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.
NOTICE: After this issue, RF Current will no longer list FCC DTV applications or actions for individual stations. Petitions for rule making to change DTV channel allocations will continue to be listed. In November, 1999 all commercial TV broadcast stations were required to file for a DTV construction permit. Many of these were filed as "minor modifications", so technical details did not appear in the FCC Public Notices. As a substitute for these listings, I'm now posting an Excel spreadsheet containing all DTV service entries in the FCC Engineering Database in Microsoft Excel 3.0 format. This file should be able to be read by all current spreadsheet programs. Please let me know if you have any problems with it. Using the "Auto-Filter" feature in later versions of Excel, it is possible to search by state, channel number or even ranges of transmitter location coordinates. Download compressed (Zip) file fccdtvdb.zip. This file will be updated weekly. The latest revision is noted on the The RF Page @ www.transmitter.com home page.
<<< Back to November 24 - Issue 192
December 6, 1999 - Issue 193 Final Edition
- CHIPS - Broadcom Demonstrates Complete Digital/Analog RF Television Tuner using CMOS (Dec. 6)
- In a press release Broadcom Delivers World's First CMOS TV Tuner, Broadcom said it has "introduced and demonstrated the world's first complete digital-analog RF television tuner in CMOS.". Microtune introduced the first single chip television tuner in June, 1999. See RF Current - June 14, 1999 for details.
Allen Leibovitch, Product Manager, Semiconductor Research for IDC's Consumer Devices program, compared Broadcom's chip with other vendor's solutions: "This technology leapfrogs other vendors of tuner ICs who are using more expensive manufacturing technologies and puts Broadcom in an excellent position to address a worldwide market approaching, by some estimates, 300 million units per year."
Broadcom Chief Technical Officer, Henry Samueli, described the work behind the chip. "The BCM3400 family of products are the first commercial RF CMOS VLSI chips ever developed. We have successfully integrated all of the traditional RF circuit blocks-synthesizers running greater than 2 Gigahertz (GHz), up conversion mixers, image-reject down conversion mixers, multi-pole filters, amplifiers, and 50 Ohm drivers-into one chip in the same standard 'digital' CMOS process that we use for all other Broadcom products. With the advent of the BCM3400 family of products, Broadcom is bringing RF CMOS out of the research laboratory and into mainstream consumer devices."
The chip receives a signal in the 50-860 MHz band, amplifies it, and down converts it to a 44 MHz IF. It uses a triple-conversion architecture, up-converting the signal to the first IF, where on-chip channel reduction filters filter it before down-converting it to the second IF. Additional filtering is done at the second IF, then it is down-converted to the standard 44 MHz output frequency. Broadcom's press release mentioned cable TV applications, but did not specifically address performance of the chip design under the wide-dynamic range and hostle interference conditions that exist in terrestrial "over-the-air" signal environments.
The up-converter mixer uses wide band synthesizer. The down-conversion to the second IF using a narrow band synthesizer. The Broadcom press release said, quot;The BCM3400 family integrates all the external Oscillator 'Tank' components associated with the RF Voltage Control Oscillator (VCO's), which removes the noise from external pins thus simplifying the RF layout, thereby eliminating the need for extensive shielding." Dr. Mehrdad Nayebi, General Manager of Broadcom's RF and Mixed-Signal Business Unit, commented that, "The performance demonstrated by these integrated VCO's is a world's first in bulk digital CMOS technology."
The first chip in the family, the BCM3415, is available in sample quantities for 10 dollars.
- RF - Univ. of Washington Researcher Finds Microwave Exposure Causes Long-term Memory Loss in Rats (Nov. 30)
- Most of the concern to date about exposure to transmissions from hand-held cell phones has focused on brain tumours. However, impairments in mental capacity may be turn out to be a greater concern. This should not be a surprise, as early research into the biological effects of RF exposure showed the first sign of excessive RF exposure was a change in mental state. (See the RF Technology Column, January 1995 by Doug Lung - "RF radiation effects -- are they in your head?")
A research study at the University of Washington has found exposure to RF emissions "similar to those emitted by cell phones" may affect long-term memory. Henry Lai, a research professor in the UW's bioengineering department, said. "Studies before this one have focused more on short-term memory. In this study, the long-term memory of microwave-exposed rats appears to have been affected."
Lai tested long-term memory by training rats to find a platform in a pool of water obscured by powdered milk. Six training sessions allowed the rats to store the method for locating the ramp in long-term memory. In the study, one group of rats was exposed to pulsed microwaves for one hour before each training session, while a control group was not exposed.
Lai said, "The microwave-exposed rats were much slower in finding the platform during the training sessions. They tended to spend more time attempting to climb the wall of the pool or swimming along the wall." When the platform was removed, the unexposed control group spent most of their time swimming in the area where the platform used to be. The RF exposed rats behaved more randomly and showed much less of a tendency to search for the platform. Lai explained, "They seemed to have trouble making a map in their heads, like the normal rats did, so they could recall where the platform was. Their spatial reference mapping or 'place learning' strategies seemed to be affected after their exposure. It could be that they had to resort to a simpler learning strategy that just didn't work as well and they couldn't remember how to find the platform."
More information on this interesting study may be found in the University of Washington News Release.
- CHIPS - LSI Logic Introduces Single-Chip DVB-T (COFDM) Demodulator (Nov. 29)
- LSI Logic has improved its L64780 DVB-T COFDM demodulator. The new device, the L64781, includes forward error correction, a 10 bit ADC and demodulator blocks on one chip. The new chip has variable bandwidth capability and can work with 6, 7 or 8 MHz systems. It also supports all DVB-T modes, including 2k and 8k carrier modes, hierarchical transmission and single and multi-frequency network configurations. Samples and an evaluation daughter board for the set-top development platform are available immediately, according to LSI Logic. It said the chip is priced under 17 dollars (US) for volume purchases.
