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 September 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 at firstname.lastname@example.org.
In Report and Order (FCC 96-377) released yesterday and made available on the Internet today, the FCC amended Part 2 of the Rules to allocate the 13.75 to 14.0 GHz. band to the Fixed Satellite service (FSS) on a co-primary basis for uplink transmissions. It also revised the associated service rules in Parts 25 and 90 to conform to this allocation. The R&O encouraged the use of ITU Recommendation ITU-R SA.1071 and the precipitation radar and altimeter critical zones developed by NASA. All FSS applications using this band must be coordinated on a case-by-case basis to minimize harmful interference to the forward space-to-space link of NASA's TDRSS system. More specific details and a history of this spectrum are available in the full text of the Report and Order (FCC 96-377).
A pre-release of John C. Dvorak's popular PC Magazine column for PC Magazine for October 8th blasted the ATSC HDTV standard and criticized Microsoft for its lack of effectiveness in opposing it. The column took issue with the ATSC's aspect ratio, pixel ratios and frame rate. The full text of this column should be available soon at PC Magazine's Web Site
Dvorak's column provided a link to Microsoft Graphics Researcher Alvy Ray Smith's Web site. On it you'll find a well written page comparing the ACATS (ATSC) plan with the recently organized CICATS plan. While you may not agree with all the conclusions, it is must reading for anyone involved with HDTV.
The FCC today held a public meeting to discuss the draft Digital Television Allotment plan outlined in the Sixth Further Notice of Proposed Rule Making on Advanced TV. Copies of the Erratum to FCC 96-317 were distributed with copies of the 6th NPRM. The Erratum corrected a typographical error which gave two Boston stations the same DTV channel and also clarified language regarding the use of channels 3, 4 and 6 for DTV operation. References to allocations that may conflict with land-mobile operations on UHF TV channels were also corrected.
The meeting itself provided little new information but did provide an opportunity to clarify some of the items in the 6th NPRM. One item which was widely misunderstood was how the DTV power levels and coverage criteria were determined. As I understand it, the allotment model first calculates a station's Grade B contour based on FCC 50/50 propagation curves using the stations current configuration, as listed in the May FCC Engineering Database. The program then uses the FCC 50/90 propagation model to determine the ERP needed to put the necessary DTV signal level for the selected DTV channel (outlined in Appendix B of the 6th NPRM) at the NTSC grade B contour. However, the interference studies and determination of percent of matching coverage are done using the Longley Rice propagation model. Because terrain may limit actual NTSC coverage to less than what the FCC 50/50 curves show, in this situation the allocated DTV power would be much higher than actually needed to duplicate real world coverage. The situation would be reversed if the NTSC station's actual coverage exceeded the FCC 50/50 predictions.
Several LPTV and translator owners and representatives expressed concern and frustration to the FCC staff present over the impact of the DTV allotments on their channels. While the FCC staff was receptive and willing to work with LPTV and translator licensees, no new plans were offered nor was there any new information on protection for LPTV and translator stations threatened by plans to reclaim channels 60 through 69.
Less than a week after Hughes agreed to purchase PanAmSat, another large satellite sale has been announced. In a press release issued today by AT&T Skynet Satellite Services, the company said it was selling its Telstar satellites and Skynet service to Loral Space And Communications for 712.5 million dollars. In addition to the satellites, Loral will acquire the tracking and control stations in Hawley, PA and Holmdel, NJ plus the Holmdel research and development facility. Loral said it plans to retain all Skynet employees. Subject to regulatory approval, the transaction is expected to be concluded by March 1997.
Virginia Tech Electrical Engineer Warren Stutzman has been granted a patent for a "a high-performance, low radiation-hazard antenna for hand-held devices operating at 1900 MHz. and above. " A Virgina Tech news release said "Stutzman's "Safetenna" eliminates transmission in the direction where the signal would be blocked by the user's head, thereby avoiding potentially harmful absorption of power by the user's body." The release also said
"Tests of Safetenna demonstrate that total radiated power is unchanged by the presence of the operator; thus, reduction of the overall radiated power by a factor of three that is typical of conventional antennas is avoided. In addition, there are no gaps in the directional properties of Safetenna as there are with conventional antennas. That is, conventional antennas experience a signal reduction by a factor of 60 due to the user's head being in the way."
