Welcome to RF Current, a weekly electronic newsletter focusing on Broadcast technical and F.C.C. related issues. This newsletter is part of The RF Page @ www.transmitter.com, a web site devoted to TV Broadcast RF engineering. For more information see the What is... guide to the R.F. Page site.

This page contains stories from RF Current issues published in November 1996. Links referenced in the articles were current when published but by this time may have changed. If you find a bad link, try connecting to the home page of the publication or company and look for an archive of past articles. If you find a changed link, I'd appreciate it if you'd let me know by dropping me a note indicating the new location at dlung@transmitter.com.


RF Current was not published in December '96.

Best wishes for a New Year...

...Doug Lung

November 27 - Issue 51 Extended Edition

DTV - FCC Seeks Comments on DTV Standards Agreement (Nov. 27)

The FCC today released the text of the agreement between the Broadcasters Caucus, the Consumer Electronics Manufacturers' Association and the Computer Industry Coalition on Advanced Television Service (CICATS). The agreement called for the FCC to "adopt, no later than December 31, 1996, the ATSC DTV Standard (A/53), except for the video format constraints described in Table 3, including aspect ratios." It also said the "FCC's Report and Order adopting the FCC standard should include language clarifying that data broadcasting is a permitted use under the standard." The group agreed that the extensibility feature in the standard can be used as long as "such services comply with the FCC standard." Finally, the organizations and their members agree not to "support efforts in Congress or elsewhere for auctioning of spectrum allocated or to be allocated for digital television in MM Docket 87-268 or other proceedings releated to the launch of digital television."

Comments are due December 6th and the Public Notice seeking comment said the Commission did not "contemplate any extension of the comment period, and there will be no reply comment filing period. The Commission contemplates action on the issue of technical standards for DTV by the end of 1996."

The Consumer Electronics Manufacturers' Association issued a Press Release supporting the agreement. NAB also issued a news release outlining the agreement. Several FCC Commissioners spoke in favor of the agreement. Comments are available on the FCC web site from:

DTV - Broadcasters' Caucus Rejects Core Spectrum Plan (Nov. 26)

In comments filed Friday the Broadcasters' Caucus said the FCC's Sixth Further Notice of Proposed Rule Making on Advanced Television represented great progress and incorporated many of the principles broadcasters supported. However, after pointing out several shortcomings in the proposal unrelated to the core spectrum approach, Broadcasters said the core spectrum plan "creates unacceptable full power and Low Power Television service losses".

As it did earlier in the proceeding, Broadcasters submitted a new DTV allocation table with its comments, this time with modification requests from stations. Because the Broadcasters Caucus used a different set of planning factors, including a 3 dB lower signal level for UHF, the power levels and coverage numbers are different from those in the FCC Table. In addition to modifying the noise factor and hence the signal levels, the table takes into account the dipole factor and assigns more power to upper UHF DTV stations than lower UHF DTV stations when attempting to match NTSC coverage. Because the same factor was applied to NTSC coverage, stations with adjacent channel DTV allocations aren't affected by this. However, high UHF stations moving to lower UHF DTV assignments will get less power while low UHF stations moving to high UHF will need more power to match coverage.

The response Broadcasters received in its regional meetings underscored its assertion that the FCC must maintain a liberal policy to DTV facility modifications. The comments addressed several other areas, including the need for rules outlining the transmitter emission mask, receiver standards and channel labelling schemes. With regard to the latter, the Broadcasters Caucus recommended an industry committee of broadcasters and manufacturers determine how channels should be identified. It rejected the idea of identifying channels by frequency.

The Broadcasters Caucus comments, including the proposed DTV allocation table and notes, are available at http://www.nab.org/scitech/files/DTVFLNG.HTM. Other comments filed in this NPRM are available on my DTV Reference Page.

