http://physics.bu.edu/~redner/211-sp06/class19/class19_doppler.html Sidney Redner: "The Doppler effect is the shift in frequency of a wave that occurs when the wave source, or the detector of the wave, is moving. Applications of the Doppler effect range from medical tests using ultrasound to radar detectors and astronomy (with electromagnetic waves). (...) We will focus on sound waves in describing the Doppler effect, but it works for other waves too. (...) Let's say you, the observer, now move toward the source with velocity vO. You encounter more waves per unit time than you did before. Relative to you, the waves travel at a higher speed: v'=v+vO. The frequency of the waves you detect is higher, and is given by: f'=v'/(lambda)=(v+vO)/(lambda)."
http://www.usna.edu/Users/physics/mungan/Scholarship/DopplerEffect.pdf Carl Mungan: "Consider the case where the observer moves toward the source. In this case, the observer is rushing head-long into the wavefronts, so that we expect v'>v. In fact, the wave speed is simply increased by the observer speed, as we can see by jumping into the observer's frame of reference. Thus, v'=v+v_o=v(1+v_o/v). Finally, the frequency must increase by exactly the same factor as the wave speed increased, in order to ensure that L'=L -> v'/f'=v/f. Putting everything together, we thus have: OBSERVER MOVING TOWARD SOURCE: L'=L; f'=f(1+v_o/v); v'=v+v_o."
Sidney Redner and Carl Mungan are the worst traitors. They not only suggest that the speed of the light waves varies with the speed of the observer, in violation of special relativity - they also deduce the Doppler frequency shift from this variation. Any sane scientist would find it very difficult to believe that the premise (the speed of light varies with the speed of the observer, c'=c+v) is false when the conclusion deduced from this premise (the frequency varies with the speed of the observer, f'=f(1+v/c)) is true.
Unfortunately there are no sane scientists in Einsteiniana. Sidney Redner and Carl Mungan would surely denounce any variation of the speed of any waves if brothers Einsteinians want them to do so. Here is an Einsteinian demonstrating how the speed of light varies with the speed of the observer and at the same time explaining that there is no variation at all: