LONDON—Digital TV Group, the U.K.’s industry organization supporting digital television research, has named Lesley Mackenzie as its new chair.

Mackenzie, the CEO of Local TV Ltd., which operates a network of local TV channels throughout the U.K., succeeds Simon Fell, who steps down from DTG after serving the maximum term permitted under its constitution, the organization said.

A 30-year industry veteran with senior leadership across broadcast, digital media and technology, Mackenzie was director of channels and operations at Sky for a decade. There, she played a central role in the launch and growth of U.K. digital TV, DTG said, including the analog-to-digital broadcasting transition and the developmnent of interactive services.

At then-Sky parent News Corp., Mackenzie helped to establish Tata Sky, a direct-to-home television joint venture with Tata Group, DTG said. As group digital director of LOVEFiLM, she drove development of the first major commercial video-on-demand business in the U.K. and Germany, the company said, scaling it across multiple platforms ahead of its sale to Amazon.

She then moved on to international roles at such companies as as ProSiebenSat.1 in Germany and MBC in the United Arab Emirates. She has more recently established her own consultancy, advising international clients on technology-led transformation in production and distribution, and has held nonexecutive roles at U.K. telecom regulator Ofcom and the British Board of Film Classification, DTG said.

“Lesley is an exceptional appointment for the DTG,” DTG Chief Executive Richard Lindsay-Davies said. “Her depth of experience across broadcast, streaming and technology, combined with a strong understanding of regulation, audiences and market change, makes her ideally placed to chair the DTG at a pivotal moment for our industry. As the sector navigates major questions around sustainability, resilience and the potential transition towards greater IP delivery, Lesley’s leadership will be invaluable.”

Mackenzie’s appointment comes as the DTG hones its focus on supporting the industry through complex strategic and technical transitions, the company said, including the long-term evolution of television delivery and the need to ensure that audiences continue to receive trusted, high-quality services in a shifting market.

“I am delighted to be taking on the role of Chair at the DTG,” Mackenzie said. “The organisation has a unique position at the heart of the U.K. television ecosystem, and its ability to convene industry, technology providers and policymakers has never been more important. I am looking forward to working with the board, the executive team and members to help the sector navigate the next phase of evolution—from distribution and delivery models to audience expectations and technological innovation.”

Lindsay-Davies also thanked Fell, founder and director of media and technology consultancy Innovizr Ltd., for his “outstanding contribution” as DTG’s chair.

“Over two full terms, Simon has provided steady leadership, clear strategic direction and unwavering support to the executive team and membership,” he said. “His impact on the organisation and the wider industry will be long-lasting, and we are deeply grateful for his commitment and service.”

Fell said: “It has been a privilege to serve as Chair of the DTG during a period of significant change for the television industry. The organisation plays a vital role in bringing the sector together to solve shared challenges, and I am proud of what the team and members have achieved together. Lesley is a fantastic successor, and I look forward to seeing the DTG continue to lead the industry with confidence and purpose.”

Back in 2004, I contributed an essay to Constance Ledoux Book's Digital Television: DTV and the Consumer, a book detailing the dawn of digital television. I wrote about discovering HDTV sets in my local Walmart Supercenter, declaring that HDTV had gone mainstream. Just seven years earlier, in 1997, the Federal Communications Commission (FCC) had released its Fifth Report and Order, which outlined an aggressive strategy for broadcasters to transition to DTV.

While HDTV should have been the new normal, at least in my eyes, sales were still catching up. The Consumer Electronics Association (CEA) estimated that one out of every four televisions sold in 2004 was an HDTV. That percentage sounds low today, but back then it was huge. The $1,600 average price tag for an HDTV set didn't help sales, but the price had dropped from $2,400 in 2003, according to the Leichtman Research Group.

Another stumbling block: There wasn't exactly an immediate windfall of HD programming. For example, NBC Nightly News was the first national evening news to broadcast in HD—in 2007—while The Simpsons didn't air its first HD episode until 2009, its 20th season. The first Super Bowl broadcast in HD was in 2000 (Super Bowl XXXIV), but Olympics fans had to wait until Beijing in 2008 to experience the entire event in HD.

These days, you can still find new Full HD consumer sets, but choices are limited (and the displays are relatively small). Instead, 4K has taken over the consumer marketplace. Without even taking Black Friday pricing into account, you can get a 55-inch LG 4K smart TV for less than $350 at Walmart. Other brands are even less expensive for larger sets. There are premium models for premium prices, too, but in 2024, you don't need to spend a fortune for 4K.

Maybe the speed of technological advancement is making us all lose a little perspective, but none of this is old. In a couple of years, the first talking picture, The Jazz Singer, will celebrate its centennial. Now that's old—we're talking black-and-white film stock, as well as a record on a turntable connected to a projector to sync the video and audio.

But HDTV? WRAL-TV in Raleigh, North Carolina, delivered the first U.S. public HDTV broadcast in 1996, while Hawaii's KITV was the first U.S. station to begin commercial digital broadcasts in 1998. And it literally took until 2014 for the networks to make the complete transition to HD. Big Brother was the last holdout in primetime due to its extensive camera (and related infrastructure) requirements.

Of course, by the time prime time was all HD, Netflix had launched streaming content in 4K. A few years later, the FCC approved NextGen TV (also known as ATSC 3.0), which opened the door to over-the-air 4K, interactive features, and much more. However, the transition to NextGen TV is voluntary, at least so far, so not every broadcaster has made the move.

Today, almost anyone with a halfway decent internet connection can stream tons of 4K content at home. Just a decade ago, it was House of Cards and a couple of nature documentaries. And a decade before that, there was only a handful of HD content, which you could only watch in high definition on a very expensive TV.

As we all welcome 2025, it’s interesting to think about what current Pro AV technologies will look downright antiquated in a decade. Will we laugh at how little AI was being used? Will HD be a distant memory? Heck, will we be in the middle of an 8K transition? Ten years is not that far down the road—but in terms of technology, what our industry relies on this year might just be considered ancient history.

