GPS is utterly useless for finding your wife or kids (or even locating yourself) at the mall. What we need is an indoor equivalent of GPS. And researchers have been working on it.
在商场，寻找你的妻子或孩子（或者为你自己定位）时GPS完全是起不了作用的。我们需要一款室内GPS装置。研究人员们已经开始了研制它的工作。

Most recently a team of Stanford students launched a project called WiFiSLAM. Their goal is to develop mobile applications that let your smart phone pinpoint its location in real-time to within 2.5 meters. It would do it by sensing ambient WiFi signals already present in buildings. The phone's internal compass and accelerometer also come into play to help determine its location.
最近，由斯坦福学生组成的团队成立了一个名为WiFiSLAM的项目。他们的目标是开发一款手机应用程序，该程序能够在2.5m之内精确定位。它通过遥感建筑物内已有的WiFi信号来实现。手机内置的罗盘和加速度计亦能帮助手机定位。
The students also want to create apps that could be use for marketing, depending upon what store a smart phone user is standing near. Another app might connect the user's location to social networks.
这些学生还想开发能够用于市场营销的的应用程序，该程序能找到手机用户附近商店的位置。另外一款应用可能将用户的位置与社交网络相联系。
Other indoor positioning systems try to find a user's position using radio, ultrasound or infrared signals. But these approaches require special radio-frequency tags. WiFiSLAM's approach is promising because it uses existing wireless networks and the smart phone already in your pocket.
其他的室内定位系统尝试通过使用无线电，超声波或者红外信号来给用户定位。但是这些方法需要特定的射频终端。WiFiSLAM项目之所以有前景，是因为它使用了现有的无线网络和你口袋里的手机来定位。（Larry Greenemeier报道）