Andros Incorporated

William L Elder

Irvin G Burough

Kevin G Williams

A method and apparatus are described for developing a series of synchronizing pulses related to a series of input pulses of variable amplitude above a background noise level. A first signal is developed proportional to the derivative of the rising or falling portion (or both) of each of the input pulses. A second signal is developed related to the first signal and having a decay characteristic such that the amplitude of the second signal becomes equal to the amplitude of the first signal at a threshold point which is proportional to the amplitude of the first signal. The synchronizing pulses are developed related to respective threshold points whereby the phase of the synchronizing signal is not dependent on the amplitude of the input pulses.

Synchronizing method and apparatus

A gas analyzer of the non-dispersive infrared type is described. An infrared beam passing through a sample cell containing a gas mixture to be analyzed is detected. The resulting electrical signals are processed to produce an output indicating the concentration of the constituents of the gas mixture in the sample cell. The gas analyzer includes provision for temperature stabilizing both a rotary filter wheel and the detector, and for compensating the output of the signal processor for variation in the absorption characteristics of gas with temperature. The emissivity characteristic of the infrared energy source substantially compensates for wavelength dependence of the detector response. The motor drive for the rotary filter wheel is servo-controlled in accordance with synchronizing pulses developed directly from the detector output.

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Richmond, CA, United States of America

William L Elder