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CHAPTER 24, Inc., MADISON, WI |
Edited by: Mark Croom Electronic Version: Leonard Charles Electronically Distributed by Chris Cain Contributors this month: Tom Weeden Chris Cain Paul Stoffel Neal McLain Tom Smith Leonard Charles Articles Welcome!! Send correspondence to: Chapter 24 Newsletter 34 Rustic Parkway Madison, WI 53713-4700 or call (608) 271-1025 (home) or (608) 221-1979 (work) MEETING ANNOUNCEMENT Tuesday, August 22, 1995 At Alt ‘N Bach’s Towne Tap 2602 Whalen Lane, next to American TV (West) Dutch Treat Dinner: 5:30PM Meeting/Program: 7:00PM Program: FACILITY SECURITY CONSIDERATIONS This month’s program will feature a representative of ADT Security services discussing some of the issues we need to consider as we evaluate our security precautions in the broadcast facility. We’ll look at building security, and will also consider tower site, satellite dish, and guy cage issues. Many stations have little if any plan for keeping facilities secure. Please come on out and let’s learn together how we can better protect the assets of our stations. Visitors and Guests are welcome at all SBE meetings. UPCOMING MEETINGS Tentative Program Subjects Wed, Sep 20, 1995 WTDY\WMGN\WJJO facility tour Thu, Oct 19, 1995 WMTV Remodeled Master Control Wed, Nov 15, 1995 Broadcasters Clinic/EAS Teleconference Tue, Dec 19, 1995 Candelabra Project facility tour Wed, Jan 17, 1996 Digital Radio Networks Thu, Feb 22, 1996 JVC Digital "S" or Panasonic Digital Tue, Mar 19, 1996 WP&L Center Tour (or Milwaukee area station tour) Wed, Apr 24, 1996 Chapter Elections and annual NAB review Thu, May 23, 1996 TCI Cable TV Technology Tue, Jun 18, 1996 Related technology; Internet/software support Sat, Jul 27, 1996 3rd annual Chapter 24 Family Picnic CHAPTER 24 OFFICERS: CHAIRMAN: Paul Stoffel (WI Public TV) W - 608-263-2175 H - 608-241-4621 F - 608-263-9763 STOFFEL@MAIL.ADMIN.WISC.EDU VICE CHAIRMAN: Fred Sperry (ECB-TOC) W - 608-264-9698 H - 608-833-6074 FRED.SPERRY@MAIL.ADMIN.WISC.EDU SECRETARY: Neal McLain (CTI) W - 608-831-4636 NMCLAIN@MACC.WISC.EDU TREASURER: Stan Scharch (WISC TV) W - 271-4321 H - 831-1168 CHAPTER 24 COMMITTEE APPOINTEES: Membership - Leonard Charles Sustaining Membership - Fred Sperry Strategic Plan - Denny Behr Newsletter - Mark Croom Program Committee: Mark Croom 271-1025 mcroom@aol.com Denise Maney 277-8001 Kerry Maki 833-0047 Steve Zimmerman 274-1234 Special Events - Kevin Ruppert Certification and Education: Jim Hermanson 836-8340 Tim Trendt (UW-Platteville) Frequency Coordination: Tom Smith 608-263-2174 (work) SMITHT@VILAS.UWEX.EDU SBE National Board Member & Chapter Liaison: Leonard Charles W - 271-4321 FAX - 271-1709 LCHARLES@WISCTV.COM JULY BUSINESS MEETING MINUTES Chapter 24 of the Society of Broadcast Engineers met on Thursday, July 22, 1995, at the Greenfield Park Shelter in Fitchburg. There were 10 persons in attendance, 5 of whom were certified. The meeting was chaired by Chapter 24 Chairman Paul Stoffel. Call to order: 1:50 pm. The minutes of the previous meeting were approved as published in the July Newsletter. An informal business meeting included announcements of awards, plans for the November meeting and teleconference, and a status report on the construction of the new candelabra tower. The business meeting was adjourned at 2:00 pm. The program featured the Chapter's annual picnic. LOCAL LEGALS By Tom Smith Berlin, Deforest, Marksman and Wautoma, WI. By request of DeForest Broadcasting Company, the FCC has allocated FM channel 226A to DeForest. The site is restricted to the coordinates of 43-16-08 and 89-20-09 (1.2 miles N of Deforest). They also modified the license of WISS- FM of Berlin to channel 284A from channel 272A. Also Modified was the Application of Wautoma Radio for Wautoma was modified from 226A to 272A. The counterproposal from Markesan Broadcasting Company for 284A for Markesan was dismissed. The filing window for applications for FM channel 226A for DeForest opens on Sept. 5 and closes on Oct. 6, 1995. Adopted July 12, 1995 and released July 19. Published in the FEDERAL REGISTER on July 25,1995 on page 37,984. From the FEDERAL REGISTER. AMATEUR RADIO NEWS by Tom Weeden, WJ9H Amateur radio went along for the ride as the Great Circus Train made its annual trip from Baraboo to Milwaukee. Amateur operators provided logistic support for the train on both 2 meters and via cellular phone. Hams also operated a mobile special event station, contacting more than 50 stations in 30 states and one Canadian province on 20 and 40 meters. The Circus Train, carrying more than 60 restored antique circus wagons from Baraboo's Circus World Museum to Milwaukee's Great Circus Parade, made the trip on July 10 and 11. The American Radio Relay League (ARRL) has filed comments on FCC WT Docket 95-57, a notice of proposed rule making on five items of importance to amateur radio operators. The FCC's proposed rules are: > Creating a lifetime amateur radio license (ARRL supports) > Changing the minimum number of members in a club for the purpose of applying for a club station license from two to four (ARRL supports) > Creating the position of "session manager" for volunteer examiner test sessions (ARRL opposes) > Making special one-by-one