When the history of digital television in the United States is written, the individuals involved will read like a who’s who of broadcast technology. Many of those have been honored by the NAB with its annual Broadcast Engineering Excellence Award, and this year’s honoree is no exception.

Dennis W. Wallace is managing partner at Meintel, Sgrignoli & Wallace, LLC, a broadcast engineering and technical consulting firm founded in 2004. He developed and implemented RF field test programs for the HDTV Model Station Project at the Advanced Television Test Center in Washington, D.C., and built and conducted studies and demonstrations at the ATSC 3.0 Test Station in Cleveland.

Over the years his field-testing projects have included assessment of mobile DTV service, interference from unlicensed devices, effects of windmills on DTV reception, Distributed Transmission Systems, comparison of UHF and VHF spectrum for ATSC 3.0 and chairing the ATSC 3.0 Field Testing Task Force.

I got a chance to talk with Dennis recently and learned a bit more about what brought him to the industry.

As a kid growing up in Indianapolis, Dennis got involved in his high school’s 400W Class A radio station but “I quickly learned that I was more interested in the technical parts of it than I was necessarily being on the air,” he said. Jack Tiller, a professor at nearby Butler University, who taught mass media, helped Dennis get his start in actually getting paid for what he enjoyed doing.

“He took me under his wing and actually employed me part time in the summers to rewire studios at the university and that sort of thing. So that was my foray into engineering.”

Although Dennis had plans to attend Butler full time, prior to entering college, he entered a competition on entrepreneurship and won at both the state and national level. The prize was a scholarship to ITT Technical University, which he decided to pursue instead.

He almost completed the course before being hired by WIIB, a new UHF station in Indianapolis, in 1989. By the mid-’90s, Dennis had landed at the ATTC, working alongside one his mentors, Charlie Rhodes, who also penned TV Tech’s Digital TV column for decades.

Dennis remembers how Charlie would urge his fellow engineers to always push for more. “He would cajole a few of us to stay late or work extra and work on whatever question he had, along with the Grand Alliance engineers, to try to explore something. Those became what we referred to as ‘the Charlie projects.’ And we always learned a lot.”

Asked about the high point of his career (so far!), Dennis points to his work with the ATTC. “I started off at analog broadcasting, did the lab testing for the RF side of DTV, helping stations transition, and then shutting down analog and now in the twilight of my career, on replacing the system that I helped build.”

Dennis’s entrepreneurial and technical skills have helped him and his colleagues create one of the leading consulting firms in the broadcast industry. “One of the unique things that I bring to broadcast engineering is an understanding of the business implications of the technical pieces of it,” he said. “And I’ve kind of built a career at the intersection of business, technology and regulatory policy matters. That’s really what I do.”

Congratulations Dennis on this well deserved honor! Dennis will be recognized along with this year’s Radio winner Paul S. Shulins, at the “We Are Broadcasters Awards,” held on the Main Stage of the 2025 NAB Show, Tuesday, April 8, in Las Vegas.

WASHINGTON—The National Association of Broadcasters (NAB) has announced that consulting engineers Paul S. Shulins and Dennis W. Wallace are the 2025 recipients of NAB’s Engineering Achievement Awards. They will be honored at the "We Are Broadcasters Awards", held on the Main Stage of the 2025 NAB Show on Tuesday, April 8 in Las Vegas.

Established in 1959, the NAB Radio and Television Engineering Achievement Awards are given to individuals who are nominated by their peers for significant contributions to advancing broadcast engineering.

The 2025 Television Engineering Achievement Award will go to Dennis W. Wallace. He is managing partner at Meintel, Sgrignoli & Wallace, LLC, a broadcast engineering and technical consulting firm founded in 2004. A consulting engineer since 1997, Wallace has completed hundreds of projects for clients including broadcast transmission facility design and construction, RF field testing, research and development lab testing projects, as well as numerous regulatory and policy matters.

A well-known expert on broadcast system field testing, he developed and implemented RF field test programs for the HDTV Model Station Project in Washington DC and built and conducted studies and demonstrations at the ATSC 3.0 Test Station in Cleveland Ohio. Over the years his field testing projects have included assessment of mobile DTV service, interference from unlicensed devices, effects of windmills on DTV reception, Distributed Transmission Systems, comparison of UHF and VHF spectrum for ATSC 3.0 and chairing the ATSC 3.0 Field Testing Task Force.

