Non-contact smart card interrogator, wherein across a transmission line from an antenna to a receiver the signal modulation varies between amplitude modulation and phase modulation

• US 7,215,239 B2
• Filed: 07/25/2002
• Issued: 05/08/2007
• Est. Priority Date: 08/03/2001
• Status: Expired due to Term

• Current Assignee: ams AG (Ams-Osram AG)
• Original Assignee: {hacek over (S)}tern, Anton, Vinko Kunc
• Inventors: Kunc, Vinko, {hacek over (S)}tern, Anton
• Primary Examiner(s): Hofsass; Jeffery
• Assistant Examiner(s): AU, SCOTT D
• Application Number:
  US10/485,561
• Publication Number:
  US 20040201453A1
• Time in Patent Office: 1,748 Days
• Field of Search: 340/10.1, 340/10.2, 340/10.3, 340/10.4, 340/572.3, 340/572.5, 340/572.7, 340/825.54, 235/462.26
• 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

In a non-contacting smart card interrogator (1) a first end (A) of an eighth-wave transmission line (13) is connected to a terminal connecting a first receiver (16) to a transmission line (14), and to a second end (B) of the transmission line (14) the carrier wave generator (11) is connected. To the first end (A) of the eighth-wave transmission line (13) the first amplitude demodulation receiver (16) and to the second end (B) thereof a second amplitude demodulation receiver (16′) are connected. In the non-contacting smart card interrogator of the invention an effective use of amplitude demodulation is made possible by changing the phase modulation into an amplitude one by means of a passive element, whereby, however, no noise source has been introduced into the system.

Claims

1. Non-contacting smart card interrogator (1), in which across a transmission line from an antenna (15) to a receiver the signal modulation varies between the amplitude and the phase and which comprises a carrier wave generator (11) and an amplitude demodulation receiver (16), both being connected to the antenna (15) through a transmission line 14, characterized in that to a terminal connecting the amplitude demodulation receiver (16) to the transmission line (14), a first end (A) of an eighth-wave transmission line (13) is connected, and to a second end (B) thereof the carrier wave generator (11) is connected, and that a signal at the first end (A) and a signal at the second end (B) of the eighth-wave transmission line (13) are sensed.

2. Non-contacting smart card interrogator (1) as recited in claim 1, characterized in that to the second end (B) of the eighth-wave transmission line (13) a second amplitude demodulation receiver (16′

) is connected.

3. Non-contacting smart card interrogator (1) as recited in claim 1, characterized in that the amplitude demodulation receiver (16) is connected alternately to the first end (A) and to the second end (B) of the eighth-wave transmission line (13).

4. Non-contacting smart card interrogator (1) as recited in claim 2, characterized in that the eighth-wave transmission line (13) is made as a filter shifting the carrier wave phase for 45°

.

5. Non-contacting smart card interrogator (1) as recited in claim 2 characterized in that the carrier wave generator (11) is connected to the second end (B) of the eighth-wave transmission line (13) through an impedance matching filter (12) attenuating the upper harmonics of the carrier wave as well.