25-02-2012, 04:17 PM
Transmission Media
[attachment=17744]
Defination
Anything that can carry information from a source to a destination.
Why Twisted-Pair Cable Reduces Noise ?
Interference from devices such as a motor can create unequal noise over two parallel lines.
The line that is closer to the device receives more interference than the one that is farther.
If however, the wires are twisted around each other, at regular intervals ,each wire is closer to the noise source for half of the time and farther for the other half.
Both receive the same amount of noise.
The noise from two wires cancel each other
out at the receiver.
Consists of 4 pairs (8 wires) of insulated copper wires typically about 1 mm thick.
The wires are twisted together in a helical form.
Twisting reduces the interference between pairs of wires.
High bandwidth and High attenuation channel.
Flexible and cheap cable.
Category rating based on number of twists per inch and the material used
CAT 3, CAT 4, CAT 5, Enhanced CAT 5 and now CAT 6.
QUICK HISTORY
Fiber optics, though used extensively in the modern world, is a fairly simple and old technology. Guiding of light by refraction, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840s. John Tyndall included a demonstration of it in his public lectures in London a dozen years later.
[attachment=17744]
Defination
Anything that can carry information from a source to a destination.
Why Twisted-Pair Cable Reduces Noise ?
Interference from devices such as a motor can create unequal noise over two parallel lines.
The line that is closer to the device receives more interference than the one that is farther.
If however, the wires are twisted around each other, at regular intervals ,each wire is closer to the noise source for half of the time and farther for the other half.
Both receive the same amount of noise.
The noise from two wires cancel each other
out at the receiver.
Consists of 4 pairs (8 wires) of insulated copper wires typically about 1 mm thick.
The wires are twisted together in a helical form.
Twisting reduces the interference between pairs of wires.
High bandwidth and High attenuation channel.
Flexible and cheap cable.
Category rating based on number of twists per inch and the material used
CAT 3, CAT 4, CAT 5, Enhanced CAT 5 and now CAT 6.
QUICK HISTORY
Fiber optics, though used extensively in the modern world, is a fairly simple and old technology. Guiding of light by refraction, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840s. John Tyndall included a demonstration of it in his public lectures in London a dozen years later.
