Duplex transmission in an electromagnetic transponder system

• US 6,784,785 B1
• Filed: 04/05/2000
• Issued: 08/31/2004
• Est. Priority Date: 04/07/1999
• Status: Expired due to Term

• Current Assignee: Molex Incorporated (KOCH Industries Incorporated), STMicroelectronics SA (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Inventors: Enguent, Jean-Pierre, Wuidart, Luc, Bardouillet, Michel
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): BROWN, VERNAL U
• Application Number:
  US09/543,824
• Time in Patent Office: 1,609 Days
• Field of Search: 340/10.1, 340/10.2, 340/10.5, 340/825.7, 340/825.72, 340/10.51, 340/825.69, 342/30, 342/43, 370/329, 370/332
• US Class Current: 340/10.1
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Abstract

A method of transmission between two elements chosen from a terminal and a transponder, each element including an oscillating circuit, a modulator and a demodulator, including simultaneously performing a transmission in amplitude modulation of a signal transmitted from a first to a second element and a transmission of a signal from the second to the first element adapted to being submitted to a phase demodulation in the latter, and wherein the amplitude modulation rate is smaller than 100%.

Claims

1. A method of transmission between a terminal and a transponder, each including an oscillating circuit, a modulation means and a demodulation means, the method including steps of simultaneously performing an amplitude-modulated transmission of a signal transmitted from the terminal to the transponder and a transmission of a signal from the transponder to the terminal adapted to being submitted to a phase demodulation in the terminal, and wherein an amplitude modulation ratio is smaller than 100%, the method further comprising regulating a signal phase in the oscillating circuit of the terminal with respect to a reference value, a response time of phase regulation being shorter than an amplitude modulation period and longer than a period of a signal that will have to undergo a phase demodulation.

2. The method of claim 1, further including a step of, on a terminal side, clipping a received signal before demodulation.

3. The method of claim 1, wherein the amplitude modulation ratio is smaller than 50%.

4. The method of claim 3, including, on the terminal side, clipping a reference signal of the phase demodulation.

5. A terminal for implementing a method of transmission between the terminal and a transponder, each including an oscillating circuit, a modulation means and a demodulation means, the method including steps of simultaneously performing an amplitude-modulated transmission of a signal transmitted from the terminal to the transponder and a transmission of a signal from the transponder to the terminal adapted to being submitted to a phase demodulation in the terminal, and wherein an amplitude modulation ratio is smaller than 100%, the terminal including:

means for comparing transmitted and received signals clipped by respective clipping means; and

means for regulating a signal phase in the oscillating circuit of the terminal with respect to a reference value, a response time of phase regulation being shorter than an amplitude modulation period and longer than a period of a signal that will have to undergo a phase demodulation.

6. A transponder for implementing a method of transmission between a terminal and the transponder, each including an oscillating circuit, a modulation means and a demodulation means, the method including steps of simultaneously performing an amplitude-modulated transmission of a signal transmitted from the terminal to the transponder and a transmission of a signal from the transponder to the terminal adapted to being submitted to a phase demodulation in the terminal, and wherein an amplitude modulation ratio is smaller than 100%, the transponder including an amplitude demodulation means sized according to attenuation introduced by a back modulation means.

7. A transponder for implementing a method of transmission between a terminal and the transponder, each including an oscillating circuit, a modulation means and a demodulation means, the method including steps of simultaneously performing an amplitude-modulated transmission of a signal transmitted from the terminal to the transponder and a transmission of a signal from the transponder to the terminal adapted to being submitted to a phase demodulation in the terminal, and wherein an amplitude modulation ratio is smaller than 100%, the transponder including an amplitude demodulation means, a result of which is only taken into account during one state out of two of an output signal of a back modulation means.