Patent ID: 8253684

Claim:
A computer-implemented method comprising: receiving for a plurality of times in a time period, a plurality of data points from an accelerometer and a plurality of data points from a magnetometer, the accelerometer and the magnetometer included in a mobile computing device; for each of the data points, determining an orientation and a position of the mobile computing device based on an acceleration output and a magnetometer output that corresponds to the particular time; determining a trajectory that represents movement of the mobile computing device during the time period based on the determined orientations and positions of the mobile computing device at the plurality of times; comparing information that characterizes the trajectory to stored information that characterizes a set of one or more base trajectories; based on the comparison, identifying an operation of the mobile computing device that is associated with a trajectory included in the set of one or more base trajectories, wherein identifying the operation of the mobile computing device comprises recognizing that a user holding the mobile computing device has made a gesture that corresponds to the trajectory and that is associated with operation of the mobile computing device, wherein the recognized gesture comprises a gesture associated with the operation of voice recording that comprises the user holding the mobile computing device to the user's face such that a microphone on the mobile computing device is close to the user's mouth and a speaker on the mobile computing device is away from the user's face; and automatically initiating a voice recording operation in response to recognizing that the user has made the gesture.