DTV - Broadcast, Computer and Motion Picture Industries Agree on DTV Compromise (Nov. 26)

After the announcement yesterday that the major parties in the battle over DTV standards had reached a compromise, people on both sides publicly praised the agreement today. Under the compromise, the Grand Alliance transmission standard remains intact but the areas on which the parties disagreed -- aspect ratios and the inclusion of interlaced scanning -- were left for the market to decide. In order to encourage the FCC to move quickly and adopt the compromise standard, the industry agreement had an expiration date of December 31, 1996. The computer industry got what they wanted -- flexibility to shape the digital broadcast image to better work with future computer designs and the TV set receiver manufacturers and other Grand Alliance members got what they wanted -- a unified multi-industry push to get the FCC to radify the core standard needed to get digital TV on the air. Some cinematographers however, were not happy, according to a news report last night. They want a requirement in the standard that motion pictures be displayed in the aspect ratio they are created in. (Ed. note - This may pose a problem for glass CRT's!)

Wayne Luplow, Vice President, Engineering and HDTV, Zenith Electronics, said

"The core technical standard -- representing the world's most flexible, computer-friendly broadcast system -- remains intact. As the developer of the digital transmission system at the heart of the HDTV standard, Zenith applauds the efforts of the consumer electronics, broadcast and computer industries in forging this agreement, which will pave the way for the final adoption of the U.S. DTV standard."

Peter S. Willmott, President and CEO of Zenith Electronics issued this statement on the agreement:

"This historic agreement gives the FCC the green light to adopt the digital TV standard before the end of this year. That's great news because it will provide the certainty we need to complete development of digital TV sets. The big winner will be the American consumer who will finally be able to enjoy the quantum improvements in television performance and new interactive services that digital and high-definition technology will deliver to our living rooms."

Watching the DTV standard battle unfold, many broadcasters were concerned that if the ATSC / Grand Alliance standard wasn't blessed by the FCC, manufacturers would be unwilling to make the investment needed to build DTV receivers and that lack of a national standard would kill off the industry before it got started. Judging from the comments of the Zenith executives quoted above, the compromises made to get this agreement haven't lessened their commitment to DTV. Indeed, the Grand Alliance standard (including aspect ratios and interlaced scanning modes) has such a head start that it is likely any the TV sets CEMA (Consumer Electronics Manufacturers Association) members expect to ship in 1998 will be the same as the ones they would have shipped if the compromise had not been reached and the Grand Alliance standard approved without modification.

The real winner in this compromise, in addition to the public, is likely to be the broadcaster. Now that the computer industry has the flexibility it wanted, broadcasters are likely to have much a greater variety of programming (including interactive computer applications) vying for their air time. By expanding the market, more broadcast station owners will be able find the revenue needed to cover the cost of making the digital transition. (Updated 11/27/96 to reflect motion picture maker objections to agreement)

DTV Reference Page Now On-Line (Nov. 26)

My DTV Reference Page is now on line. The page was created to provide a starting point for researching Digital TV (DTV), including High Definition Television (HDTV) on the web. I also offer it to broadcasters, manufacturers and related organizations as a reference point to list their web offerings on DTV. If you are interested in providing technical papers, FCC comments or related information on DTV and your company does not have its own web site, I will consider adding them to the www.transmitter.com site.

I would like to make the page a clearinghouse for comments filed in the 6th NPRM. Please e-mail me the link to comments your organization has on the 'Net or, if you wish, send me the comments in Word, Wordperfect, HTML, PDF or plain text format and I will store them on the www.transmitter.com server. Please email me at dlung@transmitter.com for more information. There is no charge for this, but, as with other items, time and disk space may prevent me from honoring all requests. If you would like me to host your FCC 6th NPRM comments, please send them to me as soon as possible.

DTV - PBS Urges FCC to Allevate VHF/UHF Disparity in DTV Assignments (Nov. 25)

Current On-Line reported on the PBS filing in the 6th NPRM in a story titled FCC urged to strike digital blow against UHF handicap. The filing asks the Commission to keep all TV channels available during the transition period and allow PBS stations operating at less than maximum power to build maximum power DTV facilities, among other things. More precise technical details were not available.

