In November, the Federal Communications Commission (FCC) issued new rules that will let TV broadcasters adopt the next-generation wireless TV standard designated ATSC 3.0. This new standard defines the specifications for ultra-high-definition (UHD) or 4K over-the-air (OTA) digital TV.
In case you haven’t noticed, TV has progressed to the 4K ultra-high-definition stage with its 3,840 × 2,160 pixel resolution. (3,840 pixels is almost 4,000, thus the 4K designation.) Big-screen LCD and OLED sets are now reasonably priced, and some UHD content at the new resolution is becoming available. If you have not experienced UHD on a big screen, give it a try. You will want to upgrade immediately. In the near future, broadcasters will be able to offer this improved technology based on the ATSC 3.0 standard.
TV Today
Roughly 75% of households pay for their TV reception for cable or satellite distribution. But you can still get free over-the-air TV from your local broadcasters. It is estimated that about 17 to 21% of households get TV this way. Just put up an antenna and receive your local broadcasters— like ABC, CBS, NBC, CW, PBS, Univision, and a few others—at no charge. More than a few households have “cut the cable,” so to speak, and moved to OTA TV to cut costs in the past few years.
Free TV currently uses the original high-definition (HD) digital format designated by the ATSC 1.0. The Advanced Television Systems Committee is that group of TV and electronic companies that put together the U.S. TV standards that are blessed by the FCC and then adopted by the broadcasters. TV sets are made to those standards. If you recall, the switchover from analog TV to digital TV (ATSC 1.0) occurred beginning in late 2008 and concluded in June of 2009.
Called HD TV, this digital standard offers 1080i and 720p resolution. It greatly improves picture and audio quality while using the same 6-MHz-wide TV channels. Now 4K sets can get content via BluRay DVD, cable, and satellite.
The original digital TV standard used today, ATSC 1.0 employs 8VSB (vestigial sideband) modulation, a form of AM using an 8-level coding with a partially suppressed lower sideband to keep the signal inside the 6 MHz channel. MPEG-2 video compression is used. The error correction code is Reed-Solomon. Resolution is either 720 scan lines with 1,280 pixels or 1,080 lines with 1,920 pixels. Frame rates run at 30, 60, 120, or 240 frames per second. Bit rate in a channel is 19.3 Mb/s.
If you haven’t experienced OTA recently, go get an antenna and connect it up. There are lots available, and usually a simple indoor antenna is all you need. Take a look: It’s probably better than you’re thinking.
ATSC 3.0
The new standard was supposed to be ASTC 2.0, which was an upgrade to 1.0 to improve resolution and add new features, while maintaining backward compatibility with the original standard. But in the end, the standards group decided to toss the old standard and forget the backward compatibility issue. That led to the adoption of orthogonal frequency division multiplex (OFDM) modulation.
OFDM is far more spectrally efficient than 8VSB and offers better performance in multipath and non-line-of-sight environments. This permits the new standard to provide acceptable performance in mobile devices and indoor sets. The U.S. finally joins all the other digital TV standards in the world—like DVB in Europe, ISDB in Japan, and DTMB in China—that use OFDM.
ATSC 3.0 defines six levels of modulation, from QPSK to 4096QAM. Data rate in the channel can be as low as 1 Mb/s or up to 57 Mb/s. Data transmission will be an IP-based format like the common internet transmission. The Low Density Parity Check (LDPC) is the forward error correcting code. This new standard also has provisions for 2 × 2 MIMO at the transmitter and in the receivers to further improve the link reliability.
Other features include a more efficient H.265 video compression method. An improved audio compression is MPEG-H or Dolby AC-4. A curious uplink feature is also defined, which will permit viewer interaction services to be implemented. It uses single carrier frequency division multiple access (SC-FDMA) and HARQ format.
The adoption of 3.0 is voluntary by the stations and, if implemented, it would run in parallel with the existing 1.0 HDTV digital standard broadcasts in use today. It will take a year or so before TV stations install the ATSC 3.0 transmitters and TV sets become available. Definitely something to look forward to.
The big question is, can OTA broadcast TV survive the rapid trend in over the top (OTT) streaming? In the meantime, 4K UHD is terrific regardless of the source if you have not yet upgraded.
