Transponder systems for automatic identification purposes

United States Patent m

D'Hont et al.

[54] TRANSPONDER SYSTEMS FOR

AUTOMATIC IDENTTFICATION PURPOSES

[75] Inventors: Loek D'Hont, Almelo; Anne Tip, Overdinkel, both of Netherlands; Herbert Meier, Moosburg, Fed. Rep. of Germany

[73] Assignee: Texas Instruments Incorporated, Dallas, Tex.

[21] Appl. No.: 83,808

[22] Filed: Jun. 28,1993

[30] Foreign Application Priority Data

Sep. 28, 1992 [GB] United Kingdom 9220412

[51] Int. CI.* G01S 13/74

[52] U.S. Q 342/42; 342/44

[58] Field of Search 342/42, 44

[56] References Cited

U.S. PATENT DOCUMENTS

4,121,102 10/1978 Wilson 342/44

4,303,904 12/1981 Chasek 342/44

4,912,471 3/1990 Tyburski et al 342/51

5,053,774 10/1991 Schuermann et al 342/44

5,128,669 7/1992 Dadds et al 342/42 X

5,245,346 9/1993 Nishimura et al 342/42

Primary Examiner—Mark Hellner

[ii] Patent Number: 5,351,052 [45] Date of Patent: Sep. 27, 1994

Attorney, Agent, or Firm—Brian C. McCormack; James C. Kesterson; Richard L. Donaldson

[57] 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 avoided. Other devices, systems and methods are also disclosed.

19 Claims, 3 Drawing Sheets