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 May 1997. 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.

May 26 - Issue 71 Final Edition

FCC Schedules Public Forum on "Smart Antenna" Technology (May 23)

The FCC has tentatively scheduled a public forum on Wednesday, July 16th,

to discuss the status of the development of "smart antenna" technology, the status of the implementation of the technology, prospects for future applications, and appropriate rule changes or avenues of approach that the FCC should take with regard to this technology.

More information is available in the Public Notice from OET. Other OET forums include a Tutorial on Digital LMDS scheduled for June 12.

DTV - Cablelabs Extends Date for MPEG Digital Insertion RFI (May 20)

Cablelabs issued a Request for Information (RFI) earlier this month dealing with the issue of systems that will allow cable operators to insert compressed programming into a compressed bit stream. The compressed programming could be commercials or programs. The RFI asks companies to share their ideas on proposed functional requirements and performance objectives, interfaces that should be standardized, how this program insertion will fit into overall cable network architecture and "constraints or recommended practices that would result in a less complex solution."

Broadcasters contemplating DTV broadcasting and manufacturers supplying both wirelessed and wired digital video distribution may find the document of interest. Refer to the letter extending the RFI deadline for the current dates.

OTHER Items of Interest

May 19 - Issue 70 Final Edition

DTV - AITech Announces Plans for $400 Set Top ATSC HDTV Converter Box (May 19)

One of the big worries broadcasters have about the digital TV transition plan is that few viewers will have the sets to receive the broadcasts when they begin. Many have questioned the premise that consumers will pay several thousand dollars for DTV sets (see the E-Town News Article from last week's edition). Today's announcement from AITech, one of the top companies in computer video scan conversion, that it plans to develop a set top converter box at an estimated price of $400 that will receive HDTV digital broadcast signals, decode them and convert them "to a format displayable on any analog TV or standard VGA PC monitor" should give those broadcasters a bit more comfort during the digital TV transition.

AITech said its box would also include "an advanced audio decoder to perform digital AC-3 decoding into 6 channels of multi-lingual or surround-sound audio.". AITech says its box will be as easy to install as a VCR and that it will draw on "many of AITech's existing technologies, including its FlicFree® filter and patented VSPro® PC/TV scan conversion.". The AITech release conceded that "Still, the digital receiving circuitry design is challenging and requires scan conversion of several resolution choices: 1920 x 1080; 1280 x 720; 704 x 480; 640 x480; with aspect ratios of 16:9 and 4:3; in 60 frames per second (fps) progressive, 30 fps progressive, 60 fps interlaced, or 24 fps progressive."

AITech's web site, unfortunately, does not have any information on this announcement. The latest information I saw on the site was dated in 1996. This might change, so you might want to check back later.

FCC Report and Orders On Digital TV Appear in Federal Register (May 16)

Many of the timetables for legal issues concerning FCC Orders are based on the date the Order appears in the Federal Register. The FCC's Fifth Report and Order on Advanced Television Systems was published in the Federal Register Friday, May 16th. The Sixth Report and Order, which established the channel allotments for Digital TV, was published on Wednesday, May 14th.

Now that the Orders have been officially published, expect to see petitions for reconsideration filed in the next thirty days. Based on comments I've heard from broadcasters and those voiced at the NAB Convention, the mandated timetable for DTV conversion in the top markets is likely to see opposition. Look for requests to extend the timetable or at least make it easier to gain extensions. Also, while the 6th Report and Order reduced to some extent the power discrepancies among DTV stations in the UHF band, existing UHF broadcasters still see problems with the wide variation in powers in the 6th Report and Order's channel plan. Look for requests to raise the minimum UHF DTV average ERP to 100 kW or 200 kW. At NAB, concern was voiced that the 1 MW cap in UHF DTV power levels may not allow full coverage for VHF stations moving to UHF. I expect some of these station owners to ask either for more DTV channel assignments in the VHF spectrum or the option to go to higher power in the UHF spectrum.

The parameters the FCC used to create the channel table are also likely to come under fire. The Association of Federal Communications Consulting Engineers has already made the case for using antenna amplifiers at distant receive sites to extend UHF coverage, instead of the impractical power levels originally proposed in the FCC's 6th NPRM. Also, while the dipole factor was considered for UHF channels, it wasn't used for the VHF band, where, of course, it also applies. Another potential area for reconsideration is how the dipole factor was applied to UHF stations with UHF DTV assignments. A UHF station on 69 moving to channel 20 would have its DTV power for matching coverage reduced to match the dipole factor reduced coverage 69 has versus channel 38. However, for the purposes of predicting coverage, a constant 41 dBu field strength is used. Therefore, the DTV coverage maps of high channel UHF NTSC stations, based on a constant field strength, will be less than that for low UHF stations. Some station owners are likely to complain about this.

While the Orders offered several concessions to LPTV and translator stations, including relaxed interference ratios and increased power levels based on ERP rather than transmitter power, the lack of any absolute protection for existing stations is likely to draw petitions for reconsideration. On the other side, some broadcasters may oppose the relaxed interference standards. Given the political pressure to move DTV along (see the story on S.705 in last week's edition), the FCC is likely to oppose any changes which would slow the DTV transition. Whether or not the technical parameters will be revised is still an open question. I suspect requested changes that do not have a significant impact on the existing channel plan may be adopted, while other, more radical changes, have much less of a chance. (Comments by Doug Lung. Your opinions are welcome.)

