A personal duress system gives each staff member a wearable device that raises an alarm and reports where they are. The location is what makes it valuable: responders go straight to the right room instead of searching a floor. How accurate and reliable that location is depends on the technology chosen and, above all, on how well the system is designed and tested for the building.
How a locating duress system works
Every locating system has the same basic parts. Location references, often small devices mounted in each room or zone, give the wearable a way to know where it is, or let the system work it out. The wearable is the button the staff member carries, sometimes with a pull cord or a fall sensor. A network of receivers, or the building's WiFi, carries the alarm from the wearable. A server, sometimes called the location engine, combines the alarm with the location and sends it to the people who respond.
Some systems work the other way round: the wearable transmits, and fixed receivers measure its signal to estimate position. Either way, the system needs supervision, meaning each wearable checks in regularly so a missing or failed device is noticed before it is needed.
Locating technologies compared
The choice of technology largely decides what accuracy is possible. Many systems combine two or more.
| Technology | Typical accuracy | Notes |
|---|---|---|
| Infrared room locators | Room level | Infrared light does not pass through walls, so a reading is confidently tied to one room; needs a locator in each room and a clear path to the wearable |
| Ultrasound | Room level | Sound is contained by walls in a similar way; needs a locator in each room |
| Radio beacons, including Bluetooth Low Energy | Zone to room, depending on density and tuning | Radio passes through walls, so neighbouring rooms can be confused unless the design allows for it |
| WiFi-based locating | Zone or floor area | Uses the existing WiFi network; accuracy depends on access point density and design |
| GPS | Outdoors only | Useful for parking lots and grounds; unreliable inside buildings |
Our guides to RFID and asset tracking and WiFi for healthcare facilities cover related locating and wireless design questions.
How accurate is accurate enough
Accuracy needs differ by area. In a ward of single rooms, knowing the zone means responders may check several doors while the person who pressed the button waits. In an open office or a parking lot, a zone may be perfectly adequate. The diagram shows why room-level accuracy matters where an area is divided into many small rooms.
Two accuracy problems deserve special attention. The first is the wrong floor: radio signals pass through floors as well as walls, and a system that places someone on the floor above sends responders the wrong way. The second is boundaries: stairwells, doorways and corridors between zones, where a person moving quickly can be reported in the place they just left. Both need to be tested specifically, not assumed.
Coverage, reliability and wearability
A wearable only helps where its alarm can reach a receiver and its location can be worked out. Coverage plans should include every area staff go, not only the main floors: stairwells, basements, service corridors, parking structures and outdoor routes between buildings. Concrete, metal and lead-lined rooms all affect radio coverage.
- Supervision: each device should check in regularly, and a missed check-in should raise a trouble signal.
- Batteries and charging: set a routine, such as charging racks at the start of each shift, and use the low-battery warning.
- Extra functions: pull cords, fall or man-down sensors and two-way voice suit some roles, particularly working alone.
- Wearability: a device left in a locker does nothing. Choose a size and attachment staff will actually wear, and make wearing it part of the job.
Connecting to other systems
A locating duress system is more useful when it works with the systems around it. Common links include calling up the nearest cameras on the security desk's screen, sending alarms to the phones or radios responders already carry, showing alarms on a nurse call or security console in healthcare settings, and recording events in the same log as access control and intrusion alarms. Each link is another point of failure, so each one belongs in the acceptance test.
Planning a system
- Define who and where. List the roles that need a wearable and the areas they work in, including after-hours routes.
- Set the accuracy for each area. Mark on the floor plans where room-level accuracy is needed and where a zone will do. Record the reason.
- Survey the building. Note construction, ceiling types, existing WiFi and anything that affects locator and receiver placement.
- Design and pilot. Lay out locators and receivers, then trial them in a representative area before rolling out across the building.
- Acceptance test. Walk every room and route, press a test device in each, and record the location the system reports against where the tester actually stood, including stairwells and floor boundaries.
- Train and keep testing. Show staff how and when to use the device, and repeat location tests periodically and after renovations.
What the test record should include
- A floor plan marked with every test point, including stairwells, doorways and outdoor routes.
- For each test, the device used, the actual location, the reported location and the time to each receiver.
- Any wrong-room or wrong-floor result, the fix made and the retest result.
- Supervision and low-battery signals confirmed at the receiving station.
A typical case
A mental health unit has an older system that reports alarms by zone, with each zone covering a stretch of corridor and several rooms. Staff report that responders often check the wrong rooms first. In a case like this, the design adds room-level locators to patient rooms, interview rooms and the activity room, keeps zone-level coverage in the corridors and adds coverage to the stairwells and the enclosed courtyard, which had none. A pilot on one corridor shows two rooms on either side of a thin partition being confused, and the locator positions are adjusted before the rest of the unit is fitted. The acceptance test then walks every room and records the result, and the test is repeated each year and after any renovation.
How ehZee can help
We help organizations choose a locating technology that fits each area, design the locator and receiver layout, and test location accuracy room by room before the system goes live. See our duress and panic alarm systems service and our guide to duress and panic alarms.
Common questions
Can we use our existing WiFi network?
Sometimes. WiFi-based systems can work well for zone-level locating where the access point layout suits them. For room-level accuracy, most systems add dedicated locators. A survey shows what your network can support.
Can staff use their phones instead of a pendant?
Phone apps are useful for staff off site, but indoor location from a phone alone is usually less precise, and pulling out a phone in a tense moment is not discreet. Many organizations use pendants on site and apps for field staff.
Does the system track staff all the time?
That depends on how it is configured. Many systems only report location when an alarm is raised. If location is recorded continuously, staff should be told, and privacy and labour relations obligations considered.