Backscattering transponder switchable between a modulator/demodulator and ground

• US 5,640,687 A
• Filed: 05/20/1994
• Issued: 06/17/1997
• Est. Priority Date: 05/24/1993
• Status: Expired due to Fees

• Current Assignee: Telematics Wireless Ltd.
• Original Assignee: Tadiran, Ltd.
• Inventors: Cohen, Dan, Meron, Peretz, Ianconescu, Reuven, Mahlab, David, Yarom, Moshe, Rosen, Yonina, Reichman, Arie
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): BANKS HAROLD, MARSHA DENISE
• Application Number:
  US08/246,872
• Time in Patent Office: 1,124 Days
• Field of Search: 340/825.54, 340/928, 340/942, 235/384, 455/78-79, 455/82-83, 455/106-107, 375/219, 375/222, 375/268, 375/300, 375/315
• US Class Current: 455/83
• CPC Class Codes: G01S 13/765 with exchange of information between interrogator and responder
• CPC Class Codes: G07B 15/063 using wireless information transmission between the vehicle and a fixed station identification of vehicles G08G

Abstract

An electronic toll system for monitoring a plurality of lanes including a plurality of lane monitoring devices operative to monitor passage of vehicles through the corresponding plurality of lanes, and a lane monitoring device coordinating system for coordinating operation of the lane monitoring devices such that not all of the lane monitoring devices operate simultaneously.

Claims

1. A backscattering transponder comprising:

a modulator/demodulator;

an antenna operative to transmit modulated data generated by the modulator/demodulator; and

antenna switching apparatus which switches the antenna between the modulator/demodulator and ground such that when the antenna is in a receiving mode, the antenna is connected to the modulator/demodulator and such that, when the antenna is in a transmitting mode, the antenna is switched between the modulator/demodulator and ground according to the modulated data.

2. A transponder according to claim 1 wherein the antenna switching apparatus comprises at least one diode.

3. A transponder according to claim 2 wherein the antenna switching apparatus comprises a single diode.