Broadcast & Distribution – At CCW, a panel of experts discussed the details of the ATSC 3.0 development program – an effort to replace the existing over the air system with a new one that will provide the features and technology to last for another 20 years.
And as panelists noted, they are seeing broad and active efforts from the broadcasters to help shape this next standard, as it may offer a way for them to be competitive even as they face the prospect of losing spectrum in the planned auction the FCC is considering for 2016.
In a presentation given by NAB CTO Sam Matheny, he said there is now broad consensus that the new standard should include:
- OFDM Modulation
- IP Transport
- HEVC encoding
- Layered coding – core plus enhancement layers
- Hybrid TV – data plus interactivity
One thing that was stressed repeatedly was the flexibility that the draft standard will offer. As shown in the graphic below, ATSC 1.0 the current standard, calls for one data rate at 19.39 Mbps, but with some flexibility to use this for one channel or multiple channels (multi-casting) plus data. Under ATSC 3.0, broadcasters have a lot more ways they can configure their transmitters. For example, they can choose the size of the pipe perhaps offering a base layer broadcast at moderate bit rates to cover a broad area. This can be augmented with additional broadcasts that can deliver enhancement layers to more narrow regions. Repeaters can also be used to expand coverage as needed.
The enhancement layers are important as these can be used to provide additional features beyond the base layer. If, for example, the base layer was 1080p/60 content, enhancement layers could be used to offer 120 fps for sporting events that you could subscribe to if your TV or SDTB supported the decoding of this enhancement layer. It could be used to offer wide color gamut programming or high dynamic range programs as well (already the concept proposed by Dolby). And, it could offer more pixels (UHD, 5K, etc.) or maybe even 360-degree content for virtual reality experiences.
While the concept sounds very powerful and flexible, Winston Caldwell, VP of spectrum engineering at FOX noted that only testing of these proposed enhancement layers will validate if the concept works in real practice. Some of these tests have started already but more will be needed before the final approval of the standard by the end of 2015.
Also unique to the standard is the encapsulation of the video and audio in an IP transport stream. The exact encodings scheme is not yet set but contenders include MPEG and ROOT (an LTE variant). This allows much better interoperability with other infrastructures to provide means for providing ancillary data, like statistics for a sporting event, for example.
Plus, ATSC 3.0 will support reception in mobile devices – even cars going as fast as 185 mph.
Surprisingly, there is still some debate as to whether to include support for interlaced content and fraction frame rates in the new standard.
Another factor that may help pursued regulators to support the standard is the ability to deliver emergency alerts. Previous disasters have proved the vulnerability of cellular and Wi-Fi networks, so ATSC 3.0 should be much more robust and offer vital services and information in emergency situations.
Some in the session expressed frustration with the pace of development of the standard, but Cox’s Dave Seigler stressed that they were working on an aggressive timeline, but that they only have one chance to do this and they need to get it right. That makes a lot of sense. – Chris Chinnock
