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.

This page contains stories from RF Current issues published in July 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 dlung@transmitter.com.

August Issue: August 1998

July 27, 1998 - Issue 126 Final Edition

FCC Commissioner Susan Ness Tells California Broadcasters "Digital world is upon us" (July 27)
FCC Commissioner Susan Ness outlined the challenges facing broadcasters in her remarks at the California Broadcaster Association in Monterey California. She applauded the pioneering efforts of the stations on the air and said "It is heartening to see broadcasters taking these deadlines seriously and moving forward with dispatch." She recognized that the conversion from analog to digital broadcasting may be the most challenging one broadcasters have ever faced, saying "Remember, the introduction of color did not render black and white sets obsolete -- or require consumers to purchase converter boxes. Yet the DTV transition will have this effect. We are asking consumers to give up an analog system that has served them well." She also said "Government only has a small role to play." She emphasized that cable set-top boxes should be capable of passing all of the DTV formats, "not just those that a particular cable operator selects for distribution."

Commenting on the "fact that the first generation of DTV receivers will generally not be able to work with cable because the standard for the IEEE 1394 'FireWire' connector is not complete", she said "This glitch has highlighted the pressing need for broadcasters, cable, consumer electronics, and computer interests, and program owners to work together." Although she said the Commission must deal with issues such as cable TV "must-carry", she cautioned that "At the end of the day, the success or failure of DTV is up to you and to the consumers you serve." Regarding the problem of DTV must-carry, she observed that this was a problem only during the transition while broadcasters are transmitting two signals. "Therefore, it is in the self-interest of cable operators to cooperate with broadcasters to expedite the deployment and popularity of digital programming."

She asked the CBA members to remember "there once was a time in the seventies when broadcasters reluctantly accepted assignments on the new FM band." She concluded her remarks by saying "I encourage you to become digital pioneers. Embrace the challenge to make this ambitious transition to digital a huge consumer success."

SPACE - SOHO Spacecraft Located Using Ground-Based Radar (July 27)
The past few issues of RF Current have reported on the loss of communication with the Solar and Heliospheric Observatory spacecraft (SOHO). Researchers at the U.S. National Astronomy and Ionosphere Center (NAIC) in Arecibo, Puerto Rico used the facility's 305-meter diameter radio telescope to transmit a signal toward SOHO on July 23rd. The 70-meter dish at NASA's Deep Space Network in Goldstone, CA listened for the reflection. Study of the echoes from SOHO indicated it was still in its nominal halo orbit near the so-called "L-1" Lagrangian point in space and turning slowly at a rate of about one revolution per minute. Analysis of the radar data is continuing. Meanwhile, ESA and NASA engineers are continuing efforts to re-establish radio data communication with the satellite.

More details are available in the NASA Press Release.

FCC Releases Tech Info for FM Broadcast Point-to-Point Field Strength Prediction (July 24)
The FCC, in a Notice of Proposed Ruemaking and Order in Mass Media Docket 98-93, specified use of a point-to-point contour prediction model for determining FM radio field strength. The FCC has posted information of interest to engineers using or evaluating these models on the Internet. Visit http://www.fcc.gov/oet/fm/ptp/ to find links to the Notice of Proposed Rulemaking, a report describing the derivation of the PTP (point-to-point) model, a FORTRAN subroutine for implementing the PTP model and comparisons of PTP predictions with field measurement data.

SATELLITE - INTELSAT Prepares For Leonid Meteoroid Storm (July 25)
Early this month INTELSAT released its risk mitigation strategy for the Leonid meteor storm expected on November 17 this year. The last Leonid meteroid storm, in 1966, had a meteor Zenith Hourly Rate close to 100,000 per hour. Current predictions are that the storm will peak during the return of comet Tempel-Tuttle either this year or in 1999. The INTELSAT report notes that the high velocity of the Leonid meteoroids results in an impact an order of magnitude larger than typical background sporadic meteroids. It outlined two threats to satellites from these meteroids. One is mechanical, where the meteroid damages the satellite structure or components. The other is electrical, where the plasma cloud generated as a result of the meteroid disintegrating upon impact with the spacecraft could leads to electro-static discharges (ESD) in the satellite. The report said INTELSAT estimates the probability of a meteroid impacting a specific satellite is very small (less than 0.02%), based on available technical information.

