Doppler or PIR — which sensor for motion-controlled lighting?
A luminaire is only as smart as its sensor. Here is how 5.8GHz microwave doppler and passive infrared (PIR) differ — and which to choose for parking garages, high-bay factories and ceiling-mount fixtures — from a manufacturer that designs both.
Different physics, different jobs
5.8GHz Microwave Doppler
- Emits a 5.8GHz signal and detects the frequency shift of waves reflected by moving objects (doppler effect)
- Radio waves pass through plastic and glass — the sensor can be fully hidden inside the luminaire housing
- Unaffected by ambient temperature (no summer sensitivity drop)
- Reliable for fast, large motion (vehicles) down to pedestrians
PIR (Passive Infrared)
- Detects changes in far-infrared radiation (body heat) focused by a Fresnel lens
- Passive — low power draw and simple construction, cost-effective
- The lens must be exposed; it cannot see through covers or glass
- Sensitivity can drop when ambient temperature approaches body temperature
At a glance
| Criteria | 5.8GHz Doppler | PIR |
|---|---|---|
| Principle | Frequency shift of reflected waves (active) | Body-heat infrared change (passive) |
| Cover penetration | Passes plastic/glass — sensor can be hidden | No — lens must be exposed |
| Temperature effect | None | Sensitivity may drop in hot environments |
| Detection range | 0.3–7 m radius / 15 m linear (BIO) | Typically a few meters |
| Detection angle | 120° | Depends on lens design |
| Best for | Parking, high-bay, group control | Low power, low cost, compact fixtures |
What we recommend by application
Parking garages → doppler + AI group control
Fast-moving vehicles and rows of fixtures. Our JA58K1(G)-3123 learns traffic patterns after 4–5 vehicle passes and lights fixtures ahead of the car (KC R-R-Ja2-JA58K1G-3123).
Factories & logistics → doppler + BLE Mesh
High ceilings demand long range and fixture-to-fixture communication: 15 m linear detection plus BLE Mesh multi-hop (>40 m, frequency hopping).
Ceiling-mount / compact fixtures → compact doppler module
BIO58K1-1818 measures 18×18 mm, embeds an illuminance sensor (5–60 LUX tunable) and supports IR-remote field tuning.
Stairs & short corridors → PIR still makes sense
Where range is short and cost matters, PIR is the rational choice. BIO also offers PIR group and individual sensors.
FAQ
Q. Can a doppler sensor sit inside the luminaire cover?
Yes. 5.8GHz waves pass through plastic and glass covers, so the sensor can be fully embedded. PIR lenses must remain exposed.
Q. Why do some sensor lights get sluggish in summer?
PIR detects the contrast between body heat and ambient temperature; when ambient approaches body temperature, sensitivity drops. Doppler sensing is unaffected by temperature.
Q. Do you provide samples or OEM development?
Yes. BIO Electronics develops from sensor SoC selection to firmware and antenna tuning in-house, and welcomes sample and OEM/ODM inquiries.
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