Transponder systems for automatic identification purposes
US5453747A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jul 18, 1994 |
| Grant date | Sep 26, 1995 |
| Priority date | — |
| Expiry date | Jul 18, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/78
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
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…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.