In the wake of complicated standards, low installation margins and a lack of qualified technicians, workflow automation is particularly important. A state-of-the-art field tester can help optimize the certification workflow.
December 1, 2000
Today, cable certification to the latest industry standards is more complex than ever before. Technicians operating field testers have to deal with a multitude of new standards and new test requirements. Field failures are more frequent, due to stricter standards and troubleshooting quickly turns into finger pointing. In addition, finding trained technicians is nearly impossible.
Field testing issues can be summarized as follows:
Configuration — There can often be too many settings and choices on the tester.
Testing — if you do not get configuration right, you can waste a lot of time. If plots are not saved, recovery from configuration mistakes is not possible without re-testing. Failures are more frequent and troubleshooting is more difficult than in the days of Category 5.
Reporting — If reporting is not done correctly, it could be confusing and may not offer sufficient information or interpretation. If plots are not saved and limits change, installations must be re-tested.
Following, is a discussion of the practical solutions to the above challenges and a look at how a field tester can help optimize the certification workflow.
Early generation testers supporting Category 5 measured only four parameters: wiremap, length, attenuation and near end crosstalk (NEXT). These testers were standardized by the TIA (Telecommunications Industry Association) as Level II testers. Today, with the emergence of 4-pair networks such as Gigabit Ethernet, Level II testers are no longer adequate. Gigabit Ethernet requires that new parameters be added to the certification test; for this reason, TIA defined Level IIE and Level III testers. These new testers measure the following additional parameters: delay, delay skew, equal level far end crosstalk (ELFEXT) and return loss. Level IIE testers are required to test Category 5e cabling and Level III testers are required to test Category 6 cabling.
The addition of Level IIE and Level III testers introduced a high degree of complexity into practically every aspect of cable certification. Because there are now more test limits, tester levels and measurements in a certification test, the selection and configuration of the testers requires considerable expertise, and is typically delegated to knowledgeable consultants. The certification workflow is more complex than it was in the days of Category 5 and is further hampered by human errors.
TYPICAL CERTIFICATION WORKFLOW
Let’s begin by investigating the work flow complexity associated with cable certification. Figure 2 (above) illustrates typical cable certification workflow.
Step 1: The test equipment is selected and sent to the job site.
Step 2: Equipment Configuration. Typically, a crew of installation technicians uses multiple test sets at a job site. All testers must be configured the same way, as per customer requirements. A consultant typically dictates the tester configuration that must be replicated on all of the testers at the site. Manual configuration of multiple test sets is subject to human error, and mistakes are common and very costly. For example, if the tester is configured with the wrong test limit (eg., Category 5 instead of 5e), the time spent testing with the wrong limit is wasted. Automation of equipment configuration can play an important role here.
Step 3: Testing and Troubleshooting. Testing is easy when the cabling passes the test. The trouble starts with the increased amount of troubleshooting required on a typical installation job. The new Category 5e and Category 6 standards specify more measurements than Category 5, and these measurements come with much tougher limits. Additional measurements with tougher limits means more time spent looking for problems on the failing runs. The failure rate on typical Category 6 installations is 10 per cent to 20 per cent, compared to the failure rate on typical Category 5 installations of less than one per cent.
Why is certifying Category 6 so much harder than certifying Category 5? The simple answer is that the test limits got significantly stricter, but the cabling technology is still catching up to these limits. The result? High failure rate on Category 6 installations.
The limit for NEXT is 13 dB tougher for Category 6 than for Category 5 (see Figure 3 below).
Using test probes that are incompatible with the installation under test causes many Category 6 failures. A tester can do a lot to prevent common failures by automating the checks and balances during the test and by issuing warnings to the user about incorrect configurations and test probes.
Step 4: Sending the Tester in for Data Collection. When certification is complete, all test data must be organized in a meaningful manner. Typically, the test equipment is shipped to a central location in order to download the test data from the tester directly to a PC-based data management and reporting utility. The problem with this step is that shipping test equipment to and from a central location keeps it out of service for a period of time and turns revenue-generating test technicians into delivery personnel.