The FCC's Mass Media Bureau established a web page with links to the last three Notices of Proposed Rule Making on Advanced TV, the "en banc" hearing on Digital Television held December 12, 1995 and the ATSC pages. You wil find it at http://www.fcc.gov/mmb/dtv/dtv.html.
Even if you started working with electronics over thirty years ago, as I did, it is hard to imagine that integrated circuits can get much smaller than they are now without looking back to the days when transistors were starting to replace tubes. It was hard to imagine then where electronics would be thirty years later. Some researchers at Purdue University may be on to the next major advance in miniature electronics - the LCN or Linked Cluster Network. A news release Friday said that "researchers have created an ultrathin film , made from tiny clusters of gold atoms, that conducts electricity by allowing electornics to 'hop' one at a time from cluster to cluster." This largely eliminates the problem of heat buildup in the circuit. The release, Move over Silicon - Here Comes Gold, is available from Purdue University. It is worth the read and includes photos.
In a news release (nrwl6041.txt) today the FCC said it had released Fact Sheet #2 on Wireless Facilities. It is 39 pages long and has four parts. Part 1 is a new FAQ from the Wireless Facilities Siting Task Force. Part 2 addresses the RF radiation issues surrounding personal wireless service facilities. Part 3 is information on what new services are most likely to be submitting facilities siting requests during the upcoming year. Part 4 is a series of maps showing the geographic areas used by the FCC to license personal wireless services and a list of certain PCS licensees by geographic area. Both this and the first fact sheet are available in WordPerfect 5.1 and PDF formats at http://www.fcc.gov/wtb/twrstng.html.
In a press release issued today Hughes Electronics Corporation and PanAmSat Corporation said they had agreed to merge their respective satellite services into a new public company, PanAmSat Corporation. After the merger Hughes Electronics will own 71.5 percent of the new PanAmSat. The new company will handle Hughes' ten domestic satellites as well as PanAmSat's four international satellites. The full text of this release is available PanAmSat's web site.
An unusual consortium of university, government and private industry groups developed an inexpensive way of collecting weather data by satellite. The group includes the University Corporation for Atmospheric Research, the University Navstar Consortium, the National Center for Atmospheric Research, the University of Arizona - Tucson, the NASA Jet Propulsion Laboratory, the Russian Institute of Atmospheric Physics, the National Science Foundation, NOAA, the FAA, Allen Osborne Associates and Orbital Sciences Corporation.
A news release described how the system works:
"The receiver flies in a 450-mile Low Earth Orbit, picking up radio signals emitted by the GPS satellites, orbiting at 12,500 miles, as MicroLab-1 slips behind the edge, or limb, of the Earth. Radio signals are slowed and bent by refraction as they pass downward through increasingly dense layers of Earth's atmosphere. By measuring the angle of refraction, program scientists theorized, it should be possible to measure changes in air density and, given that, calculate temperature, pressure and humidity with high precision for all layers of the atmosphere, top to bottom. It would be theoretically possible for a single GPS/MET receiver to get 250 "soundings" of the Earth's atmosphere every 24 hours -- twice that number if rising events as well as setting events are used. Voyager scientists in the 1970s and 1980s used the same radio "occultation" techniques to measure the properties of atmospheres of the outer solar system planets."Full details are available in the news release.
Intelsat representatives, speaking at a press conference at International Broadcasting Convention in Amsterdam, The Netherlands, announced the results of the extensive round of digital compression interoperability testing at Intelsat Technical Laboratories in Washington D.C. Nine manufacturers of MPEG-2 digital compression equipment participated. The test were voluntary and open to all manufacturers in the industry.
The test results, which focused on one of six operational parameter sets, found successful interoperation of encoders and decoders from all nine manufacturers. The Intelsat press release cautioned that "...continued development will be necessary for universal interoperation of all codecs under fixed baseband operational settings."