INTELSAT is taking precautions to guard its satellites from the meteroid storm. Satellite solar arrays will be angled edge-on in the direction of the oncoming meteoroids, to significantly reduce the satellite surface area exposed to the meteroids. Fortunately, the storm is coming at an angle almost 90 degrees to the sun, so solar panel efficiency will not be seriously impacted during the two or three hours the panels are slewed. INTELSAT said ":Critical satellite nodes will be turned off or 'safed' during this period to eliminate uncommanded events or activations." These might if electro-static discharges occur as a result of a meteoroid impact. INTELSAT will have its satellite controllers and on-call engineers at full alert during the height of the storm. Extra staff that have been briefed in procedures to follow in the event of an emergency will be at the satellite control center.

This story was based on INTELSAT's The Leonid Meteroid Storm: INTELSAT's Risk Mitigation Stragegy. For more information, see The Leonids, a short historical description. Gary W. Kronk has put together an excellent Comets and Meteor Showers page for additional links. The most detailed site is NASA's Leonid '98 Meteor Outburst Mission Home Page. It includes information on observing the meteors, the impact on satellites and observations from past Leonid meteor storms. It was updated July 24th. Also see SKY Online's Meteor Page. The best viewing for the 1998 storm is expected to be in Asia and Japan.

FCC Experimental Actions for May and June 1998 (July 21, 1998)
The FCC Office of Engineering and Technology Experimental Licensing Branch has released its list of experimental applications granted during May and June. Condor Systems, Inc. was granted permission to operate on a wide range of frequencies, including 2050, 3600, 7125, and 13500 MHz in Tulsa, Oklahoma to fulfill a Norwegian Airforce contract to test aircraft avionics. Motorola Satellite Communications received a license to use 1990-2011, 2169-2177, and 2196-2198 MHz around Prescott Arizona to collect propagation data for development of next-generation mobile satellite systems. JT Communications was granted an experimental license to operate in the 88-108 MHz FM band to test new FM broadcast antennas in Ocala, Florida. More information and more listing are available in the FCC Public Notice (pnet8014.txt).

DIGITAL TELEVISION STATION APPLICATIONS - See ap980727.txt for more information
All listings are for a new digital TV station unless otherwise indicated

OTHER Items of Interest

July 20, 1998 - Issue 125 Final Edition

WIRELESS - COMSAT Labs Awarded Contract for Sky Station Comm Networking Services (July 16)
COMSAT Laboratories was awarded a 3.5 million dollar contract to provide communications networking services to Sky Station International, Inc. Sky Station is the company planning to place floating platforms 21 km above major metropolitan areas. Deployment of the Sky StationTM platforms is to begin in 2001.

COMSAT joins the Sky Station team as Communications Systems Integrator. It will coordinate the design, development and deployment of communications systems on the platforms, at gateway earth stations and for user terminals. The platforms are being designed to deliver data rates up to 2.048 Mbps (uplink) and 10.24 Mbps (downlink). The COMSAT Press Release said the "voice and data services provided by the user terminals will be based on standard protocols such as ATM, Frame Relay, Internet, and ISDN,".

More information is available in the COMSAT Press Release, at the Sky Station Web Site and in past issues of RF Current. Refer to the November 3, 1997, July 28, 1997 and May 12, 1997 issues.

SCIENCE - Professor Observes Apparent Negative Electrical Resistance (June 16)
Deborah D. L. Chung, Ph.D., professor of mechanical and aerospace engineering at the University of Buffalo, is working to identify the mechanism behind here observation of negative electrical resistance. Continous negative electrical resistance was observed in a direction perpendicular to carbon fiber layers in a composite material. Negative resistance indicates that electrons in the system are flowing in the opposite direction they normally flow. Chung is working to identify an energy source responsible for the phenomenon. Chung demonstrated the negative resistance phenomenon at the fifth International Conference on Composites Engineering in Las Vegas by hooking a voltmeter to the carbon filber-cement-matrix composite.

The University of Buffalo News Release said Chung ":looked at their initial results skeptically, doubting at first that what they were seeing was correct. After checking and rechecking the connections, and after using different meters over a period of time, they concluded that it was truly negative resistance that they were seeing."

