With the DTV analog cutoff just two months away, work by the FCC, NAB, broadcasters and cable groups is bringing issues to light that need to be resolved for a smooth transition. Back in March, congressmen and FCC commissioners voiced their recommendation that broadcasters in some markets transition to all-digital service before the transition date. Since then, there have been various efforts to better understand transition issues, including an early switch in Wilmington, NC, and simulations in other markets.
Tests provide early heads-up
The FCC identified 80 markets in which a significant portion of viewers receive OTA broadcasts. These include major markets such as Chicago, New York City and Washington, D.C. As a result, the FCC and broadcasters have been intensifying test runs and educational campaigns in those markets. Various broadcasters have been conducting transition simulations or soft tests, whereby a simulated noisy picture is broadcast on the analog transmission, with a clean picture on the digital transmission. One such simulation has also been accompanied by fail and pass graphics on the respective signals, giving viewers an easy way to ascertain their readiness.
These tests have already brought up an extremely important aspect of the transition: that proper cooperative planning is imperative between broadcasters and the community cable operators carrying the broadcasters' signals. In one of these tests, false positives were experienced when a cable operator incorrectly retransmitted the analog fail message.
Detailed planning will be necessary to ensure uninterrupted reception and proper rebroadcast of OTA signals on multichannel video programming distributor (MVPD) systems. Earlier this year, the NAB, MSTV and various cable associations issued a “Coordination Reference Handbook,” which laid out key steps to insure a successful transition. The underlying message is to establish clear and open communications between broadcasters and their local MVPDs on various technical and logistical issues.
Transition technical issues must be resolved soon
First and foremost is to ensure that the current retransmission infrastructure operates correctly after the analog signal is terminated. In many respects, the task is similar to that of interoperating with a translator facility, but with the added burden that many of the operating parameters are not directly under the broadcaster's control. Each broadcaster, after contacting every MVPD carrying its station, must also identify the location of every local receive site, translator or cable headend in the communities served by those receive sites. With MVPDs now including fiber and telco delivery of OTA signals, the number of coordinating sites has correspondingly increased. A critical issue is whether any of those receive sites will be affected by changes to broadcast antenna patterns, multipath or channel assignment.
In addition, because some MVPDs will use IPTV to carry video, the corresponding number of signal conversions may become quite complex, especially when combinations of analog and digital video may be provided. Broadcasters should equip a good monitoring facility with the various types of subscriber terminal equipment so they can predict and monitor the compatibility of such devices with operational changes, even after the transition. For those broadcasters already on their final digital channel assignment, MVPDs have the option of switching their receivers before the transition date, possibly reducing the difficulty of transition coordination.
MVPDs will need to process broadcasters' PSIP and other signal information correctly. ATSC receivers and downconverters must be set up properly, and the appropriate ancillary data must be decoded and either re-encoded or processed to the new target signals. Broadcasters should also completely understand how MVPDs will process virtual channel numbering and Emergency Alert System (EAS) messages, as well as content advisory (V-chip) information and other program related data (e.g., Nielsen AMOL Data). Broadcasters and MVPDs also need to coordinate the handling of multiple audio programs (e.g., second languages, descriptive audio), so that these can be carried appropriately on the target systems.
Closed captioning carries with it some unique issues. Both EIA-608 and EIA-708 captioning must be sent on ATSC transmissions for all nonexempt captioned programming, so it should be verified that the cable plant as a whole will make captions available correctly to subscribers. In the past, an all-analog plant would simply pass the entire NTSC signal from source to subscriber, keeping the line-21 captions intact. Today's situation, with digital sources and mixed analog-digital cable plants, is more complex. EIA-608 captions can be re-encoded onto line 21, but EIA-708 (DTVCC) captions require different processing, as they are, in some sense, a superset of EIA-608. As always, broadcasters and MVPDs must ensure compliance with FCC regulations on correct carriage of closed captions. (See Figure 1.)
Broadcasters should coordinate the use of active format description (AFD) with their local MVPDs so the operator's receiving equipment can properly reformat images. (See Figure 2 on page 28.) AFD enables DTV receivers to automatically switch aspect ratios when signaled in the bit stream. Currently, broadcasters are not required to carry AFD. However, it is in their best interest to do so because viewers may not have the ability to change the aspect ratio of a signal that has been downconverted to analog by a service provider.
The NAB and broadcasters have created the AFD Ready initiative to promote and drive the deployment of AFD-compatible receiving equipment, including cable headend receivers and downconverter devices. More than 20 manufacturers support the initiative, and products are currently available.
If it is not possible to use AFD, then the broadcasters and MVPDs should coordinate the method of handling the downconversion, either by center cut of the image or by letterboxing. Similarly, broadcasters should make sure that the MVPDs' video processing equipment correctly respects the SMPTE clean aperture when reformatting video. Otherwise, extraneous nonvideo material (e.g., ancillary data) may become visible on subscriber TVs.
Broadcast audiences must be informed
It cannot be stressed enough how important it is for broadcasters to educate their audiences as often as possible leading up to — and after — the transition date. This should include simple links to Web sites to address what consumers must do to continue watching broadcast television. One part of this message has been largely overlooked: Consumers should rescan their DTVs and DTV converter boxes on or after the transition date, as many broadcasters will move to a different DTV channel assignment at that time. Converters and DTVs will not do this automatically, so some channels may disappear from the receivers after the transition date.
A further complication is the recent proposed congressional bill that would require stations to broadcast a barker message on the pretransition analog channel temporarily after Feb. 17. Should the bill become law, it will require additional MVPD coordination and viewer notification.
Some broadcasters will also stay on a temporary DTV channel — and may not switch to their permanent one — for up to an additional 12 months beyond the transition date. It is likewise important for those broadcasters to inform their audiences about the need to rescan their DTV receivers upon the final channel move.
The NAB has requested that its members put a voluntary four-week hold on talks surrounding retransmission-consent deals around the time of the DTV switchover. This quiet period is meant to limit “potential confusion in the marketplace” as viewers get up to speed with their new DTV receiving equipment or other aspects of the transition. This could also have the side benefit of moving any infrastructure reconfiguration to outside of the critical transition time, potentially decreasing the concentration of the technical effort.
Aldo Cugnini is a consultant in the digital television industry.
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