Following a thorough report from Pearl TV and CBS about the Phoenix tests covered in ATSC 3.0 Field Tests Report Part 1, information about other OTA ATSC 3.0 tests in other locations was also shared that day and is reported in this Part 2.

The session “Field Testing of ATSC 3.0 Layer Division Multiplexed (LDM) Signals in Cleveland Ohio,” was presented by Dennis Wallace A.B.T.E, a Managing Partner at Meintel, Sgrignoli and Wallace, and Robert Seidel, VP, Engineering and Advanced Technology at CBS Television.

Wallace said tests began in October 2016 with ATSC 3.0 test transmissions on Ch 9 to study potential impulse noise impact on high-band VHF.

From October 2018 to March 2019 ATSC 3.0 testing moved to UHF Ch 31 and focused on the behavior of LDM at fixed sites. The Ch 31 signal is 437kW ERP with elliptical polarization only to the north. A non-directional H-Pol transmitting antenna is at 1055’ HAAT. A separate 25-bay slot & dipole antenna with 0.75° beam tilt is side-mounted.

In February and March 2019, field tests on Ch 31 were performed for time division multiplexing (TDM) reception at fixed receive sites. Later in March 2019, Ch 31 field tests of LDM with mobile reception were performed.

Goals in the Cleveland field tests were the determine real-world ATSC 3.0 LDM performance with a single transmitter in urban, suburban and rural areas with a variety of terrains. The first tests evaluated the reliability of fixed outdoor LDM reception by measuring field strength (coverage), service (reception) and margin (overhead) with the directional outdoor antenna at 12’ and 30’ AGL. The tests also used a prototype commercial receiver.

One experiment evaluated proxy LDM Mod Cods that might represent scalable video coding (SVC). A speed of 3.0 Mbps was determined to be enough for the low-resolution portion of the core video, and 9.5 Mbps or better delivered the high-resolution enhanced portion of the video.

A LDM test signal generator was loaded with two mod-cod parameters. One was a robust core PLO simulating handheld/deep indoor low-resolution video reception. The other was a high data rate enhanced PLP simulating outdoor high-resolution reception. The two test signals were remotely controlled from the field test vehicle. Tests evaluated two different injection levels, -3dB and -9dB. The tests and measurements determined minimums and performance for future LDM applications.

The experimental tests concluded that a “single stick” transmitting antenna provided coverage downtown and in urban, suburban and rural areas more than 95% of the time. It also provided reliable mobile service “crawling in downtown traffic and moving 50-70 MPH down the highway.”

The results suggest 50% E-Pol or more in all directions towards areas of interest, a moderate injection level of -4 to -7dB, and SFN deployment in RF shadows and other critical locations with signal issues.

Dallas – Fort Worth Tests

At 11:20 a “Practical Model for ATSC 3.0 SFN Deployment – Lessons from Dallas Trial” was presented by Pete Starke, VP of Broadcast at American Tower and Robert Seidel of CBS.

American Tower teamed up with Spectrum Co to design and build commercial grade SFN systems for multiple high-power TV stations. Spectrum Co’s partners include Sinclair Broadcast Group and Nexstar. The final design and build project consists of four American Tower sites in the Dallas-Fort Worth market. The main transmitter location is in Cedar Hill with SFN ‘nodes’ in Ft. Worth, Denton and Garland.

SFN construction was completed in 2018. All transmitter sites connect to a hub-and-spoke configured network. The goal is to complete trial tests, and then convert to commercial operations. The objective is to unlock non-traditional broadcast services and new revenue streams.

Phase 1 of the Dallas tests were performed to identify and learn regulatory rules, market business objectives, construction requirements, network connectivity, and build-out costs. Phase 2 includes system testing and operational workflows, ongoing operational costs, performance and commercial conversion.

Choosing among network connectivity options can be complicated. It must be low latency with 99.999% availability. Connection choices include fiber, especially if already at or near the site, or line-of-sight microwave. The test group anticipates sharing trial results later this year.

DASH Service in the Cloud at Chicago 3.0

At 11:40, “Implementation and test results for ATSC 3.0 hybrid services at ‘Chicago 3.0’,” was presented by Jean Macher of Harmonic and Robert Seidel of CBS.

Macher discussed synchronization and latency of the two ATSC 3.0 paths, OTA and IP. He said this is accomplished by DASH using the MPD Table of Contents to retrieve and play the segmented stream. The MPD lists the A/V components for the channel, segments for each A/V component, Start time for each segment, the earliest availability for each segment and more. The client TV can retrieve segments from either delivery path, place them on the presentation timeline and switch between them when necessary. The DASH packager can adjust the ‘availability start time’ to cover for the latency of the longest delivery path.

He said implementation of ATSC 3.0 hybrid services based on OTA and cloud-based OTT processing was deployed in the Chicago tests. Tests used the Harmonic VOS360 SaaS to create a complete DASH service in the cloud, with the full set of representations delivered OTA and OTT. All A/V segments, plus the MPD describing the complete service are available on the VOS360 origin server. The DASH client in the ATSC 3.0 receiver can pull components of the service via the broadband path in the same way common OTT service is received.

The ROUTE/signaling server at the TV station also pulls from the origin server, but only the MPD and the components that are configured for OTA transmission. The DASH segments for the OTA representation are ROUTE-encapsulated and passed to the rest of the ATSC 3.0 transmission chain.

