Doug Lung
Many viewers rediscovered off-air TV in 2013, as evidenced by companies old and new offering new and improved antennas for free viewing of programming from television broadcasters. While the 15 year old ATSC 1.0 transmission system has its limitations, these viewers are finding that off-air TV offers not only popular network programming in high definition, as well as a variety of multicast channels often unavailable on basic cable.
I haven't seen any major improvements in receiver technology in the last year, but since the analog shutdown, TV stations have been upgrading their transmission systems with power increases and improving their coverage, thus making their signals easier to receive.
After testing the latest Dyle TV receiver from Audiovox and Siano, I would say that ATSC mobile DTV really arrived in 2013, at least as far as the technology is concerned. The major problem still existing though is that while mobile DTV is available from ABC, CBS, Fox and NBC stations--as well as Spanish language Telemundo and Univision stations in some markets--the number of mobile DTV channels available in individual markets is limited and some markets have no stations transmitting mobile DTV. I hope that more stations will launch mobile DTV in 2014.
The next-generation broadcast platform (more on that later) will be IP-based, and implementation of mobile DTV services provides broadcasters with a way to become familiar with off-air IP multicasting for around $100,000 or so--much less if they have a newer exciter that supports mobile DTV.
Most DTV broadcasts are encrypted and in order for receivers to access to the keys needed to decrypt them they must first meet Dyle TV performance standards. Broadcasters are concerned about companies such as Aereo that pick up signals off air and resell them. HEVC encoding would allow broadcasters to transmit much more robust HDTV signals over ATSC mobile DTV to mobile, handheld, portable and fixed devices using A/153 mobile DTV, with the option to encrypt it to better track the number of viewers and mandate receiver standards. 2014 is a good year for all of us to become familiar with mobile DTV
Given the advances in technology in the past decade-and-a-half since the ATSC standard was developed, it isn't surprising broadcasters are making plans for the “Next-Generation Broadcast Platform” (NGPB). Work on the new standard, which is known as “ATSC 3.0” is now taking place in the Advanced Television Standards Committee (ATSC). The ATSC made significant progress towards the NGBP in 2013, receiving 11 detailed technical proposals for the physical layer portion of the standard. Most of these proposals use COFDM, the same modulation method used for Wi-Fi, LTE wireless base stations, and most modern communications systems. Many have some relationship to the current DVB-T2 standard, and as the ATSC doesn’t have to worry about legacy support for previous DVB standards, there’s an opportunity to improve the performance and perhaps increase compatibility with wireless broadband standards such as LTE.
The ATSC 3.0 timeline calls for selection of a physical layer proposal in mid-2014 and completion of a candidate standard in the first half of 2015. I'll be following work on ATSC 3.0 and the NGBP in RF Report and my monthly TV Technology RF Technology column in 2014.
Some of the challenges facing ATSC and broadcasters in rolling out ATSC 3.0 will be in transitioning legacy ATSC viewers to the new standard and creating a standard that manufacturers will be willing to use in TV sets, notebook and tablet computers and, ideally, smartphones.
Last year, Congress authorized the FCC to conduct an incentive auction that would allow broadcasters to voluntarily give up their spectrum for use by wireless carriers. A key part of the plan is that those stations that don't give up their spectrum will be repacked onto new channels in order to make a maximum amount of spectrum possible available for auction. The Spectrum Act adopted by Congress required the FCC to make all reasonable effort to preserve a station's coverage in the repacking. The FCC’s plan does a good job of preserving coverage in most cases, but National Association of Broadcasters has found errors and assumptions that could significantly hurt the coverage of some stations.
The FCC Office of Engineering and Technology has released the source code and binaries (Linux and Apple OS-X) for TVStudy, the program it plans to use to evaluate coverage before and after the repacking. (See my 2013 articles in TV Technology on how to install and use TVStudy. Look for more about it in my 2014 columns.)
The Commission has much work to do before it can start the planned incentive auction. FCC Chairman Tom Wheeler has delayed the start of the auction to allow more time to draft the rules and thus increase the chance that the auction will succeed. One concern is that the amount of spectrum broadcasters agree to voluntarily give up will not be enough to create a successful auction. If this happens, a major concern is that the FCC and wireless industry will go back to Congress and say while they tried to protect broadcasters, they will need to reduce TV station's coverage or be given the authority to force stations to share channels in order to secure this critical 600 MHz spectrum (which I think in the end won't be as useful as hoped in urban areas). If this happens, broadcasters should be ready with an alternative plan--perhaps in conjunction with a transition to ATSC 3.0, and with a mandate requiring manufacturers to include ATSC 3.0 reception capability in certain devices.
Pressure to increase the amount of spectrum available for wireless broadband continues to threaten Broadcast Auxiliary Service (BAS) spectrum. In 2013 we saw CTIA petition the FCC to reallocate 15 MHz of the 2 GHz BAS band for wireless broadband. An agreement between NAB and the Department of Defense (DoD) that allows DoD to share the 2 GHz band in exchange for giving up some of its 1.7 GHz spectrum has alleviated that threat, but I won't be surprised if we see other proposals in 2014 that impact both the 2 GHz and 2.4 GHz BAS bands. Globalstar's proposed Terrestrial Low Power Service would impact 2.4 GHz BAS channels A9 and A10.
This year I've observed only a few problems arising after the FCC allowed Part 101 fixed service operators to license links using Part 74 BAS spectrum at 7 and 13 GHz.
One plus for broadcasters is that the rule change allowed broadcasters to use Part 101 fixed service bands for studio-transmitter links and take advantage of the wide range of IP-based microwave radios available for these bands. In 2014 I expect to see more broadcasters moving to IP-based microwave networks, initially for ENG receive site back haul but eventually for STL.
Repacking TV channels after the incentive auction is finished will also greatly reduce the amount of TV spectrum available for wireless microphones and intercoms. The FCC examined the impact of repacking on unlicensed uses (low power wireless microphones and TV white space devices) of the TV bands in a 2013 workshop, but so far I haven't seen any specific proposals on how to protect these secondary TV band uses after the repacking. As these devices operate with low power, one option may be to allow them to use the guard band spectrum between broadcasting and wireless, or perhaps the “duplex gap.” Some issues that need to be resolved before the repacking include whether or not to maintain reserved channels/spectrum for licensed wireless microphone use and also establishing allowable interference levels between TV white space devices and wireless microphones.