TECHNOLOGY - NASA Releases More Data on SOHO Spacecraft Failure (July 16)
NASA continues efforts to reestablish contact with the NASA/European Space Agency (ESA) Solar and Heliospheric Observatory (SOHO) spacecraft. NASA is using the 34 meter dishes at its Deep Space Network (DSN) to attempt to reactivate transmitters onboard the SOHO spacecraft. Based on the last telemetry received from SOHO, NASA engineers said"it appears most likely that the spacecraft is slowly spinning in such a way that its solar arrays, which generate power, either do not face the Sun at all or do not receive adequate sunlight to generate power. One concern is that due to the loss of control, the fuel and batteries may be frozen. It is hoped that an earlier assumption that the panels will begin to receive more sunlight each day as it continues to orbit the sun will be correct. If so, within a few weeks the spacecraft may receive enough sunlight for its solar arrays to begin charging its batteries. More information is available in the NASA/ESA Press Release

For a complete report on the anomaly and an excellent background in spacecraft control, refer to the SOHO Mission Interruption Preliminary Status and Background Report - July 15, 1998

FCC Amends Rules to Permit Use of Frequencies Above 40 GHz for New Radio Applications (July 15)
The FCC released its Third Report and Order on Amendment of Parts 2, 15, and 97 of the Commission's Rules to Permit Use of Radio Frequencies Above 40 GHz for New Radio Applications today. The Report and Order provides additional protection for radar collision avoidance system in the 76-77 GHz band by temporarily suspending authorization for amateur radio station transmissions in this band. However, amateur radio operators will receive a co-primary allocation in the 77.5-78 GHz band. This is an upgrade in status, which the FCC felt was necessary to remove the threat of preemption by higher priority services. The Report and Order stated "The Commission believes that this allocation is needed if we are to continue to foster amateur operator experimentation using millimeter wave technology." The authorization will also allow amateur satellite operation the band.

The FCC adopted "spectrum etiquette" rules for unlicensed operation in the 59-64 GHz band. One of the rules requires transmitters operating with more than 0.1 mW of output power transmit an identification code within one second of each transmission. Unlicensed transmitters in the 76-77 GHz band will have to meet a spurious emission limit designed to protect radio astronomy services in the 217-231 GHz band. A spurious emission limit of 1000 pw/cm2, measured at 3 meters, will apply to these transmitters. More information is available in the Third Report and Order

DIGITAL TELEVISION STATION APPLICATIONS - See ap980720.txt for more information
All listings are for a new digital TV station unless otherwise indicated

DIGITAL TELEVISION STATION ACTIONS - See ac980720.txt for more information
All listings are grants for a new digital TV station unless otherwise indicated

DIGITAL TELEVISION STATION ACTIONS - See ac980714.txt for more information
All listings are grants for a new digital TV station unless otherwise indicated

OTHER Items of Interest

July 13, 1998 - Issue 124 Final Edition

FCC Adopts NPRM Seeking Comment on DTV Cable Carriage Issues (July 9)
The FCC started its rulemaking on cable carriage of broadcast digital TV stations with the adoption of a Notice of Proposed Rulemaking (NPRM) seeking comment on possible changes to the "Must-Carry" rules. The NPRM also addresses the need for compatibility between digital systems and the impact cable carriage of DTV signals may have on other FCC rules. Existing "Must-Carry" rules apply only to TV station's analog signals. During the analog to digital transition phase, stations will be transmitting two signals and the programming is likely to be different, at least during part of the day.

In the Notice, the FCC:
"seeks comment on digital equipment compatibility issues necessary to ensure the successful introduction of digital broadcast television.

seeks comment on several possible must carry alternatives for DTV signals, ranging from full must carry requirements to no must carry requirements, during the transition period.

addresses the carriage of DTV signals by small cable operators.

seeks comment on what cable operator actions affecting the picture quality of DTV signals would be considered material degradation..."

"asks how to define the term duplication in the context of the transition period. addresses the statutory phrase 'primary video' and how it should be defined in the digital television context.

seeks comment on the definitions of ancillary and supplementary digital broadcast services.

seeks comment on channel positioning options for DTV stations.

seeks comment on the use of antennas and A/B switches to facilitate the reception of DTV signals."

