Up to 20 wireless sensors
A wireless alarm system that detects changes in the distance between a central hub and battery-powered sensor nodes, with LTE/GPS and mobile connectivity.
The system uses a central hub and up to 20 wireless sensor nodes to monitor changes in their relative distance. When the user arms the system, the current distances become the reference state. A change triggers an alarm.
The battery-powered nodes require no fixed wiring. The hub adds LTE and GPS connectivity, while mobile and cloud components provide the remote user interface.
Build a portable alarm system that can monitor several separate points without a fixed installation. The hub needs to manage one-second sensor updates, detect a change from the armed reference state and connect local sensing to the remote application.
HTS developed the hub and sensor electronics, embedded firmware, and mobile/cloud integration. The work brought together distance sensing, wireless node communication, alarm logic, cellular connectivity and the user-facing software.
| Part | Role |
|---|---|
| Sensor nodes | Measure relative distance, send updates and provide local indication. |
| Wireless hub | Manage the node network, maintain the armed reference state and handle alarms. |
| Cellular and positioning subsystem | Connect the hub over LTE and provide GPS information. |
| Mobile and cloud components | Support remote interaction with the alarm system. |
| Parameter | Specification |
|---|---|
| Network | One hub with up to 20 wireless sensors |
| Sensor update interval | 1 second |
| Hub dimensions | Ø 140 mm |
| Sensor board dimensions | 48 × 17.5 mm |
| Hub processing | Nordic nRF52840 |
| Cellular module shown in the design | Quectel EG91-X |
| Hub connectivity | LTE and GPS |
| Sensor electronics | Nordic nRF platform, distance measurement and accelerometer |
| Local interfaces | USB-C and RGB indication |
| Power | Battery-powered hub and nodes |
The resulting system combines portable distance monitoring, local event detection and a remote application in one hub-and-node design. It supports deployments with up to 20 sensing points without fixed sensor wiring.
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Tell us about your project
Tell us what needs to be monitored, how the system will be installed and how users should receive and respond to events.