OTHER Items of Interest

May 12 - Issue 69 Final Edition

FCC Grants 73 New Ka Band Satellite Licenses (May 12)

Friday the FCC released an Order authorizing the launch and operation of thirteen fixed satellite systems and assigned orbital locations to 73 Ka band (28 GHz.) geo-stationary satellites. Changes in the satellite locations will be allowed only if all affected applicants agree or if the application requesting the change can demonstrate its alternative is preferrable to the Commission's plan.

The thirteen companies receiving the licenses are:

For more information see the FCC News Release (nrin7016.txt) and the full text of the Order in ASCII text or WordPerfect formats. Click on the Order & Authorization links in the list above to see the text of the individual license authorizations.

INDUSTRY - ANSI Approves Channel Standard for Cable-Ready TV's (May 9)

In a News Release issued today, the Consumer Electronics Manufacturers Association said the American National Standards Institute (ANSI) had approved EIA-452, "a standard that defines channel allocations for cable-ready TV services and products." The standard designates 158 channels up to 1 GHz. and sets forth a plan for more channels on higher frequencies. Of interest to broadcasters, the Release said that

"For years, cable operators have moved broadcast channels to different frequencies than were originally broadcast over the air. EIA-542 does not preclude this practice but provides the common reference needed for cable-ready receivers to "map" or correct their channel read-outs to compensate for these moves. With TV receivers and cable systems using the same channel allocations, cable TV will be more user-friendly."

DTV - McCain Bill Accelerates DTV Transition - Ends Commercial Analog TV after 2005 (May 6)

Today Senator McCain introduced bill S.705, the "Digital Television Conversion Act of 1997". In the introduction, McCain said

"...the rules recently adopted by the Federal Communications Commission do not establish firm timetables and deadlines to govern the television industry's critically important digital conversion. For example, although the FCC set out target dates for television stations in each market to convert to digital, this conversion schedule is not binding on more than 90 percent of all television stations, and the Commission has not adopted any way to verify licensee's compliance with the nonbinding conversion schedule. Likewise, there is no rule requiring that television licensees return their current analog channels by any given date so they can be auctioned."

S.705 would require all TV stations in the top 10 TV markets, not only those affiliated with the top four networks, to begin digital programming by November 1, 1999. The bill also requires that "Licensees of commercial television stations providing digital video programming service shall relinquish any analog spectrum assigned to them by the Commission no later than January 1, 2006.". Non-commercial stations would have another year to return their analog spectrum.

Full text of S.705 is available in a text file or in html format with links to other references and file formats.

TECHNOLOGY - Sky Station International To Use Air Ships for Wireless Internet Service (May 6)

Sky Station International, Inc., said the FCC had approved its plan to use 47 GHz. frequencies to provide high speed wireless communications from its "Sky Stations®" hovering 21 km above major cities. A press release issued today said "The Sky Station system provides wireless T1 (1.5 Mbps) links directly to laptop and personal computers. This kind of high speed Internet service may be used for portable videophone and Web TV applications. SSI is able to accomplish its personal T1 service because of the ultra-high channel capacity available in metropolitan areas only from a stratospheric altitude." The release also said that Sky Station user terminals would cost around 100 dollars and that a small PCMCIA card would allow laptop computers access to the system.

More information is available in the Press Release and at www.skystation.com. A Frequently Asked Questions page provides more technical details, including a description of the safety precautions taken to prevent these air ships, averaging 10,540 kg each, from falling on the cities they serve. Check it out. This is certainly interesting technology!

OTHER Items of Interest

May 5 - Issue 68 Final Edition

FCC Schedules Tutorial on Digital LMDS (May 2)

The FCC Office of Engineering and Technology announced a tutorial on digital Local Multipoint Distributions Systems (LMDS), June 12, at 1:30 PM in the Commission Meeting Room, Room 856 at 1919 M Street N.W. Tom Kilgo of Texas Instruments will be conducting the tutorial. See the Public Notice for more information.

DTV - FCC Accepts KOMO Experimental License Application (May 2)

KOMO's application for an experimental license appeared in the FCC's Public Notice listing applications accepted for filing. The application specified a 350 kW transmitter operating on channels 30, 43 and 47, at KOMO's existing transmitter site. The antenna specified was a Dielectric TFU-30JSC at 740 feet above average terrain.

INDUSTRY - NAB 97 Breaks All Records (May 1)

The National Association of Broadcasters today said that its 1997 Convention in Las Vegas broke all earlier attendance records. A total of 100,245 people attended the convention and 1,244 companies exhibited at the show. More details are available in the NAB Press Release. (Corrected 5/6)

SCIENCE - Sandia Supercomputer Simulates Comet Crash into Earth (Apr. 29

Sandia Labs, during initial testing of its new teraflops supercomputer carried out a "computational simulation of a major cosmic event of potential significance to all people on earth: What would happen if a kilometer-wide comet struck the ocean?" The results were shown in color images and animation available at http://www.sandia.gov/1431/COMETw.html.

Florida and other low-lying areas would be washed over. The results also showed such an event "is very close to the size threshold at which impact experts expect that a global catastrophe could occur, by screening out much sunlight for long periods of time and disrupting agriculture, among other effects." See the Sandia Lab News Comet Story for more information.

OTHER Items of Interest

Other Issues Available:



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Last modified May 24, 1997 by Doug Lung dlung@transmitter.com
Copyright © 1997 H. Douglas Lung