Wallace has served in leadership positions for the National Frequency Coordination Committee of SBE, IEEE-BTS Ad-Com and ATSC. He has previously been awarded the Matti S. Siukola Award by the IEEE BTS, a Technical Emmy for his work on the development of digital television and the Industry Innovator Award by TV Technology Magazine. He has been a presenter at many technical conferences, including NAB, SBE and IEEE, authored significant published technical papers and represented clients before the FCC for almost 30 years. Previous to his consulting practice, he held technical positions at the Advanced Television Test Center, LARCAN and several broadcast stations.

The 2025 Radio Engineering Achievement Award will go to Paul S. Shulins. He has worked as a radio chief engineer for 45 years. Currently, he is co-owner of Over The Air RF Consulting, LLC, a radio and TV broadcast consulting firm based in Portland, Maine, that specializes in TV and FM coverage studies, FCC applications, microwave link studies and frequency coordination, thermal imaging for broadcast towers, antenna protection systems and ratings metrics. His pioneering work in the use of drone technology for infra-red measurements has improved performance and reduced costs for broadcasters.

Previously, Shulins worked at Burk Technology as vice president and chief technology officer. He also spent 29 years as head of engineering for Greater Media’s five Boston FM radio stations. Shulins is a member of the Society of Broadcast Engineers (SBE) and has held an SBE Radio Engineer Certification since 1982. He is also a member of the Association of Federal Communications Consulting Engineers (AFCCE).

As a past president of the Institute of Electrical and Electronics Engineers (IEEE) Broadcast Technology Society (BTS), Shulins has co-chaired the BTS Broadcast Symposium for several years and worked closely with NAB to introduce the “Best Student Paper Award” in conjunction with BTS in 2024. In addition to being designated a Distinguished Lecturer for BTS, Shulins has presented numerous papers at the IEEE Broadcast Symposium, the SBE regional conventions, the NAB Broadcast Engineering and IT Conference and the NAB Radio Show. He has been a frequent contributor to Radio World Magazine and authored several chapters in the 11th edition of the NAB Engineering Handbook.

The 2025 NAB Show will be held April 5-9, 2025 (Exhibits April 6-9) in Las Vegas. Learn more at NABShow.com.

LAS VEGAS--SBE announced this week that it will offer an all-day tutorial on ATSC 3.0 (aka Next Gen TV) right after the 2019 PBS TechCon, April 6 at the Flamingo Las Vegas Hotel. The tutorial is open to all, and costs $95 for SBE and PBS members, $145 for non-members.

The tutorial will cover regulations that dictate the requirements of the transition and technical compliance. These include MVPD notifications, carriage and 1.0 host requirements and agreements. It will also cover RF testing and field measurements and the importance of the scheduler feature in the standard. Additional topics will cover adoption, timing, budgeting, project planning and (looking further out), the enhanced content and services that Next Gen TV will enable.

In announcing the tutorial, the organization cautioned broadcasters to have a realistic approach to deployment of ATSC 3.0.

“Everybody in your world will want to know what NextGen is all about,” it said. “Some will have overindulged in the hype. Most will have more misunderstandings than real knowledge (we don't throw out TVs this time). For others, there will be fear, uncertainty and dread. We'll conclude with what is real and what is not, matching adoption curves with equipment life cycles. We will separate what happens today and what happens further down the road. In particular, we'll look at what changes in broadcast station architecture and workflows, including digital ad insertion and ad tech, will help move the revenue needle.

“When the hype becomes real, it is always a big deal.”

Registration is available at bit.ly/SBEatPBS.

Also on Saturday at TechCon, the the IEEE Broadcast Technology Society will host an ATSC 3.0 Roadshow, including a training seminar taught by expert Gary Sgrignoli of Meintel, Sgrignoli, and Wallace, the noted digital TV transmission consulting firm. This course will cover the ATSC 3.0 Physical Layer and prepare participants to take the SBE ATSC 3.0 certification exam.

Registration and seminar information can be found on bts.ieee.org.

For a comprehensive list of TV Technology’s ATSC 3.0 coverage, visit our ATSC3 silo.

