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A cable tester is an electronic device used to verify the electrical connections in a signal cable or other wired assembly. Basic cable testers are continuity testers that verify the existence of a conductive path between ends of the cable, and verify the correct wiring of connectors on the cable.
The delay skew test is used to find the difference in propagation delay between the fastest and slowest set of wire pairs. An ideal skew is between 25 and 50 nanoseconds over a 100-meter cable. The lower this skew the better; less than 25 ns is excellent, but 45 to 50 ns is marginal.
Murray loop test employs the principle of wheatstone bridge for locating the fault. To perform this test, it is necessary to have a sound cable running alongside the faulty cable. One end of the faulted cable is connected through a pair of resistors to the voltage source. Also a null detector is connected. The other end of the cable is shorted.
It is only after this round-trip delay that the short can be detected by the TDR. With knowledge of the signal propagation speed in the particular cable-under-test, the distance to the short can be measured. A similar effect occurs if the far end of the cable is an open circuit (terminated into an infinite impedance).
A cable terminated according to T568A on one end and T568B on the other is a crossover cable when used with the earlier twisted-pair Ethernet standards that use only two of the pairs because the pairs used happen to be pairs 2 and 3, the same pairs on which T568A and T568B differ. Crossover cables are occasionally needed for 10BASE-T and ...
The ITU-T Y.1564 (previously Y.156sam) has gained momentum in the test and measurement industry. EXFO was the first test vendor to implement the ITU-T Y.1564, and today other companies like JDSU, Albedo Telecom and Veex are also offering Ethernet and multiservice test equipment via the IntelliSAM and EtherSAM test methodologies.
Attenuation-to-crosstalk ratio (ACR) is a parameter that is measured when testing a communication link, which represents the overall performance of the cable. [1] AcR is a mathematical formula that calculates the ratio of attenuation to near-end crosstalk for each combination of cable pairs. [ 2 ]
50 Ω coaxial cable connects machines together, each machine using a T-connector to connect to its NIC. Requires terminators at each end. For many years during the mid to late 1980, this was the dominant Ethernet standard. Also called Thin Ethernet, Thinnet or Cheapernet. 10 Mbit/s over RG-58 coaxial cabling, bus topology with collision ...