For synchronizing the clocks on both the mobile phones, we designed a Bluetooth-based synchronization protocol. This protocol is similar to the precision time protocol-IEEE 1588 [3] used in wired networks.The synchronization procedure follows a master–slave architecture. The mobile phone which receives the synchronization messages acts as the master and the one sending acts as the slave.We employed the Nexus One and HTC Hero mobile phones running Android operating system. The Nexus One was equipped with a Broadcom BCM4329 chipset supporting Bluetooth 2.1+EDR (extended data rate technology) along with 802.11n WiFi and the Hero supports Bluetooth2.1+ EDR along with a 802.11b/g WiFi connectivity. The phones communicated via the Android BlueZ[4],a Bluetooth2.1 compatible stack capable of running on any Bluetooth chipset. The Nexus One used for video recording, acted as the master and the Hero, used for heart beat recording, acted as the slave. The synchronization procedure consists of two steps as explained below.