The FCC this week released a Notice of Proposed Rulemaking (NPRM) (FCC 12-86) proposed changes to its cable TV rules to update proof of performance and cumulative signal leakage rules to facilitate cable systems' transition to digital. The NRPM did not address the requests from cable companies that they be allowed to encrypt basic cable channels (see NCTA Offers Basic Cable Channels Encryption Solutions in the July 27 RF Report).
One of the challenges the FCC faces is the potential decoupling of the concept of signals of “good technical quality” from the concept of signals with “good visual quality.” A low bit-rate heavily-compressed video signal can be transmitted perfectly, yet offer poor visual quality. The FCC NPRM seeks comment “on whether we should consider qualitative measures to assess consumer perceptions of video quality.”
The NRPM observes: “We seek specific comment on the pros and cons of subjective consumer perception measures as opposed to or in addition to adopting objective measurements for assessing signal quality. Overall, we seek to develop the optimal approach to ensure that digital cable subscribers receive good quality signals, while imposing a minimal regulatory burden on cable operators, and we seek comment on the costs and benefits associated with our proposals.”
The NPRM proposes new proof-of-performance testing for QAM channels, and also considers digital cable systems not using QAM, stating that the FCC would expect each non-QAM system would have its own signal quality guidelines and would likely use such guidelines in its proof-of-performance plan. Comments were requested as to how the adequacy of such plans should be evaluated.
Interference from cable leakage will be different for digital signals. The NPRM proposes a new digital threshold of 10 microwatts average power across a 30 kHz bandwidth in any 2.5 millisecond time period for the “Aeronautical Frequency Notification (AFN). Frequency offsets that reduced interference from analog cable signals aren't effective for wide-band noise-like digital cable signals. To account for the difference, the FCC proposes decreasing the maximum leakage level by 1.2 dB. Refer to the NPRM for details on the proposed leakage rules.
Finally, the FCC proposes updating the signal-to-noise requirements of a new section 76.605(b)(7), formerly 76.605(a)(7) to reflect the completion of the DTV transition by amending any reference to Grade B Contour with a reference to the Noise-limited Service Contour as the applicable, regulatory equivalent for digital broadcasting.