call signs (such as "W9A") available for certain special-event stations (ARRL supports) > Allowing station identification by portable stations to be made with a portable indicator either before or after the station call sign (ARRL supports) The FCC's Wireless Telecommunications Bureau has produced a new "fact sheet" on the Amateur Radio Service. The two-pager describes ham radio to the general public and the FCC's regulation of the service. One excerpt states, "The FCC rules are designed to promote the amateur service in the United States to provide emergency communications, advance radio technology, improve operator skills, expand the numbers of trained operators, technicians, and electronic experts, and enhance international goodwill." The amateur fact sheet is PR-5000, Number 210. (from August 1995 "Badger State Smoke Signals" and "QST" magazines) CHAIRMAN'S NOTES Thanks goes out to Denise Maney, Dan Maney and chef Chuck for putting together another wonderful summer picnic in the park. Chapter 24 garnered four National SBE Awards for 1994. The awards are to be presented at the National Convention in New Orleans on September 9 during the SBE Banquet and Reception. Congratulations to the following: Best SBE Chapter Newsletter: Chapter 24 Newsletter, Editors: Paul Stoffel and Mark Croom Best Technical Article or Program by a SBE Member: "Fiber Optic OSP" by Neal McLain: 7-parts Best SBE Chapter Frequency Coordination Effort: Tom Smith, Chapter 24 Frequency Coordinator Best Article, Paper or Program by a SBE Student Member: "Madison Marathon" by James W. Stellpflug: July 1994 Congratulations to all Chapter 24 members. Our chapter's success is truly a result of a group effort! Planning continues for the production of the national Emergency Alert System (EAS) Teleconference to be uplinked on November 15 at 8:00 pm central time from the Broadcasters Clinic's site in Madison. The satellite coordinates are Telstar 401, full transponder 6 (11,855 MHz downlink). For educational purposes, PBS Satellite Services is donating the satellite time. WISC-TV is donating their uplink truck. As part of the program, the FCC's Frank Lucia, author of EAS Rules, Part 11, will give a presentation, as will Leonard Charles, SBE EAS Committee Chairman and Gary Timm, Wisconsin State Emergency Communications Chairman. SBE members are invited to attend a short regional SBE meeting at 7:30 pm, with the teleconference to follow at 8:00. Volunteers are needed for camera operators, lighting, floor directing and setup and strike. Call Paul Stoffel at 263-2175 for more information. Take note that the Holiday Inn Southeast in Madison is now called a Ramada Inn, though the phone number is still the same, 222-9121. Remember to mail in your ballot for the annual elections of SBE National Officers and members of the Board of Directors. Have you tried the new FCC home page (http://www.fcc.gov) for FCC online resources? Or the SBE National's home page (http://www.sbe.org)? EAS UPDATE by Leonard Charles The Industry still awaits the release of the FCC's response to the EAS petitions to reconsider. Hopefully, after June's program about EAS, you have been subconsciously forming that Local EAS Plan. We will have to meet soon to begin putting a plan to paper. Remember, it won't get done if WE don't do it. If you have yet to read the new Part 11 EAS rules, you will find a copy on our Chapter 24 BBS. In a recent phone conversation with an FCC staff member, the length of the EBS test for those stations that have optioned for the shortened encoder tone came up. The FCC has said they will release a revised EBS test script soon which will allow the shortened tone, plus script, to fit into a 30 second event. (see later article) The staffer also commented on the EAS protocol patent infringement situation. At that time, the FCC did not anticipate getting involved in the action. They feel that since it is the manufacturer's that have been contacted by the Kansas company, it is their problem to deal with. The staffer also said that there is a possibility that the NWS may look into it. Report CI 95-11 COMPLIANCE AND INFO ACTION August 4, 1995 COMMISSION RELEASES REVISED WEEKLY TEST SCRIPT FOR EMERGENCY BROADCAST/ALERT SYSTEM TESTS The Commission adopted a Report and Order on November 10, 1994, that substantially revised the Emergency Broadcast system (EBS), and renamed it the Emergency Alert System (EAS). Effective July 1, 1995, broadcasters have the option of transmitting a two-tone attention signal that only lasts 8 seconds. To perform a weekly test that is 30 seconds long using the 8 second signal, please follow this procedure. 1. Discontinue normal programming 2. Broadcast this announcement: ------------------------------------------------------------ "The following is a test of the Emergency Broadcast System" ------------------------------------------------------------ 3. Transmit the attention signal Broadcast the attention signal for 8 seconds as specified in Section 11.32 of the new EAS rules. 