Computer Operating Systems typically try to save power by turning off the display after some keyboard/mouse activity timeout: maybe 10 minutes. Wouldn’t it be better if the computer actually knew when you were at the computer and when you have left?

Overview

The Sonar Power Manager uses a new user presence detection technique to shut off the computer display when you are not present. It was developed by myself and other researchers at Northwestern University and University of Michigan. The goal is to shut off the screen immediately after you leave, even if you just moved the mouse 10 seconds ago.

It uses a very simple type of sonar system to accomplish this:

The Sonar Power Manger uses ultrasound (sound above 20kHz in frequency and which humans cannot hear) on your computer’s regular sound system. Surprisingly, we have found that many laptops can use ultrasound. However, many laptops cannot. For these unlucky users, the Sonar Power Manager will not properly detect user presence. Other unlucky users will find that their speakers produce annoying lower-frequency harmonics or noise while the sonar is operating.