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 1998. 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 firstname.lastname@example.org.
May 25, 1998 - Issue 119 Final
- Satellite - Galaxy 4 Malfunctions - What Happened?
- Shortly after 6 PM EDT Tuesday night, the CBS and Telemundo TV networks signals on Galaxy 4 disappeared,
along with all other signals from Galaxy 4. In a posting to Usenet, an engineer at a CBS affiliate reported he saw a burst of video from the crippled satellite at 6:40 PM, then back to nothing. What happened?
Robert Bednarek, Senior Vice President and Chief Technology Officer at PanAmSat, outlined the failure in a
Statement issued early Wednesday morning:
"At approximately 6:00 p.m. Eastern time on May 19, the Galaxy IV satellite experienced an
anomaly within its on-board spacecraft control processor (SCP), the primary system responsible for
pointing the spacecraft relative to earth. The automatic switch to a backup unit failed as well. As
a result of the SCP anomalies, the satellite began to rotate, thereby losing its fixed orientation. While
PanAmSat is able to receive telemetry from and send commands to the satellite, full operation of the
satellite's attitude control system has not been achieved at this time. PanAmSat has deactivated the
communications payload at this time to conserve power. The satellite is in a stable, safe mode, and
engineers at Hughes Space and Communications Co., which built the spacecraft, are examining all
pertinent data to determine the causes of and potential solutions to the anomalies."
PanAmSat was unable to restore service from Galaxy IV. Friday, PanAmSat's Bednarek said "The C-band Galaxy
VI satellite is currently moving in space and will be available for customer service at the 99 degree orbital
location on Wednesday, May 27." While this will allow restoration of C-band services that were originally
on Galaxy 4, they may not be on the same transponder. In the same statement, Bednarek said PanAmSat "did not expect to be able to use the satellite for communications services again." Thursday night it was moved from its orbital location at 99 degrees West Longitude "to a safe, higher orbit, where it will remain for
the near future."
The Wall Street Journal noted that Hughes, in an SEC filing dated May 15, had pointed to "certain
anomalies" relative to its Galaxy IV spacecraft. While this does not appear to be related to Tuesday
night's failure, the SEC 10Q filing stated "These anomalies are expected to shorten substantially the
useful life of the satellite and to affect services to some of the C-band transponder customers on the
satellite. Management is evaluating the effects of these anomalies and is working with its customers to develop
plans to meet their requirements and to satisfy the Company's obligations to certain of the customers. The
Company intends to procure a replacement satellite on an accelerated basis for a scheduled in-service date before the Galaxy IV spacecraft reaches the end of its expected useful life." The entire Hughes 10Q filing is available on the SEC Edgar web site.
FCC Chairman William Kennard issued a Statement on the Galaxy 4 Satellite Wednesday. It said "The FCC is aware of this problem and will continue
to watch it closely." He noted that "This type of disruption in satellite service is extremely
rare." However, his statement concluded, "After the problems are resolved, it is my intention to have our advisory committee in this area, the National Reliability and Interoperability Council, assess the cause of the problems and make appropriate recommendations to the Commission and to the telecommunications industry."
The FCC granted PanAmSat's Emergency request for temporary authority to operate Galaxy VI at the 99 degree
West Longitude orbital location. The FCC determined that "We find it in the public interest to grant
PanAmSat's request. The failure of the Galaxy IV spacecraft has caused substantial disruption to its
customers' communication services and PanAmSat is in need of immediate substitute capacity." See Order DA98-969 for details on this action.
