An portable tracking device integrating a mobile phone module (e.g. based
on GSM or 3G networks), a GPS module, a radio Beacon and ultrasonic
beacon. The tracking device is normally in a hibernated state when the
entire device consumes little energy and require no periodically changing
or recharging batteries to power the device. It consumes power from the
primary battery only when a tracking process is actually taken place.
With this portable tracking device on the person who is unable to
affirmatively report his or her whereabout, the remote center and/or a
search team can communicate the GPS module, radio beacon and ultrasonic
beacon of the tracking device via the mobile phone module based on
existing wireless communication technologies, such SMS, GPRS, ect, on GSM
or 3 G networks, which also serves as a means of initial rough estimation
of the tracking device's location.