This article originally appeared on TV Tech sister brand Systems Contractor News.

WASHINGTON—The FCC's Media Bureau is seeking comment on whether analog LPTV stations should be able to continue to program an analog radio service after the deadline to switch to digital.

While full power stations were required to go all digital in 2009, the FCC allowed LPTVs to continue to broadcast in analog until 12 months after the completion of the post-incentive auction repack, currently on track to meet its July 3, 2020, deadline, which means LPTVs would have to make the digital switch by July 3, 2021.

Some analog LPTVs (operating on ch. 6) use their spectrum to program an ancillary audio service available on the FM dial (87.76 MHz) and want to continue to be able to continue to deliver that analog signal after the mandatory transition to digital.

The commission has sought comment on the issue before, but citing the approaching deadline and "recent developments," said this week it wanted to refresh the record.

The FCC wants to know if its supplementary service rules mean that the ancillary analog service is OK even after the deadline, whether, in that case, the FCC could limit the number of such services—say, applying only to existing services—whether such rights could be transferred, or whether, alternatively, an analog service is not consistent with the designation of digital as being for the provision of "advanced television services."

Finally, if an analog audio service is consistent with that digital mandate, can the FCC subject it to the fee of 5% revenue currently levied on ancillary services.

The FCC is providing commenters 45 days to weigh in, with 30 days for initial comments and another 15 for replies.

This story was originally published on TVT's sister publication B&C.

Ten years ago, America said goodbye to an old era in TV technology and went all-in on a new form of broadcasting. On June 12, 2009, the federal government discontinued analog broadcasting, and TV stations across the country began broadcasting solely in digital format — the birth of high-definition television (HDTV) as we know it today.

We’re now on the cusp of introducing the American public to the latest set of improvements in the evolution of TV — broadcasting technology that delivers Ultra HDTV video, customizable audio, improved reception and interactive features all via an over-the-air signal. Navigating this national transition will be a challenge, but looking back at the original digital transition offers a clear roadmap to success.

The transition to digital broadcasting took more than 20 years, start to finish, and proved the benefits of government and the private sector working together — a victory for companies in our sectors, the federal agencies that work with us and, ultimately, consumers. But it all could have gone spectacularly wrong.

DECADES IN THE MAKING

Japan had been studying HDTV since the 1970s and was ready to begin analog satellite — but not digital — HDTV broadcasting toward the end of the 80s. Not wanting to be left behind, in 1987 the FCC began working with industry leaders here in the U.S., forming the FCC Advisory Committee on Advanced Television Service (ACATS) to explore how our country could spearhead the next wave of TV innovation.

Through an ongoing, candid conversation with consumers, government leaders and innovators, ACATS — along with the industry’s standards-setting organization, the Advanced Television Systems Committee (ATSC) — in 1995 set a standard for digital broadcasting that became the envy of the world, with HDTV as its centerpiece. Our American success story was a groundbreaking change — delivering captivating broadcast imagery, enabling exponential possibilities for content creators in Hollywood and beyond — that convinced the broadcast world our future was digital, not analog. Yet none of this could have happened without trust and collaboration from all parties.

Today, that level of cooperation seems remarkable. In an increasingly divisive political climate, building and sustaining that kind of momentum would be nothing short of miraculous. But it’s exactly what we’ll need to maintain our country’s global lead in innovation.The transformative potential of today’s cutting-edge technologies — from virtual reality to Ultra HDTV, artificial intelligence to robotics — far eclipses that of digital broadcasting. If we want to harness these technologies to strengthen our society and change our lives for the better, we’ll have to find common ground again.

CONSENSUS IS CRUCIAL

Three key elements stand out as reasons for our successful journey to digital television:

The first was its strong, thoughtful leadership model. As head of the ACATS, former FCC chairman Richard Wiley prioritized the need to establish consensus — listening carefully to all parties and “translating” each group of stakeholders’ concerns and ideas to one another. Chairman Wiley made a point of condensing what he’d heard into digestible pieces, so federal policymakers were informed of what was happening with private-sector companies but not inundated with weedy details.

Second, we established clear, shared goals at the outset. On one hand, the simplicity of our goal — build a system better than Japan’s and better suited to the lives of U.S. consumers — belied its complexity. On the other, the fact that our goal was so simple gave us the flexibility we needed to build a quality system, adjusting our approach as the technology itself evolved. Clarity and agility were crucial to implement these technologies quickly and safely.

Third, we prepared Americans for the transition to digital TV. We crafted extensive messaging around the transition, explaining to consumers how this technology made it as easy as possible for them to get more channels, better picture and better sound. We also shared our message with policymakers, giving them a glimpse of how digital TV would transform the media industry and strengthen the job market.

These factors might seem obvious, but in the whirlwind of disruptive ideas and the noise of partisan squabbling, it’s easy for the obvious to be overlooked. Paradoxically, implementing the next round of cutting-edge technology on a national scale — whether that’s the next generation of digital television debuting soon or a game-changing innovation such as self-driving vehicles — requires a return to the basics: consensus in leadership, clarity in goals and communication to consumers.

As the 2020 campaign heats up and our leaders begin to ponder their policy priorities for the coming decade, we urge them to look to the successes of the past. Only by building on these — the public and private sectors working together toward a common goal — can we lay a sure foundation for the innovation of the future.

Gary Shapiro is president and CEO of the Consumer Technology Association. Gordon Smith is president and CEO of the National Association of Broadcasters. 

This op-ed originally appeared in Broadcasting & Cable. 

WASHINGTON—This month marks the 25th anniversary of the formation of the Grand Alliance—a milestone in the history of television.

The alliance came about when a number of enterprises involved in developing an HDTV standard for the U.S. set aside their individual interests and agreed to work cooperatively to develop the world’s first digital high definition television system. Members included AT&T, David Sarnoff Research Center, General Instrument, MIT, Philips Electronics North America, Thomson Consumer Electronics and Zenith Electronics.

