difference frequency coupling的用法和样例：
- We call those interactions as the "low - frequency coupling processes" of Asian and Australian monsoon circulations.
- Different frequency resolution in human hear.
- Two different frequency, and there is no resonance.
- The heterodyning principle is well known in nonlinear optics as difference frequency generation (DFG).
- The magnitude and phase of the composed balancing vector are adjusted by means of controlling difference frequency of current in inner stator windings.