Tests at the National Institute of Standards and Technology (NIST) are underway to ensure that alarm beacons for firefighters and other emergency first responders will operate reliably while in the presence of other wireless devices.
This latest NIST test focuses on interference between Personal Alert Safety Systems (PASS) with wireless alarm capability, and RFID systems. PASS devices monitor movement and activate an alarm if a firefighter remains motionless for too long. Because firefighters may carry RFID tags for location tracking, or may be in warehouses or other buildings using RFID inventory systems, there is potential for interference.
NIST methods developed in the study also tested interference in other wireless devices such as radios, hands-free cell phone headsets, local area networks, and urban search and rescue robots – evaluating how well these devices work under realistic conditions.
The NIST research measured interference between frequency hopping PASS and RFID systems operating in similar frequency bands:
Results show that, when signals are weak due to environmental or other conditions, a portable PASS unit’s receipt of an alarm from its base station can be delayed or fail even without interference, and becomes more likely to fail in the presence of only moderate RFID interference.
Strong interference caused longer and variable delays that sometimes exceeded a minute, defined by the researchers as signal failure. NIST researchers also found that an RFID system can be less reliable when the PASS unit is nearby.
NIST is working with the National Fire Protection Association, which will consider adopting the NIST tests as part of revised PASS performance standards. The standards could be approved by 2013 at which point manufacturers would need to show that their PASS devices pass the tests.