The press generally focused on the loss of pager and data services from Galaxy 4. One paging company, SkyTel, was not affected because it maintained a backup transponder on Galaxy 7. When data from Galaxy 4 stopped, the
receivers for SkyTel's one-way paging service automatically switched to Galaxy 7. More information on
the satellite outage is available from the following sources:
PanAmSat's Robert Bednarek - Regarding the Galaxy IV Satellite
Robert Bednarek - Regarding Continguency Plan for Galaxy IV
PanAmSat's Robert Bednarek - Regarding the Status of the Galaxy IV Satellite and Customers
SkyTel Service Bulletin
Tribune - Beepless Customers Look for Answers
CNN Interactive - Pagers Beep Back to Life Across United States
NPR Tech News - All Things Considered Audio Report
Yahoo! - Full Coverage of Satellite Malfunction - links to other articles
- FCC Releases Memorandum Opinion and Order on Reconsideration of 220-222 MHz. Rules (May 21)
- The FCC acted on petitions for reconsideration and comments on those petitions filed in response to its
Report and Orders in its rule making on setting rules for use of the 220-222 MHz band by the Private Land Mobile Radio Service. Some of the technical actions in the
Memorandum Opinion and Order on Reconsideration released May 21 included denying requests to raise the power limit for fixed stations operating on mobile channels and for base stations of nationwide licensees. The Commssion also denyed petitions requesting modification of the rules to require protection of the 28 dBu, rather than the 38 dBu service contour of Phase I licensees. A petition of SEA
asking that the antenna height limitation for stations operating in the 220 MHz band be associated with the HAAT of the station's transmitting antenna, rather than the antenna's height above ground, was granted. Numerous requests for changes in the requirements for construction were denied.
More information is available in the Memorandum Opinion and Order On Reconsideration (FCC 98-93). In a related mater, see Report
WT 98-14 - Commission Adopts Rules and Sets Forth Processes for 220-222 MHz Auction.
- SATELLITE - Teledesic LLC, Motorola and Others Partner to Develop "Internet-in-the-Sky" (May 21)
- Motorola will be the prime contractor for the team developing and deploying Teledesic's global, broadband
"Internet-in-the-Sky" satellite communications system. Other members of the global team include the
Boeing Company and Matra Marconi Space. Service is expected to begin in 2003. More information is available
in the Teledesic Press Release.
- TECHNOLOGY - Lucent Announces Faster And More Accurate Method for Predicting Signal Strengths (May 19)
- Lucent presented the latest enhancements to its Wireless System Engineering (WiSE) software package at the 48th Annual Vehicular Technology Conference sponsored by the Institute of Electrical and Electronics Engineers. The new version is 10 to 1,000 times faster than previous versions. The WiSE software has been used primarily for designing indoor wireless systems. Lucent says the software uses a three-dimensional, ray-tracing technique to accurately predict signal strengths inside a building, based on precise information about wall material and thickness and room layout. Lucent said statistical models, another approach for studying indoor wireless designs, use only average parameters rather than accounting for specific features and are not as accurate. In tests at Bell Labs buildings in New Jersey comparing calculated signal strengths with actual readings, the WiSE results were off by not more than six dB in 90 percent of the locations compared with a 15 dB error using statistical methods.
The WiSE software operates on desktop personal computers and can compute results within seconds. Steven Fortune, a Bell Labs computer scientist, said the trick is "separating the building's layout into a series of triangular grids. So as the signal moves from region to region, WiSE is concerned only with one grid at a time, whereas other ray-tracing methods include information about every wall in the building." While primarily used for indoor studies, it can be used outdoors provided sufficient information is available. It has been tested in Munich, Germany and Rosslyn, Virginia. Results closely matched actual measurements, Lucent said.
More information is available in the Lucent Press Release and on the WiSE project page on the Bell Labs web site at http://www.bell-labs.com/innovate98/wireless/wiseindex.html.
- CHIPS - Broadcom to Develop VSB/QAM Receiver ICs for Sony (May 19)
- Broadcom Corporation announced today that it will develop a series of 8-16VSB and 64-256QAM receiver ICs for use in Sony's advanced digital terminals. The ICs will provide single chip solutions for receiving both terrestrial and cable signals compliant with ATSC and SCTE specification at both HDTV and SDTV quality levels. The company is also working on multimedia chips incorporating the IEEE1394 digital interference standard. No pricing or availability was mentioned in the Broadcom Press Release.
- CHIPS - Motorola LDMOS Device Models Now Available on Web Site (May 19)
- Motorola announced yesterday that a library of its laterally diffused metal oxide silicon (LDMOS) nonlinear transistor models is available on a new web site for use by RF design engineers. Motorola claims these are the first nonlinear transistor models of LDMOS devices available in the industry. Motorola's LDMOS technology has become one of the more popular devices for new high power high frequency RF amplifier designs.
The web site URL is http://sps.motorola.com/models/ldmos/ldmosmodels.html. On the web site, design engineers will find each LDMOS model has an associated Root model state file, a schematic representation of the model and a diagram that shows the range of validity of the model and outlines the electrical reference planes. Validation data is also included for each nonlinear model. More information may be found in the Motorola Press Release.
