09 April 2009

Yet Another Nokia N97 Hands-On Video
Introduction Of The Build-in Digital Compass

Combined with an 'accelerometer' which measures changes in direction and orientation, the built-in digital compass improving accuracy of determining the azimuth and makes it easy to follow the map when strolling about on foot.

By including a compass that works in conjunction with the accelerometer and new features of Maps, the pedestrian navigation experience has been significantly improved.

GPS receiver is indeed capable of fixing direction in which a user in moving (azimuth) even without compass assistance by keeping in memory some previous results of location's measures.

These points make a line that points direction in which the device is moving. Unfortunately in case of pedestrians, their speed is too low and distance passed between subsequent measures is comparable to error caused by inaccuracy of measures.

It causes growing inaccuracy of determined direction (for speed of 4 km/h inaccuracy is about 20-40º). Only speed over 20 km/h guarantees accuracy about 5º or less of determined azimuth (in urban environment).

Because of that, Nokia has equipped their latest GPS enabled phones such as Nokia 6210 Navigator , Nokia 6220 Classic as well as Nokia N97 with digital compass that using Earth's magnetic field for improving accuracy of determining the azimuth.

Such compass can determine how a user is turned toward north direction. With geographical coordinates of a target point, the device itself (fixed by satellite navigation) and direction in which the user is turned, the device can determine direction in which the user should go.

With magnetic compass, the device can determine direction even before the user moves. User is guided from the very first moment, when activates this function in the device which is especially important for blind persons. Magnetic compass also reacts immediately to changes of direction when the user is walking.

Electronic compass usually contains two magnetometers which measure magnetic field in two perpendicular directions. Measuring Earth magnetic field requires very sensitive sensors. These are magnetoresistive sensors, which use material where resistance changes under external magnetic field .