CHAPTER 24, Inc., MADISON, WI
Edited by: Mike Norton
Electronic Version: Leonard Charles
Articles Welcome!! Send correspondence to:
Contents for this Newsletter
Wednesday June 19, 1996
Dutch Treat Dinner at 5:30pm at Alt'N Bach's Town Tap
Thomas Sibenaller, our new representative from Roscor Wisconsin, will show the Panasonic DVCPRO equipment and answer any questions
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Tentative Program Subjects
Sat, Jul 27, 1996
Sat, Jul 27, 1996
Thu, Aug 22, 1996
Tue, Sep 24, 1996
Wed, Oct 30, 1996
Wed, Nov 20, 1996
Tue, Dec 17, 1996
Wed, Jan 22, 1997
Thu, Feb 20, 1997
Tue, Mar 18, 1997
Wed, Apr 16, 1997
Thu, May 22, 1997
Tue, Jun 17, 1997
Sat, Jul 26, 1997
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By Denise Maney
The annual SBE Chapter 24 family picnic is July 27, at Greenfield Park in Fitchburg (same location as last year). Noon to 5pm. Please RSVP to Denise Maney by July 24. We need to know how many in your party. Phone/Fax 277-8001 or e-mail at Sloop26@aol.com.
The SBE will be providing sliced ham and turkey, buns and fixin's, plates and cups. We will not be providing a grill this year as in the past. However, there are public grills in the park near the shelter. We ask that you bring a dish to share and your own drinks.
The annual horse shoe tournament will continue this year. As I recall Leonard "Chuck" Charles took the lead away from Kevin Rupert last year. Lets show 'em up this year gals. The men against the women. The baseball diamond is just crying to have a real game. There is a nice play ground for the younger children. We are considering door prizes this year. Kerry says he will donate a quad machine. Hmmm... Come join the fun and bring the whole family.
The Chapter 24 Newsletter is published monthly by Chapter 24 of the Society of Broadcast Engineers; Madison, Wisconsin. Submissions of interest to the broadcast technical community are welcome. You can make your submissions by e-mail to: Mike_Norton@wetn.pbs.org
SBE Chapter 24 Newsletter Editor
Please submit text file on DOS or Windows 3.5" floppy diskette if possible.
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Eighth Annual Wisconsin Broadcasters Association Summer Engineering Seminar And Regional SBE Meeting Thursday, July 18th, 1996 at the WBA Summer Convention, Heidel House Resort/Conference Center, Green Lake, WI.
Join your associates at the WBA summer convention for a full day of technical seminars designed to address issues of concern to both engineering and management. Speakers include Evans Associates (RF measurements for combined antenna facilities), Continental Electronics (ISDN basics), and a statewide EAS Summit; to finalize details of the Wisconsin State EAS Plan.
There will be a joint luncheon with managers, and joint afternoon sessions in which the finalized State EAS Plan will be presented to managers.
Sessions begin at 8:30AM and conclude at 4:00PM. Registration for the full conference is just $40, which includes exhibits and dinner on Wednesday the 17th, plus the full day of sessions, the lunch, and the evening formal HALL OF FAME Dinner on the 18th.
Or, if you prefer, attend only the conference sessions and the luncheon for $25. Same price since 1991! To register, send your check for $40 or $25 per attendee before July 8th, 1996 to:
Wisconsin Broadcasters Association
Note: On-site registration will also be available between 8:00A-8:30A on July 18th, but please call WBA to reserve your place: 800/236-1922. Separate reservations can be made for the WBA Golf Outing on Wednesday, July 17th. Contact the WBA for details.
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By Chris Cain
The Wisconsin Broadcasters Association Station Inspection program has just been completed. 123 Stations (104- Radio and 19 TV) had signed up for the program. Initial data indicates the following:
34.5% are in total compliance.
I was one of four inspectors that spent two days with three FCC inspectors in August 1995. We reviewed the rules and inspection checklists for one day and spent the next day actually inspecting an AM/FM station.
In the first installment of this article I would like to discuss what I observed to be the most troublesome areas that contributed to either advisory notices being issued or failure to pass an inspection. (Please note the following is based on my experience of inspecting approximately 1/4 of the stations. Other inspectors could have experienced entirely different situations.)