Readers responded to my article comparing indoor TV antennas—some with questions, some just with comments (Comparing Antennas for Indoor Reception, September 2018). I welcome these as they give me a better understanding of how over-the-air TV works in the real world and the opportunity to share their experiences with other readers.

Reliable VHF reception continues to be a problem and based on recent emails, interference from devices such as LED lamps and even bathroom fans seems to be the most common problem for viewers with indoor antennas.

I also heard from readers having problems with UHF reception. One reader, outside Portland, Ore., was able to get VHF channels but not UHF. There was a small mountain between him and the towers. He’d tried several different rooftop antennas with no luck, but since the performance of consumer TV antennas can vary considerably I could only recommend trying one from a reliable manufacturer that provided real specifications for the antenna (not amplifier) gain.

Another reader who was familiar with propagation of RF signals emailed with his experiences rotating TV antennas to pick up vertically polarized signals. He was able to pick up stations with the vertically polarized receive antenna that could not be received when the TV antenna was horizontally polarized. Polarization shifts on reflection or defraction, so on an obstructed path this was not surprising.

It appears UHF reception isn’t immune to interference. One reader outside Oklahoma City wrote to say sometimes he could get 81 “channels” in a scan but this would drop to 21 “channels” and poor signal at other times. He followed my advice checking for electrical interference but found LTE interference was the real problem. The final solution turned out to be the addition of a “Zenable” LTE filter. Looking at the specs for this filter, I’m surprised it helped as the upper pass frequency of 790 MHz is well above that used for LTE.

For viewers in the United States, the Channel Master LTE filter looks like a better choice, since it rejects signals above 700 MHz. The specs on the Channel Master site are limited (“Frequencies Block 700–2000”). In his September 2016 TV Technology column, Out of Band Interference: Myth or Reality?, Charlie Rhodes measured the performance of that filter, which showed the loss at 740 MHz was 44 dB.

FIELD MEASUREMENT

In December I had a chance to ride along with Gary Sgrignoli and David Lawson from Meintel, Sgrignoli & Wallace LLC (MSW) for some of the 100 measurements they will be doing checking out the performance post-repack facility for San Diego’s NBC O&O KNSD. (These are the precision measurements I mentioned in my October 2018 column, Inexpensive Tools for RF Measurement.) At two of the sites, interference from LTE signals at 740–760 MHz was observed above the KNSD channel 40 signal. (KNSD had not transitioned to channel 17 yet so programming was still on RF Channel 40 with a test pattern without PSIP on RF Channel 17 for the measurements.)

It wasn’t clear interference was occurring to the reception of Channel 40 on the demodulator, but it was quite strong on the Rohde and Schwarz FSH4 analyzer in the van. I noticed the FSH4 has a second IF of 860.8 MHz and a third IF of 54.5 MHz. The relationship of these frequencies to the 740–760 MHz interference and the linear variation of the observed signal at above 633 MHz with attenuation leads me to believe this was filter ingress in the FSH4 analyzer.

This example, and the experience of the reader outside Oklahoma City make me wonder what will happen as LTE signals pop up on what used to be Channels 38 to 51.

I was surprised to see MSW using a consumer DTV antenna rather than a professional or cable headend log-periodic antenna on the test vehicle. Sgrignoli explained that size and weight were an issue and the DigiTenna DT-S (www.digitenna.com), while small and light enough for the telescoping mast and for storage in the van, performed quite well at both UHF and VHF frequencies. My experience is corner reflector/bowtie antennas can equal or beat four-bay bow-tie antennas at UHF. Look for more on the DigiTenna in a future column.

Before starting measurements, the system is calibrated. A calibrated dipole (quite expensive) is mounted in place of the DTV antenna. The measured signal level is used to calculate the field strength of the line-of-sight signal on the channels of interest after applying the dipole calibration factor and accounting for feed line losses. The calibrated dipole is replaced with the DigiTenna and the signal levels measured again to determine the gain of the antenna. These gains are recorded and used to calculate field strength from measured channel power.

This field study includes measurements at 100 sites divided into grids covering different areas. The procedure does not involve taking measurements while driving the van in a line with the mast up or taking a cluster of measurements around each location. This approach decreases the time required to measure the signal at each site and as a result increases the number of sites that can be measured.