Encouraging them to find common ground and move forward together was Richard Wiley, former FCC Chairman (1974-1977) and partner at Washington, D.C., law firm Wiley Rein. Recruited by then FCC Chairman Dennis Patrick to serve as chairman of the FCC Advisory Committee on Advanced Television Service, Wiley pressed, prodded and cajoled these high-tech interests to form the Grand Alliance and in so doing put the nation on the path to digital HDTV. In this interview, Wiley recalls that effort.

(An edited transcript.)

TVTechnology: When I think back to the period just before the Grand Alliance, I remember that Japanese broadcasters were rolling out a direct broadcast satellite system to deliver analog HDTV to viewers in that nation. Did that light a fire here in the United States to get serious about HDTV here?

Richard Wiley: I think Congress and the FCC had noticed that there was research and development going on not only in Japan but also to some extent in Western Europe about the possibility of advanced television.

So, I got a call one day from the chairman of the FCC, Dennis Patrick, who asked if I would head up a federal advisory committee [Advisory Committee on Advanced Television Service] that would get the United States into this whole effort. They were concerned about being left behind.

You’re quite right. The Japanese had the MUSE analog system, which was pretty advanced. We saw pictures of it in operation at various conventions like the National Association of Broadcasters. So, they were moving.

TVT: What was your strategy as the chairman of the advisory committee?

RW: Basically, what I decided to do was try to have an international competition, inviting people to put forth by June 1, 1990, their individual entries. And they had to be entries that could be subject to testing under objective standards, including the MUSE system.

So, overall there were 23 entries –all of them analog. Many of them were not subject to testing; they were just kind of concepts.

We got it down to about seven systems that could be tested and put through a testing laboratory headed by Peter Fannon in Alexandria, Va. Over a long period of time, we tested each one of them.

TVT:They were all analog, but we ended up with digital television. Tell me about how that happened.

RW: Believe me, when we started out, nobody had digital in mind. It was all going to be advanced analog. That’s why we called it Advanced Television.

I had heard rumors and rumblings that there could be digital systems out there. I went up to New York one time to make a speech at a conference –not at all on high definition—and [former CBS SVP for Technology] Joe Flaherty came over to me. “We just saw a presentation on a digital system,” he said.

I said, “For goodness sakes Joe, tell them to get in here if there is such a system,” because June 1, 1990, we had to cut off the competition. The rules of the competition were you had to have a system to be judged in by that date.

So just before Memorial Day in 1990, the guys from General Instrument came east, and I went over to see their system a couple of blocks away from my office here on K Street.

They had developed a digital system. I said, “Well, give me a check for $175,000, which was the entry fee to do the testing and all the rest of it, like everyone else has done, and we will get you certified, and you will get in the competition.”

That was a big moment, I think.

TVT: There were A/D and D/A converters going back to the first digital time base correctors and frame synchronizers. But an entirely digital video systems was uncharted territory, it seems to me. What do you remember about that period when there was the decision to go digital?

RW: We tested seven systems, and they were all sort of developed on the fly. They were making improvements, so I wrote them a letter and gave them two options.

Testing cost hundreds of thousands of dollars and took well over a year. I knew they were going to be reluctant to go through it again.

But I also knew they were learning from each other and becoming closer, so my second alternative was why don’t you all get together and form –what my term was—a Grand Alliance.

Let’s put them all together and get a “best elements” system that would combine all of your entries.

TVT:How did they respond?

RW: They started thinking about the idea, and meeting on it. They had various meetings in different cities. One of them was in Chicago.

They decided to have a final meeting in 1992 at the Grand Hotel, of all things, here in Washington, D.C., to see whether they could do it.

I got a call from Robert Graves of AT&T, which was one of the companies with an entry, saying they had failed, and it wasn’t going to work. I said, “Stay there. I’m coming over.”

I went over and said I know what you disagree on –some wanted interlaced scanning, some wanted progressive scanning, but I said, “Can’t we all agree that we want over 1,000 lines of resolution?” They said yes.

“And we want widescreen.” They wanted that –16:9.

I said, “Guys, we can make this happen.”

Finally, I got them all to reconsider. The last one was MIT. Jae Lim was uncertain. I said, “Jae, call your people up in Boston. We’ve got to do this. This is our opportunity; the one thing that’s got to happen.”

He finally went along with it, but he wanted to have progressive scanning. And we dropped a footnote saying that would be something we would look at in the future.

Obviously, later Intel came along with a chip that obviated the difference between the two for the purpose of the set.

So, the Grand Alliance was formed. Obviously, it had to be built, and it had to be tested again –not only in the laboratory, but also in the field. That took another year to year and a half.

[Read: Grand Compromise Could Resolve DTV Transition]

Finally, after eight and half years we were able to come up with the final standard recommendation, went to the FCC in late 1995 and it was adopted by the commission in the fall of 1996.

The Grand Alliance was really what made this thing happen.

TVT:We’ve just gone through the ATSC 3.0 standardization process, and I am always fascinated by how these tech companies with competing interests can come to an agreement, especially when there are big bucks on the line. Can you tell me a little bit about the horse trading and how you got the individual companies in the Grand Alliance to come together and agree on the underlying technology of what we now call ATSC 1.0?

RW: I think peer review was the great thing we initiated there. We had all of these experts, and they had to get up in an open meeting, because the advisory committee had to operate under federal advisory committee standards and meetings had to be public and all open.

I think the fact that one company’s expert would get up in front of the whole group, drove people to a common result.

And, of course, I was in the background pushing everyone towards a single solution because otherwise we could have had a lot of litigation. I certainly wasn’t an engineer, so I certainly didn’t design the system, but the one thing I had my eye on was we all wanted high definition television.

That to me was the Holy Grail I was going to push for –digital high definition television.

TVT: How did you all get on the same page with MPEG-2?

RW: Well, I sent them that letter, and I started talking to them and urging them.

Along the way, a lot of people had different ideas. They wanted to have line doubling, and some people just wanted to have advanced television. They didn’t want high definition. They just wanted better television.

