您要查找的是不是：
- 差频APLLdifference frequency APLL
- 晶体分频APLLCrystal frequency-division APLL
- 差频耦合difference frequency coupling
- 差频过程different frequency generation
- 差频控制slip frequency control
- 差分difference
- 标准差root-mean-square error (RMS error)
- 频数frequence
- 差一点by a finger's breadth
- 差的inferiors
- 主频dominant frequency
- 倍频frequency doubling
- 不差little short of
- 载频carrier frequency
- 差旅travel
- 变差variation of rate
- 频点frequency point
- 越来越差worse and worse
- 差速器compensating gear
- 残差residual error