One disadvantage of the van antenna setup was that it was not possible to switch polarization, or even mount the antenna on the mast vertically polarized. That didn’t stop us from doing a test at one site surrounded by hills where KNSD was very weak. Holding the DigiTenna about 12 inches above the ground with the elements vertical brought the KNSD signal out of the noise, not enough for reception at this height, but I suspect it would have worked at 30 feet. On Channel 17 KNSD is elliptically polarized with 50 percent of horizontally polarized ERP at vertical.

ACCURATE TESTING

Little did I realize that soon after my last column on simple field measurements was published, I’d have an experience that showed the real importance of doing them as soon as possible after an antenna is ready to radiate.

Measurements the day after a post-repack antenna was put on the air didn’t look right. These were done using the Winegard Freevision FVHD30, a 12-foot painter’s pole, the Airspy SDR with Spectrum Spy and a Hauppauge WinTV dualHD tuner with LinuxTV DVB utilities to obtain signal level in dBm. I didn’t have a precision dipole for calibration, but was able to come up with a rough antenna factor to add to the dBm to dBμV/m at 75 ohm conversion factor of +108.8 by comparing the signal levels from stations on nearby channels transmitting from the same site. Since I was interested in differences more than precise field strength, this was sufficient.

Comparing the measurements to predicted values with the transmit antenna oriented as authorized and with the antenna rotated 180 degrees provided a strong indication the antenna pattern was 180 degrees off, even though the antenna was installed correctly. The manufacturer confirmed there was an error in marking the orientation and has taken responsibility for fixing it. During the transition the station helped hundreds of people rescan to get the signal and in the few cases where there were problems viewers got good reception after tweaking their antennas so it wasn’t obvious there was an antenna issue.

Without the measurements, how long it would have taken the station to determine its signal was several dB weaker than it should have been over the most populated part of the market? Reimbursement for field measurement of the post-repack signal is allowed on FCC Form 399. It is well worth the effort, just in case. I’ve come up with some scripts that make taking channel power and MER measurements from the WinTV dualHD tuner easier. Let me know if you’re interested and I can provide the code and instructions.

As always, your comments and questions are welcome. Email me atdlung@transmitter.com.

As the Nov. 30, 2018 deadline for stations assigned to Phase 1 of the FCC’s Incentive Auction approaches and stations complete plans for the transition to their new channels, I thought other broadcasters and viewers may be interested in the signal levels I’ve been using to compare coverage from different facilities and optimize antenna designs.

During the transition, many stations will be forced to use auxiliary facilities with reduced ERP, lower height or both, which will impact their coverage while their main antenna is replaced with one for the new channel.

I’ve been working on methods for mapping the coverage loss from auxiliary facilities. I’ll describe one of them here.

REQUIRED SIGNAL LEVELS FOR RELIABLE RECEPTION

Outdoor antennas are now a rare sight compared to 50 years ago, although indications are that interest in them is increasing. For most over-the-air TV viewers in and around urban areas, indoor antennas are more popular.

Some studies have been done to determine the field strengths required for indoor reception. One I’ve relied on was presented several years ago based on field measurements by consulting firm Meintel, Sgrignoli & Wallace (MSW). It showed a field strength of 75.5 dBμV/m, on average, was needed for UHF TV indoor reception.

I use that number in my coverage comparisons, but also check coverage at a higher field strength, 88 dBμV/m, for what I call “easy indoor” reception. An “easy indoor” level means the viewer doesn’t have to spend a lot of time optimizing the antenna location or orientation in order to be able to receive the station. This number provides over 10 dB extra margin compared to the MSW findings and is 40 dB greater than the level required for FCC “Community Grade” DTV coverage.

I use a field strength halfway between the 48 dBμV/m FCC Community Grade level and the 88 dBμV/m “easy indoor” level for what could be called “easy outdoor” or perhaps “indoor with effort” coverage. This signal level takes into account the loss from outdoor antennas lower than 30 feet used in the FCC planning factors, and allows for some loss for antennas installed in attics or sub-optimum locations. It can also work for indoor reception if the antenna is in a window facing the right direction and high enough to clear nearby obstacles outdoors.

While these numbers were originally designed for UHF, I’ve been using them for high-VHF coverage as well. Even though the FCC service contour for high-VHF uses a signal level 5 dB lower than that for UHF, VHF reception is usually more challenging, especially for indoor reception, due to RF noise in the house and lower antenna gain.

