| 摘要 |
Methods, systems and devices are described for detecting noise in a sensor that produces an output in response to a stimulus applied at or near a sensing region. A carrier signal is applied to the sensing region at two or more frequencies to produce an output at each frequency that is demodulated and filtered by a demodulation filter. The various frequencies applied to the carrier signal are selected such that a frequency difference is less than the demodulation filter bandwidth. At least some of the stimulus effects are removed from the outputs produced by the various carrier frequencies to produce two or more filtered outputs. The filtered outputs are then processed to detect noise contained therein. If noise contained in one or more of the filtered outputs reaches an unacceptable level, the carrier signal is shifted to a new sensing frequency for subsequent operation. |
