| Maybe here's a better analogy: Sound. If that depended on the source
| speed, the sound wall wouldn't exist.
|
| Lots of Greetings!
| Volker

Sound DOES depend on source speed.
Try moving through air toward a sound source such as a fire siren.
Relatively, the source is moving toward you. All speed is relative.
See
 http://www.place.dawsoncollege.qc.ca/~sjoseph/Chap18B.htm
 Solution to Problem 18.51

Androcles