Although the bandwidth characteristics of magnetic tape are excellent, the delay
characteristics are poor. Transmission time is measured in minutes or hours,
not milliseconds. For many applications an online connection is needed. One of
Although the bandwidth characteristics of magnetic tape are excellent, the delay
characteristics are poor. Transmission time is measured in minutes or hours,
not milliseconds. For many applications an online connection is needed. One of
the oldest and still most common transmission media is twisted pair. A twisted
pair consists of two insulated copper wires, typically about 1 mm thick. The wires
are twisted together in a helical form, just like a DNA molecule. Twisting is done
because two parallel wires constitute a fine antenna. When the wires are twisted,
the waves from different twists cancel out, so the wire radiates less effectively. A
signal is usually carried as the difference in voltage between the two wires in the
pair. This provides better immunity to external noise because the noise tends to
affect both wires the same, leaving the differential unchanged.
Although the bandwidth characteristics of magnetic tape are excellent, the delaycharacteristics are poor. Transmission time is measured in minutes or hours,not milliseconds. For many applications an online connection is needed. One ofAlthough the bandwidth characteristics of magnetic tape are excellent, the delaycharacteristics are poor. Transmission time is measured in minutes or hours,not milliseconds. For many applications an online connection is needed. One ofthe oldest and still most common transmission media is twisted pair. A twistedpair consists of two insulated copper wires, typically about 1 mm thick. The wiresare twisted together in a helical form, just like a DNA molecule. Twisting is donebecause two parallel wires constitute a fine antenna. When the wires are twisted,the waves from different twists cancel out, so the wire radiates less effectively. Asignal is usually carried as the difference in voltage between the two wires in thepair. This provides better immunity to external noise because the noise tends toaffect both wires the same, leaving the differential unchanged.
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