An autoranging scanning system and compatible methods of noise reduction

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Abstract
We have designed and constructed an autoranging scanning system to digitize the output of an infrared spectrometer and record it on magnetic tape. This system automatically scales the input signal, whose amplitude may range over ratios of 2000 to 1, to give a signal between 0.25 and 0.90 multiplied by an appropriate factor. Four noise reduction techniques compatible with the autoranging feature have been implemented. Two are a part of the electronic system itself and two utilize the computer in data processing. In particular, smoothing of data by least squares convoluting numbers and co‐addition (addition of corresponding points) of spectral scans over the same region give definite advantages when compared to narrow band amplifier methods in distinguishing and measuring real features with intensities of the order of the noise background of the system. The methods described have general applicability to scanning systems in which the profile of the curve generated is the important measurement.