Most of the cards that are contact based deteriorate
with usage and they have a disadvantage that one has to specifically put the card in a
specific slot. This means that the user must have the hands free to swipe the card. These
limitations have been removed by the Proximity card readers that require no direct contact
between the card and the reader for the system to operate, the card must only be in the
proximity of the reader. The read range will vary depending upon the card (also called
token) and the type of reader, from 1/2 inch to a few feet. So technically even if the
card is in the pocket of the visitor, the reader can read it and authenticate. Though in
practical world most of the readers that are used can read from only a few inches as the
readers that can read from a larger distance are expensive and somewhat error prone.
The other major advantage of such readers is that they operate on RF which can penetrate
across concrete, wood or any other material. So, these readers can even be concealed from
the aesthetic view point or to shield from vandals. The RF field that the reader generates
resonates on the specially designed wires that are embedded in the card and thus the
reader is able to read the data on the card.
Such cards are relatively expensive. |
