o study the principles of mechanics in relation to human movement in sports, the use of a kinematic global navigation satellite system (GNSS) is effective because a kinematic GNSS can directly measure position in millimeter-order accuracy and velocity in centimeter per second-order accuracy in principle. It has been used for sport kinesiology (Gilgien et al., 2013; Supej, 2010), and the number of researches using kinematic GNSS has increased recently. There are two other systems that are often used to measure position in sports. One is a motion-sensor system based on an accelerometer, gyroscope, and magnetometer, and the other is a 3D kinematic measurement system based on camcorders. These systems can measure position with a higher sampling rate than a kinematic GNSS system. However, these systems measure the position indirectly from, for example, acceleration and image pixels. Furthermore, they have difficulty in calibration and synchronization. On the other hand, GNSS does not require calibration and synchronization in principle. Like a motion sensor and unlike a camcorder, a GNSS receiver must be attached to the measuring subject. For sports such as skiing and snowboarding, most of the measuring subjects are athletes. Therefore, GNSS receivers have to be compact and lightweight in order to not disturb the sophisticated and complicated movements of the subjects. In this work, we have developed a kinematic GNSS receiver (AT-H-02) for advanced ski measurements that is 78 x 38 x 18 mm3 in size, 69 g in weight, millimeter order in positioning accuracy, and centimeter per second order in velocity accuracy. Postprocessed kinematics is applied for the AT-H-02 to reduce the energy consumption and battery size. To suppress the electro-magnetic interference (EMI) between the electronic circuit board and the antenna in the AT-H-02, we covered the electronic circuit board with aluminum foil to shield the antenna from radiation noise. We validated the static and dynamic positioning accuracy of the AT-H-02. Dynamic positioning accuracy was evaluated by three kinds of experiments: cross-country skiing, alpine skiing, and snowboarding.
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