Rfid interrogator device

Abstract

An RFID interrogator device has a transmission section for transmitting a command to an RFID tag and a reception section for receiving an RF signal from the RFID tag and is configured to perform backscatter radio communication with the RFID tag. The RFID interrogator device comprises a time window setting section configured to set a time window at timing of receiving preamble data added to a head of response data transmitted from the RFID tag in response to the command, and an identifying data storage section storing preamble identifying data. The RFID interrogator device compares the data received within the time window, with preamble identifying data stored in the identifying data storage section, thereby determining whether the data received is identical to the preamble data transmitted from the RFID tag.

1 . An RFID interrogator device which transmits a command to an RFID tag and receives response data at a sampling cycle corresponding to a transmission rate of the response data from the RFID tag, the RFID interrogator comprising:
 a first data storage section configured to store as preamble identifying data prescribed lower bits of preamble data attached to a head of the response data;   a second data storage section configured to store received data;   a timer to measure a predetermined time based on a time obtained by adding to a time required to receive preamble data from the RFID tag after finishing the transmission of command to the RFID tag a time obtained by multiplying the sampling cycle by a difference between the number of preamble data bits and the number of preamble identifying data bits; and   a comparator to compare data stored in the first data storage section and data received within the predetermined time and stored in the second data storage section.   
   
   
       2 . The RFID interrogator device according to  claim 1 , wherein the predetermined time is obtained by adding to a time obtained by multiplying the number of preamble identifying data bits by the sampling cycle a time equivalent to a difference between a maximum value and a minimum value for a preset response time of the RFID tag. 
   
   
       3 . The RFID interrogator device according to  claim 1 , wherein the second data storage section is a shift register. 
   
   
       4 . A radio communication method for transmitting a command to an RFID tag and receiving response data at a sampling cycle corresponding to a transmission rate of the response data from the RFID tag, the method comprising:
 preparing prescribed lower bits of preamble data attached to a head of the response data as preamble identifying data; and   comparing data received within a predetermined time and the preamble identifying data based on a time obtained by adding to a time required to receive preamble data from the RFID tag after finishing the transmission of command to the RFID tag a time obtained by multiplying the sampling cycle by a difference between the number of preamble data bits and the number of preamble identifying data bits.   
   
   
       5 . The radio communication method according to  claim 4 , wherein the predetermined time is obtained by adding to a time obtained by multiplying the number of preamble identifying data bits by the sampling cycle a time equivalent to a difference between a maximum value and a minimum value for a preset response time of the RFID tag. 
   
   
       6 . The radio communication method according to  claim 4 , wherein the preamble identifying data is stored in a memory.