COVER STORY TI ry I CCGCCCE GCCCC FM audio processing July 1994 Buying a radio transmitter Upclat ng the RF link to your listeners is an important step. Quality anc reliability are equally critical in the competitiie marke-.place faced by most stations Contract engineer Kirk Harnack has seen his stare of radio transmitters. He [re- sents a thorough overview of what every broadcaster should know when shopping for new RF hardware. Maintaining modulation within legal limits and defining a station's sound - these are the two functions of air -chain audio processing at every FM radio station. Chief engineer Chris Durso describes how today's systems can perform both tasks well. A new home for MJI Broadcasting The special facility requirements of a radio production house are difficult to provide even in the tamest of environments, but problems increase expo- nentially at a downtown New York City location. Award -winning studio designer John Storyk describes how one busy Big Apple operation handled this chtIlenge. EDITORIAL/MEWS 1 RADIO IN TRANSITION 14 18 29 AD INDEX 32 RE: RADIO NEW PRODUCTS A Supplement to: BRoaDcasT enGineeRinG *
Transcript
COVER STORY
TI ryI
CCGCCCEGCCCC
FM audio processing
July 1994
Buying a radio transmitter
Upclat ng the RF link to your listeners isan important step. Quality anc reliabilityare equally critical in the competitiiemarke-.place faced by most stationsContract engineer Kirk Harnack has seenhis stare of radio transmitters. He [re-sents a thorough overview of what everybroadcaster should know when shoppingfor new RF hardware.
Maintaining modulation within legal limits and defining a station's sound -these are the two functions of air -chain audio processing at every FM radiostation. Chief engineer Chris Durso describes how today's systems canperform both tasks well.
A new home for MJI Broadcasting
The special facility requirements of a radio production house are difficult toprovide even in the tamest of environments, but problems increase expo-nentially at a downtown New York City location. Award -winning studiodesigner John Storyk describes how one busy Big Apple operation handledthis chtIlenge.
EDITORIAL/MEWS 1
RADIO IN TRANSITION 141829
AD INDEX 32
RE: RADIONEW PRODUCTS
A Supplement to:
BRoaDcasTenGineeRinG
*
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Circle (1) on Reply Card
EDITORIAL
Resurrection of a bad idea
According to an article in the January, 1994 issue of theNational Association of Radio and Television Engineers newslet-ter, FM stations are wasting 100,000MW-hours of power eachyear. The article by Dr. Stephen Blank, a professor at theNew York Institute of Technology, also claims that FMstations represent "potential public health hazards." Dis-regarding his dubious conclusions, his solution is evenmore ridiculous. He proposes that every FM station stoptransmitting with circular polarization and use only verti-cal polarization (VP). Sounds simple enough doesn't it?
He doesn't mention that each station might have to spendperhaps $100,000 to erect a temporary antenna for the workperiod, remove the old antenna and then install a new antenna.Or, that the transmitter might also have to be modified so itcould run at half power. If the transmitter can't be modified, thestation would just have to buy another one (add another$20,000 to $40,000).
Blank claims most stations would recover the cost of conver-sion to vertical polarization within one year just from lowerpower costs. Wrong. He has clearly failed to consider themultitude of economic factors that would come into play if FMstations were required to make these changes.
If the mere economics of this proposal weren't bad enoughfor FM stations, the resulting degradation in coverage ought tobe enough to kill the whole idea. In 1993, the FCC dismissed apetition for rulemaking by the Ozark Broadcasting Corporationproposing that the commission allow, but not require, VP onlyfor commercial FM stations (RM-7566). One of the grounds fordismissal was, "As a general matter vertically polarized signals(in the FM band) do not propagate as far as horizontallypolarized signals." Also, as any broadcast engineer that's workedwith FM antennas can tell you, the vertical component of the
Survey shows consumer demandfor RBDS is high
Arecently concluded study of consumer preferencesindicates that Radio Broadcast Data System (RBDS) ser-vices will be welcomed by many radio users. The nationalsurvey, conducted for the Electronic Industries Associa-tion (EIA), polled 1,000 Americans on their awareness andinterest in RBDS.
