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(week) or two to complete each issue. Articles may be posted earlier if time permits or if there is a major, breaking story.

<<< Back to September 4 - Issue 230

September 11, 2000 - Issue 231 Final Edition

DTV - Harris and Thomcast Show COFDM Gear at IBC 2000 (Sept. 11)

Harris Corporation introduced the ITIS V-XCAST COFDM at the Internatinal Broadcasting Convention (IBC) in Amsterdam. The DVB-T modulator is designed with the flexibility to be used for Digital Terrestrial Television, digital TV news gathering links, wireless on-air signal return and digital TV signal generator applications. The unit has frequency-agile UHF or VHF outputs, digital linear and non-linear pre-correction for amplifiers and output filters and is available with various control interfaces, including RS232C, RS485, and Ethernet SNMP.

The unit can be paired with a V-TNGR demodulator for transporting DTV signals from remote sites, including moving vehicles, at rates from 5 to 30 Mbps. The system requires 8 MHz bandwidth. Refer to the Harris News Release Harris Corporation Highlights ITIS V-XCAST, Broadcasting's Most Versatile COFDM Modulator, at IBC 2000 for more information.

Thomcast used IBC 2000 to introduce its new ODYSSEY medium power DTV UHF transmitter line. The ODYSSEY features liquid-cooling, full broadband amplifiers and a built-in COFDM or ATSC channel coder and modulator/exciter equipped with Thomcast's Digital Adaptive Precorrection (DAP). The design of the cooling system allows amplifiers and power supplies to be plugged directly on to a cold plate, avoiding the need to connect and disconnect liquid cooling lines during maintenace operations. The transmitter is designed to be compatible with with Thomcast's SCOUT system for checking and monitoring the DTV RF signal.

SCOUT was introduced at IBC 2000. Using data available from the DAP exciter, SCOUT is able to measure and display signal characteristics including bandwidth (shoulders), constellation diagrams, MER or SNR, error vector, and peak to average power ratio. The exciter add-on is available in both DVB-T and ATSC versions and runs on a personal computer. In addition to working with the ODYSSEY, SCOUT will also function with other DAP equipped transmitters such as Thomcast's OPTIMUM and ULTIMATE. For the press releases announcing these products, see the Thomcast Media Center and select "Press Releases". Due to the complex design of the Thomcast web site, direct links to the ODYSSEY Press Release and the SCOUT Press Release may or may not work.

SCIENCE - 1665 Clock Experiment Duplicated to Gain Insights in Synchronized Oscillators (Sept. 8)

Physicists at the Georgia Institute of Technology have recreated a 1665 experiment by Dutch astronomer and physicist Christiaan Hughes that investigated how two pendulum clocks would synchronize, regardless of how they were started, stopped or otherwise disturbed. The researchers hope this straightforward mechanical system might help them gain insights into modem synchronized oscillators. Dr. Kurt Wiesenfeld, Georgia Tech professor of physics, said, "Having a system available that lends itself to an intuitive and physical understanding could be quite useful. We might be able to learn how this system is like laser systems or superconducting electronic systems. If there are general mechanisms affecting coupled oscillators, then perhaps we can learn about these mechanisms by using the clocks as mechanical analogs for electronic systems."

The system consists of two spring-powered pendulum clocks attached to a wooden platform with metal weights added to the platform. The weight allow the mechanical coupling between the clocks to be adjusted. As in the 1665 experiment, the researchers found the clocks synchronized in anti-phase (pendulums swinging in opposite directions), but also found a behavior Huygens did not describe - "amplitude death." In this condition, one of both pendulums ultimately stops moving altogether instead of syncrhronizing. This was found to be more likely as weight was removed from the platform (coupling increased). Wiesenfeld said the clocks may offer a new way to look at electronics such as Josephson Junction devices, "It's a very old-fashioned idea, not the way people who study coupled oscillators have been thinking about nonlinear dynamics over the past decade or so," he added. "Classical physics still has things to teach us."

Details on this interesting experiment and a photo of the clock may be found in the Georgia Tech News Release Out of Time: Researchers Recreate 1665 Clock Experiment of Gain Insights into Modern Synhronized Oscillators.

