Adaptive removal of disturbance in TDMA acoustic peripheral devices
First Claim
1. A method for removing a disturbance signal from an input signal that is induced by a transmitter that transmits bursts of energy using a frequency hopping technique, comprising the steps of:
- providing a plurality of allocatable buffers each for storing information concerning a particular frequency used during the frequency hopping;
computing a normalized summed square difference for each buffer to yield normalized residuals Rn;
comparing each normalized residual Rn against an adaptive threshold; and
when all Rn are larger than the adaptive threshold, allocating a new buffer;
else, updating a buffer where Rn is found to be the smallest and less than the adaptive threshold; and
incrementing an associated buffer counter.
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Abstract
Methods and apparatus are disclosed for suppressing transmitter burst mode disturbances in an audio band. The method and apparatus detects those signal frames wherein the input signal contains signal energy comprised substantially of only the disturbance signal; characterizes the disturbance signal in the detected signal frames to obtain a disturbance signal correction; and compensates the input signal, only for those signal frames where a transmission burst exists, using the obtained disturbance signal correction so as to remove the disturbance signal from those signal frames that contain voice, and also from certain signal frames that do not contain voice. Frequency hopping embodiments of disturbance removing circuitry are also disclosed.
39 Citations
3 Claims
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1. A method for removing a disturbance signal from an input signal that is induced by a transmitter that transmits bursts of energy using a frequency hopping technique, comprising the steps of:
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providing a plurality of allocatable buffers each for storing information concerning a particular frequency used during the frequency hopping;
computing a normalized summed square difference for each buffer to yield normalized residuals Rn;
comparing each normalized residual Rn against an adaptive threshold; and
when all Rn are larger than the adaptive threshold, allocating a new buffer;
else, updating a buffer where Rn is found to be the smallest and less than the adaptive threshold; and
incrementing an associated buffer counter. - View Dependent Claims (2)
periodically testing the buffer counters, and if a buffer counter is equal to or less than a threshold value, freeing the associated buffer for use.
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3. A method for removing a disturbance signal from an input signal that is induced by a transmitter that transmits bursts of energy using a frequency hopping technique, comprising the steps of:
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providing a plurality of allocatable buffers each for storing information concerning a particular frequency used during the frequency hopping;
computing a normalized summed square difference for each buffer to yield normalized residuals Rn;
comparing each normalized residual Rn against an adaptive threshold; and
when all Rn are larger than the adaptive threshold, allocating a new buffer;
else, updating a buffer where Rn is found to be the smallest and less than the adaptive threshold; and
incrementing an associated buffer counter, wherein the adaptive threshold has a value that is determined using a sliding median filter that is updated on every occurrence of a residual Rn being found to be smaller than the adaptive threshold.
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Specification
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Current AssigneeNokia Mobile Phones UK Limited (Nokia Corporation)
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Original AssigneeNokia Mobile Phones UK Limited (Nokia Corporation)
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InventorsKuhn, Ingo, Alapuranen, Pertti, Paksuniemi, Janne
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Primary Examiner(s)Marcelo, Melvin
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Assistant Examiner(s)KWOH, JASPER C
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Application NumberUS08/991,763Time in Patent Office1,323 DaysField of Search370/336, 370/345, 370/522, 370/343, 375/229, 375/332, 375/285, 375/340, 375/143, 375/152, 375/343, 375/131, 375/135, 375/132US Class Current370/343CPC Class CodesH04B 15/02 Reducing interference from ...H04B 2215/061 Reduction of burst noise, e...