Step 5: Reporting. The documentation is generated from the test result data. If everything has gone well, this may be as simple as printing the test reports. However, if the cable IDs are incorrect or the customer is looking for electronic test results, the task might be more complex. Today, many customers require a higher level of reporting quality than in the past; they want reports that are professional in appearance and contain useful graphical content. Users often want to view their test data from CDROM or web media, in addition to hard copy.
Taking advantage of new cable test technology will allow cable installation companies to streamline the cable test process and overcome traditional limitations.
STREAMLINING CERTIFICATION WORKFLOW
State-of-the-art test equipment can help automate the certification workflow and take a considerable load off of the technician. Figure 4 (above) demonstrates how advanced tester features, such as software configuration “wizards” and new storage media, can speed up and automate the workflow.
Step 1: Definition of Test Settings. Test settings are best defined by a foreman or a consultant specifying the certification job. An installer should not configure certification instruments by hand, especially if multiple testers are used on the job. Simple mistakes can easily happen during manual set-up of multiple instruments, and these can cost days and even weeks of wasted time. With today’s tester technology, there is no excuse for improperly configuring a test limit or a test option on one of the testers.
The set-up of a test instrument should be automated. A “settings profile”, or a collection of tester settings, can be created under Windows using a software “wizard”. A qualified person working in a Windows environment on a big screen can define all tester settings and store the settings profile onto a CompactFlash memory card. In the field, these settings are loaded into each tester from the CompactFlash, which makes the process of multiple instrument set-up a one-step operation and eliminates human error.
Step 2: Loading Test Settings. Loading test settings into each tester is as simple as inserting the CompactFlash into a tester. The tester configures itself within seconds. The settings could also be loaded into the tester via a serial port.
Step 3: Testing. Testing is performed on the cable plant exactly as defined in the test profile. The equipment should be intelligent enough to guide the user through the process of testing, troubleshooting and storing test results. For example, if a test passes, saving it would be the next logical step. If the test fails, the next logical step would be to look at the detailed fault analysis. This minimizes training requirements for all field technicians and further reduces the risk of costly testing errors.
Field testers should also be intelligent enough to detect tester configuration and test probes tha
t may be incompatible with the components used in the installation being tested. Due to the very tight Category 6 margins, such incompatibilities can drastically increase the probability of failures and increase the total test and troubleshooting time. Testers should be able to issue a warning to the user if incompatible settings or probes are detected.
CompactFlash storage should be used to save full plot information. Full plot storage allows the installer to re-certify test data to different test limits or with different test options. If a configuration error was made or if the standard limits changed, re-testing may not be necessary — software-based rectification would create new test reports from the saved data in minutes. Saving plots allows fast recovery from many configuration mistakes and protects the customer against quickly changing standards.
Step 4: If the CompactFlash memory card is left in the tester after configuration, all of the test data should be automatically saved there. This memory card is exchanged at the main office for the card containing the next day’s test profile and data storage. The technician will not have to waste time waiting for test results to be offloaded from the tester. In fact the test equipment may still be at the site, testing additional runs and generating revenue.
Step 5: Test reports should be generated and distributed to the customer, either electronically or on paper. Cable management software should be part of the electronic test result solution; this software should support the draft TIA-606A administration standard. After all of the labour and equipment is installed, the test results are the final deliverable to the customer. These results should be complete and informative. Test reports that contain tables of confusing, worst case data points are hard to interpret and are not very useful for analysis in the case of failure.
Streamlining and automating the workflow of cable certification helps to avoid human error and saves time. State-of-the-art cable testers can be automatically configured, eliminating the manual, error-prone process that often causes costly mistakes. Test results can be stored on CompactFlash media, which simplifies the process of transferring them to a PC and enables the user to save and report complete plot information to the customer. Saving plot data can also protect the installer from having to re-test in cases of configuration mistakes or changing standards.
Workflow automation is particularly important now that standards are complicated, installation margins are low and qualified technicians are hard to find. Therefore, when selecting a cable analyzer, it is wise to consider the value of additional automation software that can make life easier for those who invest in proper preparation before each job.CS
Chuck Ganimian is Product Manager and Fanny Mlinarsky is General Manager at the WireScope Operation of Agilent Technologies, Inc., Marlboro, MA. This division focuses on creating tools for installation and maintenance technicians.