DISTANCE MEASUREMENTS USING A SINGLE WIRELESS READER
A method, comprising: generating or receiving information about multiple distance measurements of distances between the wireless tag and the wireless reader at different points of time; wherein the wireless reader is positioned at different locations in relation to the wireless reader at the different points of time; generating or receiving information about a spatial relationship between the different locations or receiving information indicative of the spatial; and determining the location of the wireless tag in response to the multiple range measurements and the spatial relationship between the different locations.
1 . A method for determining a location of a wireless tag, the method comprising: generating or receiving, by a wireless reader, information about multiple distance measurements of distances between the wireless tag and the wireless reader at different points of time; wherein the wireless reader is positioned at different locations in relation to the wireless reader at the different points of time; generating or receiving by the wireless reader information about a spatial relationship between the different locations or receiving information indicative of the spatial; and determining by the wireless reader, the location of the wireless tag in response to the multiple range measurements and the spatial relationship between the different locations.
2 . The method according to claim 1 further comprising generating by the wireless reader location information about the location of the wireless tag.
3 . The method according to claim 2 comprising displaying on a display an indication about the location of the wireless tag, wherein the displaying is responsive to the information about the location of the wireless tag and an orientation of the display.
4 . The method according to claim 1 wherein the different points in time are included in a time window and wherein the method comprises ignoring distance measurements obtained outside the time window.
5 . The method according to claim 4 wherein the time window is a sliding time window.
6 . The method according to claim 1 wherein the determining of the location comprises assigning different weights to different distance measurements.
7 . The method according to claim 1 comprising generating by the wireless reader the information about the spatial relationship between the different locations by tracking by one or more sensors a trajectory of the wireless reader.
8 . The method according to claim 1 comprising providing a rough estimate of a location of the item based upon a spatial relationship between a subset of the different locations.
9 . The method according to claim 1 wherein the range measurements comprise an exchange of messages between the wireless tag and the wireless reader; wherein the method comprises receiving or calculating angular information about angles of reception of at least some of the messages; and wherein the determining by the wireless reader, of the location of the wireless tag is further responsive to the angular information.
10 . The method according to claim 9 wherein the wireless reader comprises an antenna array and the wireless reader is arranged to estimate an angle of arrival of a message received from the item in response to reception signals obtained by the array of antennas.
11 . A wireless reader, comprising a wireless transceiver and a processor; wherein the wireless transceiver is arranged to exchange wireless messages with a wireless tag at different points of time; wherein the wireless reader is positioned at different locations in relation to the wireless reader at the different points of time; wherein the processor is arranged to: (a) process at least some of the wireless messages to provide multiple distance measurements of distances between the wireless tag and the wireless reader as existed at the different point of time; (b) generate or receive information about a spatial relationship between the different locations or receiving information indicative of the spatial; and (c) determine by the wireless reader, the location of the wireless tag in response to the multiple range measurements and the spatial relationship between the different locations.
12 . The wireless reader according to claim 11 that is arranged to generate location information about the location of the wireless tag.
13 . The wireless reader according to claim 12 that is arranged to display on a screen an indication about the location of the wireless tag, wherein the display is responsive to the information about the location of the wireless tag and an orientation of the screen.
14 . The wireless reader according to claim 11 wherein the different points in time are included in a time window and wherein the wireless reader is arranged to ignore distance measurements obtained outside the time window.
15 . The wireless reader according to claim 11 that is arranged to determining the location by assigning different weights to different distance measurements.
16 . The wireless reader according to claim 11 wherein the wireless reader comprises one or more sensors that are arranged to track a trajectory of the wireless reader.
17 . The wireless reader according to claim 11 that is arranged to provide a rough estimate of a location of the item based upon a spatial relationship between a subset of the different locations.
18 . The wireless reader according to claim 11 wherein wireless reader is arranged to exchange of messages with the wireless tag, to receive or calculate angular information about angles of reception of at least some of the messages; determine the location of the wireless tag in response to the angular information.
19 . The wireless reader according to claim 18 wherein the wireless reader comprises an antenna array and the wireless reader is arranged to estimate an angle of arrival of a message received from the item in response to reception signals obtained by the array of antennas.
20 . A non-transitory computer readable medium that stores instructions that when executed by a computer cause the computer to execute the stages of: generating or receiving information about multiple distance measurements of distances between the wireless tag and the wireless reader at different points of time; wherein the wireless reader is positioned at different locations in relation to the wireless reader at the different points of time; generating or receiving information about a spatial relationship between the different locations or receiving information indicative of the spatial; and determining the location of the wireless tag in response to the multiple range measurements and the spatial relationship between the different locations.