of a reference sequence with respective elements of the radio frequency signal received on the Doppler faded radio frequency channel; and
a comparator that detects the predetermined sequence within the received signal when a cumulative level of frequency domain representations of subsets of the correlated sequence exceeds a predetermined power threshold. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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26. A method of recognizing a predetermined sequence within a radio frequency signal received on a Doppler faded radio frequency channel, such method comprising:
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dividing a reference sequence into a plurality of subsequences;
correlating elements of the received signal on the Doppler faded radio frequency channel with respective elements of the respective subsequences of the reference sequence;
determining a corresponding frequency domain representation of each correlated subsequence of the plurality of subsequences;
summing the determined frequency domain representations of the subsequences; and
detecting the predetermined sequence in the received signal when a level of the summed frequency domain representations exceeds a threshold.
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Specification