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 You may have noticed that by the end of the month, the RF Current page had grown rather large. Starting this month, each issue will now have its own HTML page. This should make it faster to load, easier to search and make it a little easier for me to edit. I now have access to an Excite search engine. As soon as I can figure it out, I plan to have all issues search able from the new back-issues Index.

<<< Back to April 5 - Issue 160

April 12, 1999 - Issue 161 Final Edition

TECHNOLOGY - USA Today Article Increases Interest In Ultra-wideband "Digital Pulse Wireless" (Apr. 12)
An article in the Money Section of USA Today describing Larry Fullerton's work with Ultrawideband (UWB) pulse technology led to many discussions and arguments among RF engineers over the weekend. Leading edge technology web site slashdot.org carried the story in a posting Saturday. By Monday night, over 100 comments had been posted on the topic.

Larry Fullerton's company is Time Domain. Simple explanations of how the system works can be found on the Time Domain Web Site. In the News section there is a link to a Adobe Acrobat (pdf) reprint of the USA Today article. Also read the Technology Overview. Follow the links at the bottom of the Technology Overview for more detailed technical information.

The Impulse Radio Overview by Time Domain Corporation's Paul Withington said Time Domain's system uses ultra-short "Gaussian" monocycle pulses with pulse widths of 1.50 to 0.20 nanoseconds and pulse-to-pulse intervals between 100 and 1,000 nanoseconds. It should be obvious these narrow pulses have energy spread over a very wide frequency band. Modulation is applied by varying the pulse to pulse interval. Since spread-spectrum modulation may also cover a wide frequency band, it is tempting to describe impulse radio as a form of spread-spectrum modulation. Conventional spread-spectrum modulation techniques use a pseudo-random code to distribute data over a specified range of frequencies. While it appears noise-like, the frequencies are defined by the code. Impulse radio, on the other hand, does not depend on coding to spread specific frequencies. Instead, Time Domain's system takes the Gaussian pulse train, which produces series of energy spikes at regular intervals in the frequency domain, and modulates it to carry information. This spreads the frequencies to some extend, but to create a pseudo-random noise response, the time offset of the pulses is varied using a pseudo-random code. So, while spread-spectrum varies frequency with a pseudo-random code, impulse radio varies time position with a pseudo-random code.

How does it work? The Impulse Radio Overview said Time Domain's engineers constructed a full duplex 1.3 GHz system operating at 5 Mpps transmitting data at either 39 kbps or 156.25 kbps over links exceeding 16 km and within buldings. How much transmitter power was needed? According to the paper, the average output power was 250 microwatts! The paper said the transmitter can be a single transistor, operating in a digital (on or off) mode. A linear amplifier is not needed. The receiver does not require IF stages. Impulse Radio Overview explained "...unlike spread-spectrum receivers, the control loop operates at very low frequencies, which also saves costs."

RF Current first reported on the FCC Rulemaking to allow ultra-wideband radar systems in the February 9, 1998 Issue. Additional news appeared in the May 18, 1998 Issue. In September, 1998, the FCC issued a Notice of Inquiry on the possibility of allowing ultra-wideband systems in the unlicensed radio service under Part 15. Ultra-wideband was not permitted under Part 15 because some of the emissions fell on frequencies in restricted bands such as those for broadcast TV. This was reported on in the September 7, 1998 RF Current. These articles contain links to relevant FCC documents. More information may also be found on the Ultra Wideband Working Group web site. The Site Contents page has links to the FCC Notice of Inquiry and industry comments to the NOI.

DTV - LG Electronics Research Center to Demonstrate DTV Products at NAB (Apr.12)
A Press Release from LG Electronics Research Center of America contained information on products the company was planning to introduce at NAB. These include the DTVCard A1000, a card to turn a Windows 98 PC into a DTV decoder that can receive DTV broadcasts and display all ATSC formats on a standard PC monitor or an NTSC TV. StreamScope builds adds the capability to record, monitor, measure and analyze DTV streams and signals using the DTVCard A1000. Other products include PSIP Builder Pro, an automated PSIP stream generator for DTV broadcasters that automatically converts program information from program listing services or traffic systems to the ATSC A/65 standard format and SkyScraper, a secure data broadcast system. Companies interested in developing new applications for the DTV datastream may be interested in LG Electronic's DTV RefStation. DTV RefStation is a reference platform for developing Java-based DTV application programming interfaces. The products will be shown at the NAB99 Premier Park Booth S849 in the Sands Expo Center.

