| 摘要 |
PURPOSE: To reduce errors in a peak detection caused as a result of signal amplitude change by providing a tracking threshold circuit as a means for calculating and determining a threshold value corresponding to a selection point. CONSTITUTION: A single tracking threshold circuit 14a includes multiplier blocks 42, 44, an adder block 46, and a register block 48. A selection point in a signal is designated, and then, a threshold value corresponding to the selection point is calculated and determined according to the following formula; mn=t0.a×n+t1.m(n-1). Wherein, n is the time of the point identifier, mn is a threshold value at the time n, each of t0 and t1 is positive fixed constant, a×n is an absolute value of an input signal, an m(n-1) is a threshold value corresponding to a previous point. Thus, the threshold value is adjusted corresponding to variations of the amplitude of the input signal. Next, it is judged whether or not the selection point is within a selected range of the threshold value, and in some cases, it is judged whether or not the selected point represents a peak, and the digital data in the signal are detected.
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