초록 ▼

A radio system and method for monitoring and locating objects, including individuals, animals and articles, both locally and on a nationwide scale use monitoring base stations communicating by ID code with portable transponders which are secured to the objects to be monitored. The transponder respon

A radio system and method for monitoring and locating objects, including individuals, animals and articles, both locally and on a nationwide scale use monitoring base stations communicating by ID code with portable transponders which are secured to the objects to be monitored. The transponder responds to signals transmitted by the base, the latter indicating by an alarm the absence of a timely appropriate response from the transponder. The base is capable of performing and participating in homing techniques to locate a lost transponder. A list of the IDs of all transponders reported missing is distributed from a central source by nationwide communication to a network of radio stations, each station broadcasting the list in an encoded signal in repetitive sequence along with regular programming. Cruising vehicles of public safety departments operating locally nationwide are equipped with automatic monitors for receiving specially coded messages including IDs from transponders within their areas. Each transponder, after failing to receive a signal from its base for a predetermined time period has the capability of scanning the band of the radio station network, locking onto the local station of the network and receiving its ID from the locked-on station when reported lost. Upon receipt of its ID from the locked-on station, the transponder initiates transmission of the specially coded message to make its presence known to the monitor of a local cruising vehicle and thereafter is capable of establishing communication with a local base for participation in local homing.

대표청구항 ▼

A monitoring and finding system comprising a monitoring base station and a transponder, said base station having a transceiver and alarm condition alerting means, said transceiver having means for intermittently transmitting encoded signals having at least an ID code, said transponder being secured

A monitoring and finding system comprising a monitoring base station and a transponder, said base station having a transceiver and alarm condition alerting means, said transceiver having means for intermittently transmitting encoded signals having at least an ID code, said transponder being secured to an object to be monitored and having means for receiving said signals, recognizing said ID code and transmitting an encoded timely response including said ID code, said transceiver having means for detecting the absence of said timely transponder response and activating said alerting means, said transceiver and transponder both having means for selectively transmitting at a normal power or at a relatively higher power, said transceiver having means for transferring the next signal in said intermittent transmission from the normal power to said higher power in the absence of said timely transponder response and for encoding instructions in said next signal for the transponder to likewise transfer to said higher transmitting power, said transceiver having means, responsive to each receipt of said timely transponder response, for setting the transmission of the next signal to said normal power and for encoding instructions to the transponder to transfer to normal power, said high power transmission enabling communication between base and transponder in an out-of-range condition, said base having manual means for de-activating said alerting means, whereby after such manual de-activation, subsequent re-activation of said alerting means indicates a probable out-of-range condition.