1) CHIEF OPERATOR RESPONSIBILITIES:
This is my take on the rules, but if I spot a problem and the Chief Operator is aware of it and noting it either daily or on the weekly
certification it gives the perception that the licensee is aware of the problem and is documenting steps that are being taken to resolve the problem. If you walk into a station where no EBS tests have been received for six months and the Chief Operator certification shows no problem or a reason for the problem, then you have to wonder if there is some sort of neglect going on.
The Weekly Certification of the logs is the absolute perfect opportunity for a licensee to identify a problem and to indicate what steps are being taken to resolve it.
2) TSA: TERMS OF STATION AUTHORIZATION.
One of the FIRST things a FCC inspector will be looking for: Is the station running within the terms of it's license?
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Submitted by Neal McLain, Secretary
Chapter 24 of the Society of Broadcast Engineers met on Thursday, May 23, at the University of Wisconsin Division of Information Technology (DoIT), Madison. There were 25 persons in attendance, 11 of whom were certified. The meeting was chaired by Chapter 24 Chairman Paul Stoffel, speaking from Vilas Hall. The two meeting locations were interconnected with an ATM audio/video link, part of the evening's equipment demonstration.
Call to order: 7:03 pm. The minutes of the April meeting were approved, as published in the May Newsletter.
Treasurer's Report: No report.
Newsletter Editor's Report (reported by Fred Sperry): Mike Norton has taken over the duties of Newsletter editor. The deadline for the June Newsletter is June 7; the folding party is scheduled for June 12, at WKOW-TV.
Membership Report (reported by Leonard Charles): Three new members have joined Chapter 24: Alan Fraser (WMTV), Donald Laubenstein (WMTV), and Robert Dischler (UW Instructional Media Development Center). The Chapter membership now stands at 71; the newsletter mailing list stands at 128.
Sustaining Membership Report (reported by Fred Sperry): One renewal has been received: Roscor Wisconsin.
Program Committee (reported by Steve Zimmerman): The next Chapter meeting will be June 18; it will feature a presentation by Tom Siebenaller of Roscor, Wisconsin.
Special Events: no report.
Certification and Education: (reported by Jim Hermanson): The next examination period will be June 14 through 24; one person has signed up to sit for the exam.
Frequency Coordination Report: No report.
National Liaison Report (reported by Leonard Charles): NAB, FEMA, and the FCC will host an EAS Teleconference on June 6, from 12:00 to 2:00 pm; the Chapter plans to provide a location for joint viewing.
Chairman's Report (reported by Paul Stoffel): A reminder that annual dues are now due.
Old business: none.
New business: Fred Sperry announced that the ECB has an opening for a full time television broadcast engineer, beginning late summer, for the overnight shift at the TOC.
Elections Committee: Committee Chair Jim Hermanson announced the results of the recent elections for chapter officers.
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by Tom Weeden, WJ9H
The amateur radio community has been stunned by a proposal of the low-earth-orbiting (LEO) satellite industry. At a May 7th meeting of an advisory committee to the 1997 ITU World Radiocommunication Conference (WRC), an LEO industry representative proposed a list of frequencies to be assigned to the LEO service, including the 2-meter and 70-cm amateur bands. The American Radio
Relay League (ARRL), representing ham radio to the advisory committee, has objected. It is asking its membership to write to the FCC, the State Department representative on the WRC committee, and the LEO industry to express its opposition to the possible loss of two popular amateur radio bands. ARRL says it is the first time in memory that another service has been proposed for the 144-148 MHz amateur band. The LEO industry says that until their spectrum needs are satisfied, all bands must remain under consideration.
In another area, the FCC has proposed a Notice of Proposed Rule Making to make available 350 MHz of spectrum at 5.15-5.35 GHz and 5.725-5.875 Ghz for use by so-called NII/SUPERNet devices. The spectrum includes the shared Amateur Radio allocation at 5.65-5.925 GHz. The unlicensed devices to use this allocation would be regulated under Part 15 to provide short-range, high-speed wireless digital information transfer. They could support new wireless LANs and facilitate access to the Internet. The proposal is in response to Petitions for Rule Making from Wireless Information Networks Forum and Apple Computer, Inc.
The first phase of the new "vanity call sign" program started May 31. The FCC announced the opening of Gate 1 which allows eligible hams to apply for calls they held previously, or held formerly by a deceased relative. The date for Gate 1A which allows clubs to apply for calls formerly held by deceased members, will be announced in a future public notice. The filing fee for the new call sign program is $30.