SCIENCE - SRI Tests Mars Relay UHF Communications Link (Nov. 23)

Early Sunday, Monday and Tuesday morning (the 24th, 25th and 26th of November) SRI International will use its 150 foot parabolic reflector and other equipment to test UHF communications to and from the Mars Global Surveyor spacecraft. The received signals can be observed on a special web page set up for the project at http://nova.stanford.edu/projects/relay. Full technical details, including frequencies, emission type, power levels, equipment and more can be found on the Mars Relay Home Page at Stanford University.

DTV - Period Ends for Filing Comment in FCC 6th NPRM on DTV (Nov. 22)

Friday was the deadline for filing comments in the FCC's Sixth Further Notice of Proposed Rule Making on Advanced Television. While much of the attention focused on the proposed DTV Table of Allotments, broadcasters questioned the planning factors used in developing the table. LPTV and translator owners looked tor answers to the question of how they would survive a doubling in the number of TV stations (as stations put their DTV channels on the air) over the next five to ten years.

The high power levels that VHF broadcasters need to replicate coverage under the FCC plan remained a concern. The Association of Federal Communications Consulting Engineers (AFCCE) has come up with what well may be the answer to this and other allocation problems. Their 6th NPRM comments propose the use of different planning factors for reception beyond the radio horizon, where the major VHF to UHF replication problem occurs. The comments are available on line at he AFCCE's site at www.afcce.org.

INDUSTRY - Dielectric Executives Perish in Plane Crash (Nov. 20)

After hearing news of the collision of two planes at the Quincy Illinois airport, I'm sure most in the broadcast industry, like me, feared that someone we knew might have been involved. Visitors to Harris Corporation's plant and Harris workers are frequent users of that airport. Sadly, two executives of Dielectric Communications were involved -- James Beville, Dielectric's President and Mark DeSalle, the company's Financial Officer perished along with 11 others.

More details are available in a Press Release issued by Dielectric. Take time as well to read the Tribute to Jim Beville and Mark DeSalle written by an anonymous Dielectric employee.

DTV - FCC Commissioner Ness Urges Industry Consensus on DTV Standard (Nov. 20)

In remarks before the Northern California Chapter of the Federal Communications Bar Association on Monday, FCC Commissioner Susan Ness said"The Commission has no interest in preserving tidy, artificial divisions between telephone companies, cable companies, broadcasters, and others. To the contrary, we are aggressively creating new opportunities for competition across business sectors." She cited the competition LMDS, DBS and OVS (Open Video Systems) will offer to cable TV as an example of this.

Ness again urged the parties arguing over the DTV standard "to meet and attempt to settle their differences no later than November 25." She added that she felt that a solution could be reached by that date and emphasized

"We need to settle the issue of a DTV standard this year, and resolve allotment and assignment issues early next year, so that DTV can become a reality. DTV can bring new video and interactive services to consumers, greater opportunities for broadcasters, and continued U.S. leadership in digital transmission technology. We cannot permit this issue to be delayed any longer."
SATELLITE - FCC Partially Grants TRW Requests for Odyssey LEO Modifications (Nov. 20)

In Order and Authorization DA 96-1923 the FCC International Bureau granted TRW's request to use Ka band frequencies for on-station telemetry and feeder links. It refused to grant TRW's request to use C-band frequencies around 7065 MHz. for transfer orbit telemetry. Several other technical modifications to the system were approved. Refer to DA 96-1923 for more details.

November 18 - Issue 50 Final

TECHNOLOGY - New AC Transfer Switch. Low Warpage Circuit Boards (Nov. 18)

I try to follow new developments in science and technology in fields. Sometimes they are related to TV broadcasting and RF, sometimes not. This past week I came across two stories that may interest my readers. Anyone who uses a high power generator is familiar with the problems associated with high speed mechanical power transfer switches. The Electric Power Research Institute released an interesting item titled POWERDIGM Switch Improves Power Quality, To Be Installed At Ford Motor Co. Detroit Plant that outlines a nonmechanical high power transfer switch using thyristor technology developed by Silicon Power Networks.