47 C.F.R. P11.32 4. Broadcast this announcement: ------------------------------------------------------------ "This station is testing its Emergency Broadcast System equipment. The EBS will soon be replaced with the Emergency Alert System. The EAS will provide timely emergency warnings. This station serves the (insert EBS/EAS Local Area name) area. This concludes this Emergency Broadcast System test." ------------------------------------------------------------ 5. Resume regular programming If a longer test is desired, lengthen either the transmission time of the attention signal and/or use the script below in place of the script in step 4. "This station is testing its Emergency Broadcast System equipment. The EBS will soon be replaced with the Emergency Alert System. The EAS will provide timely emergency warnings. If this had been an actual emergency, such as (insert the types of emergencies likely to occur in the station's coverage area), the attention signal you just heard would have been followed by an official warning or alert information. This station serves the (insert EBS/EAS Local Area name) area. This concludes this Emergency Broadcast System test." We encourage stations to broadcast public service announcements to inform the public about the new EAS. Contact: EAS Staff in the FCC Compliance and Information Bureau at (202) 418-1220. - FCC - CANDELABRA FACTOIDS Tower Built by: Kline Towers of Columbia South Carolina. Tower Erection by Tower King of Marietta Georgia. Tower Owned by: State Of Wisconsin State Supervision by University Research Park Facilities Corporation (URPFC). Television Antennas built by Dielectric Communications of Raymond Maine. Tower Tenants: WMSN-TV, WHA-TV, WISC-TV, WERN-FM, WIBA-FM, City of Madison, County of Dane, Motorola, Educational Communications Board, Sky Cable Sections: 30 feet log each / 45 Sections 12 feet wide face Heaviest section weighs 11.6 tons at the 430' level. Lightest section weighs 5.7 tons at the 1150' level. Initial 90' base section that was set by Crane weighed in at 30.1 tons or 60,200 pounds. Guy Cable:24 reels were shipped weighing a total of 349,000 pounds. Diameter range from 1 1/4" to 2 3/4". Breaking strength of the 1 1/4" guy line is 96 tons. Breaking Strength of the 2 3/4" guy line is 452 tons. Guy run #5 (2 3/4") weighs 28,600 lbs per reel. Each 2 3/4" guy cable has 151 wires and a capacity of 16 pounds per foot. Tower Legs: Solid Steel. Diameter ranges from 4 7/8" to 7 1/4". Height to the Top of the Vertical Shaft is 1300'. Add the Starmount, the WHA-TV Antenna (58') and the WISC-TV antenna (39') and you have a total height of 1423' to the top of the Beacon and lightning rods. Information Compiled by Chris Cain/ WISC-TV. Thanks to Ed Bearden of Kline Towers for data. THE WISC-TV FACILITIES AT THE CANDELABRA SITE Many new technologies and use of redundant systems are at the core of the new WISC-TV transmission facility located on the State owned tower at 8559 Mineral Point Road in Madison. Fiber Optics: Delivery and return of the Video, Audio and telemetry is accomplished by using a Digital Fiber Optics System. With the ability of running at a maximum data rate of 1.5 GigaBits per second, this will insure that WISC-TV will be able to deliver or return multiple video/ audio signals and new video delivery systems that the future might provide. One quarter of a mile of the system is Fiber Optics that WISC-TV owns and the remainder of the run has been leased through Mid Plains Telephone of Middleton. Redundancy: The WISC-TV Fiber Optics system is totally backed up with a 23 Gigahertz (GHZ) Link. (Studio to Transmitter Link/ STL and Transmitter to Studio Link/ TSL). Transmitter: The new WISC-TV transmitter is 100% Solid State. It can deliver up to 33 KW of Video output power and 4.99 KW of Aural (Audio) power. Redundancy: The WISC-TV transmitter has power output modules that provide for the failure of several units and still maintain 100% output power. One entire cabinet can fail and WISC-TV will only loose 1/3 of the output power. Antenna: The new WISC-TV antenna is specifically designed and optimized for coverage of a combination of city and country, (City Grade, Grade A and Grade B contours.) Older VHF antennas delivered the signal in a horizontal plane only. The new WISC-TV antenna delivers the signal in a "Circular" plane. This will improve reception for everyone, no matter how close or far away they live from the tower. In addition the new WISC antenna has been designed to provide a high level of power to the ground immediately under the tower. In older systems there where areas that were called "Umbrella effect" areas, wherein viewers that lived close to the tower site had difficulty receiving a signal. Redundancy: The new WISC-TV Antenna has been designed to receive a dual input power feed from the transmitter. If part of the Antenna should fail, the other section will continue to operate until repairs can be made. Overall Redundancy: - The new WISC-TV transmission site features a 125 Kilowatt/ Diesel powered generator. This will allow transmissions, at 100% power, to continue for several days if normal power is lost. - The original WISC-TV transmission plant that was built in 1956 will continue to function as a backup facility. The site can be brought into service in minutes if maintenance is required on any part of the new Candelabra site facility. - Modifications are planned for the near future that will reduce the height of the original WISC-TV tower from 1107 