Synchronization Issues in Data Acquisition on Android Phones for Acceleration Recordings

Android mobile phones are provided with sensors that allowto monitor several aspects in terms of motion and position of the device. These sensors are hardware-based, physical components built into the device, operated by software and mobile apps providing the user with data about motion, temperature, position, and environment. Data acquisition demands high level of time accuracy if time correlation analyses of data recorded by different mobile devices are to be carried out. In this paper, a solution in which acceleration data is transmitted from each smartphone over a wireless connection to a server, and then analyzed in time domain after re-synchronization, is proposed to determine and compare acceleration datameasurements from multiple Android mobile phones. The resynchronization procedure presented is useful when precise time synchronization is required, as it is the case, for example, in analyzing acceleration records of a multistory structure or to recover the mode shapes of a flexible floor from the acceleration records.