The Notice outlines some scenarios for distributing the DTV signal over cable. One scenario would pass through the broadcasters' 8VSB signals directly to the DTV set, where they would be demodulated, decompressed and display. In another, the set-top box would convert the digital signal for display on NTSC TV sets. However, to process HDTV signals, the FCC commented that "the set top box would need sufficient memory and computing power, which would add to the cost of the equipment." The Notice also discussed the use of a digital bus for addressing the set-top box issues. It sought comment on whether it should have rules requiring that set-top boxes process all types of broadcast DTV formats. Concerning DTV receivers, the Notice asks "Should the Commission take action to encourage the production of cable-ready receivers to facilitate the introduction of digital broadcast television?" Refer to the Notice (links follow) for more information.

At present, before analog TV stations can demand carriage on a cable system they must deliver a UHF signal level -45 dBm or a VHF signal level of -49 dBm. DTV stations are only required to provide a signal above the noise limited threshold over their community of license. In the Notice, the FCC said "We seek comment on whether the Commission's analog signal strength standards are relevant to digital broadcast television or new good quality signal parameters, which include normal system processing degradations and account for bit rate error, are necessary."

Comments are due September 17, 1998. Reply comments are due October 30, 1998. The complete text of FCC 98-153, Notice of Proposed Rule Making In the Matter of Carriage of the Transmissions of Digital Television Stations is available from the FCC web site as in ASCII (fcc98153.txt), Adobe Acrobat (fcc98153.pdf) and WordPerfect (fcc98153.wp) formats. For a summary of the Notice, see Cable Services Report No. CS 98-12.

DTV - Senate Commerce Committee Hearing Examines DTV Transition Problems (July 8)
In a hearing yesterday, the Senate Committee on Commerce, Science, and Transportation focused on the problems developing in the transition to HDTV. In his opening statement Senator John McCain, Chairman of the Committee, called it a "complex and frankly troubled area..." While agreeing the challenges facing broadcasters during the transition were daunting, he outlined challenges other industries faced. He said the cable industry "...must upgrade the digital capability of its systems and make sure its own digital transmission standards work compatibly with the different broadcast standards. It must make sure that it installs technology that will allow subscribers to view digital broadcasts with cable exactly as they would view them without cable. And it must grapple with the issue of how to accommodate new digital channels on cable systems whose channels may already be fully occupied by programming that subscribers don't want dropped." The equipment manufacturing industry has its challenges. Referring to consumer electronic equipment like VCRs, camcorders, DVDs and satellite TV dishes, he stated "All of these devices must be made to work seamlessly in the new digital environment, especially in its early days when consumer acceptance is so important to driving the conversion process forward." The program production industry has its challenges as well.

Senator McCain put the blame on the problems facing the DTV roll-out on government -- "The Clinton-Gore FCC has accelerated the digital conversion schedule and paid little attention to any issue other than trying to prescribe the kinds of programs that broadcasters ought to show on the new digital channels." McCain observed that "as things stand now, starting later this year digital TV sets are going to be sold, and digital TV broadcasts are going to commence, before some very pressing technical problems are solved." He listed the cliff-edge all-or-nothing nature of DTV reception as one problem, referring to over-the-air experiments that showed "discouraging results with currently available off-air antennas, whether mounted inside or outside the house." He said technology could be installed inside the DTV set to fix the interference, but noted that "so far the consumer electronics industry hasn't installed it." Digital cable won't solve the problem -- "Because development of the wire connecting the cable system's digital inputs to the digital TV set isn't yet complete..."

"Call this whatever you want, but it hardly qualifies as a success story in the making." His opening statement concluded "The failures of the Telecom Act show what happens when Congress first fails to see where the interests of industry are incompatible with the interest of consumers, and then fails to act once it does. I do not intend that we repeat either of these mistakes as we begin to see the conversion to digital TV unfold." The full text of Senator McCain's Opening Statement is available on the Senate Commerce Committee web site in Adobe Acrobat format.

The opening statements (in Adobe Acrobat format) of Mr. Alan McCollough, President and COO, Circuit City Stores, Mr. Joe Collins, Chairman and CEO, Time Warner Cable and Mr. Brian Lamb, Chairman and CEO, C-SPAN are also available..

