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...http://www.google.es/patents/US7411492?utm_source=gb-gplus-sharePatente US7411492 - Pet tracking systems, other tracking systems, and portable virtual fence
Pet tracking systems, other tracking systems, and portable virtual fence