While 80% of the respondents were not aware of RBDS,more than 25% said they would listen to the radio more if itoffered RBDS features, and 35% felt that RBDS would in-crease their enjoyment of radio listening. More than 70% ofthose surveyed were willing to pay up to 10% more for aradio with RBDS features.
Among the most popular RBDS functions were traffic andemergency news displays, with more than 60% of respon-dents.showing interest in these features, and 20% reporting
transmitted signal can be drastically affected bythe tower. Typically this pattern distortion is hidden by thehorizontally polarized signal. If you give up the horizontalcomponent, you lose this protection.
Finally, Blank's claim that CP FM antennas "generate asignificant risk of radiation hazard to populated areas" issuspicious at best and tabloid sensationalistic writing atworst. The commission already requires all FM stations toprovide an engineering exhibit showing compliance withthe ANSI C95.I standard governing human exposure to non -ionizing electromagnetic fields. Blank claims a 20dB RFRsuperiority for vertically polarized signals. Although VPOLantennas do tend to have a null straight down, modern half -lambda CP antennas also have an HPOL null straight down.Any so-called improvement would be on the order of 3dB,not 20dB as he claims.
When Blank presented his proposal at the 1990 NAB, hewas practically laughed off the stage. The basic audiencereaction was that he didn't know what he was talking about.I couldn't agree more. His idea was a bad one in 1990 and it'sno better today.
Brad Dick, editor
that they would purchase an RBDS radio for the emer-gency alerting feature alone. Also highly rated were thesystem's entertainment and convenience features. Morethan 60% of those polled were interested in program -associated data (such as song-title/artist displays),"smart -radio" features (such as search -tuning by for-mat) and built-in paging/messaging. (See "Radio in Tran-sition: New RBDS Services," p. 14.)
Younger consumers (18-26) showed 20% higher inter-est in RBDS than overall averages, indicating that RBDSmay be more highly valued by future audiences. Forexample, more than 85% of this age group expressedinterest in the song-title/artist display feature.
RBDS was introduced in the United States in 1993. TheEIA reports that RBDS radios are now available from atleast seven major manufacturers, with more than 130FM stations currently providing RBDS service.
*L.July 1994 BE Radio 1
=M 1
:L. Buying a radiofz. transmitter
By Kirk Harnack
The Bottom Line: No matter what other equipment a radio station has assembledin its facilities, its broadcast signal is delivered to listeners solely through the effortsof the station's transmitter. It is the single most important device at the station, andthe quality of its operation can make or break a station's fortunes. Therefore, choos-ing the right new transmitter is no small responsibility
hen purchasing anew transmitter,the buyer faces
myriad possibilities. It'sessential that the trans-mitter purchaser be in-formed and prepared todecide which transmitteris best for the application.
Whether shopping foran AM or an FM transmit-ter, many of the samequestions need to be an-swered in the decision -making process: New orused? Solid-state or tubeamplifier? Which manu-facturer is best? Whichtransmitter design willlast the longest? Whatabout long-term mainte-nance? Which transmitterfeatures are important?What qualities should a Solid-state transmitters are less demanding in their cooling untlow needs.
transmitter have that maynot appear on the spec sheets?
The answers must be determined inthe course of buying a transmitter.
Deciding on a newor used transmitter
An important first step is the decisionon whether to buy new or used. Onereason many purchasers are interestedin used transmitters is the belief that aused unit will cost less. The asking pricefor a used transmitter will always belower than its new counterpart. Yet allKirk Harnack is president of Hamack Engineering, a con-tract engineering firm in Memphis, TN. Respond via the BERadio FAXback line at 913-967-1905.
the attendant expenses of buying a usedtransmitter must be considered beforecosts can be compared.
