Doppler Shift Frequency Reduction Factor
The Doppler effect (or the Doppler shift) is the change in frequency or wavelength of a wave (or other periodic event) for an observer moving relative to its source.
The frequency reduction factor is the speed of sound in the medium plus the relative velocity of the observer divided by the speed of sound in the medium plus the relative velocity of the source.
Formula
![QuantityVariable[Subscript["f", "o"]/Subscript["f", "s"], "Unitless"] == (QuantityVariable["c", "SoundSpeed"] + QuantityVariable[Subscript["v", "o"], "Speed"] - QuantityVariable[Subscript["v", "w"], "Speed"])/(QuantityVariable["c", "SoundSpeed"] + QuantityVariable[Subscript["v", "s"], "Speed"] - QuantityVariable[Subscript["v", "w"], "Speed"])](https://www.wolframcloud.com/objects/resourcesystem/marketplacestorage/resources/5f6/5f612320-1da7-4f8e-8390-d965efa378e4/Webpage/FormulaImage.png "Copy to Clipboard")
| symbol | description | physical quantity |
|---|---|---|
| fo/fs | frequency reduction factor | "Unitless" |
| c | sound speed | "SoundSpeed" |
| vo | speed of the observer toward the source | "Speed" |
| vw | wind speed | "Speed" |
| vs | speed of the source away from the observer | "Speed" |