For most car owners, they like to regard the smartphones as the GPS software, in fact, GPS becomes very important in our life. Sometimes, we often hear about this kind of complaining, ‘How is the GPS navigation so bad? Why is there no signal now? Oh god, no direction, how to do now? ‘ We believe you have also met this kind of trouble. Recently, Xiaomi MI Note 2 released, it has also brought the amazing first technology- SAP Auxiliary Position system. Even if there is no satellite, no tunnel, it can also achieve the position.
So what’s the difference between GPS and SAP? How can SAP achieve positioning without signal? Today Xiaomi Technical Team has explained the question in its official forum.
First, What’s the reason that leads to the unstable signal?
When we use satellite to position in the city, due to the building, trees, and over pass bridges, smartphones can receive the signal from satellite. Sometimes the signal is reflected to reach the smartphone, this kind of reflected signal is the multipath effect we called in general, Non receiving satellite signal and multi-patch effect both can cause the smartphone place to drift, even can’t position under city environment.
Second. What’s the principal that Xiaomi MI Note 2 can position in the tunnel?
Xiaomi MI Note 2 is built in SAP and PDR which make use of phones’ gyroscope, accelerometer and magnetic sensor to improve the positioning performance of city environment. The gyroscope and accelerometer are the inertial device, acceleraometer can get the terminal speed and displacement information, and gyroscope can sense terminals rotating angle.
This information can get the terminals place by complicated operation. This kind of technology called inertial navigation. The advantages of inertial navigation is that it can navigate on its own without interfering from other environment. All of aircraft, spacecraft and large vessels are equipped with inertial navigation system.
Xiaomi MI Note 2 owns SAP and PDR function which can use satellite and inertial navigation comprehensively to become a integrated navigation technology. It can operate intelligently according to the difference of signal quality and inertial navigation, so that it can locate accurately under different environment to ensure the smartphone to have stable GPS signal.
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