Purchasing a new transmitter allevi-ates many worries and potential prob-lems. It also should evoke a certainamount of support from the manufac-turer for quick, under -warranty partsand service. Immediately after a sale,the manufacturer is interested in mak-ing sure the transmitter is trouble -freeand on the air and that the client iscompletely satisfied with the purchase.
A new transmitter will be more valu-able because the manufacturer's latestdesign improvements will be incorpo-
rated into it. Many manu-facturers work continu-ously to improve theirtransmitters' operationand reliability. Buying anew model can assurethat bugs and potentialproblems have beeneliminated.
Specialconsiderations
for used transmittersWhen buying a new
transmitter, a customercan be assured that theproduct contains all newparts and that it workedrecently. Acquiring a usedtransmitter requires thecustomer to forego assur-ances on those counts. Inaddition, a used trans-mitter often must betuned to a new operating
frequency. This process can range frommoderately easy to nearly impossible.
The new transmitter market is stableenough that most models offered bymanufacturers are available within afew weeks. On the other hand, buying aused transmitter involves luck and goodtiming. The transmitter that was on themarket yesterday may be on its way tosomeone else today.
A buyer in the used market shouldrely on the advice of engineers whohave direct experience with the par-ticular makes and models of transmit-ters under consideration. Such advicecan be the most valuable information a
2 BE Radio July 1994
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DESIGNS THAT MAKE THE DIFFERENCECircle (1) on Reply Geld
used transmitter buyer can get. Thebuyer must be ready to act when a trans-mitter is found, examined, and deter-mined to be worth its price.
Solid-state or tubeSolid-state (fully transistorized) trans-
mitters are competitively priced withtube -type transmitters for AM and FMservice at lower- and medium -power lev-els. Design improve-ments over the past 15years are resulting insolid-state transmittersthat live up to the tech-nology.
AM solid-state trans-mitters offer significantbenefits over tube -typetransmitters in most ap-plications. For instance,power consumption ofsolid-state AM transmit-ters is less than compa-rable tube -type transmit-ters. In many cases, theelectricity cost -savingscan pay to replace oldertube transmitters. Also,audio performance ofsolid-state AM transmit-ters is more consistentoverall than tube designs.
FM broadcasters havea more difficult choicewhen comparing solid-state and tube technolo-
spective transmitter's reliability. Whenchecking a transmitter model's refer-ences, ask about the installation. Keepin mind that a transmitter's reportedreliability is certainly affected by thequality of its installation. Manufactur-ers can easily duplicate the same trans-mitter design repeatedly, but differentinstallations will subject similar trans-mitters to widely varied operating con -
A small footprint can be advantageous in many installations.
without proper protection circuits orcontrary to the unit's original type ac-ceptance. At this point the transmitter'suseful life is nearing a quick end.
If continued support is important tothe purchaser, buying from a long-stand-ing, reputable manufacturer should beof significant importance.
Service and supportWhen a transmitter is
off -the -air, knowledgeabletelephone support can bevital to quick problemresolution. Some trans-mitter manufacturers of-fer 24 -hour phone sup-port while others may bedifficult to reach evenduring business hours.
Checking with otherusers of a company'sequipment is a good wayto judge support. Callinga manufacturer's techni-cal support line and ask-ing questions can reveala company's attitude to-ward technical assistance.
gies. In the higher powerlevels, tube amplifiers are much lessexpensive than solid-state units. This isbecause of the difference in the amplifi-ers' design requirements. A 10kW solid-state FM transmitter requires twice asmany parts as a similar 5kW model.However, 10kW tube -type transmittersrequire only larger tubes, power sup-plies and hardware than their 5kW ver-sions. Their parts count remains ex-actly the same.