DTV - WKOW On-the-Air With Combined Full Power NTSC and Lower Adjacent DTV Antenna (July 8)
WKOW and COMARK Communications claimed another "first" in DTV broadcasting - full power N-minus-one NTSC and DTV transmitters combined into a single antenna. The Madison Wisconsin station is now on the air with 2,500 kW ERP (peak) NTSC on channel 27 and 172 kW ERP (average) DTV on channel 26. The two channels are combined in a Dielectric Communications combiner and sent through one transmission line to a dual channel Dielectric UHF antenna. Terry Kelly, Executive Vice President of WKOW owner Shockley Communications said that even though the combiner is a prototype device, "it could have a lot of impact." He commented "From our first digital signal tests, there appears to be minimal interference with (channel) 27 (NTSC). We have to do some careful electronic testing, but we are very encouraged by what we are seeing."

COMARK supplied the analog and digital transmitters used at WKOW and worked with Shockley to implement the dual channel system. More information is available in a COMARK News Release.

SATELLITE - Third Hughes HS 601 Satellite Experiences "Anomaly" (July 8)
Engineers at Hughes Space and Communications Company are investigating the third HS-601 anomaly in less than two months. It started with Galaxy 4, which lost its main and back-up spacecraft control processors in late May. A few weeks later, Galaxy 7 lost a spacecraft control processor (SCP), but was able to continue operating on a backup SCP. On July 4, the main spacecraft control processor in DIRECTVTM, Inc.'s DBS-1 satellite failed. Fortunately, control automatically switched to the spare SCP with no loss of service to DIRECTVTM's more than 3.7 million subscribers.

A DIRECTVTM News Release said that in the event the back-up SCP failed, the affected programming services would be immediately switched to the DBS-2 and DBS-3 satellites. These satellites are co-located with DBS-1 at 101 degrees West Longitude. It also stated "...DIRECTV continues to actively pursue other satellite back-up and fleet expansion strategies consistent with its long-term business plans."

DTV - Harris Corp. Survey: Consumers Want Local HDTV; Will Trade Channels for Better Pictures (July 7)
Harris Corporation commissioned a independent survey of 700 consumers representative of the U.S. population. It showed over 90 percent felt cable providers should carry local stations' HDTV programming. This, perhaps, isn't surprising. However, when told this might result in the loss of some of their present cable channels, more than half of the respondents said they would be willing to give up of those channels to receive HDTV programming. According to the survey, 78 percent of the respondents said they watch 10 or fewer channels per week. Bruce M. Allan, vice president and general manager of Harris' Broadcast Division commented "These finding contradict the popular assumption that today's television viewers are only interested in receiving more channels. They show that consumers are willing to give up quantity in exchange for improved quality."

More information on the survey, including some of the survey results, is available in the Harris News Flash.

DIGITAL TELEVISION STATION ACTIONS - See ac980708.txt for more information
All listings are for a new digital TV station unless otherwise indicated

DIGITAL TELEVISION STATION APPLICATIONS - See ap980710.txt for more information
All listings are for a new digital TV station unless otherwise indicated

DIGITAL TELEVISION STATION APPLICATIONS - See ap980708.txt for more information
All listings are for a new digital TV station unless otherwise indicated

DIGITAL TELEVISION STATION APPLICATIONS - See ap980707.txt for more information
All listings are for a new digital TV station unless otherwise indicated

OTHER Items of Interest

July 6, 1998 - Issue 123 Final Edition

FCC Clarifies Rules Regarding the Arecibo Radio Astronomy Observatory Coordination Zone (July 6)
The FCC, in Memorandum Opinion and Order FCC 98-140 adopted June 29 and released Thursday, did not change the rules it had adopted in the Report and Order establishing the Arecibo Radio Astronomy Observatory Coordination Zone. See the October 20, 1997 RF Current for more information on these rules. Puerto Rico Telephone Company (PRTC) filed a petition for reconsideration of the rules. While it did not make any significant change to the earlier rules, the Commission did clarify the rules. In one case, the Memorandum O&O said "we are clarifying that involuntary time-sharing of frequencies between the Observatory and licensed services will not be mandated." The Commission noted, however, that "This clarification does not prohibit voluntary time-sharing arrangements between the Observatory and a service provider." The MO&O also added language omitted from the amended Part 97 rules "specifying that a licensee is required to make reasonable efforts to resolve or mitigate any potential interference problems with the Observatory and that a licensee must notify the Observatory of new or modified facilities at least 20 days in advance of planned operation." Full details, including the revised rules, are available in Memorandum Opinion and Order FCC 98-140.

