RF CURRENT

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.

Issues are dated each Monday, although recently I've needed an extra day or two to complete each issue. Articles may be posted earlier if time permits or if there is a major, breaking story.

<<< Back to February 28 - Issue 203

March 6, 2000 - Issue 204 Final Edition

SCIENCE - Radio Astronomers Meet at Arecibo to Discuss Huge Next Generation Radio Telescope (Mar. 3)

A group of more than 60 radio astronomers affiliated with the U.S. portion of the international Square Kilometer Array (SKA) project held their first meeting February 28 and 29 at Arecibo Observatory in Puerto Rico. The SKA is an enormous radio telescope composed of up to 1,000 antennas spread over more than 600 miles. The "Square Kilometer" refers to the sum of the area of the actual telescopes, not the geographic scope of the array, which is much larger.

Cornell astronomy Professor James Cordes said, "the SKA can dramatically alter our knowledge of galactic compacted objects." He explained it would be able to probe "by many factors of 10" more of the universe than is now possible with the Arecibo radio telescope. Ultimately it could help answer questions such as "What is the endgame for neutron stars?" and "What is the relation of neutron stars to supernovae?"

The SKA would require an extensive high speed fiber optic to connect the individual radio telescope. It will also need complex software to operate the individual radio telescopes and combine their signals. Two problems, however, must be overcome for the project to be successful. One of them is finding funding for the project. Another is finding a large location relatively free of radio interference, in an accessible region of a politically stable country with no weather extremes. Possible locations are the Upper Gascoyne-Murchison region of Western Australia or the Southwest United States. Wherever the site is, if the model adopted for areas around the other radio telescopes in the U.S. is adopted, users of the RF spectrum around the SKA will have to take steps to protect the observatory from interference.

More information is available in a Cornell University News Release.

FCC Issues Notice of Proposed Rule Making on 4.9 GHz Band (Feb. 29)

The FCC has issued a Notice of Proposed Rule Making (NRPM) In the Matter of The 4.9 GHz Band Transferred from Federal Government Use. The NPRM proposes licensing and service rules for the 4940-4990 MHz band. The FCC proposes the band be allocated for fixed and mobile services, except for aeronautical mobile. Initial licenses would be acquired through competitive bidding under Part 1 of the FCC Rules. Licenses are proposed to be regulated under Part 27 of the Commission's Rules, with modifications as needed to reflect the characteristics of the 4.9 GHz band.

The FCC said it would attempt to avoid assignment of frequencies in the 4950-4990 MHz band to stations that could interfere with radio astronomy observations in the same band. The NPRM requests comments on proposals on methods to prevent and deal with harmful interference to observatories. The NPRM said, "We believe that a broad and general allocation is most likely to achieve this objective. Such an approach will allow flexible use of these bands so that licensees will be able to offer a wide range of services employing varying technologies. We therefore request comment on our proposal to allocate the band 4940-4990 MHz to the fixed and mobile services, except aeronautical mobile service, and to permit any fixed or non-aeronautical mobile service use in this spectrum, rather than specify this band for particular uses."

The Association of Public-Safety Communications Officials International, Inc. (APCO) filed comments requesting use of the spectrum for public safety mobile and aeronautical video operations. The FCC, in the NPRM, the FCC said that because of its recent designation of the 794-776 MHz and 794-806 MHz bands solely for public safety use on a primary basis, "we do not propose designating the 4.9 GHz band, or any portion of the band, for public safety use."

The FCC seeks comments on whether the spectrum should be paired or unpaired. The NPRM leans towards unpaired spectrum, implying that it would be allow more efficient operation since pair spectrum is not needed for one-way or time division duplex communications.

Regarding technical rules, the NPRM said "The application of general provisions of Part 27 would include technical standards relating to power limits, equipment authorization, Radiofrequency (RF) safety standards, emission limits, frequency stability, antenna structures and air navigation safety, international coordination, and disturbance of AM broadcast station antenna patterns." In addition rules regarding antenna registration, quiet zones and enviromental requirements would also apply to all 4.9 GHz licensees, regardless of the service provided or technology used.

Several other critical issues are addressed in the NRPM. Refer to it for details on proposals for controlling harmful interference between systems and what power limits (if any) are needed. The NPRM also discusses possible problems with the U.S. Navy Cooperative Engagement Capability System, which operates immediately below this spectrum.

Comments on the NPRM are due April 26, 2000. The deadline for reply comments is May 17, 2000. A summary of the NPRM is available in a News Release - FCC Proposes Licensing and Service Rules for the 4.9 GHz Spectrum Band.

TECHNOLOGY - New Digital Storage System Could Replace Hard Drives (Feb. 28)

The U.S. Office of Naval Research (ONR) and Carnegie Mellon University have begun testing and debugging a new storage technology, Vertical Giant Magnetoresistance Random Access Memory (VRAM). ONR says VRAM "has the potential to replace all mechanically driven storage media, including computer hard drives and compact discs." The goal of the technology is to produce a non-volatile memory with capacity 100 to 1,000 times greater than that possible with semiconductor memory. Access speed should be greater than 10 times that of current storage medium.

Nonvolatile Electronics, Inc. was awarded the contract to develop enabling technology for VRAM. The company have completed a preliminary circuit design and outlined a process for fabricating integrated VRAM memory arrays. In the second phase of the contract, Nonvolatile Electronics will design the circuits, develop processing technology, fabricate, test and debug the technology. Finally, the compamy will produce and demonstrate a protoype VRAM array. More information on this technology may be found in the ONR News Release Better Memory.

OTHER Items of Interest

FCC Memorandum Opinion and Order Denying Petitions for Reconsideration and Clarification on FCC Broadcast Competitive Bidding Rules
Andrew Corporation Introduces the STACKER Optimized Antenna Structure for Television Broadcast Applications - press release - new construction method and computer analysis integrates antennas into the tower support structure. Allows multiple antennas on one tower at less cost than a candelabra and less pattern degradation than side mount and some stacked antenna configurations.
American Tower and Richland Towers To Jointly Build 1,902 Foot Broadcast Tower in Mobile-Pensacola - press release - the Kline Iron and Steel built tower will serve the combined Mobile, Alabama and Pensacola, Florida broadcast market.
American Tower and Telemedia Corporation to Form Canadian Venture - press release - joint venture will be called Canadian Tower and will develop and acquire wireless and broadcast towers throughout Canada
EE Times article - Researchers demo wireless chip-interconnect scheme - article by David Lammers

>>>>Next March 13 - Issue 205

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