But Al Sikes, who was chairman of the FCC, and I agreed we should try to go for the gold and get the best standard we could possibly have, and that was digital high definition television.

So many of these systems were excellent, but when they got together and worked together, they made it even better.

TVT:What about 8VSB? How did that happen?

RW: We had committees and bake offs, that’s what they called it. They were done by the experts, and they came up with VSB as against the QAM cable system. And VSB got it.

At the very end of the game, some people suggested COFDM. So, I set up another special technical advisory committee. They tested it again. I think COFDM had great potential, but it was not quite as developed. So, the engineers I talked to all suggested staying with VSB.

TVT: Tell me a little more about the Advanced Television Testing Center and Peter Fannon having to test and evaluate the performance of all these new TV systems.

RW: It was a tremendous effort by Peter and his gang down there over the years. And they had to develop a whole testing mechanism, and then we had to redo it because digital came.

We had spent years developing the analog testing regime, and when we switched to digital, they had to come up with a new system. And the first entity that went in there was tested improperly –not by the laboratory, but by the engineers who brought it in.

The other people wanted to throw them out, but I didn’t want to disqualify anybody. I wanted to have them all to have the best brains possible.

So, we gave them a redo, and when I ordered the redo, I had a bunch of people come in here and argue with me about it and giving me all sorts of heat.

But I didn’t have any dog in the hunt. That was the good thing about it. There wasn’t anybody that I was cheering for. I just wanted to get the best system possible because otherwise we would really goof up our television system in this country, which everyone had enjoyed since the ‘50s when it first came out.

TVT: As you look back at the Grand Alliance and what was accomplished, are there any other thoughts you’d like to share on its 25 Anniversary?

RW: You know, the advisory committee was only 25 people. It was the Rupert Murdochs of the world. The head of CBS at the time, Larry Tisch.

But the heart of it really was the cream of our nation’s video engineering technology talent. Those are the guys who developed this in a peer-reviewed process. Those are the heroes in my opinion that made it happen.

[Read: ATTC Closing Marks End Of An Era]

I take a lot of pride when I see what a milestone it was in their lives. It was for me as well. It was a great development.

Editor’s note: Readers interested in learning more about how digital HDTV came to be in the United States may wish to read “Defining Vision” by Joel Brinkley.

Throughout the 35-year history of this magazine, there have been numerous contributors who have put the “technology” into TV Technology. Perhaps no other writer exemplified this fact than Charles W. Rhodes.

“Charlie,” as he was known to friends and colleagues, passed away on March 20 from complications after a fall in his home. He was 88. When the news hit, the tributes came forth. Calling him one of “television’s great engineers,” the NAB said that “Charlie had a tremendous role in leading the transition from the analog system of the 1950s to the digital television system we know today.”

Mark Aitken, vice president advanced technology for the Sinclair Broadcast Group and recipient of this year’s NAB Television Engineering Excellence Award (which Charlie received in 1996), said, “the industry just lost one of its greatest friends and valiant warriors. Charlie was a friend and a mentor.”

[Read: Charlie Rhodes' "Digital TV" columns]

For more than 30 years, Charlie wrote about, analyzed and offered his keen insight into the broadcast television engineering issues of the day in the pages of TV Technology. His first article for the magazine appeared in August 1985 on the European MAC standard. During his time with TV Technology, he covered the entire course of the digital TV transition from its beginnings all the way to interference issues resulting from the current channel repack. He was truly an “engineer’s engineer” and his influence on the television industry was felt from the local station all the way to the halls of the FCC.

Charlie got his start at Tektronix where he was responsible for numerous products including the RFA 300 8VSB measurement set. In 1987, he was hired as the Chief Scientist by the board of the newly formed Advanced Television Test Center and this is perhaps where he made his biggest impact on our industry.

Peter Fannon, former president of the ATTC and recently retired from Panasonic, called Charlie an “extraordinary scientist and just the right one at an extraordinary time, helping write the future of television and speeding the onset of the digital communications age.”

Fannon remembered how Charlie’s influence extended worldwide. “When visiting equipment vendors and development labs in Japan and China before the ACATS testing had begun, he was treated as a ‘rock star’ by scores of TV and RF engineers in those countries, most of whom had watched and learned from Charlie on a series of instructional tapes about TV test and measurement tools and techniques,” Fannon said. “Some of the asked him to autograph their treasured copies.”

Fannon said that Charlie’s tests were rarely ever wrong, but that he was “old school in his approach, rigorously probing any and all areas of uncertainty—yet totally open-minded to new information and so always ready to recognize and accept it.”

Charlie’s work over the years was deservedly recognized, with a Technical Emmy for his efforts in developing vertical interval test signals as well as the SMPTE David Sarnoff Award in 1992.

Charlie never really retired, conducting interference tests in his lab in Washington state and reporting on his results in the pages of TV Technology right up until last year. Last November, he notified me of his decision to end his column.

“At the end of 30 years writing for TV Technology, I have decided not to continue writing. One reason is that for the next three years, I believe that there will be very little to report to broadcasters. Furthermore after July 2020 when all stations will be settled in new channels, whatever interference is discovered, there will be nothing to be done about it that I have not already covered.”

That was typical of him—testing and analyzing right up until his final days.

Farewell, Charlie. TV Technology is immensely proud to have given you the opportunity to share your engineering genius with the television industry for so many years.

In my April column (“Auction Over, Now Let’s Assess the Damage”), I wrote about the damage in terms of unanticipated (by the FCC) interference to DTV reception after the repacking of the 600 MHz band.

The FCC has noted that there will be very little additional interference after repacking. Their studies examine both co-channel (CCI) and adjacent channel interference (ACI). There are other kinds of interference known, but the FCC does not consider these in its calculations.

I am referring to interference to DTV reception by certain pairs of undesired signals that generate third-order intermodulation products, which happen to fall into the desired channel and to certain triplets of undesired signals that generate triple beats whose spectrum overlaps the desired channel. My April column explained these additional kinds of interference.

