Team of researchers at Microsoft has taken up the task of giving you a perfect solution in the situations where GPS refuses to work. A prototype device called Menlo phone will collect the data with the help of the sensors, as the user walks indoors or in the places where GPSâ€™s signals are weak. This data is called the trail data, as the sensors basically collect the footprints, as a person walks. These sensors are called an accelerometer, which detects movement, a side-mounted compass, which determines direction, and a barometric pressure sensor, which tracks changes in altitude. In addition to these sensors, Menlo packs an app called Greenfield, which makes the entire data collecting complete, as it takes the collected data from the sensors. In fact, this is the app that really makes this phone different form others also having the sensors. This app is called activity based navigation and in the paper, which is to be presented at the MobileHCI conference in Lisbon, next month, Microsoft team has positioned Greenfield as an ideal method of navigation in places where maps cannot reach.