Geiger counter

noun2

1. •
   A device designed to detect radioactivity and measure its intensity.
2. •
   a feature of an RFID reader that emits a sound indicating the signal strength of an RFID tag that is being searched for.

   • Any Geiger Counter feature can direct a user towards an RFID tagged item or at least point the user in the right direction, depending on how far away the RFID tag is. — 2021