THE CHICAGO EXAMPLE
Recently the FCC published the list of TV channel allotments following its repacking of the UHF channels. Now we can assess the likelihood of such interference as may be found within about three years when all stations will be operating on their new channels.

I chose stations in Chicago as examples. You can follow my calculations for your station in your community by emulating my example.

First, the FCC chose its “Scenario No. 7” as the basis for reallocating stations in the 600 MHz band. This is shown in Fig. 1.

Fig. 1: FCC Scenario 7—The Frequency Planning Basis of the 600 MHz Band

Click on the Image to Enlarge

The UHF TV spectrum extends from Channel 14 to and including Channel 36. The spectrum sold to broadband operators extends from Channel 38 to and including Channel 51. This spectrum is 35 MHz wide and was sold in blocks of 5.0 MHz each. Some broadband operators now own two or more contiguous blocks. The power of a 15 MHz block is yet to be determined, but the power limit for two contiguous blocks will be 3 dB higher than for a 5.0 MHz block, so the radiated LTE signal power density (watts per MHz) is constant between 5, 10 and 15 MHz emissions from base stations.

If the FCC were to hold all LTE signals to the same radiated power then the coverage of a 5 MHz system would exceed the coverage of a 10 or 15 MHz system. This is because receivers for LTE signals must have the same bandwidth as the signal from the base stations with which they communicate.

Fig. 2: Mkr. 1 608.5 MHz; Mkr. 2 617.5 MHz; Mkr.3 626.5 MHz; Mkr. 4 635.5 MHz

Assume that these LTE signals are 5 MHz wide each. If one of these overloads a DTV receiver near a base station, third-order distortion products will spread to be 15 MHz wide. Likewise, if a 10 MHz LTE signal overloads a DTV receiver, the LTE signal will be spread over 30 MHz; 10 MHz will be below the LTE signal and 10 MHz will be above the LTE signal. (See Fig. 2.) A 15 MHz wide LTE signal will spread out over 45 MHz.

You may wonder why all LTE signals are not 5 MHz wide. The answer is that in a second auction successful bidders in the first auction now owning two or more 5 MHz blocks can and will combine them into what I call a “super block” of 10, 15 or even 20 MHz width.

You might think that broadband systems would all start off with 5 MHz LTE signals, increasing their bandwidth as the business grows. But that would make all the cell phones in service obsolete. So I expect that systems will start up with all the bandwidth they now own.

Systems on the air in three years can be 5, 10, 15 or even 20 MHz systems. It also means that when they start radiating at their maximum power allowed, whatever interference results will be immediately evident if this interference blocks DTV reception near a base station.

CHANNEL 37
Now suppose that an LTE signal is 10 MHz wide as in Fig. 2. The signal occupies blocks A and B (617–627 MHz). If it overloads a receiver, third-order products will extend 9 MHz below block A to 606.5 MHz below block A (617–622 MHz), and third-order products will also extend 9 MHz above block B up to 636.5 MHz.

In Fig. 1, we see that Channel 37 is between 608–614 MHz. Channel 37 is used for medical telemetry in U.S. hospitals. However, base stations transmitting on both blocks A and B (617–627) may jam Channel 37 transmissions if the base station signal overloads nearby hospital receivers.

The situation with a 5 MHz LTE signal on block A is quite different. Third-order distortion products from block A only fall between about 614 and 617 MHz so there is very little noise in Channel 37 from a 5 MHz wide LTE signal on block A, and there is no noise in Channel 37 from a 5 MHz LTE signal on other blocks.

The FCC wisely provided a guard band between 614 and 617 MHz. But this is too small a guard band where a 10, 15 or 20 MHz LTE is deployed because the third-order distortion spectrum extends further downwards from 617.5 MHz into the TV spectrum.

Fig. 3: Twelve examples of the third-order interference spectrum products generated by pairs of downlink LTE blocks

Click on the Image to Enlarge

Fig. 3 (courtesy of my colleague Stanley Knight), shows the spectrum spreading for various combinations of undesired signals at the frequencies (shown vertically); the spectrum ends in a TV channel. However, the power per MHz (spectrum density) rolls off sharply as the frequency approaches zero power.

An interesting case would be with one 5 MHz LTE on block A and a second LTE on block G. It can be shown that third-order distortion products would be found centered at 590 MHz, Channel 34. I believe that this unanticipated interference will be to Channels 33–36. Channels below 34 will also be subject to interference of this kind from an undesired ATSC signal and a base station or by signals on certain pairs of DTV channels pairs.

Fig. 4: Current and repack Chicago DTV assignments and their interference noise due to IM3 and triple beats

In Figs. 4 and 5, Knight plotted the situation that will exist in Chicago, after the repacking and all stations are at full power. He took into account the third-order distortion products, not only from base station emissions, but also the TV signals.

In Fig. 4, Knight compares the interference (noise) in Chicago today in blue with the noise after repacking in red. This demonstrates the effect of packing signals closer, which is what repacking is all about. Note that there is no noise now above block E. This is the downlink signal from base stations. That changes after repacking.

At some sites, receivers may be overloaded by the combination of base station signals and remaining TV signals in the 600 MHz band. Fig. 4 indicates that the noise level increases by about 6 dB with repacking. And it also extends the noise power spectrum across Channel 37 by about 5 dB. There is no noise above the highest base station downlink frequency Ed.

Fig. 5: Scenario 7—Chicago repack and broadband block interference noise due to IM3 and triple beats

Fig. 5 compares the interference noise for a number of downlink base station blocks, so it is clear that this interference—when you take into account both downlink base station and cell phone (uplink) emissions and TV signals—extends across the 600 MHz TV band.

Closing on a cheerful note, these unanticipated signals can be kept out of receivers by means of a low pass 75 ohm filter, which passes signals on and below Channel 36. That is how this problem is dealt with in Europe.