This scale -factor issue gives rise toanother advantage of tube transmit-ters. A 10kW, 20kW or 30kW FM trans-mitter from any given manufacturer isnearly identical in design, parts count,and reliability to that manufacturer'slkW, 2.5kW, or 5kW models. On the otherhand, solid-state transmitters increasein complexity linearly with increasingpower level.
ReliabilityA broadcast transmitter must be reli-
able. Given a choice between a great -sounding transmitter that's frequentlyoff -the -air and a mediocre -sounding unitthat never fails, the latter will always bemore desirable.
When reviewing different transmit-ters, ask current users about their re-
ditions. Hence, surveying a number ofusers of identical transmitters is criticalto obtaining a true impression of a par-ticular model's reliability.
Longevity ofmanufacturer
Many of the day-to-day and occasionalpurchases we make are from long-stand-ing manufacturers. Names such as Gen-eral Motors, Kroger and IBM are such apart of everyday life that we can takemanufacturer longevity for granted. Thisis often not the case with broadcastequipment and other specialized prod-uct manufacturers.
Ten years after purchasing a newtransmitter, it will likely still be in useand will require maintenance and parts.Yet a decade from now, will mechanicalparts be available? Will technical assis-tance and advice be available? Willcomponents made by other vendors ex-clusively for this transmitter manufac-turer be available anywhere at any price?
Often, when proper replacement partsbecome unavailable, a repair engineeris forced to use makeshift parts, disablecertain transmitter circuits, or other-wise modify the transmitter. Frequently,these modifications result in operation
Ease of maintenanceDuring the 1970s, a U.S.
auto maker sold thou-sands of cars that weredifficult to service in onerespect: To replace onespark plug, the entire en-gine had to be removed.
Consequently, few of those spark plugswere ever replaced.
Transmitter designs can suffer simi-lar problems. Some designs require shut-down of the transmitter in order tochange the air filters. Another designresults in going off -air for a few secondsbefore and after adjusting the automaticpower control setting or the filamentvoltage. These design quirks are notdescribed in the manufacturer's specsheet. To discover these problems sooner,rather than later, seek the opinions ofqualified and trusted engineers regard-ing particular transmitter models.
In recent years, several transmittermanufacturers have given attention toease -of -maintenance issues. One im-provement has been solid-state Inter-mediate Power Amplifiers (IPAs) withconvenient patching systems to routearound a failed module or system. Thisfactor may also come into play if a fu-ture in -band DAB system requires anymodification of existing transmitters.
When choosing a transmitter look forroadblocks to convenient and safe ser-vicing. Look at the overall componentlayout. For example, what if a blowermotor fails? How difficult would it be toremove and replace?
4 BE Radio July 1994
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Check the overall fit and fin-ish of the metalwork. A fairamount of time can be wastedfighting with access doors thatdon't fit properly, or with fas-teners that aren't correct forthe task or are poorly installed.
Availability of partsSome transmitter purchasers
want the latest technologicaldesigns and capabilities. Thesedesigns are often achieved us-ing uncommon, esoteric com-ponents. Such components maynot be available in several yearsif they do not sell in sufficientquantities to justify their con-tinued manufacture.
For other transmitter pur-chasers, a simple, proven de-sign using more commonlyavailable parts is appropriate.The more advanced designs willalways offer more bells andwhistles, many of which are im-portant and significant. Never-theless, simpler designs, whiledevoid of certain convenienceand performance features, aremore likely to be supplied withreplacement parts in years to
Traditional tube designs from well -established manufacturersoffer long-term reliability.
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come.Physical size
considerationsIn some cases, an important
criterion in transmitter selec-tion is physical size and con-figuration. If a particularly smallfootprint is required, somemanufacturers offer transmit-ters that are rack -mountable inpower levels up to 2kW for FMand up to 1kW for AM.
Broadcasters who rent roof-top or penthouse space fortransmitter placement oftenpay by the square foot. For theseinstallations, choosing a trans-mitter based largely on foot-print size may be prudent.
