# US 2018/0321371 A1 · Method for determining a distance between a vehicle and a vehicle access and starter identifier

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- Number: US 2018/0321371 A1
- Document ID: US20180321371A1
- Status: Published application
- Kind: A1
- Application number: 15/756,186
- Filed: 2016-08-31
- Published: 2018-11-08
- Earliest claimed: 2015-08-31
- Assignees: Valeo Comfort and Driving Assistance
- Applicants: Valeo Comfort and Driving Assistance
- Inventors: Eric Leconte
- Web page: https://patentgrep.com/patent/US20180321371A1

## CPC

- G01S 13/825: {with exchange of information between interrogator and responder}
- G01S 13/84: for distance determination by phase measurement
- G07C 9/00309: {operated with bidirectional data transmission between data carrier and locks}
- G07C 2009/00325: {and the lock having only one limited data transmission range}
- G07C 2009/00793: {by Hertzian waves}
- G07C 2209/63: Comprising locating means for detecting the position of the data carrier, i.e. within the vehicle or within a certain distance from the vehicle
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G07C: TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE

## 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.

## Claims

### Claim 1

A method for measuring a distance R separating a vehicle (V) and an identifier (I) for accessing and starting the vehicle, the vehicle and the identifier being synchronized, the method comprising:
N sequences Sqp, p∈[1;N], N being a natural number at least greater than 3, each sequence Sqp comprising the following steps:
transmission, from a transmitter of the vehicle to a receiver of the identifier, of a first signal of frequency fp;
measurement, by a computer of the identifier, of a phase ϕvip, modulo 2π, of the received first signal, in relation to a second signal of phase ϕip(t)=ϕ0ip+2πfpt;
transmission, from a transmitter of the identifier to a receiver of the vehicle, of the second signal;
calculation, by a computer of the vehicle, of a phase ϕivp, modulo 2π, of the received second signal, in relation to the first signal;
calculation of the average ϕp of the phase ϕvip and of the phase ϕivp;
for each value of p between 1 and N−1, calculation of a gradient Pp using the formula Pp=(ϕp+1−ϕp)/(fp+1−fp);
filtering of the N−1 values of calculated gradients Pp so as to determine an optimum gradient P; and
calculation of the distance R on the basis of the optimum gradient P.

### Claim 2 (depends on 1)

The method as claimed in claim 1, wherein the distance R is calculated, during the calculation step, using the following formula:
R=−c/(2π)*P
where c is the speed of propagation of the first signal and of the second signal.

### Claim 3 (depends on 1)

The method as claimed in claim 1, wherein the N sequences Sqp, p∈[1;N] are such that, for all values of p between 1 and N−1, fp+1−fp is constant.

### Claim 4 (depends on 1)

The method as claimed in claim 1, wherein the filtering comprises selecting a plurality of gradients from among the N gradients Pp calculated during the calculation steps.

### Claim 5 (depends on 4)

The method as claimed in claim 4, wherein the filtering comprises averaging the plurality of selected gradients.