Receiver having an adaptive filter and method of optimizing the filter
First Claim
1. A method of dynamically adapting a digital filter characteristic, the method comprising:
- storing a frequency domain representation of the filter characteristic;
analyzing an input signal to determine a required filter characteristic;
adapting the frequency domain representation to match the required filter characteristic;
transforming the adapted frequency domain representation to a time domain so as to obtain filter coefficients relating to the required filter characteristic;
applying the filter coefficients to effect adaptation of the filter characteristic;
wherein adapting the frequency domain representation to match the required filter characteristic includes altering a frequency of the frequency domain representation; and
wherein altering the frequency of the frequency domain representation comprises shifting samples of the frequency domain representation to a higher or lower frequency.
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Abstract
A receiver comprises an adaptive filter having an input for a digitized input signal, means for storing a pre-designed filter characteristic, means for analyzing a digital. representation of the input signal to determine a desired position of the filter characteristic to match the system requirements, and means for adapting the stored pre-designed filter characteristic in the frequency domain and/or the time domain to match the system requirements and for transforming the adapted filter characteristic to the time domain to update coefficients for the adaptive filter and for loading updated coefficients into adaptive filter. The updating of the coefficients may be done periodically. The adaptation may be one or more of adjusting bandwidth, frequency shift and, in the case of a bandpass characteristic, superimposing characteristics.
36 Citations
18 Claims
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1. A method of dynamically adapting a digital filter characteristic, the method comprising:
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storing a frequency domain representation of the filter characteristic; analyzing an input signal to determine a required filter characteristic; adapting the frequency domain representation to match the required filter characteristic; transforming the adapted frequency domain representation to a time domain so as to obtain filter coefficients relating to the required filter characteristic; applying the filter coefficients to effect adaptation of the filter characteristic; wherein adapting the frequency domain representation to match the required filter characteristic includes altering a frequency of the frequency domain representation; and wherein altering the frequency of the frequency domain representation comprises shifting samples of the frequency domain representation to a higher or lower frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A receiver comprising:
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a memory device configured to store a frequency domain representation of a filter characteristic; and a processor configured to analyze an input signal to determine a required filter characteristic, to adapt the frequency domain representation to match the required filter characteristic, to transform the adapted frequency domain representation to a time domain so as to obtain filter coefficients relating to the required filter characteristic, and to apply the filter coefficients to effect adaptation of the filter characteristic of an adaptive filter in the receiver; wherein the processor is further configured to adapt the frequency domain representation to match the required filter characteristic by altering a frequency of the frequency domain representation; and wherein the processor is further configured to alter the frequency of the frequency domain representation by shifting samples of the frequency domain representation to a higher or lower frequency. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method of dynamically adapting a digital filter characteristic, the method comprising:
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storing a frequency domain representation of the filter characteristic; analyzing an input signal to determine a required filter characteristic; adapting the frequency domain representation to match the required filter characteristic; transforming the adapted frequency domain representation to a time domain so as to obtain filter coefficients relating to the required filter characteristic; and applying the filter coefficients to effect adaptation of the filter characteristic; wherein the required filter characteristic includes a bandstop filter characteristic; wherein adapting the frequency domain representation includes shifting the bandstop filter characteristic to block an interfering signal; and wherein when the interfering signal is a narrowband frequency hopping signal, a hopping sequence is prestored to facilitate the adapting of the frequency domain representation.
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18. A receiver comprising:
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a memory device configured to store a frequency domain representation of a filter characteristic; and a processor configured to analyze an input signal to determine a required filter characteristic, to adapt the frequency domain representation to match the required filter characteristic, to transform the adapted frequency domain representation to a time domain so as to obtain filter coefficients relating to the required filter characteristic, and to apply the filter coefficients to effect adaptation of the filter characteristic of an adaptive filter in the receiver; wherein the required filter characteristic includes a bandstop filter characteristic; wherein the processor is further configured to adapt the frequency domain representation by shifting the bandstop filter characteristic to block an interfering signal; and wherein when the interfering signal is a narrowband frequency hopping signal, a hopping sequence is prestored to facilitate the adapting of the frequency domain representation.
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Specification