Required airflowconsiderations
All too often, proper cleanairflow is improperly addressedor ignored altogether in trans-mitter installations. Proper con-sideration of cooling airflow isimportant to a transmitter's lon-gevity. For this reason it's wiseto examine the transmitter'sairflow requirements.
For lower -powered AM andFM transmitters, solid-state
units tend to require less cooling airthan tube -type models. At least one solid-state AM transmitter model on the mar-ket doesn't use any internal blower upto the 2.5kW level.
When comparing transmitter specsheets, be sure to note the airflow re-quirements listed by the manufacturer.Be certain that the transmitter's in-tended environment can be made suit-able for that unit's requirements.
Also check the design and ratings ofthe components in the transmitter's in-ternal airflow system. Some manufac-turers allow more "headroom" than oth-ers for inefficient or restricted airflow. Ifa particular model's components areemployed at their maximum ratings, anyrestriction or inefficiency could causeoverheating. In cases of marginal de-sign by the manufacturer, ease of acces-sibility is important for cleaning squir-rel cage blowers and fans.
Deliverability to siteA transmitter site that is particularly
remote could have a bearing on whichtransmitter model is chosen. Most trans-mitters can be made lighter by remov-ing heavy components such as high -
voltage transformer(s) and choke(s).Some transmitter designs do not lendthemselves well to easy transport, how-ever. These include designs where sev-eral cabinets are connected together insuch a way that disconnecting them isimpractical.
Circle (14) on Reply Card6 BE Radio July 1994
The AphexAudiophileAir Chain
Higher Quality and Extended Coverage!Smart broadcasters know that quality sound is essential "We have gotten a few responses from listeners in the
to attract and keep loyal listeners ... and advertisers. fringes of our coverage area saying our signal is muchThat's why premier stations around the U.S.A., and stronger. They are reporting the actual carrier level has
around the world, rely on the Aphex Audiophile Air increased and they can hear us where they could not get a
Chain. clear signal before," - Herb Squire, CE, WQXR, NYC.Now there's one more reason to turn to Aphex - better The Aphex Audiophile Air Chain allows maximum
coverage of your listening area. loudness and modulation while maintaining the naturalStations that have installed the powerful combination of dynamic feel of the program. Quick and easy to set up, it
the Aphex Compellor® Model 320, Aural Exciter® Type maintains the same high quality regardless of the type ofIII, Dominator" // Model 720 and the new DigicoderTM programming or who is controlling the board.digitally controlled stereo generator - as well as their lis- Other processors need to be tuned for almost everyteners - are raving about better signal quality and a re- song, and achieve loudness only by crunching to the pointduction in multipath. of listener fatigue. But Aphex helps you reach more lis-
"A surprise bonus has been the apparent increase of teners - and keep them longer.coverage in fringe areas - we are getting very' positive If you want to be a winner in the "no win modulationresponses from listeners in Sacramento, 100 miles away," wars", contact your Aphex dealer to arrange a demonstra-
- Tim Pozar, CE, KKSF- FM, San Francisco. tion of the Aphex Audiophile Air Chain. You can't buy"Immediate improvements in fringe signal quality were better quality at any price.
noted. These improvements included a reduction in multi -path and picket -fencing," - Gary Greth, CE, KLON, Long Circle (15) on Reply Card
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Also examine before-hand the difficulties thatcould result from attempt-ing to squeeze a largetransmitter through allaccess doors and into itsfinal position at the site.
Getting thebest price possible
When the choice isdown to a few competingbrands, it's time for seri-ous bids from the manu-facturers' representatives.Bidding practices seem tovary widely from onemanufacturer to another.A few will bid their list Proper ventilation is important to any transmitter's longevity.
price and allow no furthernegotiation: "The product stands on itsown and here's the price" is their ap-proach - the Saturn dealer school oftransmitter sales. Other manufacturerswill bid below the equipment's list priceand usually keep a little more negotiat-ing room available in case it's needed.
