Method for estimating the covered area of a directive antenna of a local positioning system while setting up said system

Abstract

The invention relates to a method (MTH) for estimating the coverage area of a directive antenna of a local positioning system while setting up said system, said antenna being located in the vicinity of an area of interest, the method (MTH) comprising the following steps: —Distributing (DIS_TR) a plurality of transponders over the area of interest—Performing (MSD_SS) measurements of signal strength between the antenna and said transponders—Estimating (EST_CV) the coverage area by using said measurements.

Claims

1. A method for estimating a coverage area of a local positioning system including a directive antenna and tracking athlete positions and motion trajectories while setting up said system, the method comprising: distributing a plurality of transponders over an area of interest; performing measurements of signal strength between the directive antenna and said transponders, the directive antenna being located in a vicinity of the area of interest; and estimating the coverage area of the local positioning system tracking athlete positions and motion trajectories by using said measurements, wherein the distributing further comprises homogeneously spreading the transponders on the area of interest, and wherein the estimating the coverage area further comprises sorting the transponders according to whether or not a signal they have emitted has been received by the antenna and according to power indicators for the received signals.

2. The method according to claim 1, wherein the performing measurements further comprises: emitting a signal by each of the plurality of transponders; receiving at least two of said signals by the antenna; and measuring a power indicator for each received signals.

3. The method according to claim 2, wherein the power indicator is a Received Signal Strength Indicator.

4. The method according to claim 1, wherein the estimating the coverage area further comprises producing a coverage map of the area of interest, according to the sorting.

5. The method according to claim 1, wherein the sorting includes designing one of three categories for each transponder, each category corresponding to an indication of signal quality.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Other features and advantages of the present invention will appear more clearly upon reading the following detailed description, made with reference to the annexed drawings, given by way of non-limiting example:

(2) FIG. 1a shows the horizontal radiation pattern of a typical directive antenna

(3) FIG. 1b shows the vertical radiation pattern of the antenna to which reference has been made in FIG. 1a

(4) FIG. 2 shows an environment comprising an area of interest on which a plurality of transponders are distributed, a directive antennae being located in the vicinity of said area of interest

(5) FIG. 3 shows a flow diagram illustrating the steps of a method according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) The method MTH offered by the invention addresses the difficulty in estimating the coverage area of a directive antenna of a local positioning system. FIG. 2 shows such a directive antenna A1, located in the vicinity of an area of interest AOI. For illustrative purposes, the coverage area CVA of said antenna A1 is approximated as a triangle.

(7) In a first step DIS_TR of the method MTH according to the invention, a plurality of test transponders T1-T28 are distributed over the area of interest AOI, advantageously in a homogenous manner, that is to say spread all over the area of interest AOI and regularly spaced, as shown in FIG. 2.

(8) In a second step MSD_SS of the method MTH according to the invention, measurements of signal strengths are performed.

(9) According to a sub-step EMT_SG of this second step MSD_SS, each of the test transponders T1-T28 emits a signal. Understandably, depending on its position and its orientation, the antenna A1 can only receive some of these signals. In the example of FIG. 2, only seven transponders T1-T7 out of the twenty-eight depicted transponders are in the coverage area CVA of the antenna A1.

(10) According a subsequent sub-step RCV_SG of this second step MSD_SS, as already mentioned, the antenna A1 receives some of the signals emitted by the transponders.

(11) According to a subsequent sub-step MSD_PI of this second step MSD_SS, a power indicator relative to each received signal is measured. The power indicator is for instance calculated using the Received Signal Strength Indicator (RRSI), which is a measurement of the power present in a received radio signal. Most positioning systems provide a value for the RSSI for each signal transmission between a transponder and an antenna. A high RSSI indicates good signal strength/quality and vice versa.

(12) In a third step EST_CV of the method MTH according to the invention, the coverage area CVA of the antenna A1 is estimated, on the basis of said measurements.

(13) According a sub-step SRT_TR of this third step EST_CV, the test transponders T1-T28 are sorted in different categories, by using the measurements. For instance, the transponders the antenna received no signal from (T13-T28) are sorted in the category “no coverage”, and the others (T1-T12) are sorted in the categories “good signal quality”, “medium signal quality” and “poor signal quality”. Of course, other categories and a different number of categories are conceivable. In the example of FIG. 2, five categories are represented: from white which is equivalent to a good signal quality to black which is equivalent to no coverage.

(14) According a subsequent sub-step PRD_CM of this third step EST_CV, a coverage map is produced, by using the sorting. This provides intuitive feedback about the coverage of the antenna which helps optimizing the setup of the positioning system, that is to say find the optimal positions and orientations of the antenna, find out which parts of the area of interest are sufficiently covered, etc.

(15) Of course, the present invention is not limited to the illustrated example but may be subject to various variants and alterations, which will be apparent to those skilled in the art.