RF Technology: Doug Lung

What to Expect at NAB2006 for RF

NAB2006 this year should be interesting as manufacturers deal with an anticipated drop in demand for high-power TV equipment after the last maximization deadline passes in July and stations wait for the announced end of analog TV transmission in February 2009.

TRANSMITTERS

Improvements in TV transmitters at NAB last year were more evolutionary than revolutionary.

At this year's NAB, I expect to see less booth space devoted to high- power TV transmitters for the U.S. TV market and more space devoted to transmitters for other markets, including DVB-H and other multimedia-to-cell phone transmission equipment.

Thales is moving from its usual location in the Central Hall to the South Hall where it hopes to be able to attract more attention for its multimedia products and digital processing/distribution/ monitoring equipment.

Thales is providing transmitters to Crown Castle and Qaulcomm for DVB-H and MediaFLO networks. I expect them to focus on this side of the business. However, on the high- power side, Thales has been showing prototypes of a new ATSC exciter system at past NAB shows and I hope to see a production version this year.

I'm sure Harris will have some high-power transmitters sitting around its large booth in the Central Hall, but as with Thales, I expect Harris to focus more on medium power transmitters for DVB-H and other multimedia-to-cell phone technologies.

Acrodyne Industries' main products are high-power UHF transmitters but it will be interesting to see if they too see the need to expand into the medium-power multimedia transmitter area.

Axcera was demonstrating high- and low-power distributed transmission system solutions before ATSC adopted the DTS standard. Will other companies join them in showing DTS equipment at NAB2006?

As we near the sunset of analog TV, many broadcasters will want to improve their DTV coverage. Due to FCC build-out requirements, most stations will have to build out their maximized facilities this coming July.

I wouldn't be surprised to see a transmitter company, perhaps one of the smaller ones, offering a CP saver transmitter that can be shipped soon after NAB to give procrastinators an opportunity to preserve their authorized DTV coverage area.

Once maximized facilities are completed, if over-the-air coverage is important the focus will shift to filling in areas with bad reception. This should lead to more interest in TV translators, boosters and, of course, distributed transmission.

LPTV and TV translator stations are just starting their transition to digital. The FCC recently allowed these stations to file applications to transition to DTV on-channel or, where possible, file for a second channel for DTV operation. This should be good news for companies like Larcan, which has introduced new digital LPTV and TV translator products at past shows.

ANTENNAS

With the July 2006 maximization deadline approaching, the market for high-power UHF TV antennas should diminish until stations start constructing new facilities in anticipation of the end of analog TV.

Recognizing this, antenna manufacturers are likely to be promoting new designs for the lower 700 MHz band, digital low-power stations and DTS more than for high-power operation. As with transmitters, I wonder if we'll see a CP saver antenna that can be delivered in time for stations to make the July 2006 deadline.

Distributed transmission systems demand antennas with carefully controlled azimuth and elevation patterns to avoid creating interference to other transmitters in the network. I will be looking for new antenna designs that may be useful for DT systems I'm planning.

RF Technologies LLC is one company that has focused on developing antennas that require specialized elevation patterns with low downward radiation. Many markets have DTV stations on adjacent channels. To avoid interference with stations on adjacent channels, broadcasters wanting to use DTS will have to avoid RF hot spots around transmitters in populated areas.

I was impressed with the quantity and quality of reasonably priced RF test equipment at NAB last year. I expect the trend to continue this year.

Lack of 8-VSB demodulator chips that output detailed signal quality information is one thing that could hinder production of lower cost 8-VSB test gear. Software-based demodulators, such that developed by the GNURadio project, offer one solution. I'll be looking around the smaller booths to see if anyone has incorporated this software into an 8-VSB test instrument.

Last year, Pixelmetrix and others introduced products designed to make it easier to monitor DTV signals over a WAN or the Internet. I expect that trend to continue.

Along with the interest in transmitting video (and multimedia) to cell phone and handheld devices, I'm sure the major test equipment manufacturers will be featureing products designed for monitoring and testing DVB-H and similar transmission systems. These products may also be useful for DTS.

With the conversion of the 2 GHz band to narrower digital channels well underway, many broadcasters will be deciding what equipment to order and what add-ons to purchase.

In addition to equipment from the major broadcast microwave suppliers like BMS, MRCicrowave Radio and Nucomm, I'll be looking for new products from smaller companies to improve digital news gathering operations.

Some broadcasters have already begun providing HDTV video from the field and more are planning to add HDTV ENG capability.

Contribution- quality HDTV requires higher data rates or at least more complex compression technology such as MPEG-4 and Windows Media 9. Will the demand for higher bit-rates increase interest in the VSB modulation technology Nucomm has demonstrated at past NAB shows?

I look forward to seeing you at NAB. Don't miss my presentation on "RF Delusions" Saturday. It's the last presentation of the day at 4:30 p.m. and I've allowed plenty of time for your questions, and, I hope, my answers!

Doug Lung is vice president of engineering for Telemundo.