The release quoted Vince Walisko, Intelsat's Group Director for Global Broadcast and Special Services, saying "These results show us that the various manufacturers' equipment can operate with each other, given laboratory conditions. These tests are quite important for all aspects of the global occasional use, contribution and SNG broadcast community -- by opening up new types of programming and making collection possible from previously inaccessible locations. We also see broadcasters and earth station operators using these results as a key element in making their equipment purchasing decisions."
Tony Uyttendale, Senior Advisor of Science and Technology at Cap Cities/ABC, and chairman of an ITU SNG Working Group also spoke at the press conference and was quoted in the release. He said "This testing truly brings the MPEG-2 standards off the drawing board and into the field -- demonstrating that these standards are serving their purpose in making digital video transmission globally accessible".
Another broadcaster participating in the press conference voiced his impressions on how important these tests were for global satellite news gathering. Tony Naets, Head of the TV News Division of the EBU was quoted as saying that these tests "...will have a major impact on how news, sports and special events are reported, by allowing greater versatility in how and where stories are collected. These results give us and our network customers the security in knowing that we will get more of the stories and programs we need. INTELSAT is doing a great service in leading the whole digital television industry forward by taking this type of initiative."
The following manufacturers participated in the tests. The model or series name where available is shown in parenthesis after the manufacturer's name. More detailed information is available from the Intelsat Web Site. The September Intelsat Broadcaster has full details on the tests, including a more detailed list of specific equipment and software/firmware versions used in the testing. The Press Release referred to here is also available.
Monday the International Bureau granted Directsat Corporation's request for authority to launch the USABSS-4 DBS satellite, position it at 118.8 degrees W.L. and operate it using its DBS channel assignments at that location. The Office of Engineering and Technology joined the International Bureau in granting Directsat's request to use FSS frequencies in the 3698.3 to 3699.7 MHz., 5923 to 5924 MHz. and 6426 to 6427 MHz. bands for TT&C functions on USABSS-4. Directsat had originally planned to use C-band frequencies for launch and ascent operations then switch to Ku-band frequencies for on-orbit TT&C functions.
The C-band frequencies requested are allocated to Radiolocation, Amateur Radio, or Mobile Services. The Commission said that "Directsat's operations must not cause harmful interference to other authorized users of these frequency bands; if such interference occurs Directsat will be solely responsible for alleviating it; and Directsat's TT&C operations in these bands will not be protected from harmful interference to its operations from other authorized Government users." The same conditions apply with respect to non-Government operations. The FCC, in granting the modification, also said this nonconforming use is not authorized on a permanent basis. The authorization will conclude January 1, 1999.
The grant for authority to launch is Order DA961502 and the grant for modification is Order DA961514.
Today's FCC Daily Digest contained a note that the Commission's Office of Engineering and Technology "Issued erratum to correct errors in the text and Appendix B of Sixth Further Notice of Proposed Rule Making in the matter of Advanced Television Systems and their impact upon the existing television broadcast service." As of Friday evening, the erratum had not been posted on the FCC's Internet site.
The FCC's Daily Broacast Applications Report today listed KTLA, Inc.'s experimental TV broadcast station application as "Accepted for Filing". The application proposes a station on channel 12, transmitting from the Mount Wilson antenna farm north of Los Angeles with an effective radiated power of 300 watts. The application specified a Dielectric model TWC-6/CP antenna.
In a press release issued today EchoStar Communications Corporation said its second Direct Broadcast Satellite, Echostar II, was launched successfully from Arianespace's launch facility in Kourou, French Guiana. The Lockheed Martin Series 7000 satellite has 16 transponders, allowing up to 100 digital channels. Its final orbital location is 119 degrees West Longitude. It should be operational from there by November 1, 1996.
The press release noted that in addition to programming complimentary to that on EchoStar I, EchoStar II will also begin testing business television delivery and Internet applications. EchoStar III is scheduled to be launched from Cape Canaveral in Fall 1997.
