| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and a device easily producing trapezoidal pulse response of a leveling filter, and eliminating the use of a multiplier for evaluating the frequency of digital signal, preferably a gate intensive multiplier. SOLUTION: This frequency evaluation device for evaluating the frequency of a digital input signal x(k) contains a phase detecting device 2 deciding the phaseϕ(k) of the input signal x(k), a differentiator 3 producing the phase differenceϕdiff1(k) between adjacent phase samplesϕ(k) andϕ(k-1), and a filter 4 leveling the phase differenceϕdiff1(k) having the trapezoidal pulse response hM(k). The trapezoidal pulse response hM(k) is produced by laying a first triangle pulse response on top of a second triangle pulse response temporally offset in regard to the first triangle pulse response.
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