Question for transmission media:

Tuesday, September 22, 2009
QUESTIONS:
1. how the cross talk is done? reason for crosstalk?
2.what is repeater? what is purpose of using it?


TEAM MEMBERS:
Swetha.M
Shruthi.K.N
Baharan
Malihe
at Tuesday, September 22, 2009

2 comments:

Unknown said...

A-2 A repeater

A repeater is the simplest facility used for network interconnection, whose major function is to receive a network signal from one LAN terminal cable segment and to regenerate and retransmit the signal as it is in its original strength over a one or more other cable segment. Basically repeater regenerates the strength of the signal before transmitting it

Repeaters operate in the OSI model Physical layer and are transparent to all the protocols operating in the layers above the Physical layer.

A specific LAN implementation usually places a limit on the physical size of a single cable segment. The limit is based on the physical medium and transmission techniques used

Repeaters allow a network to be constructed to exceed the size limit of a single, physical, cable segment. The number of repeaters that can be used intandem is generally limited by a particular LAN implementation. Using a repeater between two or more LAN cables segment requires that the same physical layer protocol be used to send signal over all the cable segments

Example of how this work

Two LAN cable segment in an Ethernet LAN that both use baseband transmission could be connected with a repeater. Different types of physical transmission medium can be connected using a properly designed repeater as long as they handle similar type of signal, as explained below: Ethernet repeaters are available that allows all the various types of baseband Ethernet transmission medium, including 10baseT, Coaxial cable, 10base2 and twisted pair cablesegment to be interconnected in the same LAN

Advantages of a repeater

· Simple to connect

· Cost effective

· Ability to strengthen signal

Disadvantages of a repeater

· Repeaters provide no method for isolating traffic generated on one cable segment from traffic generated by the other cable segment

· When network uses a repeater to connect cable segment A to segment B whether or not there is a station in segment B that is the destination of the signal

September 22, 2009 at 10:03 PM
Unknown said...

A-1 A disturbance, caused by electromagnetic interference, along a circuit or a cable pair. A telecommunication signal disrupts a signal in an adjacent circuit and can cause the signals to become confused and cross over each other.

Crosstalk occurs in twisted pair wire when a current or signal in one wire can produce an unwanted current or signal. If the two wires run parallel to each other the chance for crosstalk increases.


Mutual inductance is a consequence of an alternating current (AC) in one conductor developing a fluctuating magnetic field which induces current flow in another close-coupled conductor. In computer networking or communication, this is termed cross-talk.

The signal in the source wire is mirrored (at a lower strength) in the other. Where two conductors run parallel to one another for long lengths, the cross-talk signal is additive and can be considered as noise, where the other conductor is carrying its own signal.

September 22, 2009 at 10:24 PM

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