- OTHER Items of Interest
May 18, 1998 - Issue 118 Final Edition
- FCC Invites Comments on Zircon Ultra-Wideband System Part 15 Waiver Request (May 18)
- Zircon Corporation is requesting a waiver of Part 15 of the FCC rules in order to permit the authorization, importation and operation of a system for through wall imaging radar systems used in construction environments. The transmission system operates with an average radiated power of 125 microwatts between 200 MHz. and 4 GHz. Zircon is seeking a waiver to operate in the restricted frequency bands shown in Section 15.205. It also requests the removal of the requirement for application of a pulse desensitization correction factor in measuring emission.
The FCC Office of Engineering and Technology is seeking comments from interested parties concerning this request. This proceeding will be treated, for ex parte purposes, as a "permit-but-disclose" proceeding. Comments are due no later than June 17, 1998. Reply comments are due by July 2, 1998. More information is available in the Public Notice DA 98-924.
- SATELLITE - Iridium Completes Satellite Constellation Deployment (May 17)
- The Delta II launch of five Iridium satellites from Vandenberg Air Force Base Sunday afternoon marked the technical completion of the 66 satellite Iridium constellation. This was the 15th successful launch in 12 months. Iridium claimed it marked "the quickest deployment of the largest number of satellites in human history." A total of 72 satellites were launched, 67 of which are operational. The company plans to begin commercial service in September of this year.
Dr. Edward F. Staiano, Iridium LLC Vice Chairman and Chief Executive Officer, said "With 67 operational satellites in orbit, we have achieved one of the critical milestones necessary to provide the first truly global, hand-held wireless phone service." The system will offer a variety of services, including voice, data, fax and paging to customers with handheld telephones and pagers. More information is available on the Iridium web site. More information on Sunday's launch is available in an Iridium Press Release. Information on viewing the flares from Iridium satellites is available in the May 4 RF Current.
- CHIPS - LSI Logic and BBC Announce First Single Chip DVB-T 2K/8K COFDM Demod (May 14)
- One of the barriers to deployment of Coded Orthogonal Frequency Division Multiplex (COFDM) for terrestrial digital TV reception has been the cost and complexity of the demodulator required to receive it. The announcement by LSI Logic and the BBC of the immediate availability of the L64780 single chip COFDM demodulator has greatly reduced that barrier. The L64780 is priced at "sub $20 for volume purchases".
Given enough bandwidth, the L64780 is capable of delivering up to 31.7 Mbit/sec. It works by sampling an IF signal from the tuner and converting it digitally to a baseband signal. Once converted, the L64780 is capable of applying all the digital processing steps needed to demodulate the digital data. These steps include FFT, timing and frequency synchronization, channel estimation and equalization, generation of optimal soft decisions using channel state information and symbol and bit de-interleaving. Samples and an evaluation daughter board are available now. The daughter board includes the L64780, a tuner module and software drivers.
This chip is the result of a joint development effort by the BBC and LSI Logic. Jean-Luc Droitcout, Marketing Director of Digital TV, LSI Logic, said "This is an outstanding example of collaboration. The BBC provided DTT expertise and an intimate knowledge of the European broadcast market, while LSI Logic provided the expertise to implement the BBC's DTT expertise into working, cost-effective silicon." More information is available in the LSI Logic Press Release.
- FCC Proposes Streamlined Equipment Approval Proceedures (May 14)
- The FCC has taken several steps to streamline approval of global telecommunications equipment. It proposed to enable designated private parties in the U.S. to approve equipment as an alternative to certification by the Commission. It also proposed to modify its rules to implement a US/EC MRA so that products may be tested by private bodies in the United States for compliance with the technical requirements of EC member countries. In addition, the proposed US/EC MRA would allow parties in the EC to test and approve equipment for compliance with U.S. requirements. The FCC proposed an interim procedure to issue equipment approvals for Global Mobile Personal Communications by Satellite (GMPCS) terminals. The interim procedure would benefit certain GMPCS systems that are now or soon will be operating.
More information on these proposals is available in the OET Press Releases - Report GN 98-6 and Report GN 98-7.
