Introduction
The primary function of any make of field tester is to ensure that the installation is free from any short circuits or continuity faults which could corrupt the transmission of signals being sent from point to point around the system. A system that has no faults is one where the system conforms to the requirements of the standards governing the installation of structured cabling and will be able to support all of the system protocols.
Modern portable testers are programmed to test the latest international standards and are capable of performing at accuracy levels previously only attainable with expensive laboratory equipment.
Testing
The type of test carried out and the expected performance level are dependant on the type of system cable link being tested. The test requirements of a Category 5 link are different to those required for Category 6. Some of the tests are common although the limits are different.
The testers themselves must perform to the requirements of EIA/TIA TSB67 (Transmission Performance Specifications for Field Testing of Unshielded Twisted Pair Cabling Systems). This standard sets the performance parameters and accurcay levels required.
Most portable testers not only carry out the required tests but also provide additional features such as providing a two way talk link and diagnostic tools.
All portable testers have an 'Autotest' or similar button. This single button will execute a complete set of tests to fully qualify the installed link or channel to the desired specification. Also, the testers will display individual test results for all of the standard elements of a complete test and will store the information for later downloading and printing.
The table shows the lists of tests carried out by the testers for different categories of structured cabling.
| Tests | Category 5 | Category 5e | Category 6 | Category 7 |
|---|---|---|---|---|
| (100MHz) | (100MHz) | (200MHz) | (600MHz) | |
| NEXT | X | X | X | X |
| PSNEXT | X | X | X | |
| ACR | X | X | X | X |
| PSACR | X | X | X | |
| ELFEXT | X | X | ||
| PSELFEXT | X | X | ||
| Return Loss | X | X | X | |
| Impedence | X | X | ||
| Attenuation | X | X | X | X |
| Delay | X | X | X | X |
| LCL | X | X | ||
| LCTL | X | X |
Seven different tests are conducted on the cable link and channel to ensure that an accurate evaluation of the performance is achieved.