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Updated 2017-10-16-02-26

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What's common

Commonly known contactless chipcards communicate with the coupler through only one single (magnetic) antenna. Therefore the unnoticed access to the card's contents from a remote coupler is not precluded by an intrinsic property: The card holder's sovereignty over her/his own data is not assured by principle this way (See an example of this problem here, in German by Stuttgarter Zeitung of 2006-02-03, page 1.). A more recent one is here by ConsumerReports® of June 2011 (more ...) or here, in German by DER SPIEGEL of 2012-06-11, page 128 or here, by Los Angeles Times of 2016-12-10, page C3.). A quite straight-forward antidote ist the RFID Blocker envelope like this. Google knows a lot about them too.

What's new

To overcome this drawback, ADE's C2® fashion implements two spatially separated antennas rather than only one. Since these two antennas carry two distinctively modulated signals, a sum/difference matrix within the card can decide whether the card is located quite close to the coupler or more distant. As a consequence, the usability of the card ist clearly limited by the pure geometry of the card - not any more by sheer intensity of the coupling field. It is assured that such a card can only be communicated with in a limited coupling environment (say, a bank terminal), that the coupling mechanism can withhold the card reliably in case of trouble.

Not the environment governs the access to the card data - the card itself does:

The reason why

 Schematic cross section through
 the principal field pattern
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The figure attempts to give an idea of how the effect is achieved. It shows a cross section availing a plane where all the centers of both the coupler's antenna pair and the card's antenna pair are located in at the same time. Here, the coupler's antenna pair is supposed to be located fixed in space (the upper pair of short black bars, fed from the generator through two opposite phase shifters). On the other hand, another pair of short bars represents the card's antenna pair that is not fixed in space and therefore depicted at several distinct positions. For the drawing, these positions are selected as typical for the different situations in order to prove the principle of operation: The card works in such positions (green bars), where not only the magnetic flux (the solid blue circles) penetrates the card as most dense and perpendicular, but also the two timing vectors (the straight lines in the tiny circles) in both of the card's antennas are most perpendicular to each other. The long blue dash-dotted straight lines are polarity separators: Here, one of both fields ceases because of the flux lines running parallel to the card's antenna. The yellow position is weak, the red ones do not operate.

Several patent applications are granted or pending, e. g. 4327334 (Germany), 94111981 (Europe), 5,648,761 (USA).

Made in China 
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Search strings for full-text search engines, which do not scan Meta keywords:
moses electronic, C2, C2-CARD, chipcard, contactless, close-coupled, stereo, secure

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