The Office of Engineering and Technology, in cooperation with the Mass Media Bureau and the Office of Plans and Policy have scheduled a public forum on the key technical and engineering issues in the recently released Sixth Further Notice of Proposed Rule Making on Advanced TV. A list of issues that may be discussed is available in the Public Notice (pnet6015.txt). They include discussion of the DTV Allotment methodology and approach and the computer software used in developing the DTV table. Other possible topics include DTV Allotment Negotiations and Modifications and NTSC station facility changes.
Friday the International Bureau of the FCC "granted AT&T's application to 1) extend Telstar 303's license term, 2) reassign it to another orbital location, and 3) allow it to operate in an inclined orbit mode." When and if the International Bureau issues the full text of this order, it should be available as Order DA961499.
In two recent press releases Dielectric Communications showed how it is responding to increased broadcaster interest in preparing for Digital TV transmission. In an August 30 Press Release it announced the introduction of a new medium power side mount UHF antenna, suitable for DTV use. Today, in another Press Release, Dielectric Communications reported it had been awarded its 50th HDTV design contract. Sites include the World Trade Center in New York and Mount Sutro in San Francisco.
The FCC today made available a Public Notice (pnmc6033.txt) alerting laboratories that RF immunity testing of electronic equipment "may not be performed on open area test sites without a station license." For those tests that require outdoor testing, the FCC said:
Parties wishing to perform RF immunity tests on an open area site are reminded that they must be conducted in a manner that confines the RF energy to the immediate area, such as a shielded room or anechoic chamber, to prevent interference to radio communications. Failure to do so is a violation of Section 301 of the Communications Act of 1934, as amended. In special cases, where it is impractical to test in a shielded area because of the size of the equipment, applications for a Special Temporary Authority (STA) to conduct testing on an open area site will be considered by the Commission. However, STAs will be granted only for limited power, frequencies and times of operation.
The Wireless Telecommunications Bureau and the International Bureau of the FCC released an Order on August 30 stating that:
Effective upon the release date of this Order, we will not accept or process, except as described below in para.6, any applications for new licenses, renewals, extensions, amendments, or modifications for terrestrial fixed services at 18.820-18.920 and 19.160-19.260, or any applications for nongeostationary fixed satellite service (NGSO\FSS) earth stations which are intended for use in the 18.8-19.3 GHz frequency band ("18 GHz band").
The Order noted that 247 applications for Digital Electronic Message Service (DEMS) in the 18 GHz. band are pending before the Wireless Bureau. Approximately 70 percent of these were filed for additional sites within already licensed exclusive defined areas. The order said "These applications were filed the day after the Commission's release of its decision to designate the 18 GHz band for co-primary use by fixed terrestrial and NGSO\FSS downlinks." Teledesic Corporation requested a freeze on acceptance and processing of applications for DEMS licenses and NGSO/FSS earth stations in the 18 GHz. band, saying that would preserve "a level playing field for both Teledesic and DEMS licensees to discuss the potential for sharing and conserving Commission resources." This was opposed by some DEMS licensees.
The Commission said it would soon address the coordination issues arising from the co-primary status of the two services. The Order did allow that
...with respect to existing licensees that hold authorizations to use a channel on an exclusive basis within a defined area, we do not seek to take action that would freeze their ability to build-out pursuant to their pending applications. Rather, those pending applications for build-out of already authorized exclusive defined areas shall remain subject to regular Bureau processing, including the current notice and comment period.
Full details are available in the Order
Elizabeth Downing, a graduate student studying electrical engineering at Stanford University, solved the material problems involved with creating a true three dimensional display in fluorescent glass. Downing said "There are a number of different 3-D display technologies, but this technology has some unique features. For one thing, it doesn't create an image that appears to be three dimensional, it actually produces an image that is drawn in three dimensions. As a result, there are few restrictions on the viewing angle and a number of people can view the images at the same time. Also, the images are emissive they glow rather than reflective, so they can be seen easily in ordinary room light." Because the images are transparent, they are more likely to be used in scientific and medial applications than in television applications. The story behind the work is interesting - Downing used surplus scanners from optical disk players to scan the two laser beams vertically, horizontally, and backward and forward through the volume of the cube. Full details are available in a news release from Stanford University.
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Last modified September 29, 1996 by Doug Lung email@example.com
Copyright © 1996 H. Douglas Lung