Method and apparatus for acquiring noise reduced high frequency signals

摘要

A system and method receive the output signal from a capacitance diaphragm gauge (CDG) and generate a noise reduced output signal. An input signal processing circuit receives an input signal from a signal source that drives the CDG. The input signal processing circuit generates a segment of N normalized digital samples of the input signal. An output signal processing circuit receives the output signal from the CDG and generates M segments of N digital samples of the CDG output signal and averages the corresponding samples in the M segments to generate a signal segment of N averaged samples. Each of the N averaged samples is multiplied by a corresponding one of the N normalized samples to generate N products. The N products are averaged to generate an average product, which is multiplied by a constant to generate a system output signal with reduced noise.

主权项

1. A method for reducing the noise in an output signal from a capacitance diaphragm gauge (CDG) that operates in response to a signal source that generates an input signal at a predetermined frequency and amplitude, the method comprising:
amplifying the output signal from the CDG; converting the output signal to N digital samples during a duration of a first predetermined time segment; converting the output signal to N digital samples during at least one additional predetermined time segment, each additional predetermined time segment having a duration corresponding to the duration of the first predetermined time segment; averaging each digital sample in the first predetermined time segment with a corresponding digital sample in each additional predetermined time segment to generate N averaged samples; converting the input signal to N digital samples during a time segment having a duration corresponding to the duration of the first predetermined time segment; normalizing the N digital samples of the input signal with a maximum amplitude of the N digital samples to generate N normalized samples of the input signal; multiplying each of the N normalized samples of the input signal with a corresponding one of the N averaged samples to generate N digital products; averaging the N digital products to generate an average product; and generating an output signal responsive to the average product, the output signal having a value representing a pressure applied to the CDG.