Ultrasonic sound wakes up small devices in IoT networks

February 14, 2018 | 10:56
Ultrasonic sound wakes up small devices in IoT networks
Ultrasonic sound wakes up small devices in IoT networks
A switched off device does not reduce battery life, but is does not work either. Now, an energy-efficient system that is always on alert can turn on devices when needed. This saves energy for applications in IoT network.

Just as smartphone users know only too well, a sleep mode can drain a battery. One solution to increase battery life of wireless devices batteries is to add a wake-up receiver that can turn on an on/off device at some point.

Researchers from the Arbabian Lab at Stanford University have developed an alarm receiver that turns on a device via incoming ultrasonic signals. These work on a significantly smaller wavelength and switch from radio waves to ultrasound. As a result, this receiver is much smaller than similar alarm receivers that respond to radio signals while operating at extremely low power and with a wider range.

Once attached to a device, an alarm receiver listens to a unique ultrasonic pattern indicating when the device should be turned on. It only needs a very small amount of power to maintain this constant listening experience.

In order to miniaturise the alarm receiver and reduce the amount of power it consumes, researchers used the highly sensitive ultrasonic transducers that convert analogue sounds into electrical signals. This system detects a wake-up action of 1 nanowatt signal power.

According to the designers, the alarm receiver has many potential applications, especially when designing the next generation of network devices that can communicate directly with each other without human intervention.
Source: Stanford University
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