“Channel 48 Main Coverage Thresholds” (Fig. 1) shows Washington D.C.’s WRC-TV main transmitter facility coverage plotted with these thresholds. Green areas are “easy indoor,” above 88 dBμV/m. Yellow-green areas extend indoor coverage to the 75.5 dBμV/m field strength. The blue areas are those where the predicted field strength is between 68 and 75.5 dBμV/m. Finally, the purple areas extend coverage to the FCC noise limited threshold. Cells with no service due to signal level aren’t shaded and cells with interference (there are 33 of them) are red. This map was created using the “coverpts.shp” files from TVStudy and the open source QGIS GIS.

A simpler way to find a station’s predicted field strength at a location is to use the FCC’s excellent DTV Reception Maps at www.fcc.gov/media/engineering/dtvmaps. Enter a zip code or more precise location and click on the station’s call sign for the predicted field strength from that station. This page only displays the facilities currently on the air.

To see a “rainbow” coverage map for any FCC authorized or applied for facility, use RabbitEars at www.rabbitears.info. Enter the call sign of the station on the first page; scroll down until you see the details on the station; click on “Technical Data” and then “RabbitEars TV Query.” On the new page, scroll down to the facility you want and click on “Longley-Rice Coverage Map” at the bottom of the technical details. RabbitEars is more generous than I am, considering signal levels above 80 dBμV/m “easy indoor” and above 51 dBμV/m “easy outdoor.” (Fig. 2.)

The TV Fool website provides many options for displaying signal power in dBm and noise margin in dB on maps and in tables. Using these values instead of field strength makes it easy to calculate the impact of adding antenna gain or amplification on reception. In many cases, however, adding an amplifier will increase the noise and interference along with the signal level and provide no benefit or even worse reception.

Measuring signal level can be done using any number of signal strength measurement instruments.

A bit of time with your favorite search engine will turn up several options. I’m not going to describe them this month, but will provide a tip on an easy and inexpensive way to measure a TV signal’s power in dBm. The Hauppauge WinTV dualHD USB tuner uses a Silicon Labs Si2157 tuner. The Linux “dvb-fe-tool” will display the signal power in dBm of the station currently tuned to in another program, such as Kaffeine, when run as “dvb-fe-tool-m” in a terminal. The program is available for Ubuntu in the “dvb-tools” package. It is also possible to derive MER (Modulation Error Ratio) from the WinTV dualHD using the “femon” command line program, but I haven’t verified the accuracy.

COVERAGE LOSS FROM TEMPORARY REPACK FACILITIES

Many stations will have to use auxiliary or interim facilities while doing antenna and tower work necessary to switch to their new channels. Stations not changing channels on a tower with stations changing channels are likely to be impacted as well. I’ve been looking at some methods to visualize the impact of the use of these facilities on viewer reception. I recommend stations begin operation on their new channel at full power to insure viewers catch the channel during the market rescan even if this results in coverage loss on the original channel prior to the transition.

The map “Channel 48 Aux Facility Coverage Comparison” (Fig. 3) is an example of a comparison of the main WRCTV facility and the auxiliary WRC-TV facility. Areas where the signal levels from the aux facility are within 6 dB of the main facility or equal to greater than 88 dBμV/m are shown in green.

Areas where the aux facility is over 12 dB weaker than the main facility are shown in gray. In these areas viewers are likely to have more difficulty seeing the aux facility, perhaps requiring an outdoor antenna if they weren’t using one before or upgrading an existing one.

Finally, areas where the main facility has FCC predicted service and the auxiliary facility does not, either due to signal below threshold or interference, are shown in red. For details on how to create such maps, see my article in the fall 2018 edition of IEEE Broadcast Technology or contact me.

If your TV station is operating at reduced power or on an auxiliary antenna during the repack process, I’d be interested in your opinion on whether the thresholds I’ve used for this analysis match your real-world experience. The example I used in IEEE Broadcast Technology had a narrower threshold (+/–3 dB) for equivalent reception since I’ve heard very few viewer complaints when a station has had to go to 50 percent power. Is 6 dB too generous?

As always, your comments and questions are welcome. Email me atdlung@transmitter.com.

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