As circuit boards get larger and more complex, warpage has become a problem. The Georgia Institute of Technology has come up with a new technique for reducing it. Full details are in the story NEW PROCESS TRACKS CIRCUIT BOARD WARPAGE, COULD IMPROVE MANUFACTURING PROCESS on the Georgia Tech web site.

FCC Proposes New "Wireless Communications Service" (Nov. 15)

Anyone who doubts that Congress intends to use spectrum as a income source should take a look at the Notice of Proposed Rule making for the Wireless Communications Service, GN Docket 96-228. The Omnibus Consolidated Appropriations Act of 1997 requires the Commission reallocate frequencies between 2305 and 2320 MHz. and those between 2345 to 2360 MHz. to "wireless services that are consistent with international agreements concerning spectrum allocations, and to assign the use of such frequencies by competitive bidding pursuant to Section 309(j) of the Communications Act of 1934 ("Communications Act")."

There are few technical rules for this services -- only a mask for out of band emissions, some non-interference provisions and a field strength limit at the edges of the licensed area. The frequencies overlap some amateur radio allocations as well as broadcasting-satellite and terrestrial sound broadcasting (Digital Audio Radio Service or DARS). The Commission is considering a reduction of the satellite DARS band, which would avoid limit satellite DARS to the 2345 to 2360 MHz. portion of the WCS spectrum. As noted above, all frequencies would be auctioned.

A summary of the plan is available in News Release nrmc6096.txt. Full details are available in the Notice of Proposed Rule Making - Amendment of the Commission's Rules to Establish Part 27, the Wireless Communications Service (WCS) GN Docket 96-228.

FCC Wireless Databases Now Available on the 'Net (Nov. 15)

The FCC announced today, in a Public Notice that the complete database tables for services under the Wireless Telecommunications Bureau are now available on the Internet via the FCC's web site. The "home page" http://www.fcc.gov/wtb/databases.html will direct you to databases for land mobile, airport, aviation, coastal, commercial, marine, microwave, paging, pcs facilities and more. The tables are ASCII, field delimited, text files compressed with PKZIP. Cellular and Antenna Structure Registration data are not offered in this listing. See the Public Notice for more information.

FCC Releases Transcript of Forum on ATV Standard Economic Issues (Nov. 14)

The FCC today released the Transcript of its public forum on "Economic Considerations for Alternative Digital Television Standards" on its web site. Jeff Rohlfs, from Strategic Policy Research, argued the broadcasters' case, Lee Selwyn, from Economics And Technology, Incorporated, took the computer industry position and Bruce Owen, from Economists, Incorporated, filed his study on behalf of the National Cable Television Association.

Each participant presented his case and took questions from the audience. The results were largely as expected. Dr. Rohlfs argued that the opponents of the standard would benefit from its failure and "the computer applications down the line are certainly secondary. They may or may not occur at all. If they do occur, they may not have substantial value, and those considerations should not result in government mandating that the broadcasters can't broadcast in the format that they think best serves their interest."

Dr. Selwyn questioned the need for a government enforced standard, indicating there was little public demand for a costly HDTV receivers. He said "In effect, the grand alliance proposal, while professing not to require receiver standards, is requiring receiver standards. In fact, the grand alliance proposal just doesn't work. It doesn't make any sense without mandatory receiver standards. Now, let's sort of think about what happens here in terms of the way the market works. First, I don't think we can presuppose a priori consumer demand for high definition television. In fact, if one had to make a judgment based on revealed behavior of consumers, I think it would be an odds on bet that the demand for HDTV is very limited." He pointed to the thriving World Wide Web as how successful technology could be without government mandated standards.

