Proof-Of-Performance Testing: Just Do It

What does proof-of-performance testing mean to you? Does it mean fulfillment of Federal Communications Commission (FCC) mandates or does it mean day-to-day maintenance of your network or both?

The way the current system stands, proof-of-performance testing is required for all cable systems serving 1,000 or more subscribers. Smaller systems are required to comply with the Cumulative Leakage Index requirements (including quarterly measurements) but they aren’t normally required to demonstrate proof of performance of the other technical standards; however, even though small systems are not required to file reports with the FCC, they still are expected to meet the same technical standards, as do their larger brethren.

According to the FCC’s Media Bureau, most tests need to be conducted at least twice each calendar year (at intervals not to exceed seven months). Test results must be kept on file at the operator’s local business office for at least five years, and the test data must be made available for inspection by the FCC or by the local franchiser (the city or town in which the operator provides service) upon request. 

Joe Jensen, executive vice president/Cable & Telecommunications at Ohio-based Block Communications Inc., CTO at Buckeye CableSystem, and Region 7 Committee Chair/Engineering Committee Chair for the Society of Cable Telecommunications Engineers (SCTE), says his operation undergoes proof-of-performance testing twice a year – summer and winter. “We test 10 or 12 channels at various locations,” he adds. “We use a mix of automated and manual testing. The tech hooks up the equipment in the field, tests the channels, collects the data and then moves on to the next site.”

According to Jensen, Buckeye enjoys a 98-percent/99-percent success rate when its channels are tested. Those that exhibit problems are repaired, and then those repairs are documented.
 
Some of the proof-of-performance tests required by the FCC are cumbersome, especially tests that need to be done more than the requisite twice a year. Repetitive test set-ups take up a technician’s precious time and can end up costing a lot of money. More and more test-equipment vendors are developing gear that makes it easy to format and report the results. For example, the recently introduced AT2500Plus spectrum analyzer from Sunrise Telecom is a one-button, automated analog and digital proof-of-performance suite that standardizes testing through a Web browser interface.

According to the manufacturer, the AT2500Plus includes automated FCC and SCTE-40 digital tests, including frequency, group delay, frequency response, digital HUM, and micro reflection margins. An optional cloud-based realPOP SaaS report generator helps consolidate test results into a FCC-ready report, including headend, end-of-line and 24-hour test data. Additionally, a 43 dB Modulation Error Ration (MER) range allows users to see impairments and identify marginal performance issues in the headend or hub before they impact the customer experience.

Must Digital Networks Be Tested?

Note that the testing of all-digital networks is becoming an important part of the U.S. process.

“I’m occasionally asked about whether or not cable operators should do some sort of proof-of-performance tests on digital signals, and when is the FCC going to require digital proofs?,” wrote Ron Hranac in a 2010 Communications Technology column. “The answer to the first question is, in most cases, yes. What about the second question? Did you know the FCC has required digital signals on most cable networks to meet certain specs, and that this requirement has been on the books for several years? §76.640(b)(1)(i) is where you’ll find the rules for digital signals.”

Here’s what that subsection says:

(1) Digital cable systems with an activated channel capacity of 750 MHz or greater shall comply with the following technical standards and requirements:
(i) SCTE 40 2003 (formerly DVS 313): “Digital Cable Network Interface Standard” (incorporated by reference, see §76.602), provided however that with respect to Table B.11, the Phase Noise requirement shall be −86 dB/Hz, and also provided that the “transit delay for most distant customer” requirement in Table B.3 is not mandatory.

“Yep, digital signals in most systems are supposed to comply with the technical parameters in SCTE-40 SCTE-40," Hranac added. “What’s not in Part 76 of the FCC Rules is the how to behind ensuring those digital signals comply with SCTE-40. The good news is that several digital measurement procedures are described in Recommended Practices for Measurements on Cable Television Systems, 3rd Ed., also available from SCTE. If you have a modern combination QAM analyzer/spectrum analyzer, most of the required measurements can be performed fairly easily using that kind of test equipment.”

Proof Of Performance And Franchising

While the FCC admits it seldom looks at the reports filed by cable operators (although a few fines have been assessed in recent years), franchising officials – especially around renewal time or when a new competitor wants to provide services – are not as casual. Every cable provider has had to stand up in front of a municipality to either apply for or defend a cable franchise. If there is something wrong, it will be discovered at that time. With the number of competitive content providers now vying for marketshare – including established wireline and wireless concerns – winning or renewing that license is not the slam-dunk it once was.?

A cable franchise-renewal process involves numerous tasks and the coordinated efforts of a team of people ranging from cable experts to city employees to residents. This team will examine a cableco’s past technical performance alongside its plans for system updates moving forward. Two of the more important aspects of cable service a franchise team would consider include a technical evaluation of the cable plant (headend and quality of past plant maintenance) and results of a customer service and satisfaction survey.

Here’s what one law firm wrote just a few years ago: “Remember that a cable operator that repeatedly breaks your laws or that isn’t capable of building a code-compliant system may not be legally, financially or technically qualified to hold a franchise.”

The Bottom Line

Aside from FCC legalities, it’s just good engineering practice to run most of the proof-of-performance tests on a regular basis to help ensure high-quality service to customers.

The most important thing is to find the problems, fix them and keep a log of the whole process. You never know when a FCC inspector may show up. It happened to Buckeye CableSystem’s Jensen:  “We were asked once for our records because a FCC guy happened to live in the neighborhood. There can be unpleasant consequences if you aren’t prepared.”