Charles Rhodes is a consultant in the field of television broadcast technologies and planning. He can be reached via e-mail atcwr@bootit.com.

For more information on the repack, visit TV Technology's repack silo.

With the end of the FCC’s spectrum auction in January, it’s time to measure its damaging effects on broadcasters.

What damage, you ask? Interference to reception of your signal after the “Great Repacking.”

The FCC claims negligible interference is predicted after repacking. If so, that would be great, but wouldn’t your station manager like to know? The FCC says only co-channel and (first) adjacent channel signals cause interference. Others are worried about interference generated in DTV receivers. There are three such sources for this interference:

● Desensitization not due to receiver nonlinearity;
● Third order intermodulation (IM3) due to receiver nonlinearity; and
● Triple beats, which require three signals, also due to receiver nonlinearity.
● Triple beats are generated when there are three or more strong undesired (U) signals at the receiver’s input. They come from:
Fa + Fb – Fc, Fb + Fc – Fa and Fc + Fa – Fb

The easiest way to work with triple beats is to let Fa equal the lowest channel number, Fb equal the middle channel number and Fc equal the highest channel number.

For example, suppose the FCC allocates four UHF channels to your community. You have three U signals on channels 24, 27, and 29. Triple beats will be centered on channels: 24 +27 – 29 = 22. Also on channel 27 + 29 – 24 = 32 and Channel 29 + 24 – 27 = 26. If your station is to operate on any of these three channels, there may be interference; if your station is not going to operate on any of these three channels, you are in luck!

Fig. 1THE EFFECTS OF TRIPLE BEATS
Fig. 1 shows the number of triple beats generated by all triplets of U signals in the UHF band. There can be no triple beats where the number of U signals is less than three (that is where the name “triple beats” comes from). Fig. 1 shows this and it also shows that where the number of U signals in the UHF band is greater than four, the number of triple beats increases at an amazing rate. There will be some communities with 11 or more UHF channels; the number of U signals will be 10, 11, or more. The number of triple beats is 360, but there aren’t that many UHF channels so there will be multiple triple beats falling in some channels.

Fig. 2 shows that the spectrum of triple beats can be extremely wide. In fact, channels 37–49 won’t really be TV channels anymore, they will belong to broadband operators. Nevertheless, triple beats will fall in the broadband spectrum where formerly channels 38–51 have been auctioned. Channel 37, which was never assigned to a TV station, was—and will continue to be—used for medical telemetry, primarily in hospitals and radio astronomy.

Fig. 2 Let’s look at the column for channel 7 in Fig. 2. The lowest trace is for three U signals and is centered on channel 35. Channel 37 will have six triple beats, which will increase the noise floor of telemetry receivers.

That was the good news. The bad news comes where the number of U signals is higher. With 10 U signals, the number of triple beats falling in channel 37 is 20.

The noise power of a single triple beat is 4 dB greater than a IM3 product, assuming the same power is in the U signals. This 4 dB difference is due to the fact that three signals are involved while only two generate IM3.

Fig. 3 Fig. 3 compares noise power density per channel of triple beats with respect to the noise power of a single IM3 for a number of U signals. For seven U signals that means eight channels allocated to the repacking process. This exceeds 15 db for eight channels! It gets worse with more channels allocated. The best case, of course, is three U signals, but even then the difference is 5 dB. All of this suggests a strategy by which the channels allocated to a given community can be used to minimize such interference.

If the chief engineers in a given large DMA— where there will be more than five stations in the UHF band—were to agree on a repacking scheme to minimize the number of triple beats, perhaps the FCC could be persuaded to grant their petition. If that is to be done, now is the time to start such a program.

Note: My friend and colleague, Stanley Knight, generated the data and created the three graphics for this column. Readers might like to know that Stan I have never met face-to-face. Nevertheless he collaborates with me generating all my graphics. Thanks, Stan.

Charles Rhodes is a consultant in the field of television broadcast technologies and planning. He can be reached via email atcwr@bootit.com.

In the past, I have written about out-of-band (OOB) interference between ATSC signals in different bands: the low VHF band into a high VHF channel and a high VHF band ATSC into a UHF channel. Another example of OOB is where FM radio signals (88–108 MHz) interfere with reception of an ATSC signal on a high VHF channel. More recently, I have been concerned with interference to ATSC signals on a UHF channel being jammed by LTE signals in the 600 MHz band after repacking, which is no longer far into the future. But why worry about OOB from LTE signals? Why wouldn’t the FCC protect TV broadcasting from such interference? We will come back to this later in this column.

NEW LTE FILTER

Channel Master recently introduced a filter designed to eliminate interference to ATSC reception in the present UHF Band (470-698 MHz) from LTE signals in the 700 MHz band. You can find this filter (CM 3201) on the Channel Master website, www.channelmaster.com. Don Everist, president of Cohen, Dippell and Everist,P.C., a prominent Washington, D.C.-based consulting firm, ordered two of them and sent them to me.

Channel Master has dedicated four pages to the the new LTE filter on its web site, most of which are testimonials from satisfied customers around the U.S.

This is an unexpected development. OOB may have already arrived already in the U.S.; at least there is enough of a need now for such a filter that a prominent U.S. electronics firm invested in it.

In the case of LTE signal interference to ATSC reception, it results when a base station transmitter nearby goes to maximum power each time it seeks to establish communications with a subscriber. For 1ms, when the base station transmitter is establishing communication with another subscriber, interference may result. In our experience, up to 20 seconds can pass between consecutive interruptions, so testing for OOB requires more than the usual 20 seconds. This OOB doesn’t usually take out an entire frame of video; just a small portion of a frame may be affected/But who wants such interruptions? We did not listen to the program audio; with perfect hindsight, we would do so if ever we run more tests. I will not speculate whether disruptions to the picture or its audio will be most objectionable.

This is a 75 ohm Low Pass filter which according to the literature should be installed at the antenna and before any Low Noise Amplifier (LNA) if there is an LNA in the customer’s receiving system.

