| 摘要 |
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, pϵ[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_ φvip) with a calculator (Xi) of the identifier a phase φvip, modulo 2π, of the first signal (Svp) received, relative to a second signal (Sip) of phase φiP(t) = φ0ip + 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_ φivp) with a calculator (Xv) of the vehicle (V) a phase φivp, modulo 2π, of the second signal (Sip) received, relative to the first signal (Svp), - calculating (Cal_φp) the average φp of the phase φvip and of the phase φivp; the method (METH) further comprising: - for each p between 1 and N-1, calculating (Cal_Pp) a ramp Pp using the formula Pp=(φp+1-φp)/(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. |
