Signal detection in frequency division modulated touch systems
Abstract:
A frequency division modulated touch detector having row and column conductors arranged such that the path of the row conductors cross the paths of the column conductors, and signal emitters associated with each row, the emitters being adapted to transmit a signal having a specific frequency and initial phase on each row conductor, and a receiver associated with each column to receive signals present on the column conductor. A signal processor is adapted to determine an in-phase and a quadrature component for each of the transmitted signal found in the received signals, and to project a vector representing the transmitted frequencies at their initial phase onto the respective in-phase and quadrature component to determine a measurement for each transmitted signal on each column, and create a heat map reflecting those measurements, the heat map thus containing data reflective of touch.
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