My colleague, Linley Gumm and I measured the frequency response of a CM 3201 filter.

Table 1: The results of measuring the frequency response of a CM 3201 filter Table 1 presents our results.

As my colleague and I had never heard of this OOB interference from an LTE signal in the 700 MHz Band, I would welcome readers having any experience with it to contact me (cwr@bootit.com). Specifically, please cite the channel number that was suffering interference and the distance between the transmitter and the receiver sites if it is known.

Fig. 1: A plot of a CM 3201 filter’s swept frequency response. Fig. 1 is a plot of this filter’s swept frequency response. The vertical orange line at 725.5 MHz is a recent artifact of the display of my spectrum analyzer. The insertion loss increases to about 60 MHz at 750 MHz. LTE signals may appear anywhere between 700 and 750 MHz.

My own observation is that this filter’s insertion loss above 600 MHz may cause problems where the desired signal is weak if the manufacturer’s recommendation is followed by placing the filter ahead of an LNA. In such cases, place the filter after the LNA.

Now, back to the FCC rules.

WHAT IS ‘HARMFUL’ INTERFERENCE?

In 2015, the FCC created a new and novel definition of harmful interference to the reception of DTV signals in the 600 MHz band.

The definition is found in Part 27 of the FCC Rules, specifically “Sub-Part N in the 600 MHzBand,” paragraph 27.1310: protection of broadcast television service in the 600MHz band from wireless operations:

“Licensees authorized to operate wireless services in the 600 MHz Band must cause no harmful interference to public reception of the signal broadcast stations transmitting co-channel or on the adjacent channel.

“Such wireless operations must comply with the D/U ratios in Tables 7–13 in OET Bulletin No. 74 if the 600 MHz licensee causes harmful interference to the public reception of a broadcast that is operation co-channel or on an adjacent channel, that licensee must eliminate the harmful interference.”

Please note that according to this definition, harmful interference can only exist between an undesired signal on the same channel as the desired ATSC signal or on either channel adjacent to the desired ATSC channel. If this is correct, then the licensee of the wireless system is not required to remedy OOB interference.

Furthermore, what about interference arising from third order intermodulation products generated by two undesired signals? Or from interference caused by multiple undesired signals desensitizing the affected receiver?

I should give credit to my colleagues, Linley Gumm and Stanley Knight for without whose help and encouragement, this column and the three IEEE Broadcast Society Newsletters we produced could never be written. The fall 2016 newsletter will soon be published. IEEE Broadcast Society members will receive our latest, and perhaps final work product. IEEE members who are not members of the IEEE Broadcast Society should look into joining this group (http://bts.ieee.org/).

Charles Rhodes is a consultant in the field of television broadcast technologies and planning. He can be reached via email atcwr@bootit.com.

Click on the Image to Enlarge
Click on the Image to Enlarge

In 2014 the FCC published details on how it will configure the 600 MHz Band. The 11 scenarios under consideration are shown in Fig. 1: TV channels are shown in green, base station transmissions will be on 5 MHz wide blocks shown in blue, and cellphones will transmit on blocks shown in yellow.

Fig. 1

A call originates from a cellphone transmitting on one of the yellow blocks, say Block F. A base station would reply also using Block F shown in blue.

This so-called “duplex system” that allows both parties to talk at the same time, requires that the base station transmit on a different block of frequencies (blue block) than a caller transmits on (yellow block). Both will use the same letter code. This duplex system illustrates how phone services have always worked.

‘BRICK WALL’ FILTER NEEDED?
Both base station and cellphone user equipment have a filter called a “frequency duplex filter” or “frequency diplexer” between the antenna and the transmitter output and receiver input. An incoming signal passes to the receiver from the receiver port of this filter, and when transmitting, its signal is routed to the antenna and not to the receiver input.

Here is the problem: Suppose the base station transmits on 600–602.5 MHz, while the cellphone transmits on 602.5–605 MHz. That would be a very efficient use of spectrum, but the duplex filters in both the base station and the cellphone would have to be “brick wall” filters—flat across their passbands and zero outside of the passband. Physics decrees that such a filter cannot be designed. Yes, it can be approached by using many poles, but such a filter is too large and too heavy for a cellphone, and by the way, its insertion loss would be unacceptable as it would reduce receiver sensitivity and battery “play time.”

But suppose there is a gap between the two blocks. Say the upper edge of the blue block is 600 MHz and the lower edge of the yellow block is 611 MHz. A very simple filter can be designed for this duplex gap between transmit and receive signals. This filter’s transition bandwidth of 11 MHz wastes spectrum because there should be no signals allowed within a duplex gap, but that is the price that must be paid to make wireless phones possible.

WIRELESS COULD SUFFER, NOT BROADCASTERS
That was the way it was until recently. Many stations volunteering their 6 MHz channel hope to receive up to $120 million; approximately $20 million per MHz per community. Some in Congress questioned the $220 million loss of revenue that results from these 11 MHz duplex gaps. Recently, the FCC has reported that in a “few unidentified communities,” it will have to place DTV stations within a duplex gap.

Each full-power TV station in the 600 MHz band radiates an average power of 1 million Watts, while a cellphone radiates a maximum average power of approximately 0.005 W. Base stations can radiate up to 720 W average power in 6 MHz bandwidth. As shown in Fig. 2, depending on what frequency scenario the FCC decides for a given community, a DTV station allotted a channel in the duplex band gap may end up centered in the duplex band or may be positioned hard against an edge of the wireless band as illustrated in scenarios 6 and 12.

The megawatt of power radiated within a UHF channel is accompanied by up to 34 W of sideband splatter (noise) falling in each adjacent channel. With an ATSC signal within a duplex gap, this legally radiated sideband splatter falls into either a base station block (blue area in Fig. 1) or a cellphone transmitter block (yellow areas in Fig. 1).

