Engineered Systems Magazine

Wireless sensor system

April 28, 2011

Powercast, a developer of radio frequency (RF) energy harvesting and wireless power technology, has announced its Lifetime Power Wireless Sensor System for environmental monitoring in HVAC control and building automation. It features transmitters that broadcast RF energy to perpetually power wireless sensors without batteries or wires.

The system includes three parts: a family of battery-less sensor nodes embedded with Powercast’s Powerharvester receivers, a WSG-101 Building Automation System (BAS) Gateway, and Powercast’s TX91501 Powercaster transmitter.

The first sensor is a temperature and humidity sensor, to be followed shortly by sensors to measure CO2, pressure, light, and motion.

In the wireless powering system, Powerharvester receivers embedded inside the sensor nodes receive RF energy up to 60-80 feet away from the Powercaster transmitters broadcasting radio waves at 915 MHz. The receivers then convert the RF energy into DC current to power the sensors wirelessly, similar to RFID, but with longer range and greater functionality. Broadcasted RF energy can reach and power sensors even through walls, above ceilings, and behind objects, and provides a reliable energy source as opposed to pure ambient energy-harvesting technologies such as indoor solar, thermal, or vibration.

The BAS gateway can scale up to 100 sensor nodes and 800 sensor points, interfaces to wired BAS networks via industry-standard protocols (BACnet, Modbus, Metasys, and LonWorks) and communicates wirelessly at 2.4GHz using 802.15.4 radios.

Powercast developed the system using its core RF transmitter and receiver energy-harvesting technology, and the other devices in Powercast’s P2110-EVAL-01 Energy Harvesting Development Kit for Wireless Sensors. The receiver embedded in the sensor nodes is based on Powercast’s P2110 Powerharvester receiver, which is available for OEMs to design into their own products.

The Lifetime Power Wireless Sensor System costs around $300 per node for typical, multi-node deployments. A starter kit (2 temperature and humidity sensors, a transmitter and a BAS gateway) is available for $799.