By Jeffrey Krauss, wiring wizard and President of Telecommunications and Technology Policy
Part 68

Part 68 of the FCC Rules contains detailed technical rules that were adopted to limit hazardous voltages that might be produced by customer-owned telephones, in order to protect the health and safety of telephone company employees. But it was quickly expanded at the request of telephone companies to prevent customers from bypassing the telephone network billing systems.

Because these provisions are part of the Code of Federal Regulations, amending them requires a rulemaking proceeding to comply with the Administrative Procedures Act. It typically takes the FCC about two years or so to adopt rule changes from the time a Petition for Rulemaking is filed.

This combination of detailed technical specifications and the administrative difficulty of making changes has constrained the introduction of beneficial new technologies into the telephone network. For example, many new private telephone switching systems use telephone sets that communicate with the switch using digital control channel signals; this permits a variety of new services, such as allowing a telephone set to change its identity so that a telephone number can follow an employee as he moves through the building. But these digital telephone sets cannot be connected directly to the telephone network, because their digital signals do not conform to Part 68. The private switch filters out the control channel and other digital signals before any calls are connected into the public telephone network.

Part 68 has prevented residential subscribers from using these new digital phones, because we don't have switches to filter out the digital signals. But the FCC prefers to believe that Part 68 has brought nothing but benefits to telephone subscribers, in the form of increased competition in the supply of telephone sets. The FCC intends to impose a similar regime on the cable industry.

The FCC's goal is to promote customer ownership of cable boxes, and one way to do this is to assure "portability." This means a set-top box that works in one cable system must also work if the subscriber moves to another city. The cable industry does use one standard connector, and it does use one standard channel plan (three of them, actually, but that's close enough for government work). But a cable box that works in one city won't work in another city because the security and system designs - scrambling methods, channel capacities and control channel specifications - are different.

Descrambler authorization messages, channel tuning data and other commands and messages are transmitted from the headend to set-top boxes over a control channel. The frequency, bandwidth, modulation, data rate and internal structure of the control channel vary from manufacturer to manufacturer, and from one model to another from the same manufacturer.

To thwart cable pirates, the structure of the data within the control channel is a closely held secret. Set-top box portability would require a standardized control channel, and the data structure of the channel would have to be published in Part 68 or its cable TV equivalent. This would simplify the pirate's attacks on the security of addressable cable systems.

The FCC evidently wants more than just set-top portability, it wants a competitive supply of set-top boxes. This means no more proprietary boxes for services like the Sega Channel. A generic game box would have to be used. And I guess we will wind up with a single, generic, program guide service. Too bad, StarSight.

Signal leakage

Customer ownership of set-top boxes and inside wiring will lead to more signal leakage problems. Today, the cable operator is responsible for eliminating leakage, even if the customer uses a lamp cord to carry the video signal from one room to another. The operator must, as a last resort, disconnect the subscriber from the network, if that's what it takes to eliminate a leak.

The FCC does recognize that telephone companies will soon be installing broadband networks that could create new leakage problems. Until now, telephone networks have not used frequencies that would cause interference if they leaked. Satellite master antenna systems have operated on critical frequencies, and informal information in the cable industry suggests that SMATV systems have been responsible for serious signal leaks. But the FCC has never considered SMATVs to be enough of a problem to impose the same stringent standards that cable systems must meet.

Cable signal leakage can be a serious threat if it interferes with aeronautical communications. For this reason, the FCC would be expected to impose the same leakage rules on telco broadband systems that now apply to cable. But there is no indication that the FCC has thought about the signal leakage implications of customer ownership of set-top boxes. Maybe someone will point this out. Or maybe we should rely on Circuit City to send a crew around to track down leaks.

The FCC is pursuing an industrial policy to change cable TV business practices. But it's trying to fix something that isn't broken.