Fig. 2

Fig. 2 shows that a full power station in three of the 11 scenarios can jam blue blocks 5 and 11 or yellow block A. DTV signals in the duplex gaps of three other scenarios: 4, 10, (in magenta) and block A (yellow) can to a slightly lesser extent jam LTE signals in the 600 MHz band. Note that it is the wireless operators who will suffer, not broadcasters. In Fig. 2, I have placed the ATSC signal on the FCC standard TV channel frequencies within the 11 MHz duplex gaps. At first, I thought to center these ATSC signals in the duplex band gaps, but that won’t work. My colleague, Linley Gumm and I found by testing, that modern DTV receivers cannot lock to an ATSC signal which is not at the FCC standard channel frequency. A few receivers tolerated a displacement of about 1 MHz, but certainly no more than that.

You may be thinking: Why should broadcasters be concerned that placing TV signals in these duplex gaps may harm wireless transmissions? Well, in my next article, I plan to discuss the effect of placing a 1 Megawatt TV signal between TV spectrum (green in Fig. 1) and base station transmitter frequencies (shown in blue). Broadcasters and broadband operators will both see RED if there are TV signals between the green and blue areas of Fig. 1.

I wish to acknowledge the work of my colleagues, Linley Gumm and Stanley Knight which underlies the writing of this column for almost a decade.

Charles Rhodes is a consultant in the field of television broadcast technologies and planning. He can be reached via e-mail at cwr@bootit.com.

ALEXANDRIA, VA.—Radio amateurs, or “hams,” have been involved in one way or another with television practically ever since commercial entities began developmental work in the medium during the 1920s. And many TV engineers have held ham licenses and performed their own share of experimental work in their off-duty hours. Early on, at least one manufacturer offered camera pickup tubes at discounted prices to encourage experimentation by the radio amateur community.

Ham TV has evolved right along with the rest of the industry, moving from mechanical scanning to all-electronic operation, then color, and eventually to digital video and most recently, high-definition imaging. And while commercial television entities have routinely spent hundreds of thousands of dollars in retrofitting analog plants for digital broadcasting, hams—being an ingenious and creative lot—have managed to go digital on the cheap.

Art Towslee

Art Towslee (amateur station call sign WA8RMC) is one of these DTV pioneers. He’s now 74 and a retired Ohio electrical engineer who once specialized in the design of industrial weighing equipment. His interest in both ham radio and television date back to the mid-1960s.

“A bunch of guys I knew were playing with some war surplus UHF radio gear and actually using it to transmit video,” said Towslee. “I became very interested and got my ham license in 1965.”

For the past 50 years, Towslee has continued to experiment with television transmission in the amateur radio spectrum—they are assigned chunks of RF real estate in the UHF and higher frequency bands for such work—and a few years ago, along with other members of his Columbus-area amateur radio club, transitioned to digital video, becoming the first such group in the U.S. to do so.

“Our club, ATCO [Amateur Television in Central Ohio], was formed in 1989,” Towslee said. “We established a video-capable repeater [a “translator” with elevated receive and transmit antennas used to increase the range of amateur radio transmissions] in 1994 and used it to relay analog video transmissions between club members. Later on I had heard of some European amateurs who were experimenting with digital television and said ‘wouldn’t it be wonderful’ if we could do that here.”

Towslee, who is president of ATCO and publishes the club’s newsletter, did some investigation and eventually located an engineer in the Netherlands who had designed a digital video encoder/decoder board set and was now marketing these. The price selling tag was in the $1,000 range and they were designed for the DVB-S (satellite) standard. Towslee and his group purchased the encoder in 2003 and installed it at their repeater site to provide a channel with digital video transmission capability.

FIRST ON THE BLOCK WITH AMATEUR DTV
“We were first in the U.S. to have digital amateur TV capability,” Towslee said. “We claim bragging rights.”

He explained that the card set (MPEG compression and DVB-S modulator) was fed incoming analog video and its RF output was coupled to an amplifier operating in the amateur service 23 centimeter band (1,240-1,300 MHz). The club made a group buy of “free-to-air” digital satellite receivers that decoded DVB-S and soon some 20 Ohio ham operators were exchanging digital television images.

“We added DVB-S receive capability to the repeater around 2010—DTV in/DTV/out,” said Towslee. “This made us the first amateur radio group in the country with full digital repeater operation.”

The $300 DATV Express digital television board developed by the ATCO amateur radio group

Towslee admits that interest in the digital video operation has dwindled a bit in the past five years (“you get bored seeing the same things over and over”), but says that some of the digital devotees are still at it.

“We now have two digital channels at our repeater,” he said. “One in the 23-centimeter band at 1,268 MHz and another in the 70-centimeter band on 423 MHz. The 23-centimeter is set up to operate in 3.5 MHz of bandwidth and the 70-centimeter uses only 2 MHz.”

MADE IN THE USA
In an effort to make DTV more accessible for amateur radio operators, Towslee, along with two others, has launched a small manufacturing operation that produces a digital encoder card—the DATV (Digital Amateur TV) Express board—that sells for $300. It operates in conjunction with a PC, as it’s a software-defined device, and provides either a DVB-S or -T output.

“Our purpose was to get people in the U.S. interested in DTV,” said Towslee. “So far we’ve sold 120 of the cards. However, I am a little disappointed as most of the sales have been to people in Japan and Europe.”

When asked about the sort of experimentation hams are doing with their digital video gear, Towslee said that “d-xing” or attempting to cover long distances with fairly low power is one of these.

This rack contains the workings of the Columbus, Ohio amateur radio television repeater system. The digital processing gear is in the box atop the rack.

“Using DVB-S we’ve achieved about 100 miles,” he said. “With DVB-T and operating on 423 MHz one person in our group has done over 500 miles running about 400 Watts EIRP; of course this was over some pretty flat Ohio country.”

When asked if any of his DTV group had attempted high-definition operations, Towslee stated that all operations were still being done in 480-line SD; however, he added that the DATV Express could be upgraded for HDTV operation.

“The board is absolutely HD-capable,” said Towslee. “If there is a demand we will write code for HD operation.”

Continued at “Ham TV Operators Go HD.”