- FCC Names Dale Hatfield to be Chief, Office of Engineering and Technology (May 14)
- If the name Dale Hatfield sounds familiar, it is probably as a result of his respected telecommunications consulting business based in Boulder Colorado and his advice on technology, economic and regulatory issues. After a 15 year break from government service, Hatfield joined the FCC as Chief Technologist last December. Effective July 6, he will become the Chief of the Commission's Office of Engineering and Technology. FCC Chairman William E. Kennard praised Hatfield, saying "Dale has provided invaluable advice to me and the staff of the Commission on many of the extraordinarily important engineerng, technical and spectrum issues facing the Commission and I am thrilled that he will bring his immense depth of knowledge and understanding of the telecommunications technology and policy to the issues and concerns handled by OET." More information on Dale Hatfield and the appointment can be found in the FCC News Release (nret8007).
- SCIENCE - Policies for Reporting Potential Asteroid Collisions with Earth (May 13)
- Recent reports of a possible asteroid collision with Earth in 2008 created concern worldwide. Later data showed the asteroid had little chance of hitting our planet. This false alert has prompted the astronomy community to consider how it communicates such information to the public. New technology will dramatically increase the rate at which new asteroids and comets approaching Earth are discovered. The expected increase in discoveries will also increase the risk of false alarms. Of the thousands of new comets and asteroids that may be discovered, some will initially appear likely to collide with Earth until their orbit is more accurately determined and interpreted to show otherwise. NASA funded a study by the National Research Council of the National Academy of Sciences and the National Academy of Engineering to set policies and priorities for exploration of near-Earth objects.
The report recommended priorities be given to telescopic studies, laboratory investigations and, where possible, robotic and manned spacecraft missions. Much more information is available in National Academy of Sciences Press Release. Information is also available on the full report and how to buy it.
- DIGITAL TELEVISION STATION APPLICATIONS - See ap980515.txt
for more information
All listings are for a new digital TV station unless
- KTTV-DT Channel 65 - Fox
Television Stations, Inc., Los Angeles, CA - 680
kW - 902 meters HAAT on Mount Wilson. (channel
corrected May 19 by FCC
- WTTG-DT Channel 36 - Fox
Television Stations, Inc., Washington, DC - 1000
kW - 201 meters HAAT at 51 51 Wisconsin Avenue,
- WJLA-DT Channel 39 - Allbritton
Communications Company, Washington, DC - 646 kW -
254 meters HAAT at 4010 Chesapeake St, NW.
- WFLD-DT Channel 31 - Fox
Television Stations, Inc., Chicago, IL - 200 kW -
475 meters HAAT at Sears Tower
- WLS-DT Channel 52 - WLS
Television, Inc., Chicago, IL - 152 kW - 507
meters HAAT at Sears Tower
- WNYW-DT Channel 44 - Fox
Television Stations, Inc., New York, NY - 248 kW
- 368 meters HAAT at Empire State Building
- KXAS-DT Channel 41 - Station
Venture Operations, LP, Fort Worth, TX -
modification to change ERP to 891 kW and antenna
to Dielectric TFU-30GTH-R 04 at 448 meters HAAT.
- KTVT-DT Channel 19 - New Gaylord
Broadcasting Company LP, Fort Worth, TX - 565.8
kW at 500 meters HAAT at Cedar Hill
- OTHER Items of Interest
May 11, 1998 - Issue 117 Final Edition
- DIGITAL RADIO - Lucent Venture to Develop Digital
Radio Broadcast Systems (May 11)
- Lucent Technologies announced today that its new Lucent Digital Radio venture will develop In-Band On-Channel (IBOC) digital radio systems for AM and FM radio. Suren Pai, president of Lucent Digital Radio, said "Lucent Technologies is making a significant commitment to digital audio broadcasting through the formation of this Digital Radio venture. Lucent has the resources and the expertise to develop a successful IBOC DAB system for both AM and FM, and we will work with individual stations and radio network groups to achieve this goal on behalf of the radio broadcast industry. IBOC DAB is the most significant innovation in terrestrial radio broadcasting since the introduction of the FM band,"
Bell Labs helped pioneer commercial radio broadcasting with station WEAF in New York in the 1920's. In the field of Digital Audio Broadcasting, Bell Labs has a developed a number of patented technologies. One is the Perceptual Audio Coding (PAC) algorithm for digitizing and compressing audio signals. More information is available in the Lucent Technologies Press Release.
