Exponential decay time constant measurement using frequency of offset-phase locked loop: system and method专利检索- 测量频率的装置;频谱分析装置专利检索查询-专利查询网

Exponential decay time constant measurement using frequency of offset-phase locked loop: system and method
申请号	EP88304136.0	申请日	1988-05-06	公开(公告)号	EP0294938A3	公开(公告)日	1990-03-28
申请人	Hewlett-Packard Company;			发明人	Dukes, John Noland; Carlsen, William F.,Jr.; Pittaro, Richard J.;
摘要	Oxygen determination based on luminescence quenching of fluorescent dye is effected by using the frequency output of an offset-phase locked loop (15) to calculate the time constant for the exponential decay of fluorescence. An offset phase angle between a periodic stimulus signal used to excite the dye and a response signal based on fluorescence detection is predetermined to optimize signal-to-noise ration for a wide range of time constants. An offset-phase locked loop (15) is used to vary the frequency of a periodic stimulus signal until the predetermined phase relationship is established, and the frequency forms a measure of the decay rate. Where the stimulus and response signals are substantially sinusoidal, the offset phase angle is ideally about 49.3°, although substantially optimal performance is achieved using a more conveniently generated 45°. The 45° angle offset can also be used with a square-wave stimulus signal.
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