Electronic devices with motion characterization circuitry

The invention discloses an electronic device with a motion characterization circuitry. The electronic device may include a motion sensor for detecting movement of the electronic device. Applications that run on the electronic device such as fitness applications or activity logging applications may use motion sensor data to track a user's physical activity. To avoid mischaracterizing a user's movement, motion sensor circuitry in the electronic device may supplement motion sensor data with additional information in instances where motion sensor data alone may be insufficient to distinguish between different types of physical activity. For example, information on a user's speed may be synthesized with motion sensor data to help characterize a user's movement. Information on a user's speed may be determined based on location information. The location information may, for example, be gathered using IEEE 802.11 transceiver circuitry or, in more rural areas, may be gathered using Global Positioning System receiver circuitry.