Non-Orthogonal Demodulation for Narrow-Band Touch Sensing
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Solution Overview
Problem
Existing touch systems face challenges in reducing the signal band when transmitting multiple non-orthogonal signals to multiple electrodes, which complicates the design and increases bandwidth requirements.
Innovation Solution
A non-orthogonal demodulation module that includes a mixing-and-integrating unit and a decoding unit, which generates in-phase and quadrature components and computes energies for non-orthogonal transmitted signals using a decoding matrix, allowing for demodulation and determination of touch event coordinates with a smaller signal band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If orthogonal signals with different frequencies are transmitted through two transmitting electrodes, then signals can be differentiated in the demodulation process, but the bandwidth occupied by the signals (signal band) becomes large
Solution Approach 1:
The patent changes the fundamental parameter of signal orthogonality from frequency-based orthogonality to non-orthogonal signaling. By transmitting non-orthogonal signals and using a decoding matrix to compute energies, the system achieves signal differentiation without requiring large frequency gaps, thereby reducing the occupied signal band while maintaining the ability to distinguish between different transmitted signals
2Measurement precision
If multiple orthogonal signals are transmitted, then signals at different frequencies can be differentiated, but the design of the touch system becomes complicated due to the need to guarantee no interference with the signal band
Solution Approach 1:
The patent fundamentally changes the signaling approach from orthogonal frequency-division multiplexing to non-orthogonal signaling with matrix-based demodulation. This parameter change eliminates the need for complex frequency gap management and interference guarantee mechanisms, simplifying the overall touch system design while maintaining signal differentiation capability through the decoding matrix computation
Data Source
AI summary
The present application provides a non-orthogonal demodulation module, receiving a received signal and the received signal is related to a summation of a plurality of transmitted signals. The plurality of transmitted signals are corresponding to a plurality of frequencies, and the plurality of transmitted signals are not orthogonal to each other. The non-orthogonal demodulation module comprises a mixing-and-integrating unit, configured to perform mixing operations and integrating operations on the received signal respectively at the plurality of frequencies, to generate a plurality of in-phase components and a plurality of quadrature components corresponding to the plurality of frequencies; and a decoding unit, configured to generate at least a decoding matrix, and compute a plurality of energies corresponding to the plurality of transmitted signals according to the at least a decoding matrix, the plurality of in-phase components and the plurality of quadrature components.