A recent patent filing, submitted by Apple, describes an anti-theft system that utilizes acceleration data to detect if a portable device is stolen. Information from the accelerometer would be analyzed by a controller to determine if the particular direction and speed of movement indicates that a thief might be taking the device.

To avoid false alarms, the system would include a filter for attenuating common acceleration frequencies and "isolating those representative of theft." The software plays a role in determining if the acceleration data matches a "known acceleration profile characteristic of theft."

Fig. 5 shows an outline of the basic functions available through the graphical user interface. Controls would be provided for enabling the alarm, setting the volume, or displaying a personalized warning message. The sensitivity can also be adjusted, along with the time it takes before the alarm reaches full volume. A password dialog would provide a way for the owner to disable a false alarm.

Apple integrates accelerometers in a variety of portable devices. In a MacBook, the sensor is used to lock a hard drive to protect data if the notebook is dropped. The iPhone, iPod touch and iPod nano use an accelerometer for several different functions such as screen reorientation, tracking steps while walking, or as input for playing games.

It remains unclear if Apple plans to add the anti-theft protection to its mobile products. The company files for a variety of patents, although not all of the technology is immediately integrated.