Wireless Sensor

A Wireless Sensor is a self-contained monitoring device that measures physical or electrical parameters (current, voltage, temperature, vibration, humidity, etc.) and transmits the data over a wireless network (LoRa, Zigbee, NB-IoT, Wi-Fi, or Bluetooth). In AGL applications, these sensors are deployed on:

• Lighting Fixtures: Monitoring current, temperature, and lamp status to detect failures early.
• Isolating Transformers: Measuring primary and secondary current, and winding temperature.
• CCRs and Power Equipment: Monitoring load current, ambient temperature, and vibration.
• Cable Systems: Detecting current imbalance or earth leakage using clamp-on current sensors.
• Environmental Conditions: Tracking ambient temperature, humidity, and precipitation near critical equipment.

Wireless sensors reduce installation costs, enable retrofitting of existing infrastructure, and provide real-time visibility into the health of AGL systems, supporting predictive maintenance and operational efficiency.

The wireless sensor's purpose is to extend the same current, temperature, or vibration monitoring available on smart fixtures and transformers to equipment and locations where running new cabling would be impractical or prohibitively expensive — making retrofit monitoring of existing airfield infrastructure genuinely feasible rather than something that only applies to newly installed equipment. Its long battery life and low-power wireless transmission exist specifically so it can be installed and largely forgotten for years, providing the same early-warning visibility into equipment health as a wired sensor without requiring trenching, conduit, or a hard-wired power supply. This is what allows an airport to add condition monitoring incrementally across its existing lighting circuits rather than needing a wholesale infrastructure upgrade to gain that visibility.

Wireless sensors are deployed across the airfield where monitoring is needed but cabling is impractical:

• Runway and Taxiway Lighting: Monitoring individual edge, centreline, and threshold lights for current and temperature anomalies.
• Isolating Transformers: Monitoring transformer health to predict failures before they cause circuit outages.
• CCR Rooms: Environmental monitoring (temperature, humidity) of equipment shelters.
• Approach Lighting: Monitoring barrette and flashing light status for approach systems.
• Obstruction Lighting: Ensuring beacons and obstruction markers are operational.
• PAPI and VASI Systems: Verifying correct lamp current and tilt angle.
• Remote Equipment: Monitoring wind cones, VDGS, and other standalone systems.

Sensors are typically mounted inside or adjacent to the equipment being monitored, with antennas positioned for optimal wireless coverage.

The sensor is fixed to (or placed directly inside) the fixture, transformer, or shelter it monitors, using adhesive, a magnetic base, or a small bracket, positioned so its measurement point (current clamp, temperature probe, or humidity element) sits in direct contact with or close proximity to what it's sensing. Because there's no cabling to a control room, siting is driven mainly by radio performance: the unit is placed to keep line-of-sight or minimal obstruction to the nearest gateway, clear of dense metal enclosures that would attenuate the signal, and a coverage check is carried out at installation before the sensor is sealed into its final position. Battery-powered units are sited for reasonable access at replacement intervals, and the sensor's location and parent asset are registered on the monitoring platform so its readings map to the correct piece of equipment.

A wireless sensor operates through a combination of sensing, processing, and communication. The device includes:

• Transducer/Sensor Element: Converts the physical parameter (current, temperature, vibration) into an electrical signal (e.g., Hall effect for current, thermistor for temperature).
• Signal Conditioning: Amplifies, filters, and digitizes the signal using an analog-to-digital converter (ADC).
• Microcontroller: Processes the data, performs local calculations, and determines if alerts need to be triggered.
• Wireless Transceiver: Transmits the data using a low-power protocol (LoRa, Zigbee, NB-IoT, etc.) to a nearby IoT Gateway or directly to the cloud.
• Power Source: Typically a long-life battery (3-10 years) or energy harvesting (solar, inductive) to ensure maintenance-free operation.
• Enclosure: Rugged, weatherproof housing (IP67/IP68) to withstand airfield environments.

The sensor typically operates in a low-duty cycle mode, waking up periodically (e.g., every 5 minutes) to take a measurement, transmit data, and then returning to deep sleep to conserve battery. Some sensors also support event-driven transmission when a threshold is exceeded.

Battery life over years, not raw performance, is what shapes this device's control logic. For most of its life the MCU sits in a deep-sleep state drawing microamps, woken only by one of two triggers: a real-time-clock interrupt on a fixed schedule (e.g., every 5 minutes) or an interrupt from the sensing element itself when a configured threshold is crossed. On waking, the MCU powers up the sensor and analog front end just long enough to take and condition a reading, then powers up the radio transceiver, forms a small data packet, and transmits it to the nearest gateway using whatever low-power protocol the sensor is built around (LoRa, Zigbee, or NB-IoT) — the radio is the single largest power draw in the system, so the firmware minimises its on-time rather than the sensing itself. If the gateway does not acknowledge receipt, the MCU can buffer the reading and retry on the next cycle rather than holding the radio on to wait. Once transmission (or buffering) completes, every subsystem is powered back down and the MCU returns to sleep until the next scheduled or threshold-triggered wake, a pattern that is what allows a coin-cell or small battery pack to last several years in the field.

The sensor node is built into a compact, sealed polymer or die-cast enclosure rated IP67/IP68, sized to house the sensing element (current transformer, thermocouple, accelerometer, or humidity/pressure element), signal-conditioning circuitry, wireless radio module, and battery pack within a single weatherproof shell. The enclosure incorporates a moulded antenna window or external whip antenna positioned to maximise radio range while remaining protected from physical damage, and cable glands or potted cable entries seal the connection to the sensed conductor or mounting point against moisture ingress. Mounting features, such as DIN-rail clips, magnetic bases, or bolt-on brackets, are integrated into the housing to suit installation on cables, conduits, or fixture bodies without additional hardware. The battery compartment is designed for field replacement without breaking the main enclosure seal, and the overall unit is built to withstand the wide operating temperature range and vibration typical of outdoor, unattended AGL monitoring points.