Tracking System and Portable Virtual Fence

A tracking system includes a global positioning system (GPS) module and a modem for mobile communications both attached to a pet (or other trackee), and a virtual fence (which includes a base station sending a signal to a certain range and a receiver attached to the pet (or other trackee) and receiving the signal sent by a base station when the receiver is within the range of the base station). A portable virtual fence system includes a signal-sending base station, and a signal-receiver worn by a to-be-fenced pet or other trackee. Advantageously, the base station is portable. The size of the virtual fence can be expanded to fit any shaped geometry using signal repeater or transceiver devices. In addition, more than one pet can be tracked using a single virtual fence and base station.