We are developing a telemeter based on the measurement of the phase accumulated by a RF sine wave during its propagation in air. This wave is carried by a laser beam thanks to an intensity modulation. The main limitation of this technique lies in amplitude-to-phase conversion occurring in the detection of this modulation. Therefore, we characterized in this paper this phenomenon for a given telemetric system and discuss on how to reduce its effects on the resolution and the accuracy of the distance measurement. Finally, a solution is implemented and tested outdoor, in real conditions of use.