e die, it is the only sensing system that gives us information on what's happening behind us. Perceptions of video quality improve if audio quality is improved. Ring tones also sound better. How and why ring tones became a multibillion pound business remains a compete mystery to me but then that's why I don't drive a Porsche and have time to write a book like this. 5.2.2 Positioning Capabilities Positioning includes micropositioning and macropositioning. Many iPhone applications ex- ploit information from a three-axis gyroscope, an accelerometer and a proximity sensor to perform functions such as screen reformatting. This is micropositioning. Macropositioning typically uses GPS usually combined with a digital compass. Gyroscopes are MEMS elements that sense change in an object's axis of rotation including yaw, pitch and roll. Traditionally, a separate sensor would be needed for each axis but the example shown from STMicroelectronics in Figure 5.3 uses one MEMS-based module taking up 4 by 4 by 1 mm. An accelerometer takes up about 3 mm square. By the time you read this these two devices will probably be available in a single package. The devices have a direct cost but an indirect real-estate cost and a real-estate value. The value is realised in terms of additional user functionality. In the previous chapter we referenced products in which the display turns off when the phone is placed to the ear. The gyroscope can be set at one of three sensitivity levels to allow speed to be traded against resolution. For example, for a gaming application it can capture movements at up to 2000 degrees per second but only at a resolution of 70 millidegrees per second per digit. For the point-and-click movement of a user interface - a wand or a wearable mouse - the gyroscope can pick up movements at up to 500 degrees per second at a resolution of up to 18 millidegrees per second per digit. The 3-axis gyroscope illustrated draws 6 milliamps compared to 5 milliamps for each of the three devices needed two years ago. The device can b