| 摘要 |
PROBLEM TO BE SOLVED: To obtain the frequency deviation of a periodic generator by a variable sampling system and monitor the frequency deviation. SOLUTION: An input signal A1 is sampled for a period at every 30 deg. of current frequency B in S1, the input signal A1 is A/D converted in S2, and a frequency deviation C with current frequency B is obtained from the digital signal of the A/D converted input signal A1 and a frequency deviation ΔF with fundamental frequency A is calculated as ΔF=C+B-A in S3. B=A and C=0 hold during linkage, and Δ=C+B-A=0 holds in the frequency deviation ΔF. The above-mentioned calculated C and a fixed value such as 0.5 are compared in S4, a sampling period is changed in S5 when C>0.5 holds, and current frequency B at a time when the above-mentioned ΔF is computed is altered into B'=C+B and processes are repeated from S1 for the altered sampling period in S6. Since C in B' is output as ΔF, ΔF is obtained even in a variable sampling. The error of fixed sampling is not generated because of the variable sampling. |