- SATELLITE - NOAA-K Launch Scheduled for May 13 - View Its Images on Your PC (May 11)
- The next NOAA Polar Operational Environmental Satellite (POES) is scheduled for launch Wednesday, May 13th from Vandenberg Air Force Base in California. The POES mission is composed of two orbiting satellites carrying seven scientific instruments and satellite search and rescue equipment. NOAA K, like the polar orbiting NOAA 12 and NOAA 14, will provide also real-time images of Earth.
The lower resolution APT signals from these satellites may be received on 137.5 and 137.62 MHz. Complex equipment is not required. For example, the Yaesu FT-50R handheld radio has wideband FM demodulator and sufficient sensitivity to allow reception with simple whip or turnstile dipole antennas. Software for demodulating the data and displaying the satellite images is available for Microsoft Windows(TM) computers equipped with sound cards. Because these are not geostationary satellites, the signals are available only while the satellite is above the horizon at the receive location. The pages listed below should provide some help tracking the satellites.
For more information on the POES mission, see NASA's POES web site. For more technical information, refer to the NOAA KLM User's Guide. A good source for information on decoding weather satellite data on computers is available from the Radiofacsimile Homepage. An excellent, free software program WXSat -available listed on the same site's Weather Satellite page.
- WIRELESS - Wireless Application Protocol (WAP) V1.0 Specifications Now Available (May 8)
- The Wireless Application Protocol (WAP) Forum announced that the WAP Version 1.0 specification is now available on from the WAP Forum Web Site. The Version 1.0 Specification is posted in Adobe Acrobat format. The specification defines the overall WAP architecture. This architecture include the Wireless Application Environment, the Wireless Telephony Application Interface, a transport layer and a Wireless Session Protocol specification supporting both connection-mode and connectionless services. The WAP works with GSM, PDC, CDMA, US-TDMA, iDEN, DataTAC, Mobitex, CDPD, DECT, PHS, FLEX and ReFlex wireless networks. The technical documents can be found on the WAP Forum Web site at http://www.wapforum.org/docs/technical.htm. Also see the Nokia Press Release on the public release of the WAP specifications.
- DTV - CEMA and NAB Sponser DTV Summit (May 7)
- Manufacturers of consumer electronics, broadcasters and retailers will meet at the Omni Park West in Dallas, Texas July 15-16 to share information and strategies for the transition to digital television. Topics covered at the summit will include reports on the latest consumer research, market projections for DTV products, regulatory issues, manufacturers plans for DTV, broadcasters' transition efforts and more.
The summit is open to retailers, manufacturers, engineers and broadcast executives. Pre-registration (prior to July 10) is 175 dollars for CEMA and NAB members and 225 dollars for non-members. For more information call (703) 907-7605 or visit the CEMA Web Site. More information is available in the Press Release.
- DTV - CEMA Concerned about TCI Shift on HDTV (May 5)
- The Consumer Electronics Association (CEMA) expressed "surprise and dismay that, less than three weeks after TCI President Leo Hindrey promised Congress that TCI would carry all HDTV formats, TCI Chairman John Malone told the media that it would not carry the HDTV formats chosen by CBS and NBC."
Gary Shapiro, president of CEMA, said "With more than two-thirds of American home relying on cable for their television service, cable companies must carry all HDTV formats. Must carry is not only good public policy, it is the law. It is now obvious that the FCC needs to enforce the must carry laws for HDTV to succeed. American consumers, including TCI customers, deserve the very best quality TV signals." - from CEMA Press Release, May 5.
- CHIPS - Spectrian RF Bias Control ASIC Improves RF
Amplifier Linearity (May 5)
- RF amplifier supplier Spectrian Corporation announced today that it has been granted a U.S. patent for the design of a temperature compensating RF bias controller. The ASIC, named BiASIC(TM), is designed to dynamically adjust the bias current supplied to RF amplifier transistor while providing for the instantaneous increases in DC collector current as a result of varying RF signals. Of potential interest to DTV transmitter manufacturers, Spectrian said the invention is based on the discovery that with accurate dynamic control of the DC bias in the RF power transistor is is possible to improve the linearity of the power amplifier. Spectrian's BIASC has an internal temperature sensor, an option input for a thermal reference that can be mounted on the RF power transistor and an additional modulation input to customize the dynamic bias condition for improved linearity.
