MagTek InSpec 9000-2005 - Manual (Page 56)

InSpec 9000-2005 Encoded Card Tester
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The key interchange parameters, that card readers rely upon, are Signal Amplitude and Jitter.
These parameters are measured by the Encoded Card Quality Tester and are defined and
explained in the pages that follow. First, some basic concepts are presented.
BASICS OF MAGNETIC RECORDING
Digital magnetic recording requires three basic components for the technology to be worthwhile:
the Recorder (or Encoder), the Magnetic Tape, the Reader. We will first focus our attention on
the Magnetic tape as it is the fundamental component from which the Encoder and Reader are
designed to work.
Magnetic Tape
A discussion of magnetic tape must first start with the tape's most basic ingredient: Iron.
Modern magnetic tapes are made with various types of iron (ferrites) or metal oxides. However,
before we complicate matters further, an understanding of iron, the basic element in any
magnetics discussion, is needed.
The fundamental characteristic of iron is its ability to become magnetized when subjected to a
magnetic field. As you know, a direction finding compass works because the Earth has magnetic
fields directed toward the North Pole. Magnetic fields can also be created by the flow of electric
current. Electric current is the fundamental way that magnetic fields are controlled and directed
in billions of products. A coil of wire, wrapped around an iron rod, will produce a magnetic
field when a DC (Direct Current) current flows through the wire, as illustrated in Figure A-1.
Figure A-1. Magnetic Field