Submission for the CDTV Newsletter (Full version)
ATSC Task force on RF System Performance
Bruce Cowan - CHUM Television
The Advanced Television Systems Committee (ATSC), a private sector organization was founded in the early 1980’s. The ATSC, along with the FCC’s Advisory Committee on Advanced Television Service was responsible for developing and documenting the detailed specifications for digital TV
The ATSC, working with numerous organizations, including the Grand Alliance consortium, approved the ATSC Digital Television Standard (A/53) on September 16, 1995.
In December 1996, the FCC adopted the major elements of the ATSC Digital Television (DTV) Standard and mandated its use for digital terrestrial television broadcasts in the U.S. Shortly thereafter, the FCC adopted companion DTV rules and assigned a DTV channel to approximately 1,600 broadcasters to permit them to transition to digital terrestrial broadcasting.
On November 8, 2021 Industry Canada formally adopted the ATSC DTV Standard for use in Canada.
U.S. digital television service was first launched in November, 1998. As of May 2, 2021 NAB reports that 127 Stations in 49 Markets were on the air.
Following the launch of DTV service, there were reports of reception problems. The main issue focused on the receivers failure to adequately to deal with multipath (which commonly appear as ghosts in NTSC). Sinclair Broadcast Group, based in Baltimore, was the most vocal about the apparent limitations of 8VSB reception and made it very clear that they supported the use of COFDM. Sinclair petitioned the FCC to add COFDM to the US standard.
COFDM has features that make it very robust in a multipath environment (the Canadian DAB radio system uses COFDM).
In February, 2000 the FCC rejected Sinclair’s' petition, however they did commit to holding a review of the entire DTV rollout process.
Shortly thereafter, the ATSC established an RF Task Force to review the roll-out of over-the-air digital transmission.
The Task Force, chaired by ATSC Executive Director, Mark Richer, has a general mandate but will "examine technical issues related to DTV RF system performance and, based upon this technical analysis, expeditiously make recommendations to the Executive Committee regarding potential ATSC technical initiatives”.
The first meeting was held on Friday March 31, 2021 at WETA-TV in Arlington, VA.
Over 100 people consisting of Broadcasters, chip, professional equipment and consumer electronics manufacturers, NAB, MSTV, and industry consultants attended the meeting. CDTV was represented by Bruce Cowan, CHUM Television.
A "straw-man" list of suggested work items was created.
Does 8VSB replicate the NTSC service area ?
What are the Broadcaster’s requirements for DTV ?
Development of uniform practices for field measurement ?
It was quickly realized that in order for the designers and manufacturers to come up with solutions, the Broadcaster’s expectations and requirements of the system had to be clearly defined.
Three ad hoc groups were created:
1) Broadcaster requirements
2) VSB performance
3) Field Test & Measurement Methodology
The first two groups, are to operate in parallel. Each group reports back to the main Task Force committee.
The expectations, as defined by the Broadcaster Requirements group, will be the impetus for the other ad hoc groups including the main task force. It is therefore an important committee.
Since the creation of the 8VSB format, and due to changes in the marketplace, Broadcaster expectations have shifted somewhat. Suggested requirements include the need for maximum digital throughput, portable reception, on channel repeaters, ease of use for the consumer, simple receive antennas and some form of mobile reception.
The requirements group will also try to define the meaning of “replicate the NTSC service area” given the inherent differences between analog and digital reception.
Once a final list is created, the Performance and Test ad hoc groups will attempt to apply solutions.
The main Committee and the ad hoc groups are fast tracking their work to prepare recommendations to the ATSC Executive Committee.
The Task Force is expected to complete its proceedings within six months.