Dr. Owen took a strong stance against government induced standards. "In summary, my most basic point is that when a broad-based industry group comes to the government and asks the government to in effect pass a law making it illegal for either them or anybody else to do things in a way other than the way prescribed by the standard that they propose, we have all got to watch for our wallets. Something is fishy. If the standard is a great standard, it will surely be adhered to voluntarily. And if it isn't, we shouldn't pass a law that forces people to adhere to it involuntarily," he said.

Each participant argued his case well and the audience provided good input on both sides of the standards issue. If you are interested in this debate, it's worth the time to read the entire Transcript.

DTV - Survey Shows Most TV Stations Plan to Air DTV within 5 Years (Nov. 12)

Harris Corporation released the results of a study it commissioned to determine broadcaster interest in DTV. Some of the key numbers: 72% hope DTV becomes a reality, 83% prefer the Grand Alliance Standard and 79% plan to convert to DTV within five years after the government sets a time line and a standard. Of that 79%, 28 % plan to convert within two years.

Ninety one percent of the participants said auctioning off the spectrum would delay the introduction of DTV. Forty-five percent said they expected DTV receivers on the market within three years, twenty-eight percent as soon as two years.

Concerning expense, 65% of particpants said they expected the conversion will cost each of their operations $5,000,000 or less. Sixty-three percent of the station executives in the top 50 markets felt they could afford it. One surprise was that 69% felt there should be a mandated conversion time-line of ten years or less and only 31% said there should be no mandated conversion time-line.

The study was conducted for Harris Corporation by Systems Research Corporation and involved 400 television executives representing 479 of the 1,551 TV stations in the U.S. The potential error rate is +/- 4%. I'll attempt to provide a copy of the press release here if it is not published on the Harris Broadcast Press Release web page.

November 11 - Issue 49 Final

SCIENCE - Mission to Mars - Global Surveyor Launched Friday (Nov. 11)

JPL reported that "After a successful launch, DSN acquisition went normally and spacecraft telemetry is being analyzed. All systems are working well, however there is an indication that the -Y inner solar array panel has not deployed fully. It is about 18 degrees short of full deployment. Efforts are underway to play back the data that were recorded during the deployment and further planning will take place when these data are evaluated. The solar arrays are providing plenty of power and the partial deployment presents no near-term threat to either the spacecraft or the mission." Background information on the mission is available in an article Return to the Red Planet from ScienceNow.

Two more launches are scheduled this year, the Russian Mars96 on November 16 and NASA's Mars Pathfinder, scheduled for December 2nd. As expected, you will be able to track the launches and the mission on the web. Here are some sites to bookmark to keep track of the Mission to Mars

RESEARCH - Study Says No Evidence EM Fields Harmful to Health (Nov. 5)

A committee of the National Research Council concluded that "No clear, convincing evidence exists to show that residential exposures to electric and magnetic fields (EMFs) are a threat to human health. There is no conclusive evidence that electromagnetic fields play a role in the development of cancer, reproductive and developmental abnormalities, or learning and behavioral problems." More information is available in a news release from the National Academy of Sciences. Copies of the report can be purchased from the National Academy Press by calling (202) 334-3313 or 1-800-624-6242.

DIGITAL - General Instrument Offers Royalty-Free 64/256 QAM/FEC Technology Licensing (Nov. 6)

In a press release issued today General Instrument said that it would license its essential ITU J.83B patents on a world-wide, non-discriminatory, royalty-free basis "to all companies which agree to cross-license, on reciprocal terms, any relevant patents they may have which are necessary to conform to the ITU J.83B standard." General Instrument developed the QAM modulation and Forward Error Correction (FEC) technology which, after modification, has been adopted as a standard by the ITU and the Society of Cable Telecommunications Engineers (SCTE), which is accredited by ANSI. Dick Green, President of Cablelabs, said "This action is significant because it establishes with certainty that GI will license ITU-T J.83B/FEC technology royalty free. This contribution is a welcome step in permitting the specification of a common downstream modulation for all cable services. We hope that other companies will follow GI's lead."