Narrow Path to UHD?

According to Macher, Harmonic’s ‘First Use Case’ is occasional UHD delivery. In this case the DASH client in the TV receiver sends requests for HD segments to be served from the broadcast OTA connection. It sends requests for the UHD segments to be served from the broadband connection. In this case, OTA-only receivers get good HD quality and hybrid receivers with a broadband connection get the best UHD quality.

The UHD channel is encoded as a 1080p60 base layer, plus a UHD enhancement layer. The base layer is normal HEVC video that can be decoded by a standard HEVC player. The enhancement layer is an add-on to the base layer that needs a specific SHVC decoder. The problem today is that a specific SHVC decoder is required in the ATSC 3.0 receiver and that SHVC decoders are not currently available in the OTT world.

The second use is time-shifting using the broadband connection. The third use is for accelerated channel changing.

Network Engineering

Wayne Pecena began his session with a quick review of ATSC 3.0 and standards organizations such as IEEE and the INTERNET Engineering Task Force (IETF). He then discussed network models and ATSC 3.0 multi-layer architecture, and he explained the components in a block diagram of an actual ATSC 3.0 station.

His discussion moved to ‘The Competencies of the Broadcast Engineer.’ Pecena said “The use of IP as a core transport platform creates the need for the broadcast engineer to have a high competency in networking technology to successfully design, build, and support the ATSC 3.0 infrastructure.”

He then discussed ethernet switching, internet protocol (IP), TCP, UDP, IPv4 address classes, IP multicasting models, cybersecurity and securing the ATSC 3.0 broadcast system.

Interactive Apps

Mark Corl of Triveni Digital presented information about Interactive Apps and Broadcasting.

The ATSC 3.0 Interactive Content Standard is A/344, and it specifies how Broadcast Applications are distributed and defines how receivers should manage interactive content. It specifies the APIs in the receiver environment where the Broadcaster Application will execute. It is not a normative specification of an ATSC 3.0 receiver implementation.

The Interactive Content Standard A/344 Broadcaster Application Interactive environment describes the Interactive Environment Content Display model. This is where receiver media player video is mixed with Broadcaster App Graphics to create a composited display.

Corl also described the receiver environment with multiple contexts, and how ATSC 3.0 Interactive Content WebSocket API features work.

He explained Companion Device Concepts A/338, which describes a standard protocol to allow a Next Gen TV to discover companion devices (CDs) such as smartphones and tablets, notify the CDs and allow them to communicate with the receiver. He went on to show a diagram and explain a detailed studio architecture example, and concluded by saying “TVs are not browsers,” “Program content is King,” and “ATSC 3.0 Receivers are still prototypes.”

New Business Structure

“NextGen Broadcast is OTT Over-The-Air, Converged Broadcast/Broadband Platform” was presented by Mark Aitken, VP Advanced Technology and President of One Media, Sinclair Broadcast Group (SBG).

SBG is committed to leading TV broadcasting into ATSC 3.0 and Next Gen TV with partners focused on mutual success. 

Aitken began with what he called The 5 Guiding Principles of 'Next Gen':

1) It is a "Mobile-First" IP-based standard.
2) Supports an end-to-end hybrid converged environment.
3) Enables targeted advertising and personalization.
4) Supports conditional access.
5) "Dramatic" increase in capacity.

After reviewing the opportunities ATSC 3.0 offers, he said "IP transport is beginning to place broadcast at the middle of a rebuild, an overbuild, of the internet itself." He continued, "The bits we deliver get multiplied by every individual that consumes them." The mathematics and concept is simple. "Our job is to provide that overlay to ensure that our industry can stand up alongside the rest of the wireless industries and provide the usefulness and utility that broadcasting provides for."

He discussed the Next Generation Broadcast Platform (NGBP). It is a “high-level view of a new broadcast system architecture representing a vision of a NGBP with six major high-level entities.” Those entities include Regional Data Centers, Remote Radio Heads (RRH), Broadcast Market Exchange (BMX), cloud with BSS, central private cloud with OSS, a Network Operations Center (NOC) and a BaaS Tenant Dash Board.

Aitken explained Sinclair’s NetworkCo and InfrastructureCo whose entities and participants are being developed, and provided details on the SpectrumCo Consortium with Sinclair and Nexstar. SpectrumCo marks a significant business commitment to lead the broadcast industry into ATSC 3.0 and Next Gen TV and build on its success. SBG and Nexstar represent 350 stations reaching more than 60% of the US market.

Brave New Ad Insertion

“The Brave New World of Application TV (Dynamic content replacement techniques and implementations for broadcast, Broadband and Beyond),” was presented by Jim DeChant, VP of Technology at News-Press & Gazette Broadcasting.

DeChant began the session outlining the dreams of ATSC 3.0, such as IP packets delivered over Wi-Fi without concern about multiple users requesting content simultaneously and with no data download charges or data caps. He said broadcasters intend to build and deploy ATSC 3.0 transmission systems in many of the top TV markets by 2020. He said HTML-5 based applications will decode and display text, photo, video and audio content almost anywhere, and emphasized the need for conformance.

DeChant then moved on to a technical discussion on defining clip order, interfacing with content decision engines and the use of media cashing to facilitate Dynamic Content Replacement in live and video on demand environments.