Perhaps it is coincidence, but LSI Logic seems to have anticipated some of the concerns U.S. broadcasters have with COFDM. The 6 MHz bandwidth capability was a major issue. LSI Logic also says the chip has better performance than the L64780. Justin Mitchell, senior research and development engineer at the BBC said, "The L64781 has consequently achieved better performance levels, especially in the area of co-channel interference. This is particularly important for the deployment of DTT while analogue transmissions remain on-air. The co-channel immunity of the L64781 is such that, in certain modes, it is possible to receive a perfect digital picture even in the presence of a strong analogue signal on the same frequency. The analogue signal, on the other hand, offers a viewable, if somewhat snowy picture, on a conventional analogue TV set."
Elie Antoun, executive vice president, Consumer Products Division at LSI Logic, commented that "While other solutions fall short of industry performance benchmarks, our second generation, true single-chip solution will enable LSI Logic to maintain its position as the dominant player in this market." Antoun, however, appeared to be focusing on the European market, stating that, "Digital terrestrial TV has been hugely successful in the UK and in Sweden and is soon to be rolled out in the Spanish market. LSI Logic's aim is to enable equipment manufacturers and broadcasters in other European markets to repeat that success, while strengthening our leadership in existing markets."
An LSI Logic Press Release explained that "Set-top boxes and integrated digital televisions (iDTVs) receive digital terrestrial television broadcasts in the same way as traditional broadcasts, with an antenna, but rely on demodulator chips, such as LSI Logic's L64781, to 'translate' these signals into the higher quality sound and images available with digital TV. In addition, as many more channels can be broadcast digitally than with previous analogue broadcasts, it is critical that the demodulator chip effectively eliminates interference and noise to deliver optimum performance. Broadcasters and viewers can expect to see improvements in both coverage and reception."
- SATELLITE - PanAmSat Announces First of Seven Satellites Shipped to French Guiana for Late 1999 Launch (Nov. 29)
- PanAmSat said its Galaxy XI satellite has arrived in Kourou, French Guiana, for a late December launch. Galaxy XI is the first of the advanced HS 702 spacecraft from Hughes Space and Communications. It has 40 Ku-band and 24 C-band high power power transponders. PanAmSat will initially locate the satellite at 99 degrees west longitude where Galaxy VI replaced Galaxy IV last year.
PanAmSat also announced a comprehensive redeployment plan for its Galaxy satellite line up. Specifically:
- Galaxy XI will be launched to 99 degrees west longitude (WL)
- Galaxy VI will be moved from 99 degress WL to 91 degrees WL as a backup for Galaxy VII
- Galaxy XR will be launched to 123 degrees WL in 1Q 2000
- Galaxy IX will be moved from 123 degrees WL to 127 degrees WL
- Galaxy IVR will be launched to 99 degrees WL in 1Q 2000
- Galaxy XI will be moved to 91 degrees WL to replace Galaxy VII
- Galaxy VI will then serve as the permanent in-orbit spare for the Galaxy cable neighborhood
For a visual representation, see the Adobe Acrobat PanAmSat Redeployment Diagram. This information was taken from a PanAmSat Press Release - PanAmSat Expansion Plan Begins....
- FCC Reaffirms Over-the-Air Reception Devices Order (Nov. 24)
- The FCC denied petitions by the Community Associations Institute, the Personal Communications Industry Association, Teligent, Inc., the Association for Local Telecommunications Services, WinStar Communications,Inc., Nextlink Communications, Inc., the Association for Maximum Service Television and the National Association of Broadcasters to reconsider its November 20, 1998 Second Report and Order concerning over-the-air reception devices.
Some of the issue raised in the petitions included tenants' rights to install antennas without the owners' approval and the prohibition on antenna restrictions in common or restricted access areas. More information is available in the FCC News Release (nrch9019) and Order on Reconsideration - Restrictions on Over-the-Air Reception Devices.
- DTV - New Zealand Terrestrial DTV Plan Based on DVB-T COFDM (Nov. 23)
- New Zealand has drafted a channel plan and engineering criteria for digital terrestrial broadcasting in New Zealand. The system is based on the DVB-T COFDM standard, using 64QAM modulation on each carrier, with a 22 Mbit/s payload. Power levels are to be reverse engineered to provide a 20 dB C/N ratio, starting at 30 dBW (1,000 watts). Communications Minister Maurice Williamson said, "Following consultation with major network providers and transmission consultants, a draft frequency channel plan and detailed engineering criteria for digital television transmissions in New Zealand has been developed. I'm delighted to have reached this key milestone in the engineering project. This milestone represents great progress towards a successful introduction of this exciting new technology. The technical work completed to date is a fine example of Government and industry working in close consultation to maximise the value of the resource to the benefit of the viewing public."
Under the plan, three separate national frequency networks will be reserved for the transition of free-to-air broadcasts. The plan also allows for up to five additional networks for sale by auction.
More information is available in the New Zealand Ministry of Commerce Media Release. The draft channel plan and the engineering criteria document are available as Adobe PDF files at http://www.moc.govt.nz/rsm/planning/dttv/index.html. The four page engineering criteria document contains details on calculating interference protection ratios.
- DIGITAL TELEVISION STATION ACTIONS - See ac991206.txt
for more information
- DIGITAL TELEVISION STATION ACTIONS - See ac991201.txt
for more information
||Fort Worth TX
- OTHER Items of Interest
>>>>Next December 13 - Issue 194
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