CHIPS - Philips Announces Second Generation DTV/analog Front-end Chip Set (Apr. 12)
Philips Semiconductor announced a new two-chip hybrid analog/DTV front-end receiver solution - the TDA8980 input processor and the TDA8961 DTV demodulator/decoder. The chips support both 8VSB and NTSC channel decoding. Philips sees a large market for these chips. Gerry Kaufhold, principal analyst at Cahners In-Stat Group, said "We predict one million HDTV sets will be sold over the next three years and sales of Digital TV set-top boxes to grow at an even faster pace. Many of these will have more than one receiver chip set. With an explosion of new computer applications, we also predict that over 20 million DTV receiver-ready PCs will ship by 2002."

The TDA8961 8VSB demodulator/decoder IC adds features to reduce signal degradation due to interference and multipath distortions. It also contains a "unique co-channel filter that reduces interference from strong NTSC signals." More information is available in the Philips Product News Announcement.

DTV - CDS Demonstrates Simultaneous HDTV and Multiple SDTV Service (Apr. 8)
WTHN-DT (Hartford-New Haven), a member of the LIN Television family of stations, is now transmitting a 720P HDTV service and two SDTV program services in its 6 MHz DTV channel. The feeds consist of ABC network HDTV feeds and locally upconverted material. The SDTV services include weather and sports programming. The encoding system and on-site integration, installation and testing for the entire system was supplied by the THOMCAST Communications CDS Unit. DiviCom provided the SDTV encoders and Tiernan the HDTV encoder.

Matt Tietze, Director of Marketing and Sales for CDS, commented "The ability to do a single high definition program feed along side multiple standard definition services, such as weather and news, is an important model for the commercial broadcaster." WTNH Director of Engineering Marty Peshka, claiming this was the first known regularly broadcast commercial transmission and reception of simultaneous HDTV and two SDTV program services, remarked "The ability to broadcast these three services simultaneously sets a new standard in commercial DTV transmission." The THOMCAST Communications Press Release said all three signals were successfully decoded and displayed "with no objectionable picture artifacts."

DIGITAL TELEVISION STATION APPLICATIONS - See ap990409.txt for more information
Call (DT) Ch. Licensee Location ERP (kW) HAAT (m) Antenna / Notes
KTVU 56 KTVU Partnership Oakland CA     License to cover CP
WPXJ 53 Paxson Buffalo Batavia NY 800 279 Dielectric TFU-18DSC P230
WMFD 12 Mid-State Television Mansfield OH 4.8   Cablewave RD-2VO (mod)
KSL 38 Bonneville Holding Salt Lake City UT 295 1267 Kathrein KK773928

DIGITAL TELEVISION STATION ACTIONS - See ac990407.txt for more information
Call (DT) Ch. Licensee Location ERP (kW) HAAT (m) Antenna
WHIQ 24 Alabama Ed. TV Comm. Huntsville AL 50 340 Dielectric TFU-30GTH-R DC
WEIQ 41 Alabama Ed. TV Comm. Mobile AL 50 185 Dielectric TFU-30GTH-R DC
WLJC 7 Hour of Harvest Beattyville KY 15 192 Andrew ATW9V3-HTO-7
KBLR 40 Summit Media LP Paradise NV 32.4 357 Andrew ATW16H3-HSC5U-39S
WAIQ 14 Alabama Ed. TV Comm. Montgomery AL 50 161 Dielectric TLP-24 A

OTHER Items of Interest

April 19 - Issue 162 Next >>>

RF Current Index: 1995 - Present

Links to news items and press releases that might be of interest to other RF and broadcast engineers are always welcome. Please e-mail me at dlung@transmitter.com or phone me at Telemundo, (305) 884-9664.

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Last modified April 13, 1999 by Doug Lung dlung@transmitter.com
Copyright © 1999 H. Douglas Lung