短語詞組短語difference -frequency distortion [電子]差頻失真difference of frequency 頻率差relative difference on frequency [測]頻率相對誤差nonlinear difference -frequency 非線性差頻效應(yīng)allowable difference of frequency 周波數(shù)許容偏差Difference -frequency Detection 頻差檢測phase difference high frequency protection 相差高頻保護 返回 difference frequency