Location sensing using a radio frequency tag

Abstract

Embodiments herein describe RFID systems that include multiple RFID tag readers that each use a different frequency to communicate with an RFID tag. For example, each of the tag readers may transmit a tag query command using different modulated frequencies. In one embodiment, the RFID tag includes multiple receivers each tuned to one of the different frequencies generated by the tag readers. For example, one receiver in the tag is tuned to receive 200 MHz signals while another receiver is tuned to receive 900 MHz signals. To provide location information, the RFID tag compares power values associated with the received signals to determine which of the RFID tag readers is closest to the tag. The RFID tag conveys this location information to the tag readers by selecting one of the frequencies of the tag readers to use when generating a reply message.

Dependencies are inferred from the claim text.