TECHNOLOGY - Military Uses GPS Signals to Measure Atmospheric RF Refraction (Sept. 6)

A researcher funded by the Office of Naval Research (ONR) has developed a method for using GPS signals and the precise position of the GPS satellites to determine the amount of bending other signals would experience going through the same atmospheric region. This technique has applications in high-precision tracking radars. ONR Program Manager Scott Sandgathe explained, "The preliminary results are very successful, but it will need to be tested in more environments and seasons before it finds its way into the Fleet." The next planned experiment will be in Southern California during September to coincide with the strong Santa Anna winds. This information was obtained from an ONR News Release.

FCC Preempts Local Zoning Restrictions on New York Uplink Dish (Sept. 5)

In a Memorandum Opinion and Order (DA 00-2023), the FCC's International Bureau granted a petition filed by Atlantic Satellite Communications, Inc. (ASCI) requesting preemption of the zoning restrictions of the Town of Orangetown, New York. The Orangetown Zoning Board of Appeals denied ASCI's request to replace and relocate a satellite antenna on its commercial property and to construct a new earth station antenna that exceeded Orangetown's size limitations.

Section 25.104(a) of the FCC rules applying to satellite dishes with a diameter greater than two meters states that "any local zoning regulation that materially limits transmission or reception by earth station antennas, or imposes more than minimal costs on users of such antennas is preempted unless the promulgating authority can demonstrate that such regulation is reasonable." ASCI uses "broadcast-quality" antennas to provide national and international broadcast services to the public through programming providers. The facility, which includes three antennas, is on six acres of leased property in an area zoned for light industrial business. The FCC Order said Orangetown "failed to provide any factual support for its assertion that granting the variance will have a negative impact on nearby residential property. The Commission does not regard testimony by non-party, neighboring property owners to be reasonable in assessing an antenna application or variance request. In addition, Orangetown's suggestion that ASCI consider alternative sites does not sustain its burden to show the ordinance is reasonable. The property is zoned for commercial use, and Orangetown does not oppose ASCI's use of the property for signal reception and transmission for business purposes."

The FCC concluded: "Based on the foregoing, we find that Section 8.14 of the Orangetown Code materially limits reception and transmission under Section 25.104 of the Commission's rules, and that Orangetown has failed to demonstrate the ordinance is reasonable. It has not shown that the ordinance furthers aesthetic objectives given that ASCI's lot and surrounding areas are zoned light industrial and that the view of the proposed new antenna will largely be shielded from view by residences in the area. Nonetheless, even assuming the ordinance furthers some aesthetic objective, Orangetown has not shown that the ordinance does not unnecessarily burden the federal interest in ensuring access to satellite services. Therefore, we preempt the Orangetown ordinance as it applies to ASCI's application."

FCC Grants Change to DTV Table of Allotments in Norfolk, VA (Sept. 8)

The FCC has granted the request of WTKR-TV, Inc, licensee of WTKR-TV, NTSC Channel 3 in Norfolk, VA, to substitute DTV channel 40 for channel 58.

The FCC agreed the public interest would be served by the substitution since "it will enable station WTKR to continue to broadcast on its transitional in-core DTV channel after the transition period has ended.". The parameters of the Channel 40 DTV allotment to Norfolk specify an effective radiated power of 1,000 kW at a height above average terrain of 313 meters serving a population of 1,761,000. Reference coordinates are 36-48-56 N and 76-28-00 W.

This information is from the Report and Order (Proceeding Terminated)(MM Docket 00-68).

FCC Grants Change to DTV Table of Allotments in Klamath Falls, OR (Sept. 7)

The FCC has granted the request of California Oregon Broadcasting (COBI), Inc., licensee of KOTI-TV, NTSC Channel 2 in Klamath Falls, Oregon, to substitute DTV channel 13 for channel 40.

The FCC agreed the public interest would be served by the substitution since "it would allow Station KOTI-TV to replicate a larger portion of its analog service area.". The parameters of the Channel 13 DTV allotment to Klamath Falls specify an effective radiated power of 45.3 kW at a height above average terrain of 671 meters serving a population of 102,000. Reference coordinates are 42-05-48 N and 121-37-57 W.

