Patent ID: 7640003

Claim:
A handheld mobile computing and communication device powered by a battery system for use at least as a mobile phone in a normal operation mode and for use as a survivability detecting device when a person is trapped in a disaster situation, the device comprising: (a) a first communication unit providing a means for communicating with another communication device through a public telephone network; (b) a second communication unit providing a means for communicating with another communication device through an ad hoc communication network after said first communication unit is powered off; (c) an accelerometer/gyroscope for detecting motion of said device induced by the trapped person; and (d) a power management unit comprising: a means for supplying power for the first communication unit in a normal operation; a means for measuring remaining power of the battery system in a normal operation; a means for switching off power supply to the first communication unit if the measured power is below a predetermined value; a means for supplying power for said second communication unit after said first communication unit is powered off; and a means for supplying additional power to activate said accelerometer/gyroscope if an authorized external signal is received by said second communication unit, whereby said power management unit enables said device to operate for a prolonged period of time by efficiently utilizing the reserved battery power while the trapped person is waiting for the rescue, which maximizes the opportunity that a trapped person is rescued in a disaster situation such as after an earthquake or a terrorist attack.