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 March 27 - Issue 207

April 3, 2000 - Issue 208 Final Edition

WIRELESS - Adaptive Broadband(TM) Promotes Wireless Access Technology Standardization (Apr. 3)
Adaptive Broadband has launched an initiative to promote its AB-Acess(TM) technology as an open standard for broadband wireless technologies. Dr. Demosthenes Kostas, director of standardds for Adaptive Broadband explained, "Today we have the ability to use TDD [Time Division Duplexing] or FDD [Frequency Division Duplexing] for point-to-multipoint broadband wireless access systems. A problem we are seeing is the proliferation of adaptations of emerging wireline technologies, such as DOCSIS-based FDD systems, being used for point-to-multipoint broadband wireless access systems. Global channel plans require efficient usage of bandwidth. TDD permits simple and efficient dynamic allocation of the radio uplink and downlink bandwidth, and TDD does not require paired frequencies. These efficiency and flexibility attributes cannot be met by FDD broadband wireless access systems."

Adaptive Broadband is working with various international standards bodies "to establish fixed broadband wireless access standards that consider the proven AB-Access physical and media access control layer." Standards bodies include the IEEE 802.17 on Broadband Wireless Access, ETSI Project-Broadband Radio Access Networks, and ETSI TM04 Work Group on Fixed Radio Systems. Dr. Kostas said, "In the IEEE 802.16 we are currently focusing our efforts to actively support two newly formed groups. One is developing a point-to-multipoint broadband wireless access system air interface standard for the licensed bands between 2 and 11GHz. The other group is studying the issues relating to developing a similar standard for the license-exempt bands between 5 and 6 GHz, that will enable public metropolitan area network access to connection oriented and/or connectionless data, video, and voice services,"

Additional information is available in the Adaptive Broadband press release Adaptive Broadband(TM) Promotes Standardization for Wireless Broadband Access Technology.

TECHNOLOGY - Purdue University Develops New Cellular Channel Sharing Scheme (April)
You have probably experienced losing a cell phone connection as it is being handed off to another cell site. This often happens when the new cell site doesn't have the capacity to handle the call handed to it. Edwin K.P. Chong, associate professor at Purdue University in West Lafayette, Indiana says Purdue engineers have developed a technique that could make cell phone users 100 times less likely to be cut off. The Purdue technique is called a "localized channel-sharing scheme." Two adjacent cells are allowed to share many of the same channels. In effect, the channel itself moves with the caller into the adjacent cell. Chong explained, "If I am driving and I start getting too far from the base station, I must at some point be handed off from one base station to the next. In our scheme, you cooperate with your neighboring cell in a way that you can share channels." The channels shared between two cells form "meta-cells". While it might appear this would reduce efficiency, Chong said the computer simulations said it could increase a network's overall efficiency by up to 60 percent. The simulations also showed the technique would make cell phone users up to 100 times less likely to be cut off than with conventional cellular techniques. The technique has not been tested in the real world.

More information is available in a paper by Junyi Li, Ness Shroff and Edwin Chong that appeared in the December issue of the journal Wireless Networks and in the Purdue University News Release Method Could Prevent Disconnection for Roaming Cell Phone Users.

DTV - DiviCom Introduces New Datacasting and Transcoding Products (Apr. 3)
DiviCom has introduced a variable bit rate datacasting encoder that uses statistical multiplexing to make the most efficient use of channel bandwidth without degrading the quality of video streams. The new technology, called "DataTrack", uses Divicom's LookAhead(tm) technology to allocate the bandwidth for data on a frame by frame basis. Geocast said it would use DiviCom's technology to enable broadcasters to deliver both data and video content to PC users.