feet to 303 feet 10 inches. Transmissions from this facility will adequately cover our City Grade and Grade A contours. Chris Cain Chief Engineer ENGINEERS ATTEND WBA WORKSHOP part 1 by Paul Stoffel SBE Chapter 24 Chairman The seventh annual Wisconsin Broadcasters Association (WBA) Summer Engineering Workshop was held on July 19 in La Crosse. Over 50 engineers from around the state heard presentations on digital video and audio servers, ISDN, LAN, the FCC's EAS and station finance. While welcoming workshop attendees, John Laabs, WBA President, took the opportunity to mention the WBA's commitment to the annual Broadcasters Clinic. Laabs said, "The WBA Board of Directors endorsed keeping the Clinic alive." Earlier this year, after the University of Wisconsin announced it could no longer support the Clinic, the WBA was approached about hosting the yearly Clinic. Don Borchert will continue to program the Clinic for another two years. Plans beyond 1995 have not been finalized. The 41st annual Broadcasters Clinic 1995 will be held in Madison on November 14-15-16. The first presentation of the workshop, Digital Audio Servers, was given by Ted Lance from Broadcast Electronics. "Why digital audio?" asked Lance, because, it offers "great sound quality, no generation loss, random and simultaneous access to audio files, consistent on-air quality, expandability, and back-up options." Applications would include: live assist operation (to replace cart machines), and satellite and program automation. Total station integration would increase efficiency and profitability. The most common sample rate is 32kHz. (Other sample rates available are 48, 44.1, 26 and 22K.) A sample rate of 32K gives a bandwidth of 16K. Many factors, such as delivery bandwidth and available hard drive storage, affect the user's choice of sample rate. Lance also talked about compression standards and about being aware of the effects of cascading compression devices. All that digital audio data is best handled by an off-buss technology where the digital audio is processed separate from the computer bus. This technology also offers easier compatibility. Redundancy of hard drives is important. Mark Ostland, BTS Director of Corporate Products, talked about video servers. Ostland asked two difficult questions, "Today's chief engineer is faced with upgrading and purchasing equipment with so many choices and new technologies. Do you stay with the 'tried and true', or do you try something new? It is becoming more difficult to 'plug and play.' Will this be true with the next system you buy?" The video server's advantages include improved reliability, instant access, flexibility and greater operational efficiencies. Ostland talked about server requirements: scalability, modularity, compression quality, redundancy, compatibility, random access, simultaneous users, editing, defragmentation, undo, computer interfacing, and cost effective. And, is it future-proof? When purchasing a video server, Ostland said, "Focus on the capabilities you want from a particular server," such as the number of channels, VTR emulations, raid supported, computer interfacing, and "are you required to purchase all applications from one manufacturer?" Daryle Brown, Ameritech, and Lynn Distler, Comrex, together talked about ISDN (integrated services digital network). Brown said, "Most any RBOC (regional bell operating company) now have ISDN, so it is very available." ISDN offers a common digital network which facilitates world-wide communications. Also, end- to-end digital connectivity ensures high quality transmissions and a standard interface increases connectivity options. Simultaneous video, graphics, text and audio connectivity provides users with new communications options. In radio broadcasting, ISDN provides an excellent alternative to using multiple POTS (analog plain old telephone service) lines or broadcast audio circuits. Other uses for ISDN are remote access to office computer or LAN, videoconferencing and Internet access. For broadcasters, Distler said, "High quality audio can be carried on a dial-up service, including cueback." For what equipment is needed, Distler added, "A terminal adapter (TA) and a digital codec (enCOder/DECoder)." The TA does the answering, dialing, channel allocating, diagnostics and BONDING (bandwidth on demand interworking group). The CODEC takes analog audio in/out, performs analog-to-digital and digital-to-analog conversion, applies or decodes a data reduction algorithm, and provides a standard communications interface to the TA. Operationally, Distler said you should consider a CODEC's degree of data reduction, delay inherent in the algorithm, compatibility and cost. Broadcast applications are remote broadcasts, studio- to-studio links, voice-overs, STL backup, out-of-studio talent and sports networks. Distler offered attendees a booklet titled, ISDN FOR BROADCASTERS from Comrex. Neale Koenig presented "LANS and Hardwired Networks." Neale said the purpose of a network is to share unprocessed data, other file information, and programs. The types of networks include client/server (LAN), peer-to-peer and wide area/switched. With today's LAN, the server deals with files and the end user computer (client) does the processing of the