Hams will operate on board the Great Circus Train on July 8 and 9 as it travels from Baraboo, Wisconsin to Milwaukee. Operation will be around 7.240 and 14.240 MHz and possibly 146.550 MHz VHF. Special event station K9JYX/railroad mobile will offer certificates to hams who contact the station during its two-day trek.
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PART 3 - CABLES
by Neal McLain
This is the third in a series of articles about coaxial broadband networks. In this article, we'll discuss the characteristics of the coaxial cables used in typical networks.
MECHANICAL INTEGRITY In broadband networks, cables are installed outdoors, where they're subjected all sorts of hazards: weather, corrosion, lightning, vandalism, hungry squirrels. Most cables include jacketing materials to protect the signal-carrying components from mechanical damage.
SHIELDING INTEGRITY The outer conductor - the shield - must provide sufficient isolation between the cable signal and the over-the-air environment outside the cable to prevent interference (leakage). Leakage from the cable to the outside world (egress) can cause interference to licensed over-the-air services, a problem long familiar to amateur radio operators. Leakage from the outside world into the cable (ingress) causes interference to the cable signal.
CHARACTERISTIC IMPEDANCE Like everything else in a broadband network, the cable must be designed to maintain a constant characteristic impedance of 75 ohms. As we noted last month, impedance discontinuities cause signal reflections which manifest themselves in a number of ways: trailing ghosts in video signals, phase-cancellation in audio signals, and high bit-error rates in
data signals. Even very small impedance discontinuities (such as dents in the cable shield) can cause low-amplitude microreflections. In video transmission systems, microreflections are too far down, relative to the visual carriers, to produce visible ghosts; however, a buildup of multiple microreflections can cause the resulting picture to appear out-of-focus.
SIGNAL ATTENUATION Signal attenuation varies as a function of the physical dimensions of the cable, the dielectric constant of the insulating material, and the frequency. Attenuation is typically measured in decibels per hundred feet at a specified frequency.
DC LOOP RESISTANCE In some applications, it's necessary to send a low-frequency AC (typically 60-Hz) powering voltage down the cable along with the signal. In these cases, Ohm's Law applies: the DC loop resistance of the cable reduces the available voltage.
TYPES OF CABLE
As we noted two months ago, a broadband network incorporates three distinct sections:
Each section utilizes a specific type of cable. The trunk and feeder sections of the network typically use cable constructed with a solid aluminum shield, often called hard cable. The drop section of the network typically uses cable constructed with an aluminum foil shield, called, unsurprisingly, drop cable.
All hard cables are identical in internal construction: all employ a solid center conductor, foamed plastic dielectric, and a solid aluminum shield.
Let's examine hard cable in light of the physical characteristics we discussed earlier.
Mechanical Integrity - Hard cables are available in several configurations of varying mechanical integrity:
BARE ALUMINUM This configuration has no external protection: the outer surface of the cable is the aluminum shield itself. It is frequently used in aerial construction when lashed to a separate steel supporting strand. This configuration is the least expensive; however, it's vulnerable to corrosion, especially in industrial or coastal areas.
JACKETED This configuration includes a plastic jacket over the aluminum shield to protect it from corrosion. For aerial use, the jacket is placed directly over the shield. For direct-burial use, the jacket is separated from the shield by a layer of flooding compound, a sticky viscous substance which reseals minor cracks in the jacket, rather like a self-sealing tire.
ARMOURED This configuration includes two plastic jackets and steel armor over the aluminum shield. The inner jacket protects the cable from corrosion the armor provides mechanical protection; and the outer jacket protects the armor from corrosion. It's available with or without flooding compound.
MESSENGERED This configuration includes a steel messenger cable to provide mechanical support in aerial construction. Flooding compound is generally not used in aerial construction (it's a sticky mess if it drips onto a parked automobile).
SHIELDING INTEGRITY - The solid aluminum shield provides excellent shielding integrity, typically on the order of 70 to 80 db. Indeed, shielding integrity was the main reason for selecting solid-aluminum shielding in the first place.
CHARACTERISTIC IMPEDANCE - The characteristic impedance is a function of the physical dimensions of the cable and the dielectric constant of the insulating material. Critical physical dimensions include the outer diameter of the center conductor, the inner diameter of the shield, and location of the inner conductor relative to the shield. Slight errors in any of these factors causes an impedance discontinuity. Typical sources of dimensional error are mechanical damage (dents) in the shield, and failure of the manufacturer to maintain the proper physical dimensions during the manufacturing process (in my experience, the most common manufacturing error is off-center center conductor). By and large, however, manufacturers do an excellent job of maintaining the
physical dimensions of hard cable within very close tolerances.
