Track verification of smartphone users

Kurzfassung

Verification of tracks provided by smartphones is based on integrity check of the two types of data: Global Navigation Satellite System(GNSS) measurements and Inertial Measurement Unit (IMU) measurement. In ‘ I/O of 2016’ , Google announced that GNSS observations from devices running the Android version 7 operating system would be available to developers. The IMU measurements from motion sensors in the smartphone can be also retrieved by Android application program interface (API) function. By acquiring both GNSS and IMU data and doing the integrity check, the quality of data can been assessed. The integrity check includes static check and dynamic check. Amounts of articles about the quality assessment under the static situation has been published, however the dynamic check has not be done until now. In the static check, the position error, the carrier-to-noise density ratio (C/n0), pseudo-range noise, phase noise and pseudo-range rate noise of GNSS observations are evaluated. The noise type of the IMU sensor in the smartphone has been analyzed. In dynamic check, the data acquisitions are done under different environments and moving statuses. The urban environments with surroundings influence the quality of GNSS signals. The stronger moving status influence the quality of IMU measurements. The accuracy of GNSS and IMU measurements of smartphone is evaluated. Some useful indicators about the quality of data given by the Android system has been found out.