How can I filter an ambiguity function

I have been working on through-the-wall sensing using GSM signals. To do this, somebody running toward the antenna and we are recording the data. The data includes direct signal from the phone and the signal reflected from moving person. We extract ambiguity function of that data. When we plot this ambiguity function we can see a little impulse on the frequency which we expected to see the result of the movement. How can we concretize the doppler frequency.