AUTOMATIC BACKGROUND LEVEL COMPENSATION

专利名称：AUTOMATIC BACKGROUND LEVEL

COMPENSATION

发明人：ROLAND WERNER GUBISCH申请号：US3525869D申请日：19680726公开号：US3525869A公开日：19700825

摘要：1,214,153. Selective signalling. NATIONAL RESEARCH DEVELOPMENT CORP. 31July, 1968 [31 July, 1967], No. 35130/67. Heading G4H. [Also in Division G1] In a circuit forobtaining a signal free of baseline drift from a signal V, Fig. 3 (e.g. from a chromatogram),having base-line drift, the signal V is differentiated and when the derivative V 1 exceeds apre-set threshold level found by experiment to be just larger the maximum rate of base-line drift, a signal V 3 is produced which causes the input signal V to be inverted andclamped, V 4 , at its value at that instant, which clamped signal V 4 is added to the inputsignal V to produce a signal V 5 substantially free of base-line drift. As described, thederivative signal V 1 , produced by a circuit 21, Fig. 2, is rectified, 22, before being appliedto a threshold circuit 23 set just higher than the maximum rate of base-line drift, and theoutput signal V 3 is used to control a circuit which inverts and clamps the input signal V,the output of which, V 4 , is added, 25, to the input signal V to produce the required signalV 5 . The trough in the rectified signal V 2 identifies the peak of the input signal and isparticularly useful when two adjacent peaks occur without an intermediate return to thebase-line. So that such overlapping peaks may be detected, the output signal V 5 isapplied to a threshold circuit 26 the output V 6 from which only falls to a low level when

the signal V 5 falls below a threshold level, and this signal V 6 is also applied to thethreshold circuit 23 so that its output, having gone high because the derivative signal V 1has exceeded the maximum rate of base-line drift, remains high until the signal V 5 fallsto below its threshold. In a modification (Fig. 5, not shown) a second derivative is used inplace of the first derivative. The Specification also outlines a system for digitizing anypeaks in the output signal V 5 , using the rectified signal V 2 to identify them, and forintegrating the signal V 5 for the duration of signal V 3 to find the area under each peakor multiple peak.

申请人：NATIONAL RESEARCH DEV. CORP.

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