Cablelabs has placed the Digital Video Transmission Standard for Cable Television on-line. You will need Adobe's Acrobat reader to view it.

HDTV - NAB Outlines Broadcasters' Case for Grand Alliance Standard and Digital TV Channels (Nov. 5)

Last week the NAB posted three issues papers concerning Digital Broadcast standards on its World Wide Web site. The three issues papers are Interlaced versus Progressive Scanning, ATSC Standard versus the Computer Companies Scheme: A Side-by-Side Comparison and Virtual Myths About Digital Broadcast Standards. The papers make an excellent case for the Grand Alliance / ATSC digital video standard and point out the weaknesses in the computer industries opposition to it.

November 4 - Issue 48 Final

INDUSTRY - S. A. To Receive Emmy for Digital Video Compression System Development (Oct. 30)

Last month's RF Current reported on General Instrument's Emmy for its Digicipher product. Today Scientific Atlanta announced it would receive an Emmy at the November 19th Academy Engineering Awards Luncheon. Dwight Duke, President of the Satellite Television Network Division at Scientific-Atlanta, said "We are especially pleased and honored by the fact that this award is based on the engineering committee's recognition of our contribution to digital video compression. This gives special significance to the award since it is founded on the committee's knowledge of not only the well-publicized technical and engineering aspects of this industry, but also on their unique insight into our behind-the-scenes labors and efforts that made digital video compression's potential become a reality." Refer to the press release for more information.

DTV - CEMA Urges Quick FCC Action on Digital TV Standard (Oct. 29)

In a press release issued yesterday, the Consumer Electronics Manufacturers Association said it had joined with broadcasters, union officials and consumer advocates to urge the FCC "to adopt the digital HDTV standard as soon as possible." Gary Shapiro, President of CEMA said: "This open nine-year process produced a result that will deliver true over-the-air TV that meets the public interest. Consumers would not be served by a TV that requires repeated high-cost expenditures for hardware and software upgrades." He added "the standard itself is the compromise product of an open, consensus-driven process in which the computer industry fully participated."

FCC Opens Spectrum for New "Little LEO" Satellite Providers (Oct. 30)

Low Earth Orbiting (LEO) satellites have the potential to offer easy satellite communications around the world using frequencies in the VHF and low UHF bands. In a Notice of Proposed Rule Making FCC96-426 titled "Amendment of Part 25 of the Commission's Rules to Establish Rules and Policies Pertaining to the Second Processing Round of the Non-Voice, Non-Geostationary Mobile Satellite Service" the FCC proposed technical rules that could allow one to three additional additional LEO satellite systems in this processing run. The details are complex and readers interested in this topic should review the FCC text. Frequency band affected include 149.81 to 149.9 MHz. and 149.95 to 150.05 MHz. for uplinks and 400.150 to 400.505 and 400.645 to 401.000 MHz. for downlinks. One proposal that may be controversial is use of sub-bands in the 137 to 138 MHz. spectrum for downlinks. The NPRM sets forth several proposals for protecting existing users of this band. RF engineers interested in space / earth spectrum sharing may find it interesting reading even if not involved in the LEO business.

FCC Experimental Licenses Show RF Technology Trends (Oct. 29)

The FCC today released its list of experimental licenses granted in September. Harris Corporation and Digital Radio Technology, Inc. received licenses to test digital links in the VHF aircraft band. Harris' application was to test a "VHF digital link" on 136 MHz. frequencies. The Digital Radio Technology application was more sweeping, with a stated purpose "to develop datalink radio equipment for both aircraft control and Differential Global Positioning System navigational landing systems." General Motors received a license to test and develop collision-avoidance radar in the 17 GHz. range. Winstar has received a lot of press for its "wireless fiber" technology using 31 GHz. microwave. They received a license for "for test, development, and demonstrations of point-to-point services, and to conduct limited market studies."

Other Issues Available:



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