Impulse response filtering of code division multiplexed signals in a capacitive sensing device
First Claim
1. A method for digital signal processing (DSP), comprising:
- receiving at least one code division multiplexed (CDM) signal transmitted from different transmitters using different codes over a plurality of signal bursts, wherein a length of each of the different codes is equal to or greater than a number of the different transmitters; and
filtering the at least one CDM signal using an impulse response filter, wherein the filtering comprises;
accumulating the at least one CDM signal over the plurality of signal bursts to obtain measurements of the at least one CDM signal; and
for the measurements of the at least one CDM signal, applying different filter weights over a number of the plurality of signal bursts that is greater than the length of the different codes.
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Accused Products
Abstract
An example method of capacitive sensing includes: receiving at least one code division multiplexed (CDM) signal transmitted from different transmitters using different codes over a plurality of signal bursts, wherein a length of each of the different codes is equal to or greater than a number of the different transmitters; filtering the at least one CDM signal using an impulse response filter, wherein the filtering comprises: accumulating the at least one CDM signal over the plurality of signal bursts to obtain measurements of the at least one CDM signal; and for the measurements of the at least one CDM signal, applying different filter weights to the resulting signals over a number of the plurality of signal bursts that is greater than the length of the different codes.
13 Citations
20 Claims
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1. A method for digital signal processing (DSP), comprising:
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receiving at least one code division multiplexed (CDM) signal transmitted from different transmitters using different codes over a plurality of signal bursts, wherein a length of each of the different codes is equal to or greater than a number of the different transmitters; and filtering the at least one CDM signal using an impulse response filter, wherein the filtering comprises; accumulating the at least one CDM signal over the plurality of signal bursts to obtain measurements of the at least one CDM signal; and for the measurements of the at least one CDM signal, applying different filter weights over a number of the plurality of signal bursts that is greater than the length of the different codes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A processing system for an input device, comprising:
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sensor circuitry configured to; receive at least one code division multiplexed (CDM) signal transmitted from different transmitter electrodes using different codes over a plurality of signal bursts, wherein a length of each of the different codes is equal to or greater than a number of the different transmitters; and a processing module, coupled to the sensor circuitry, configured to; filter the at least one CDM signal using an impulse response filter, wherein the filtering comprises; accumulating the at least one CDM signal over the plurality of signal bursts to obtain measurements of the at least one CDM signal; and for the measurements of the at least one CDM signal, applying different filter weights over a number of the plurality of signal bursts that is greater than the length of the different codes. - View Dependent Claims (10, 11, 12, 13, 14)
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15. An input device, comprising:
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a plurality of sensor electrodes comprising a plurality of transmitter electrodes and a plurality of receiver electrodes, wherein the plurality of receiver electrodes are configured to receive at least one code division multiplexed (CDM) signal transmitted from different transmitter electrodes of the plurality of transmitter electrodes using different codes over a plurality of signal bursts, and wherein a length of each of the different codes is equal to or greater than a number of the different transmitter electrodes; and a processing system coupled to the plurality of sensor electrodes, the processing system configured to; filter the at least one CDM signal using an impulse response filter, wherein the filtering comprises; accumulating the at least one CDM signal over the plurality of signal bursts to obtain measurements of the at least one CDM signal; and for the measurements of the at least one CDM signal, applying different filter weights over a number of the plurality of signal bursts that is greater than the length of the different codes. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification