| 摘要 |
1. A system responsive to a composite signal including first signals in the presence of second signals and detecting the presence of said first signals with a selected threshold level ratio of signal voltage to noise voltage comprising means for integrating the composite signal over selected intervals of time, means for comparing a selectable threshold level with the integrated signals, means for storing data to provide said threshold level, counting means responsive to the integrated signals exceeding the threshold level to accumulate a count thereof, constant selector means responsive to the count of said counting means to establish a proportion of the value of said stored data for changing said threshold level to maintain the selected threshold level ratio, and means responsive to said constant selector means for correcting the stored data after a selected number of said intervals of time.
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