More information is available on the Spectrian web site and in its Press Release.
- DIGITAL TELEVISION STATION APPLICATIONS
- KGO-DT Channel 24 - KGO
Television, Inc., San Francisco CA - 561 kW - 437
meters HAAT at Sutro Tower - see ap980505.txt.
- KNBC-DT Channel 36 - NBC
Subsidiary (KNBC-TV), Inc., Los Angeles, CA - 380
kW - 991 meters HAAT at Mount Wilson - see ap980505.txt.
- WUSA-DT Channel 34 - The Detroit
News, Inc., Washington, DC - 646 kW - 254 meters
HAAT at 4010 Chesapeake St NW - see ap980505.txt.
- WXIA-DT Channel 10 - Pacific And
Southern Company, Inc., Atlanta, GA - 16.5 kW -
303 meters HAAT at 110 Arizona Avenue - see ap980505.txt.
- KCBS-DT Channel 60 - CBS Inc.,
Los Angeles, CA - 469 kW - Dielectric TFU-18DSC-R
antenna at 1087 meters HAAT on Mount Wilson - see
- KABC-DT Channel 53 - ABC Holding
Company, Inc., Los Angeles, CA - 182.5 kW -
Dielectric TUP-14-04 antenna at 924 meters HAAT
on Mount Wilson - see ap980508.txt.
- WBBM-DT Channel 3 - CBS
Broadcasting, Inc., Chicago, IL - 3.0 kW - Jampro
JAT-2/1 antenna at 366 meters HAAT on the John
Hancock Building - see ap980508.txt.
- WBZ-DT Channel 30 - Westinghouse
Electric Corporation, Boston, MA - 600 kW -
Harris TAD-24UDA-5/60 antenna at 390 meters HAAT
in Needham MA - see ap980508.txt.
- WCVB-DT Channel 20 - WCVB
Heart-Argyle Television, Inc., Boston, MA - 200
kW - Dielectric TLP-16M(C) antenna at 191 meters
HAAT in Needham MA - see ap980508.txt.
- WWJ-DT Channel 44 - CBS, Inc.,
Detroit, MI - 200 kW - Dielectric TFU-18GTH-R04
DTV antenna at 323 meters HAAT at 20931 Meyers
Road, Oak Park, MI - see ap980508.txt.
- OTHER Items of Interest
May 4, 1998 - Issue 116 Final
- DTV - Scientific-Atlanta and Mitsubishi Demo HDTV on OpenCable Set-Tops (May 4)
- While the battle continues on broadcast DTV must-carry for cable, Scientific-Atlanta and Mitsubishi are demonstrating HDTV signals passing through an OpenCable-compliant digital set-top box. Using HDTV content provided by IntrisHD-KCTS Television, the demonstation shows Scientific-Atlanta's Explorer 2000® set-top box passing an HDTV signal through a IEEE 1394 "firewire" connection to a Mitsubishi Electric receiver. Richard Green, president and CEO of Cable Television Laboratories, commented "Through the OpenCableTM process, traditional cable vendors and consumer electronic manufacturers are coming together to advance the position of the cable industry. This demonstration is another example of the great strides we are making towards a plug-and-play system in which the consumer can tap into the exciting new applications being developed by our members."
More information is available in the Scientific Atlanta Press Release and from Mitsubishi.
- SATELLITE - Iridium Constellation Nears Completion - Catch their Flare as they Pass By (May 2)
- Today two more Iridium satellites were launched on a China Long March rocket from the Taiyuan Satellite Launch Center in China, the fourteenth successful launch for Iridium in the last 11 months. When complete, the constellation will consist of 66 satellites and provide a global wireless personal communications network for voice, data, fax and paging services using a handheld telephone and pager. See the Iridium Press Release for details.
