Wireless tag reading apparatus, storage medium, and method

A non-transitory computer readable storage medium storing a program for causing a computer to execute a method comprising:

• (a) causing a driving mechanism to move an antenna from a first position to a second position, and controlling the antenna to transmit radio waves to one or more wireless tags each attached to an object, one or more times when the antenna is between the first and second positions;
• (b) acquiring, from response waves from the wireless tags:
• information that is registered in each of the wireless tags and indicates an attribute of the corresponding object and an attribute of the wireless tag, and
• signal strength and phase values of the response waves;
• and
• (c) calculating an estimated position of each of the wireless tags and a reliability level of the estimated position based on the signal strength and phase values,
• wherein the method further comprises:
• when the reliability level of the estimated position of one of the wireless tags is less than a threshold value or when the information registered in one of the wireless tags indicates an attribute that can affect radio communications, performing step (a) again, acquiring signal strength and phase values of response waves received from said one of the wireless tags, and calculating an estimated position of said one of the wireless tags and a reliability level thereof based on the signal strength and phase values acquired again;
• increasing power of the radio waves transmitted from the antenna by a first amount when performing step (a) again;
• and
• decreasing the signal strength values of the response waves received from said one of the wireless tags based on the first amount before calculating again the estimated position of said one of the wireless tags and the reliability level thereof.

A method performed by a wireless tag reading apparatus that includes an antenna and a driving mechanism configured to move the antenna between first and second positions, the method comprising:

• (a) causing the driving mechanism to move the antenna from the first position to the second position, and controlling the antenna to transmit radio waves to one or more wireless tags each attached to an object, one or more times when the antenna is between the first and second positions;
• (b) acquiring, from response waves from the wireless tags:
• information that is registered in each of the wireless tags and indicates an attribute of the corresponding object and an attribute of the wireless tag, and
• signal strength and phase values of the response waves;
• and
• (c) calculating an estimated position of each of the wireless tags and a reliability level of the estimated position based on the signal strength and phase values,
• wherein the method further comprises:
• when the reliability level of the estimated position of one of the wireless tags is less than a threshold value or when the information registered in one of the wireless tags indicates an attribute that can affect radio communications, performing step (a) again, acquiring signal strength and phase values of response waves received from said one of the wireless tags, and calculating an estimated position of said one of the wireless tags and a reliability level thereof based on the signal strength and phase values acquired again;
• increasing power of the radio waves transmitted from the antenna by a first amount when performing step (a) again;
• and
• decreasing the signal strength values of the response waves received from said one of the wireless tags based on the first amount before calculating again the estimated position of said one of the wireless tags and the reliability level thereof.