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 synchronised. The method (METH) comprises N Sqp, p∈[1;N] sequences, where N is a natural number at least higher than 3, each Sqp sequence comprising the following steps: —transmitting (Em_Svp) a first signal (Svp) of frequency fp from an emitter (TXv) of the vehicle (V) to a receiver (Rxi) of the identifier (I); —measuring (Mes—vip) with a calculator (Xi) of the identifier a phase vip, modulo 2π, of the first signal (Svp) received, relative to a second signal (Sip) of phase iP(t)=0ip+2πfpt; —transmitting (Em_Sip) the second signal (Sip) from an emitter (TXi) of the identifier (I) to a receiver (RXv) of the vehicle (V); —calculating (Mes—ivp) with a calculator (Xv) of the vehicle (V) a phase ivp, modulo 2π, of the second signal (Sip) received, relative to the first signal (Svp), —calculating (Cal—p) the average p of the phase vip and of the phase ivp; the method (METH) further comprising: —for each p between 1 and N−1, calculating (Cal_Pp) a ramp Pp using the formula Pp=(p+1−p)/(fp+1−fp); —filtering (Fil_Pp) N−1 values of the calculated ramps Pp in order to determine an optimum ramp P; —calculating (Cal_R) distance R from the optimum ramp P.

Dependencies are inferred from the claim text.