초록 ▼

A system and method which conserves energy in the operation of a transponder or tag (14) by providing that the transponder (14) be enabled or awakened in multiple stages. A threshold detector (62) is provided which measures the power level of received RF energy. If the RF energy received by the dete

A system and method which conserves energy in the operation of a transponder or tag (14) by providing that the transponder (14) be enabled or awakened in multiple stages. A threshold detector (62) is provided which measures the power level of received RF energy. If the RF energy received by the detector (62) exceeds a pre-determined level, the transponder (14) then employs a modulation detector (64) to ascertain whether it has been awakened by a valid interrogation signal from an interrogator (12) or whether the RF energy received was merely a spurious burst of RF energy from some other source. If a pre-determined modulation is detected by the modulation detector (64), the transponder (14) is then fully activated to its normal operational state.

대표청구항 ▼

A remote identification system comprising an interrogator and a transponder for identifying and locating a vehicle comprising: an interrogator having a transmitter for transmitting a wake-up signal, an interrogation signal and a continuous wave RF signal and a receiver for receiving a transponder re

A remote identification system comprising an interrogator and a transponder for identifying and locating a vehicle comprising: an interrogator having a transmitter for transmitting a wake-up signal, an interrogation signal and a continuous wave RF signal and a receiver for receiving a transponder response signal; a transponder comprising a wake-up circuit for receiving said wake-up signal and in response to said wake-up signal, applying a clock signal to a modulating circuit in said transponder; a discriminator for receiving said interrogation signal and determining which lane said transponder is located; said modulating circuit for modulating said received continuous wave RF signal with transponder reply data upon receipt of said clock signal.