data. In the peer- to-peer set-up, any computer can be a server or client. All information on the network is fed via packets between the server and client. The client's PC has an address on the LAN for sending and receiving. Data speed must be addressed when designing network architecture. The network configuration types are circular, star or bus with packet transmission types being switched, relayed or broadcast. The packets are sent over a medium of fiber, coax or twisted pair. The network administrator must deal with transmission interference, noise (real or perceived) and security. Koenig feels networks of the future will be peer-to-peer, digital & switched, and connected using fiber for speed. Next month, a not-so technical look at Station Networking: Broadcast Financial Realities and Organizational People Realities. CLASSIFIEDS Wisconsin Public Television (WPT) is looking to fill the following positions: WPT has an immediate need for a part-time Master Control Operator within the Telecommunication Operations Center. Contact Bonnie Briggs at (608)264-9623 for further information. WPT is also looking for a part-time Engineer to work overnights at the Telecommunication Operations Center beginning in January. Please contact Dennis Behr at (608)264-9746 for further information. THE LIAISON LETTER by Leonard Charles You should have received this year's National SBE Ballot. Because of the early Fall Conference/Expo, it is important that you return your ballot quickly that it may be counted in time for the winners announcement at the Conference. By now you must have heard or read that Chapter 24 did very well again in this year's National Chapter Awards competition. As National Awards Chairman, my role in the process was supervisory, with the only chance at casting a ballot to break a tie. My ballot was never necessary as all the winners were decisive by committee member voting. Therefore, no one will ever know which way I would have voted. Congratulations to all the victors of Chapter 24. Hope to see some of you in New Orleans to accept your awards! HOUSE PASSES TELECOMMUNICATIONS BILL By Tom Smith In the same week as mega-mergers between Disney, ABC, Westinghouse, CBS and NBC occurred, as they positioned themselves for the future, the House of Representatives passed its version of telecommunication reform. The final House bill differs little from the original proposals that came from committee. The biggest changes were the acceptance of two amendments from the ranking minority member of the House Telecommunication Subcommittee, Ed Markey of Massachusetts. The amendments set a limit for TV station ownership of a 35% reach of the national audience and would require the so called V-chip in new TV's. The bill must now go to a House-Senate conference committee to iron out the differences between the two versions. Both bills would allow for unlimited ownership of radio stations, limit TV ownership to a 35% reach of the national audience with no limit on the number of stations, and require the V-chip in new TV's. The House bill would allow for doupoly's in TV, but the Senate's would continue the one-to-a-market-rule, with existing local marketing agreements (LMA's) grandfathered. The House would repeal the crossownership bans on radio-TV stations and would allow for broadcast crossownership with one other media outlet such as a newspaper, wireless cable(MMDS) and telephone services. The House would retain the TV-cable crossownership ban. The Senate would repeal the TV-cable crossownership ban, but would keep the other crossownership bans. Both houses would make license renewal easier and lessen license challenges. The House would make both radio and TV license terms for 7 years and the Senate would make them for 10 years. Both bills would give TV stations a second channel for digital TV with the Senate requiring a fee if the digital channel is used for subscription services. Both bills would end cable rate regulation and would allow the cable industry into the phone business and the telephone business into cable. The regional Bell companies would be allowed to offer long distance service and the long distance carriers (AT&T, MCI, Sprint) into local phone service markets. President Clinton said he would like to sign a telecommunication reform bill, but he would veto the bill if it would allow for too much media concentration. The bill passed in the House by a 305 to 117 margin and the Senate passed the bill by an 81 to 18 margin. That would give both houses over a 2/3 margin for a veto override. Compiled from Broadcasting and Cable and The Wisconsin State Journal. FCC RULEMAKINGS By Tom Smith Notice of Proposed Rulemaking. Broadcast Services; Network/Affiliate Programming Rules MM Docket No. 95-92; FCC 95-254 The FCC is seeking comment concerning the updating of the rules that govern the relations between TV stations and the networks they are affiliated with. The current rules were originally written in the late 1940's when there were few TV stations and cable did not exist. The FCC is asking, that with the increased competition, should these rules be updated. There are five rules that the FCC is seeking comment on. Three of these rules concern the relation between the network and the affiliated station. The fourth rule concerns networks, their affiliates, and other stations in the affiliates market. The last rule concerns the owning of more then one broadcast network. The three rules that concern a network and its affiliates are the following: 1) The first rule is the Right to Reject rule. This rule allows a station to reject a networks programming for programming that they may consider not in the public interest or of greater local or national importance The FCC wishes to clarify this rule to state that a station does not have the right to reject a program on the basis of financial considerations. 