Stanford University researchers use ultrasound signal to trigger smart devices

Stanford University researchers use ultrasound signal to trigger smart devices
The future home as we imagine nowadays is full of connected devices, from tiny sensors, carbon monoxide detectors to security cameras and smart speakers. However, what is the most energy-saving way to awaken a device? A team of researchers at Stanford University said ultrasound is the answer.

Some connected devices are always on at home, such as Wi-Fi routers. However, not all devices, like light bulbs and speakers, need to be turned on all the time. Nonetheless, we still need to minimize the required energy to transmit the wake-up signal.

Sensors now use radio to transmit and receive the signal, which is actually very energy-consuming. Keeping the antenna and signal processor ready and listening uses very much energy.

Angad Rekhi, a graduate student at Stanford University, and Amin Arbabian, assistant professor of electrical engineering, have developed a wake-up receiver that turns on a device using ultrasonic signals, which is outside the range of audible sounds for human beings.

It uses less energy because detecting ultrasonic signal is easier in many ways than detecting radio frequency.

The system developed by the team uses an always-on receiver, which consumes only 4 nanowatts of power and is able to detect a signal with a single nanowatt’s strength. In terms of sensibility and power consumption, ultrasonic outperforms radio waves.

The ultrasound wake-up receiver does require a battery but can function in greater range than wirelessly powered devices. It has a longer lifetime because it consumes less power.

Although ultrasound signals can’t go through walls, its applications in future smart homes and the IoT industry can still be expected.

For instance, a security camera can use the technology to send signals to smart lights at the doorway when detecting intruders. Both devices will consume very little power while talking to each other.

“As technology advanced, people use it for applications that you could never have thought of. The internet and the cellphone are two great examples of that,” said Rekhi. “I’m excited to see how people will use wake-up receivers to enable the next generation of the Internet of Things.”
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