DiviCom also announced its new technology for MPEG-2 manipulation. "TransRater" technology allows service providers to modify incoming compressed programming without decoding and recompressing the data stream. The TransRater TR200 allows frame accurate splicing, format conversion, pixel-lvel processing, logo insertion and overlays. The TransRater TR400 adds the ability to sleamlessly splice compressed streams from various broadcast sources, allowing real time insertion of digital advertising and local programming without visibile picture quality deterioration. Tom Lookabaugh, President of DiviCom said, "With TransRater technology, service providers are able to work in the compressed domain just the same as they would in the uncompressed domain. TR200 and TR400 dramatically expand service provider capabilities while improving network efficiency, maintaining video quality and conserving bandwidth"

More information is available in the following DiviCom Press Releases: DiviCom Revolutionizes Data Broadcasting to Consumers, DiviCom and Geocast Ally to Enable Broadcasting to PC Users, and DiviCom Introduces Stream Processing Solution.

ANTENNA - TCI International Completes on Air Tests of Wideband Digital Slot Antenna (Mar. 30)
TCI International said it has successfully completed full power, on-the-air field, field strength tests of its new Model 888 DigitalPLUS Wideband UHF Slot antenna at WRLK in Columbia, South Carolina. The TCI DigitalPLUS antenna uses columns of cavity backed T-bar slots to provide an omnidirectional antenna capable of operating UHF channels 14-69. The antenna has windloading comparable to other top-mount UHF slot antennas. WRLK is owned by South Carolina Educational TV (SCETV). SCETV Vice President of Engineering, L.W. "Hap" Griffin, Jr. said, "We are very pleased the TCI Model 888 has met our performance expectations. SCETV selected the Model 888 Wide Bandwidth Slot Antenna because it allows us to broadcast digital television without having to replace or modify our tower. If we had used other antennas, we would have had to strengthen our tower or move to a new tower, either of which would have been expensive and delay our DTV conversion."

KCSM-TV, the Public Broadcasting System station at the College of San Mateo in California, selected the TCI DigitalPLUS antenna for transmitting its DTV and analog signals on channels 59 and 60, respectively. Marilyn Lawrence, General Manager of KCSM-TV, commented, "Since the TCI 888 antenna will handle both types of transmissions simultaneously, the tower will not have to be modified, and this is very attractive to us." Since both channels are outside the core spectrum, the station will have to move to an unspecified channel between 2 and 51 at the end of the DTV transition. KCSM-TV will be able to use the DigitalPLUS antenna can operate on any UHF channel they are assigned in this range. TCI International will also provide a turnkey installation of the antenna and feeder system.

More information is available in the TCI International Press Releases TCI International Completes On The Air Tests of World's First Wideband Digital TV Slot Antenna and TCI International Announces Sale of Wideband Digital TV Slot Antenna.

SATELLITE - PanAmSat Announces Network for Broadcasting IP Video, Audio and Data to wired and wireless ISPs (Mar. 29)
PanAmSat will allocate up to 24 Ku-band satellite transponders worldwide for its new NET/36 broadcast network for high-speed, IP video, audio and data. NET/36 is designed to provide an overlay to the congested terrestrial Internet network. PanAmSat said it has entered into alliances with U.S. West and RealNetworks to deliver streaming multimedia and other Internet content over NET/36 to U S West's MegaBit ServicesSM and U S West.net's subscriber base. RealNetworks will collaborate with PanAmSat to provide video and audio streaming software for NET/36.

NET/36 will be offered starting in third quarter 2000 and, according to the PanAmSat Presss Release, will have the capability of supporting approximately 3 million simultaneous broadband video end users by late 2002.

ANTENNA - Southwall and MegaWave to Design and Build Wide Bandwidth Auto Windshield Antenna (Mar. 29)
Broadcasters may remember MegaWave as the company that was given the task of developing an improved set-top TV antenna a few years ago. The company is now working with Southwall Technologies, Inc. to build a protoype wide bandwidth antenna for automobile windshields. The antenna would use Southwall's flexible infrared reflecting film and MegaWave's antenna technology. Southwall's President and CEO, Thomas G. Hood, said, "The automotive marketplace has long been searching for an invisible antenna that could be used in any vehicle to receive and transmit AM, FM, GPS and cellular telephone signals." The protoype antenna will use Southwall's XIR(r) infrared reflecting film.

More information is available in the Southwall Press Release.

OTHER Items of Interest

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