2) The second rule in this group, the Time Option Rule, concerns giving the network an option on the use of blocks of time on a station. These is currently prohibited, but the FCC wishes to repeal this rule. The repeal of this rule would make it possible for a network to request a block of time to be set aside should they wish to use it, but the network would be free to return the time to the station when they have no need for it. 3) The third rule of this group, the Exclusive Affiliation Rule, prohibits a network from preventing an affiliated station from taking programs from another network. The FCC is proposing to repeal this in larger markets. The rule concerning affiliated stations, their networks and other stations in their market is the Network Territorial Exclusivity Rule. This rule prohibits a station from making an agreement with a network that would prevent the network from offering a program that the affiliate rejected to another station in the same community of license and from preventing the network from offering any programming to a station in another community. The FCC proposes to repeal the first part and would like information on increasing the area of exclusivity beyond the community of license to some larger portion of a stations coverage area. The last rule, the Dual Network Rule, prohibits an over the air broadcast network from serving a community with more then one network. This rule, in effect, limits one company to only one broadcast network. The FCC would like to know if this rule should be changed. The Commission notes that there has been an increase of stations since this rule was adopted and of the possibilities of multiple channels with digital TV. Comments are due on August 29, 1995 with reply comments due on September 27, 1995. This notice was released on June 15, 1995 and published in the FEDERAL REGISTER on July 7,1995 on pages 35,369 through 35,372. From the FEDERAL REGISTER GEOSTATIONARY ORBITS PART 1 - PHYSICAL PRINCIPLES by Neal McLain Communication Technologies, Inc. (Editors note: Parts of Neal’s article that specifically referred to graphics, were omitted from this electronic version of the newsletter. If interested, contact Neal McLain or hard copy newsletter editor Mark Croom for a hard copy complete with the graphics. Their addresses appear elsewhere in this newsletter) This is the first of a series of articles about geostationary orbits; i.e., the orbits occupied by communications satellites which remain at fixed points in the sky. In this series, we will cover some basic physical principles, orbital geometry, antenna mounts, and pointing angles. This first article deals with basic physical principles: time, the geographic coordinate system, and Kepler's Laws. TIME The earth moves through space in two ways: The earth rotates about its polar axis. The time interval required for the earth to rotate exactly once is called one sidereal (sigh-DEAR-e-al) day. The earth revolves round the sun once per year. The rotation of the earth about its axis causes the sun to appear to rise in the east and set in the west. At one critical instant during the sun's daily course across the sky, it reaches its maximum height; this instant is called solar noon. The time interval between two successive solar noons is called one solar day. During one solar day, the earth rotates slightly more than once about its polar axis. Thus, one solar day is slightly longer (by about four minutes) than one sidereal day. A solar day is subdivided into solar hours, solar minutes, and solar seconds: Solar day = 24 solar hours. Solar hour = 60 solar minutes. Solar minute = 60 solar seconds. Measured in solar units: Sidereal day = 23 hours 56 minutes 4.091 seconds. GEOGRAPHIC COORDINATES Any point on the earth's surface can be specified by two geographic coordinates, called latitude and longitude. Latitude and longitude are measured in arc degrees, or simply degrees. One arc degree equals 1/360th of the circumference of a circle. Latitude is measured in arc degrees north or south of the equator. The equator itself is defined to be 0° latitude; the North Pole is at 90° north latitude, and the South Pole is at 90° south latitude. Lines of equal latitude are called parallels. Longitude is measured in arc degrees east or west of the Prime Meridian at Greenwich, England. The Prime Meridian itself is defined to be 0 longitude; points to the west of the Prime Meridian are called west longitude, and points to the east are called east longitude. Lines of equal longitude are called meridians. The intersection of the 28th parallel north and the 81st meridian west is represented as follows: 28 