smart board mounting brackets wall.?Accuracy and linearity are directly proportional to the signal-to-noise ratio of the system. Since the noise floor does not change with the input, signal degradation can have a large impact on the signal-to-noise ratio. The signal level of a capacitive touch screen is basically determined by the coverage area of ??the touch input. That is to say, the signal strength of a 2 mm passive stylus is 25 times smaller than that of a typical 10 mm finger touch. This gap in signal strength creates many problems for touch engineers. Even with large touch signals, the firmware must be able to detect smaller stylus signals, which often requires different sensor scan modes, and both noise immunity and refresh rate are affected. In addition, passive stylus is best suited for use with larger touchpads, but large touchpads have low refresh rates or larger pitch sensors, both of which affect system performance.