使用声纳软件来管理笔记本的电源

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使用声纳软件来管理笔记本的电源

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使用声纳软件来管理笔记本的电源，当使用者暂时离开电脑时，该软件就能自动让笔记本进入省电or休眠or关闭显示器模式，使得电源管理变得更加人性化。

既然是声纳，所以这个软件必须得用上笔记本上的话筒和扬声器。据说这个东西能够在你离开笔记本一定距离时，立马关闭显示器以达到省电的作用。这样就可以避开目前比较弱智的winodws电源管理系统，例如常常在我们看电影时跳出黑屏。

研究人员Tarzia 介绍到：如果该声纳系统10秒钟内未收到任何回音，那就说明该电脑目前木有人使用了。该软件大约可以探测笔记本周围2.43米的地区，一旦发现没人就立即关闭显示器，并且只能使用鼠标才能重新开启电脑。
# 该软件由美国西北大学、Michigan 联合研究小组发布，并且已经开源和供免费下载

For better power-savings from your computer display

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 and UMichigan. 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 ultrasonics (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 ultrasonics. 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.

Screenshot

The blue line is the history of sonar readings, taken about once every second. The black line is the average of the last ten consecutive sonar readings (in other words it is a smoothed version of the blue line). The red line is the presence threshold. When the black line dips below the red line, the display is shut off.

Calibration: After ten readings are taken, the presence threshold is set to one half of the blue line average.
Activity: When the user moves the mouse or types a key, the sonar stops doesn't start again until the user is inactive.
Absence: In this example, the user walked away here.
Sleep: Several seconds after the user left, the screen is shut off. Sonar resumes after the user has both woken up the screen and become inactive again.

Technical details

The following technical publication describes our sonar presence detection system in detail:

S. P. Tarzia, R. P. Dick, P. A. Dinda, G. Memik. Sonar-based Measurement of User Presence and Attention. In Proc. 11th Intl. Conf. on Ubiquitous Computing (UbiComp'09). September 2009. pages 89-92.