North Latitude 81 West Longitude These are the geographic coordinates for a point near Orlando, Florida. Divisions within an arc degree can be specified in either of two ways: - By decimal notation, such as: 28.47 North Latitude 81.61 West Longitude - By arc minutes and arc seconds: One arc minute (') = 1/60 arc degree One arc Second (") = 1/60 arc minute Using this notation, a point near Orlando might be represented: 28 43' 56" North Latitude 81 21' 44" West Longitude SATELLITES Satellite is the name given to any body which revolves around the earth in the space above the earth's atmosphere. Satellites may be natural or artificial: The earth has one natural satellite: the moon. The earth's first artificial satellite, Sputnik 1, was launched by the USSR in 1957. In the years since, hundreds of other artificial satellites have been launched. Satellites move about the earth in paths called orbits. From the study of astronomy, we know three important facts about orbits. These facts, known as Kepler's Law's, were first set down in the early 1600's by the German mathematician and astronomer Johannes Kepler. Kepler defined these laws to describe the motion of the planets about the sun; however, these laws apply equally to the motion of satellites about the earth. KEPLER'S FIRST LAW Each planet moves in an ellipse with the sun at one focus. More generally, this law can be stated as follows: every orbit is an ellipse with the primary at one focus. We know from the study of geometry that every ellipse has two foci (that's the plural of "focus"). In the case of an artificial satellite moving about the earth, the earth is the primary, and the center of the earth is one focus. The location of the other focus (the empty focus) depends on the shape, or eccentricity, of the orbit: If the orbit is long and narrow (high eccentricity), the empty focus is a point out in space. If the orbit is more nearly circular (low eccentricity), the empty focus is a point inside the earth. If the orbit is a circle (zero eccentricity), both foci merge to a single point at the center of the earth. The Space Shuttle is an example of an artificial satellite with low eccentricity: when watching the NASA SELECT channel, one frequently hears Houston Ground Control say things like "an orbit 360 miles by 430 miles." KEPLER'S SECOND LAW The radius vector from the sun to a planet sweeps out equal areas in equal times. More generally, this law can be stated as follows: the radius vector from the primary to a satellite sweeps out equal areas in equal times. Stated non-mathematically, this law simply says: the farther a satellite is from its primary, the slower it moves. Again, the shape of the orbit is important: - If the orbit is long and narrow (high eccentricity), satellite velocity varies over a wide range. - If the orbit is more nearly circular (low eccentricity), satellite velocity is more nearly constant. - If the orbit is a circle (zero eccentricity), the satellite moves at constant velocity. The highly-eccentric orbit of a comet moving around the sun illustrates this idea. When the comet is moving toward the sun, its velocity increases: it's "falling" toward the sun. At the point nearest the sun, it whips around the sun (one focus), then moves off into space again, slowing as it moves. When it reaches the point farthest from the sun, its velocity is minimum. It passes around the empty focus (simply a point in space), then begins to "fall" toward the sun again, gaining speed as it moves. KEPLER'S THIRD LAW The relationship R3/T2 is the same for all planets, where: R = average orbit radius T = orbit period. More generally, this law can be stated as follows: for any given satellite system, the relationship R3/T2 is the same for all satellites. The real significance of this law is this: there is a FIXED RELATIONSHIP between average orbit radius R and orbit period T. If we know either, we can calculate the other. We can apply this law to earth satellites. Let's start with the Moon. The moon moves in a very high orbit (R = about 383,000 km.) and has a very long orbit period (T = about 27.3 days). The moon moves so slowly that the earth rotates under it faster than the moon moves about it. From the point of view of an observer on the earth's surface, the moon appears to rise in the east and set in the west, just like the sun and the stars. If we plug R and T into the third-law equation, we can determine R3/T2 = 7.532 x 1013 Knowing this, we can now work backwards to determine R or T in other situations. Consider the space shuttle: the typical orbit height (above the earth) is around 600 Km. Adding the earth's radius (6370 Km) gives us the shuttle's orbit radius R = 6970 Km. Applying the third law equation yields T = 0.067 days, or about 1.6 hours. From the point of view of an observer on the earth's surface, the shuttle streaks across the sky every 1.6 hours. Now suppose we wish to know the orbit radius of a satellite whose period T equals one sidereal day. This is, of course, the average radius of a geosynchronous satellite. Using the third-law equation, we discover that R = 42,155 Km. Subtracting the earth's radius (6370 Km) yields the orbit height above the earth: 35,777 Km., or about 22,231 miles. Bingo. See you next month. SIDEBAR 