Descrizione
Motion sensors have a design flaw that nobody mentions on the box: they detect movement, not people. Sit still and the room goes dark. The Quiet Witness is built around the correction to that flaw. A 24GHz millimeter-wave radar reads the micro-movement of a human body, including breathing, so presence is presence even when the only thing moving is your chest. A PIR element and a lux sensor sit alongside the radar, and the automation logic can require all three to agree before it decides the room is occupied and dark enough to matter.
The radar is the part that earns the name. It covers up to six meters with a 120 degree field and a beam pattern shaped at 94 degrees in one plane and 114 in the other, mounted on a wall between 1.2 and 2 meters high. Detection delay is adjustable from 10 to 600 seconds, so a hallway can switch in ten seconds while a living room waits ten minutes after the last person stands up. Light sensing runs to 12,000 lux, which is what lets the same rule behave correctly at noon and at midnight without a second device.
It communicates over ZigBee to Tuya Smart or Smart Life, running on a CR2450 cell at roughly 50 microamps average draw so it does not need wiring in the place where a sensor is most useful, high on a wall opposite the door. When presence drops, the sensor can command the rest of the home: lights off, gas valve closed, door locked, alarm armed. That is a different job than switching a lamp. It is the moment your house decides it is empty.
A sensor that only sees movement is a switch. One that knows you are still there is an instrument.
Why It Earns Its Place
- ✦ 24GHz millimeter-wave radar detects stationary human presence, including breathing, so lights do not cut out while someone is reading or working at a desk.
- ✦ Three sensing elements in one body: radar, passive infrared, and a 0 to 12,000 lux light sensor, allowing rules that require both occupancy and darkness.
- ✦ Six meter range at 120 degrees, with a beam shaped 94 degrees by 114 degrees for wall mounting between 1.2 and 2 meters.
- ✦ Adjustable 10 to 600 second hold time, so a corridor and a living room can use the same hardware with different patience.
- ✦ ZigBee mesh connection to Tuya Smart and Smart Life, which means it extends the network it joins rather than sitting outside it.
- ✦ CR2450 battery at roughly 50 microamps average, with no mains wiring required at the mounting point.
- ✦ IP20 rated for indoor use from minus 10 to 50 degrees Celsius and up to 95 percent humidity.
- ✦ Acts as an automation trigger, not just a light switch: presence states can arm security, close a gas valve, or lock a door when the last person leaves.
Technical Specifications
- Brand: GIRIER
- Sensing: 24GHz mmWave radar plus PIR plus lux sensor
- Protocol: ZigBee (2.4 to 2.425GHz)
- Platform: Tuya Smart, Smart Life
- Detection range: Up to 6 m, adjustable
- Detection angle: 120 degrees
- 3dB beam angle: 94 degrees (XZ plane), 114 degrees (YZ plane)
- Presence radius: Maximum 6 m
- Light sensing range: 0 to 12,000 lux
- Hold delay: 10 to 600 seconds, adjustable
- Power: CR2450 battery, 2 to 3.3V DC
- Average operating current: 50 microamps or less
- Power consumption: 150 microwatts
- Mounting height: 1.2 to 2 m (side mounting)
- Operating temperature: minus 10 to plus 50 Celsius
- Operating humidity: Up to 95 percent RH
- Ingress protection: IP20, indoor use
- Certification: CE, RoHS
Where It Belongs
This is the sensor you install when a motion detector has already failed you. In a home office the PIR version turns the lights off every time you stop typing, which is why so many people disable their automations. Radar presence fixes that without asking anyone to wave an arm. In a hallway it handles the ten-second case, switching the light on before the door is fully open and off shortly after the last person passes. In a bedroom it holds the light long enough for someone to fall asleep, then releases. Paired with a Tuya hub it becomes the occupancy input for a much larger rule set: heating that drops when the room empties, a security system that arms itself, a gas valve that closes when the kitchen has been clear for thirty minutes. One device, one battery, no wiring, and the house finally knows the difference between an empty room and a still one.
Questions Buyers Actually Ask
Q: Does it detect someone sitting still?
A: Yes. The millimeter-wave radar reads micro-motion including breathing, which is the specific problem passive infrared sensors cannot solve. A person reading or working at a desk stays detected as long as the hold delay allows.
Q: Do I need a Tuya hub?
A: Yes. The sensor communicates over ZigBee, which is not a protocol a phone or a Wi-Fi router speaks directly. A Tuya ZigBee gateway is required, and it will also act as the bridge to Smart Life for remote access and automation.
Q: How long does the CR2450 battery last?
A: It depends entirely on hold time and how often the room is triggered, because radar plus PIR draws the most current while active. Average draw is rated at 50 microamps or less, which is what makes months of runtime realistic rather than weeks. Set the hold delay to the shortest period your room actually needs.
Q: Can it trigger anything other than lights?
A: Yes. Any Tuya automation can use presence as a condition or a trigger, so it can arm a security system, close a gas valve, lock a smart lock, or drop the thermostat when the room empties.
Q: Will it see through a wall or window?
A: Millimeter-wave radar does not pass through walls, but it can be affected by glass and thin partitions. Mount it facing the area you want to cover rather than aiming through a window, and expect some sensitivity to large moving objects in the same room.
Q: Where should it be mounted?
A: Side-mounted on a wall between 1.2 and 2 meters high, facing the space rather than across it, which is what the 94 by 114 degree beam pattern is shaped for. Avoid pointing it directly at a radiator, a curtain in a draught, or a doorway where people only pass through.
Q: Does it work with Home Assistant or Apple Home?
A: The listing specifies Tuya Smart and Smart Life. Home Assistant users typically integrate it through the Tuya or LocalTuya integration rather than a native ZigBee coordinator, because the device pairs to a Tuya gateway.
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