SIGNAL ATTENUATION - Like characteristic impedance, attenuation is a function of the physical dimensions of the cable and the dielectric constant of the insulating material. As a general rule, the larger the cable, the lower the loss. Hard cable is manufactured in a variety of sizes, identified by the outside diameter of the shield, in inches. The standard trade sizes are 0.500, 0.625, 0.750, 0.875, and 1.000. As might be expected, there's another, related general rule: the larger the cable, the higher the cost. Signal attenuation is also a function of frequency.
DC LOOP RESISTANCE - To compensate for signal loss due to signal attenuation, amplifiers are spaced along trunk and feeder cables at regular intervals. In most broadband distribution systems (including virtually all conventional cable television systems), operating power for these amplifiers is distributed along the same hard cable that carries the signal. The DC loop resistance of the cable imposes limits on the number of amplifiers and their placement, relative to the power source. DC loop resistance follows the same
general rule as signal attenuation: the larger the cable, the lower the resistance.
Most drop cables are identical in internal construction: solid center conductor, foamed plastic dielectric, aluminum-foil shield, braided shield, and an overall plastic jacket. Drop cable can be examined in light of the same physical characteristics we discussed earlier.
MECHANICAL INTEGRITY - All drop cables incorporate plastic jackets for weather protection. Most drop cables also include flooding compound (for direct-burial installation) or messenger cables (for aerial installation).
SHIELDING INTEGRITY - The shielding integrity of a foil shield is around 50 to 60 dB. While not as good as hard cable, this level of shielding is still adequate because drop cables are typically used only for short distances.
CHARACTERISTIC IMPEDANCE - The characteristic impedance of drop cable can't be controlled as tightly as the impedance of hard cable. This results from the construction of the cable: since the outer shield is flexible, it is subject to mechanical deformation during shipping and installation. Nevertheless, minor impedance discontinuities are rarely a problem, again due to the fact that drop
cables are used only for short distances.
SIGNAL ATTENUATION - Compared to hard cable, drop cables exhibit much higher attenuation. Drop cables are manufactured in a variety of sizes, identified by code numbers such as RG-59, RG-6, and RG-11.
DC LOOP RESISTANCE - In conventional cable television systems, power is not sent into customer premises; accordingly, DC resistance is not a relevant issue. However, newer broadband networks are being designed to carry telephone signals as well as video and data signals; these networks must provide operating power for telephones connected to the network. There are many techniques for doing this; one technique involves sending low-frequency AC along the drop cable. In such cases, DC resistance must be kept as low as possible; however, as of this writing, there are no published DC resistance standards.
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by John L. Poray, CAE, SBE Executive Director
CHAPTERS TO BE REPRESENTED AT STRATEGIC PLANNING MEETING
MEMBERS INVITED TO NOMINATE CANDIDATES
The SBE By-Laws provide that additional nominations may come from the membership. Members can be placed on the ballot for officer or board positions when nominated by a minimum of ten members. All nominees must be members in good standing and have current SBE certification. Nominations, in writing, are due to the SBE National Office by Friday, July 12, 1996.
Any member, nominated for the same position by at least ten members, and who agrees to run and serve if elected, will be added to the ballot. Ballots will be mailed to all voting members in good standing by August 12 and must be returned to the SBE Office by 5:00PM, Thursday, September 12, to be counted. Ballots are counted that evening by a Board of Tellers and results will be
announced the following day.
RENEW MEMBERSHIP BY JUNE 30 TO AVOID BEING DROPPED
SBE CONFERENCE HEADS TOWARD THE DIGITAL CENTURY
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WHA-TV, Madison, WI is seeking a highly qualified television maintenance technician with 5+ years of proven broadcast maintenance experience. Qualified candidates will possess expertise in the following areas:
- Proven bench servicing and maintenance of analog and digital devices down to the component level
Job duties include: repair of Betacam tape recorders, field cameras, field support equipment, studio cameras, videotape editing systems, and a large compliment of other equipment normally found in a broadcast/production operation. Additional tasks will include, among others:
- installation of equipment
Work assignments will include occasional shifts operating cameras, audio equipment, and videotape machines in studio and
FCC General class license and SBE certification preferred.
Schedule will include evenings and weekends.
To request special application/examination materials, call or write to:
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Thanks to all our Sustaining Members