1 WISCONSIN: CENTER OF THE NORTHERN HALF OF THE WESTERN HEMISPHERE The following geographic coordinates define the center of the northern half of the western hemisphere: 45 00' 00" North Latitude 90 00' 00" West Longitude This point falls in Marathon County, Wisconsin, near the unincorporated village of Poniatowski. A USGS benchmark marks the spot. A nearby sign reads as follows: GEOLOGICAL MARKER This spot in Section 14, in the Town of Reitbrock, Marathon County, is the exact center of the Northern Half of the Western Hemisphere. It is here that the 90th meridian of longitude bisects to 45th parallel of latitude, meaning it is exactly halfway between the North Pole and the equator, and is a quarter of the way around the earth from Greenwich, England. MARATHON COUNT PARK COMMISSION Visitors to the spot are invited to visit Gesiki's bar and general store in Poniatowski, where they can add their signatures to John Gesiki's looseleaf notebook, and buy a T-shirt attesting to their membership in "The Geological 45 x 90 Club of Poniatowski." Source: Wisconsin State Journal, May 26, 1991. SIDEBAR 2 JOHANNES KEPLER: THE SEARCH FOR "HARMONIES" For hundreds of years, up until the 16th Century, mankind had accepted the idea that the earth is the center of the universe. The Greek astronomer and mathematician Potolemy (A.D. 127-151) had published a unified theory supporting the idea, and it was not seriously challenged for the next fourteen centuries. But by the middle of the 16th Century, a new idea was beginning to take hold: that the sun is the center of the universe. The Polish monk Nicolaus Copernicus (1473-1543) had first published the idea as early as 1510; but it was only after his death that the idea began to spread. During the latter half of the 16th Century, the principal exponent of this idea was the Danish nobleman Tycho Brahe (1546- 1601). Using funds provided by his patron, King Frederik II of Denmark, Tycho built a great observatory on the island of Hveen. He called it Uraniborg, The Castle of the Heavens, and he filled it with the best astronomical instruments of the day -- many designed and built to his own specifications. Over the next 25 years, he proceeded to assemble the most precise set of astronomical observations the world had ever known. After the death of Kind Frederik, Tycho fell out of favor, and eventually moved his observatory to Prague. It was in Prague that he met the young German mathematician Johannes Kepler (1571- 1630). He took Kepler on as a student, gave him access to the astronomical tables he had compiled at Uraniborg, and assigned to him the task of calculating the orbit of Mars. Just before his death, he formally presented his tables to Kepler. Kepler believed fervently in the idea of divine creation, and he was convinced that God had created a universe based on mathematical "harmonies". It seemed obvious to him that these harmonies would turn to out be elegantly simple, if only he could discover them. And so it was that Kepler spent the last thirty years of his life searching for harmonies. He studied Tycho's tables, adding many of his own observations, all the while pursuing his old problem: the mathematical definition of the orbits of the planets. He tried and rejected many theories: concentric circles based on regular geometrical figures, concentric bowls based on regular geometrical solids, and an endless variety of numerical series. It was out of this work that Kepler's three great laws emerged. When he finally determined the orbit of Mars, he had discovered what turned out to be the First and Second Laws, which he published in 1609. It took him another nine years to discover the mathematical connection between orbit radius and orbit period; this became the Third Law, published in 1618. Kepler was never able to explain the theoretical basis for the laws; indeed, there is no evidence that he ever tried. He derived the laws solely from empirical observation. But in his own mind, he had proven his thesis: God had indeed created a universe based on simple mathematical harmonies. It would be another 70 years before Kepler's laws were finally proven mathematically. This was the work of the English mathematician Isaac Newton (1642-1727), who developed the fundamental theory that made the mathematical proof possible: the theory of universal gravitation. Once universal gravitation was understood, the proof of Kepler's laws followed directly. But it is Kepler who first discovered the laws that bear his name. Like all significant physical laws, Kepler's laws have stood the test of time: they are as clear and true today as they were in Kepler's day. Indeed, Kepler's Laws form the fundamental basis for the entire modern field of satellite communications. Source: PHYSICS FOR THE INQUIRING MIND by Eric M. Rogers. Princeton: Princeton University Press, 1960. CHAPTER 24 SUSTAINING MEMBERS: Our latest renewals: BTS MRC Telecommunications Skyline Communications Thanks to all our Sustaining Members: Broadcast Communications CTI Clark Wire and Cable Comark Communications Electronic Industries Emmons Associates Fuji Film I&I Maney Logic Panasonic Broadcast Roscor Wisconsin Scharch Electronics Sony Broadcast Tectan, Inc. 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