# Doppler and Speed of light

If an an over-the-air radio signal of a certain frequency $$f_c=300$$ MHz travels in my direction while I'm standing still, then I observe the signal travelling towards me at the speed to light and I measure no Doppler switch.

However, if the speed of light is always constant to the eyes of a the observer regardless if the observer is moving or not, I should also measure $$300$$x$$10^6$$ periods a second (and thus no Doppler shift) if I move towards the light source. But theory tells that, when moving towards the light source, positive Doppler should happen.

Where is the mistake in my understanding?