Data Stored on Magnetic Strips - Is it repeated, or linear?

[Strifer]

On a magnetic strip, is the data repeated throughout the length of the strip, or is it linear--starting at the beginning of the strip and terminating at the end? If the latter is true, I would assume that the entire strip must be swiped for the data to be read.

The reason I ask is this: my apartment building requires that we swipe in with Identicard access cards. Instead of taking the card out of my wallet to enter the building, I would like to be able to have a sort of "key fob" that I can keep on my key ring.

So, for this purpose, must the entire magnetic strip be intact, or is it possible to use a mere segment?

 

[Devilpapaya]

In most magnetic stripe cards, the magnetic stripe is contained in a plastic-like film. The magnetic stripe is located 0.223 inches (5.56 mm) from the edge of the card, and is 0.375 inches (9.52 mm) wide. The magnetic stripe contains three tracks, each 0.110 inches (2.79 mm) wide. Tracks one and three are typically recorded at 210 bits per inch (8.27 bits per mm), while track two typically has a recording density of 75 bits per inch (2.95 bits per mm). Each track can either contain 7-bit alphanumeric characters, or 5-bit numeric characters.

Sincerely,
Wikipedia.

So then it depends, really, especially considering -

"Counterexamples of cards which intentionally ignore ISO standards include hotel key cards, most subway and bus cards, and some national prepaid calling cards."

point being there isn't a standard on what form the data takes on the card, only that its divided into the three sections, and even if their were a standard, your apartment complex may not follow that standard. You'd probably have to get a card reader to check manually.

 

[Modelworks]

That data is repeated multiple times so that if part of the card stripe becomes scratched it is still readable. Most cards use linear tracks but there are some higher security cards that are designed with the tracks laid out diagonal requiring a special reader to access the data. You can't swipe these cards vertical or horizontal because the reader has to match the angle of the data in the stripe perfectly.

Just a tip , use some junk or purchased blank cards for playing with this, you don't want to screw up a card you need and it is VERY easy to do.

 

[Strifer]

Thanks! I intend to purchase a card reader before I experiment with my one and only access card. I've got to do my homework on those now.