Method for determining a distance between a vehicle and a vehicle access and starter identifier

Abstract

The invention relates to a method (METH) for measuring a distance R between a vehicle (V) and an identifier (I) for accessing and starting the vehicle (V), the vehicle (V) and the identifier (I) being synthronised. The method (METH) comprises the following steps: —selecting (Sel_f) N frequencies f, pϵ[1;N], N being a natural number at least higher than 3; —implementing N sequences Sq, each sequence Sqcomprising the following steps: •transmitting (Em_S) a first signal (S) of frequency ffrom an emitter (TXv) of the vehicle (V) to a receiver (Rxi) of the identifier (I); •measuring (Mes_ϕ) with a calculator (Xi) of the identifier (I) a phase ϕ, modulo 2π, of the first signal (S) received, relative to a second signal (S) of phase ϕ(t)=ϕ+2πft; •transmitting (Em_S) the second signal (S) from an emitter (TXi) of the identifier (I) to a receiver (RXv) of the vehicle (V); •calculating (Mes_ϕ) with a calculator (Xv) of the vehicle (V) a phase ϕ, modulo 2π, of the second signal (S) received, relative to the first signal (S); •calculating (Cal_ϕ) the average ϕof the phase ϕand of the phase ϕ; —for each p between 1 and N−1, calculating (Cal_P) a ramp Pusing the formula P=(ϕ−ϕ)/(f−f); and—calculating (Cal_R) distance R front the ramps P, pϵ[1;N].