OV125 LF Activator
125kHz Wake‑up · 1.5m radius · 500+ tags · 100ms response
The problem with always‑on wireless tags
If a BLE or UWB tag transmits continuously, its battery dies in months. If it sleeps to save power, it might miss the moment a worker enters a hazardous zone or crosses a gate. Semi‑active tags solve this by staying in deep sleep until they feel a low‑frequency wake‑up field – then they transmit their ID and sensor data for a few seconds before going back to sleep.
The OV125 is that wake‑up trigger. It continuously emits a 125kHz magnetic field. When a compatible tag (wristband, badge, helmet tag) enters the field, it wakes up, captures the activator ID and RSSI, and then sends its data via UHF or BLE to your gateway. The OV125 does not receive data; it only wakes tags. This gives you years of battery life for tags while still providing real‑time zone detection and in/out counting.
How it works
Place the OV125 at a gate, doorway, or hazardous zone boundary. Connect the two external antennas (10‑metre cables included) and bury them in the ground or mount them on walls. The activator generates a 125kHz field around each antenna, forming a "virtual fence" of about 1.5 metres radius. When a semi‑active tag enters this field, the tag's LF receiver decodes the activator ID and RSSI, then wakes up its main radio (2.4GHz) to transmit its location and ID to your BLE/UWB gateway. The system can track entry/exit direction (if two activators are placed on both sides of a door) and can trigger alarms when a tag enters a restricted zone.
System architecture
Technical specifications – OV125
| Dimensions (W×D×H) | 253 × 250 × 100 mm |
|---|---|
| Enclosure material | ABS+PC, IP66 (dust‑tight, water jets) |
| Power input | 5V DC (power supply not included; standard 5V/2A adapter recommended) |
| Antenna type | External buried‑type coil – two independent channels |
| Antenna cable length | 2× 10 metres (included) |
| Operating frequency | 125kHz |
| Wake‑up distance (radius) | 1.5 metres (adjustable by shortening antenna cable; shorter cable increases range) |
| Concurrent tag capacity | ≥500 tags simultaneously (tags only wake; no congestion) |
| Detection speed | 100ms from tag entry to wake‑up pulse |
| Interference immunity | Multiple activators can be placed near each other without mutual interference (encrypted coding) |
| Security | Encrypted password verification – prevents false wake‑up by unauthorised LF sources |
| Operating temperature | -20°C to +60°C |
| Mounting | Wall or pole mount (screws not included) |
* Wake‑up distance depends on environmental conditions (metal, soil moisture). The included 10m cables can be shortened to increase field strength (shorter cable = stronger field, greater range). Consult our engineering team for customisation.
What the OV125 is NOT (honest limitations)
Not a reader or gateway – It does not receive any data from tags. It only transmits a 125kHz wake‑up signal. You still need a separate BLE/UHF gateway to collect tag data.
Not a general‑purpose LF transmitter – Designed specifically for semi‑active tags that comply with our LF encoding protocol. Test compatibility with our tags (OV series wristbands, badges).
Antenna cable length affects range – Longer cables reduce field strength. We include 10m cables; shortening them increases range. Do not extend beyond 20m without a line driver.
Not for use with active RFID readers – Does not support ISO 11784/11785 or animal tag standards. It's a proprietary wake‑up system.
Power supply not included – You need a 5V DC power source (2A minimum). The unit does not have PoE or battery backup.
No wireless configuration – All settings (power, frequency tuning) are factory preset. No user‑adjustable parameters over the air.
We're upfront about what it does and doesn't do. If you need a full RFID reader or a different LF standard, this product is not for you – but we can point you to alternatives.
Use cases
Gate in/out detection
Place two OV125 units (or one with dual antennas) on both sides of a doorway. Tags determine direction based on which antenna wakes them first. Ideal for nursing homes, schools, factories, and prisons.
Hazardous zone alert
Install a single OV125 at the entrance to a dangerous area (e.g., chemical storage, heavy machinery zone). Tags that enter wake up and transmit an alert to the control room.
Attendance tracking
Workers passing through a gate automatically trigger their tag to send ID and timestamp – no manual card swipe.
Asset in/out logging
Attach semi‑active tags to valuable assets (laptops, tools, pallets). Gate activator logs movement in/out of a building or warehouse.
Sleep‑wake for long‑term deployments
Tags can be programmed to sleep for 10 seconds, wake for 100ms to check for LF field, then sleep again. Battery life extends to 5+ years while still providing sub‑second response at the activator zone.
Real deployment: 600‑bed nursing home
A large elderly care facility in Germany installed OV125 activators at every unit entrance and exterior door. Each resident wore a semi‑active wristband (OV series). The activators triggered the wristbands to transmit their ID and RSSI to BLE gateways in the corridors. The system tracked resident movement between zones and generated alerts if someone exited a secure door after hours. The nursing home reduced elopement events by 90% and eliminated manual door checks. Activators operated continuously for 4 years with zero failures; wristband batteries lasted over 3 years because they only transmitted when passing an activator or pressing the SOS button.
Another client, a petrochemical plant, used OV125 activators to enforce safety zones around high‑temperature reactors. Any worker entering a restricted area triggered an immediate alert to the control room, and the worker's wristband vibrated as a local warning. The system proved far more reliable than camera‑based monitoring and required no wearable recharging.
Ready to implement zone‑based wake‑up for your semi‑active tags?
Request an OV125 sample or a technical consultation. We'll help you design the activator layout and integrate with your existing BLE/UWB gateways.
Request pricing & sample →Mobile: [+86] 189-7480-9810 (supports calls, WhatsApp, and WeChat)
Email: sales@cumond.com
Website: www.iot-solutionhub.com