Hey guys,
I will explain How to study the testing of network cable.
To check continuity of cable.
To check the resistance of the cable.
Digital Multimeter.
Crossover cables-
A crossover cable, which is used to connect UTP computers without a hub, is also a good tool for eliminating the hub and the cables as a possible source of a network communications problem. If you have two computers that seem to be properly connected using a hub and prefabricated
cables (or an internal cable run and patch cables), and they are not communicating, try connecting the computers with a crossover cable that you know works properly.
Hardware Loopback Connectors-
A Loopback connector is an inexpensive device that you plug into a jack, which redirects the outgoing signals from the device right back into it. You can purchase loopback connectors for parallel and serial ports, for example, that work in conjunction with diagnostic software to check the transmission and receive capabilities of the ports. In the same way, you can purchase a loopback connector that plugs into a UTP network interface adapter's RJ45 port.
Be aware that running a test using a loopback connector is completely different from transmitting packets to the TCP/IP loopback address (127.0.0.1). Even though using that address causes all transmitted traffic to return to the incoming buffers of the same computer, the signals never actually reach the network interface adapter.
Tone Generators and Tone Locators-
When you install UTP cable internally, testing each of your connections should be an absolute requirement. The last thing you will want to do - after you've pulled all of your cables, secured them all in the walls and ceilings, punched them all down, installed all the wall plates, and cleaned everything up - is tear everything apart again because of an improperly wired connection.
One of the most basic ways to identify and test cable connection is to use a tone generator and locator (seen figure), also known as a "fox and hound" cable tester. The tone generator is a device that you connect to one end, and which transmits a signal over the cable. the tone locator is a separate device that has a probe capable of detecting the generator's signal. You can use this type of device to test an entire cable or to test the individual wire connections inside a UTP cable.
Tone generators and locators are most commonly used to identify the cable belonging to a particular connection. for example, if you're performing an internal cable installation, and you forget to label one of your cables, you can connect the tone generator at the wall plate end and touch the probe to each of the cables at the patch panel end until you find the one that produces a tone. the tool is also valuable for identifying one particular cable in a bundle in the middle of the connection.
You can also use a tone generator and locator to test the individual wire connections inside a UTP cable. you connected the generator to a signal wire or connector contact using an alligator clip, and then touch the locator to each wire or contact at the other end of the cable.
for example, if you fail to detect a signal on the connect to which you have the generator connected that the other end, you have an open circuit.
The tone generator and locator is the simplest and most expensive type of cable tester, but this method of testing UTP cable connections is relatively unreliable and incredibly time-consuming. For troubleshooting a single cable connection, it's a useful tool. for testing a large number of newly installed cable runs, you can purchase a wire map tester instead that detects that all the same faults by testing all of the wire connections in the cable at force.
Wire Map Testers-
A wire map tester is a device that is similar in principle to the tone generator and locator, except that it tests all the wire connections in a UTP cable at once. this device also consists of two parts, which you connect to the opposite ends of a cable. the unit at one end transmits signals over all the wires, which are detected by the unit at the other end. A wire map tester can detect transposed wires, opens, and shorts, just as a tone generator and locator can, but it does all the tests simultaneously and provides you with a simple readout telling you what's wrong (If anything).
However, the wires that are actually carrying the signal are improperly paired. Normally, a UTP cable has one transmit wire and one receive wire, each of which is twisted into a separate pair with its corresponding ground wire. In a split pair situation, the transmit and receive wires can be twisted into one pair and their two ground wire.
Wire map testers are available as standalone devices that are relatively inexpensive. you can also find the same functions as part of a multiplication cable tester, which costs a great deal more. for a small to medium-sized internal cable installation, a wire map tester is a good investment, both for the installation and for troubleshooting purposes later.
Multiplication Cable Tasters-
Multiplication cable testers are handheld devices, like the one shown in the figure, that perform a variety of tests on a cable connection and compare the results to standard values that have been programmed into the unit. the result is that these are devices that anyone can use. you simply connect the unit to the cable, press a button and the device comes up with a list of pass or fails ratings for the individual tests.
