Abstract: A blue tooth communication system for a mobile device includes a mobile device and a cooperated device. The mobile device has a blue tooth module. The cooperated device has a blue tooth module and a radio emitting-receiving module. The blue tooth module of the cooperated device is in communication with the blue tooth module of the mobile device. A network is established between the user with the blue tooth communication system and different users with the same systems. The user is able to send messages, pictures and precise positions by using GPS. When there is no service signals for the mobile device, the system is used as a radio communication device.

Abstract: A calorie counting racket has a skeleton (10) with a hollow grip (11) and a counter unit (20) secured inside the grip (11) with multiple press buttons and a display (25) protruding from a side surface of the grip (11). The counter unit (20) has a microprocessor (21), a frequency counter (22) to record numbers of swings of the racket, a force estimating unit (23) to detect acceleration of the skeleton (10), a set of press button to control the microprocessor (21), and a display (25) to show calorie data. So that the calorie counting racket determine the burned calories immediately and precisely in accordance with different users.