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When performing magnetic encoding the encoding head alignment (write head) as far as Track placement on the stripe, is critical. If the encoding is out of placement it will affect the read back of the POS (Point of Sale) systems in the field. So QA tests are performed every hour at many card manufacturers facilities to ensure signal amplitude, bit space, and jitter are within ISO specifications.
Amplitude is essentially the signal strength. The stronger the signal encoded the easier it is for the magnetic reader to amplify that signal and decode the message.
Jitter Bit-to-bit jitter is a change in bit length from one bit to the next on a magnetic stripe. Ideal cards would have no jitter, but real cards do! Cards with high jitter are generally unreadable, because the decoder electronics in the card reader cannot tell a binary “1” bit from a “0” bit. Precision jitter test cards are ideal for testing readers and encoders. They are also good as standards of comparison when checked against production samples.
Magnetic stripes come in two main varieties: high-coercivity (HiCo) at 4000 Oe and low-coercivity (LoCo) at 300 Oe, but it is not infrequent to have intermediate values at 2750 Oe. High-coercivity magnetic stripes require higher amount of magnetic energy to encode, and therefore are harder to erase. HiCo stripes are appropriate for cards that are frequently used, such as a credit card. Other card uses include time and attendance tracking, access control, library cards, employee ID cards and gift cards. Low-coercivity magstripes require a lower amount of magnetic energy to record, and hence the card writers are much cheaper than machines which are capable of recording high-coercivity magstripes. However, LoCo cards are much easier to erase and have a shorter lifespan. Typical LoCo applications include hotel room keys, time and attendance tracking, bus/transit tickets and season passes for theme parks. A card reader can read either type of magstripe, and a high-coercivity card writer may write both high and low-coercivity cards (most have two settings, but writing a LoCo card in HiCo may sometimes work), while a low-coercivity card writer may write only low-coercivity cards.
In practical terms, usually low coercivity magnetic stripes are a light brown color, and high coercivity stripes are nearly black; exceptions include a proprietary silver-colored formulation on transparent cards. High coercivity stripes are resistant to damage from most magnets likely to be owned by consumers. Low coercivity stripes are easily damaged by even a brief contact with a magnetic purse strap or fastener. Because of this, virtually all bank cards today are encoded on high coercivity stripes despite a slightly higher per-unit cost.
For copies of specifications contact:
American National Standards Institute
11 W. 42nd Street, New York, NY 10036
*White boxes identify control characters
*White boxes identify control characters
The track formats used in this document are based on ISO Standards, however, other formats may be used.Contact your card issuer for your exact requirements
The encoder reads and writes standard ISO track data formats in standard ISO track locations. The following shows the three standard ISO track.
Each track can be encoded and decoded with ASCII characters in the standard default ISO data formats:
|Track||Density (bpi)||Bits per character||Character parity||Length (characters)||LRC parity||Start sentinel||End sentinel||Start sentinel offset|
|1||210||7||Odd||76||Even||%||?||0.293″ (7.4 mm)|
|2||75||5||Odd||37||Even||;||?||0.293″ (7.4 mm)|
|3||210||5||Odd||104||Even||;||?||0.293″ (7.4 mm)|
The magnetic encoder can read or encode up to 3 tracks of digital information onto CR-80 cards incorporating a HiCo or LoCo magnetic stripe in the ISO 7811 format.
Encoding for the three tracks uses ISO 7811 format.
The ISO data formats include a preamble (all zeros), a start character, data (7-bit or 5-bit as specified by ISO), a stop character, and a Longitudinal Redundancy Check (LRC) character. The 7-bit data format has 6 bits of encoded data and parity bit. The 5-bit data format has 4 bits of encoded data and a parity bit.
The ISO data format include a data field separator (or delimiter) that allows parsing of the encoded track data. An example of separate data fields would be the ABA data format (Track 2) that includes a Primary Account Number (PAN) field and an account information field (for expiration date, country code, etc.).
The data stored on magnetic stripes on American driver’s licenses is specified by the American Association of Motor Vehicle Administrators (AAMVA).
Alpha-numeric characters on Track 1 and 3, numerals only on Track 2.
|Track||Density (bpi)||Bits per character||Character parity||Length (characters)||LRC parity||Start sentinel||End sentinel||Start sentinel offset inches (mm)|
If a custom format is desired, the ISO standard format may be used as a starting point. The standard format can then be modified by assigning different values to any or all of the density, characters and sentinel attributes. (If any of these attributes is missing, its corresponding value in the standard ISO format will be substituted.).
The binary option allows the user to specify directly the value for each each bit on the mag stripe:.
In this “direct binary ” mode, it is the host’s responsibility to fully populate the magnetic stripe;
i.e., the hex data provided by the host must include the leading zeroes, start sentinel, data, end sentinel, LRC, and trailing zeroes. Note that the magnetic stripe is encoded from the right-hand end as viewed from the “stripe“ side, with the stripe uppermost. The least significant bit of the data is encoded first.
A sufficient number of leading zeroes should be prepended to offset the start sentinel by approximately 0.3” (7.5 mm) from the right-hand end, as in the ISO format. Care should be taken to ensure that the payload data does not exceed the capacity of the tracks at their specified recording densities. (In the binary mode, out-of-range data is not recorded, and no error condition will result.).
A CR-80 size card has a nominal capacity of 252 bits per track at 75 BPI, and 708 bits at 210 BPI. These capacities equate approximately to 31 hex bytes (248 binary bits) and 88 hex bytes respectively.