This information is from the Report and Order (Proceeding Terminated)(MM Docket 99-296).

FCC Notice of Proposed Rule Making to Modify DTV Table of Allotments in Thief River Falls, MN (Sept. 8)

Red River Broadcast Company, LLC (Red River), licensee of station KBRR, NTSC Channel 10 in Thief River Falls, MN has requested the substitution of DTV Channel 32 for its assigned DTV Channel 57. Red River stated that because channel 57 is not a "core" channel, KBRR could be forced to incur additional costs to move to a different DTV channel in the future. It noted other stations that have the same concern have requested substitute DTV allotments.

The FCC has found this channel change would meet its requirements and warrants consideration. Due to its location within 400 km of the U.S-Canadian border, the station must obtain concurrence by the Canadian government. The technical parameters of the modified allotment on Channel 32 would specify an effective radiated power of 1,000 kW at a height above average terrain of 183 meters.

Interested parties may file comments on or before October 30, 2000. Reply comments are due on or before November 14, 2000. Refer to the Notice of Proposed Rule Making (MM Docket 00-163) for details on the request and information on filing comments.

FCC Notice of Proposed Rule Making to Modify DTV Table of Allotments in Fresno, CA (Sept. 8)

Fisher Broadcasting-Fresno, L.L.C. (Fisher) licensee of station KJEO, NTSC Channel 47 in Fresno, CA has requested the substitution of DTV Channel 34 for its assigned DTV Channel 14. Fisher stated, "the substitution of DTV Channel 34 is necessary to avoid the possibility of unintentional interference to land mobile operations that may occur if KJEO-DT were to optimize its transmitting facilities on Channel 14." Fisher explained that the characteristics of the 8-VSB DTV spectrum place more energy closer to the edge of the channel. Because of this, it believes if it optimizes its DTV facilities on channel 14 it would likely cause interference to adjacent land mobile frequencies.

The FCC has found this channel change would meet its requirements and warrants consideration. The technical parameters of the modified allotment on Channel 34 would specify an effective radiated power of 330 kW at a height above average terrain of 597 meters.

Interested parties may file comments on or before October 30, 2000. Reply comments are due on or before Movember 14, 2000. Refer to the Notice of Proposed Rule Making (MM Docket 00-162) for details on the request and information on filing comments.

OTHER Items of Interest

ATSC Data Broadcasting Standard Now Available On-Line - Standard A90 is available for download.
ERRATUM to FCC International Bureau Order and Authorization FCC 00-277 granting Comsat Corp. authority to assign its space and earth station licenses to Comsat Government Systems, LLC - List of affected applications added and paragraph 26 listing corrected.
New Staff Assignments at FCC Enforcement Bureau - News Release - Alex Starr named Chief of the Enforcement Bureau Market Disputes Resolution Division (MDRD), Radhika Karmarkar replaces Alex Starr as one of two Deputy Chiefs of MDRD.
Harris Corporation's RF Communications Division Celebrates 40th Anniversary - News Release - RF Communications was started in 1960 by three General Dynamics engineers and a local attorney - Bill Stolze, Elmer Schwittek, Roger Bettin and Herbert VandenBrul - in Rochester NY. The company merged with Harris in early 1969.
New 5.6 Meter Ka-Band Earth Station Antenna from Andrew Corporation - Press release - Antenna features uniquely formed dual-reflector Gregorian optics system.
Three New Dehydrator Products from Andrew Corporation - Press release - New PMT200 Dryline(R) Dehydrator works with low and medium volume systems and does not need bypass kits and ancillary airtanks. SD-001 Static Desiccator works with system volumes up to 2.8 liters, SD-002A covers systems up to 28 liters (1 cubic foot).
EE Times article - Noisy dispute erupts over audio technology - story by Sunny Bains covers battle over technique for using intermodulation of ultrasound beams to create highly directional sound beams.

>>>>Next September 18 - Issue 232

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