SBE 24 August 1995 Newsletter


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)

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
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.

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


Paul Stoffel (WI Public TV)
W - 608-263-2175
H - 608-241-4621
F - 608-263-9763

Fred Sperry (ECB-TOC)
W - 608-264-9698
H - 608-833-6074

Neal McLain (CTI)
W - 608-831-4636

Stan Scharch (WISC TV)
W - 271-4321
H - 831-1168


Membership - Leonard Charles

Sustaining Membership - Fred Sperry

Strategic Plan - Denny Behr

Newsletter - Mark Croom

Program Committee:
Mark Croom 271-1025
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)

SBE National Board Member & Chapter Liaison:
Leonard Charles
W - 271-4321
FAX - 271-1709

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.

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.

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"

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 ( for FCC
online resources? Or the SBE National's home page

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
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 -

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

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
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.

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

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).

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)

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.

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

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,

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

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

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!

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

Compiled from Broadcasting and Cable and The Wisconsin State

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
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.

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
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.

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

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.

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

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,

Divisions within an arc degree can be specified in either of two
- 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
28 43' 56" North Latitude
81 21' 44" West Longitude
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.

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."
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.

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.


See you next month.


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:
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.

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
Source: Wisconsin State Journal, May 26, 1991.

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.

Princeton: Princeton University Press, 1960.


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By Laws Committee..................................Sandy Sandberg
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