You may not be aware that the Iridium satellites are often quite visible as they pass overhead. The highly reflective Main Mission Antennas (MMAs) reflect sunlight back to the earth. The flares created by these antennas can be quite bright - some are visible on thin cloud layers! The effect can be quite dramatic if seen when the satellites are still clustered together after the launch. Knowing your exact location is critical for catching these flares. Once you have accurately determined your location, visit the German Space Operations Centre at http://www.gsoc.dlr.de/satvis/ to find out when the flares will be visible at your location. Much more information on Iridium flares, including details on how the flares are created and links to other sites with software and orbital information, can be found at http://www.satellite.eu.org/sat/vsohp/iridium.html. While flares are most visible in the evening and at dawn, they can be seen during the day if you know where to look.
- DTV - TV Receive Antennas A Critical Link to the Digital Future (Apr. 30)
- The popularity of DBS satellite dishes has increased consumer interest in TV antennas for reception of local TV stations. At the same time, TV set manufacturers, concerned that cable companies may not carry broadcasters' full digital signals, are taking an interest in antennas. Gary Shapiro, president of the Consumer Electronics Manufacturers Association (CEMA) observed that "Until cable companies pass through a full HDTV signal, antennas may be the only way for consumers to experience the almost three-dimensional picture quality and digital surround-sound that HDTV offers and our research shows consumers want." He added, "...today's antenna technology brings new, sleek, innovative designs that, in most cases, provide remarkable reception if the correct type of antenna is being used."
CEMA recently organized an Antenna Subdivision of the CEMA Associates Division. The group will promote the growth of the antenna market by "coordinating and energizing the technical and market development activities of broadcasters and receiver/reception systems manufacturers and distributors." A key element of the problem is to teach consumer retail salespeople how to use the new voluntary antenna specification standards and a color-coded local reception map, currently under development. Companies participating in the effort include Channel Master, DirecTV, Gemini Industries, Jasco Products, RDI Electronics, Recoton Corporation, Sony Electronics, Tandy Corporation, Terk Technologies, Thomson Consumer Electronics, USSB, Winegard and Zenith. The National Association of Broadcasters (NAB) and the Satellite Broadcasting and Communications Association (SBCA) are also providing technical assistance to the group.
More information is available in the CEMA Press Release. Also this week, Antennas America, Inc. said its pending patent on a TV antenna assembly including the use of an antenna circuit and associated cable as part of the antenna as been allowed. The technology is used in Antennas America products, including the Freedom(TM) antenna designed to mount on the back of a small DSS dish and the Walldo(TM) Antenna -a flat antenna that can be installed on a chimney, eave or roof and painted to match the house. More information on the patent is available in the Antennas America web site.
- WIRELESS - System for IP Data over DVB Network Demonstrated (Apr. 30)
- Although the primary focus of digital broadcast systems has been video programming, there is increasing interest in transmitting data over these systems, particularly IP (Internet Protocol) services. Logical Innovations will be demonstrating its IP Encapsulator Data Gateway (IPEDG) at the NCTA convention May 4 through 6 in Atlanta. Logical Innovations IPEDG can multiplex numerous IP data streams into one DVB compliant transport stream. This allows data such as Internet web sites to be combined with regular digital TV broadcasts. The system is not limited to terrestrial data rates - it can operate up to 45 Mbps over cable, satellite, or terrestrial systems. More information is available in the Logical Innovations Press Release.
- DIGITAL TELEVISION STATION APPLICATIONS
- KTVU-DT Channel 56 - KTVU
Partnership, Oakland, CA - 501 kW - Dielectric
antenna at 432 meters HAAT at 1 La Avanzada St,
San Francisco - see ap980430.txt.
- WHSH-DT Channel 23 - SKMA
Broadcasting Partnership, Marlborough, MA - 49.6
kW - Dielectric antenna at 326 meters HAAT - see ap980430.txt.
- WDIV-DT Channel 45 -
Post-Newsweek Stations, Michigan, Inc., Detroit,
MI - 973 kW - Dielectric antenna at 281 meters
HAAT at 15700 Lincoln Drive, Southfield - see ap980430.txt.
- WPVI-DT Channel 64 - Capital
Cities/ABC, Inc. - 1000 kW - omnidirectional
antenna at 332 meters HAAT at the foot of Culp
Street, Philadelphia - see ap980430.txt.
- OTHER Items of Interest
Other Issues Available:
1995 and 1996
Return to The RF Page @
Last modified June 15, 1998 by Doug Lung email@example.com
Copyright © 1998 H. Douglas Lung