FCC Issues NPRM for On-Line Assignment and Change of Radio-TV Call Signs (June 30)
The FCC is proposing to allow broadcast licensees and permittees to instantly reserve call signs using a system accessed through the FCC's Web Site. Recognizing that an all electronic system could be inconvenient for some licensees and permittees, the Commission asked for comments on whether its use chould be mandatory or permissive and whether, if it is manditory, if its use should be phased-in. The FCC NewsREPORT MM 98-10 described how the system would work:
Under the proposed system, broadcasters who want to change station call signs, as well as initial license applicants who have received a construction permit, would be able to electronically access the FCC's call sign data base, verify that a desired call sign is available, and instantly reserve it. The computer system would trigger error messages for any mistakes or omissions by the applicant, thereby insuring that the request is ready for immediate reservation. If a fee is required, as in the case of call sign changes for existing commercial radio and tv stations, the electronic system would automatically provide the applicant with the proper form with the correct amount to be submitted already written in.
Call sign applications would continue to be assigned on a "first-come, first served" basis. Unless the licensee holds a grandfathered three-letter call sign, the call requested consist of four letters (plus the LP, FM or TV suffix, if used). In additions, call signs must comply with the existing rules requiring that they start with the letter "K" if west of the Mississippi River and "W" if east of it. The FCC NPRM said that the system wouldn't catch these geographic errors, but it proposes to rescind any call assignment violating the rule. Comments are requested on this.

LPTV permittees would be able to request four-letter calls (with the -LP suffix) without certifying that the station has been constructed, that physical construction is underway at the transmitter site, or that a firm equipment order has been placed, as now required. The NPRM also proposes to eliminate all restrictions preventing licensees or permittees in the same service from agreeing to exchanges or transfers of call signs.

To prevent unauthorized persons from attempting to change a station's call sign, the FCC proposes to send out postcards to both the affected licensee and to the person making the call sign change request on its behalf. If the licensee receives a postcard for a call sign change it did not authorize, the licensee should immediately notify the Commission that the request is unauthorized. If the call sign is a secondary call sign (the same as an existing call sign with a suffix added), the primary call sign licensee or permittee will also be notified.

Complete details on how the proposed system would operate are in the Notice of Proposed Rule Making. FCC 98-130 is available in ASCII text, WordPerfect and Acrobat (PDF) formats. For a short summary, see the NewsREPORT MM 98-10

SPACE - More Spacecraft Problems - Contact Lost With NASA/ESA SOHO (June 30)
NASA reported that engineers are continuing efforts to reestablish contact with the NASA/European Space Agency (ESA) Solar and Heliospheric Observatory (SOHO) spacecraft. Contact was lost June 24th during maintenance operations. A NASA/SOHO News Release said "Engineers are concentrating on gaining a full understanding of the events which led to the loss of signal, information which might help them devise procedures which may recover contact with SOHO. Commands are being sent to SOHO about once per minute through the DSNŐs 34-meter antennas instructing the spacecraft to activate its transmitters." The report said that while it appears the spacecraft is spinning in such a way that its solar panels do not receive adequate sunlight, the last data received indicates the panels may be exposed to an increasing amount of sunlight each days as the spacecraft orbits the sun. If this is the case, in a few weeks enough sunlight might be hitting the solar panels to charge the spacecraft's batteries.

Additional information is available on the SOHO Home Page and in a June 30 update.

DIGITAL TELEVISION STATION ACTIONS - See ac980630.txt for more information
All listings are for a new digital TV station unless otherwise indicated

OTHER Items of Interest

Other Issues Available:

1998

1997

1995 and 1996

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Last modified August 4, 1998 by Doug Lung dlung@transmitter.com
Copyright © 1998 H. Douglas Lung