Sure!
f ' = f (v +- Vd) / (v -+ Vs)
+ = detector moves toward source
- = detector moves away from source
- = source moves toward detector
+ = source moves away from detector
How to Learn this Concept with Less Memorization!
The observed frequency f ' will increase if the 2 things (detector/source) move toward each other.
The observed frequency f ' will decrease if they (detector/source) move apart.
If the source moves toward the detector, observed frequency should INCREASE.
For this to happen, you must use v - Vs in the denominator of the above equation.
By decreasing the denominator you increase the observed frequency.
Make sense?