Transponder systems for automatic identification purposes

US5351052A · kind A · utility

Assignee

• TEXAS INSTRUMENTS INCORPORATED · US

Inventors

• Loek D'Hont · Plano, US
• Anne Tip · Hengelo, NL
• Herbert Meier · Regensburg, DE

Key dates

• Filing date: Jun 28, 1993
• Grant date: Sep 27, 1994
• Expiry date: Jun 28, 2013

Classification

• Technology area (CPC G): Physics
• CPC primary: G01S13/78
• WIPO field: Control
• WIPO sector: Instruments

Abstract

A method of communicating between an interrogator (10) and at least a first and second transponder (12). The transponders (12) are separately located within a first and a second vehicle (20) travelling within a first and a second traffic lane, respectively. The method has the steps of providing a first and a second LF antenna (16) associated with and proximity to a first and a second traffic lane, respectively. From each of the first and second LF antennas (16) a continuous LF subcarrier is transmitted to serve as a clock signal for each antenna's associated transponder (12). Initially, a wake-up signal is sent by each of the LF antennas (16) to its associated transponder (12). Following the wake-up signal, a unique lane code is sent by each of the LF antennas (16) to its associated transponder (12). The transponder (12) stores its unique lane code in its memory (70). The transponder then sends a UHF response in a pre-determined time period depending on the unique lane code stored in each of the transponders (12). The time period in which the transponder (12) sends its UHF response is unique to that transponder (12) so that interference between responding transponders (12)is avoide…