Try to keep price comparisons in the"apples -to -apples" domain. Standardequipment and features vary quite a bitfrom one manufacturer to another so atrue price comparison may not be en-tirely possible nor desirable.
Manufacturers' representatives areoften in a position to include other trans-mitter installation accessories in theirbids at discounted prices. Items such astransmission line, line hardware, con-nectors and the like are sometimes soldnear cost when included with a trans-mitter purchase.
When negotiating price, rememberthat a personal relationship with themanufacturer's representative can bevital in obtaining a good transmittervalue. Remember also that such good
value may not necessar-ily be the lowest bid onthe table, but will involvebuying what is proper todo the job at hand.
SummaryBuying a transmitter
involves at least as manychoices as buying a car.When considering the de-grees of quality and reli-ability available, remem-ber that every song, news-cast, talk show, PSA andcommercial that will beaired for years to comewill depend upon thetransmitter and its re-lated systems.
The transmitter is a station's vital linkto the public. Its purchase decisionshould be treated accordingly.
*For more information on radiotransmitters. circle (65) on
Reply Card. See also "Transmit-ters," pp. 68-69 of the BE
Buyers Guide.
131-:
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Low cost of ownership - withtypical efficiency ratings up to 80percent, a totally solid state Nauteltransmitter pays for itself in tubereplacement and utility.
Superior audio transparency -Nautel AM transmitters utilizeinherently linear Pulse DurationModulation for the cleanest soundyou can broadcast. Audio is ruler -flatthroughout the range and distortionis typically less than 0.5%.
Field -proven reliability -Nautel transmitters give youmultiple protection systems for bothpower line and lighting transients,VSWR protection, soft failuredesign, reserve cooling and safeon -air servicing.
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8 BE Radio July 1994Circle (16) on Reply Card
September
Audio managementA look at how
digital technologyis changing the face
of audio in radio.From digital cart machinereplacement to integrated
storage, production and on -airsystems, radio stations have
a wide variety of optionsavailable for audio
management.
Radio consolesDon't buy that new radio
console until you'veread this article.
Control roommonitoring
Radio control roommonitoring systems areimportant to maintaining
a top-quality on -air sound.The author looks at ways
you can improveyour system.
Jse the BE
Radio F
AX
back line to suggest articlesyou
would like
o see on any radio technology.=
ax this form to the editors at B
E R
adio.
need more inform
ation about:
FA
Xback this form
to: 913-967-1905
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The Bottom Line: Audio processing is an essential part of any radio station's uirchain, and it can significantly affect the perception of the station in its market. Theever-growing number of products on the market make it difficult for a station to stayahead of the pack. Knowing what tools are out there and how they work are the firststeps toward successful processing at your station.
oday's FM audio processing is atonce both science and art. Itserves a specific function with
respect to modulation limits set by theFCC (which can be precisely measured),while simultaneously creating a feel orsound for the radio station (that may bedifficult to quantify).Therefore, a station's au-dio processing serves twomasters - the chief engi-neer and the program di-rector.
As the digital age hasmatured, the choicesavailable to meet both ob-jectives have expanded.
Audio processing101
To accomplish these
cessors have made it much easier toachieve high levels of average modula-tion (thereby increasing perceived loud-ness) without introducing objectionableamounts of distortion, however.
Ultimately, signals of excessive levelthat find their way past the limiter un-
The Orban Digital Optimod 8200 is adigital audio processor that includesa stereogeneratorand offers optionalAES/EBU I/O and sampling rate con-version.
twin tasks, processing sys-tems perform at least twoimportant functions: limiting and com-pression. Limiting audio results in amaximum level (or voltage) that will beapplied to the exciter baseband input.This level will result in modulation thatwill not exceed the maximum allowableamount. While the amount of limitingand its attack/release times can vary,the process usually creates some un-avoidable distortion artifacts. Thegreater the amount of limiting: the morenoticeable this distortion can become.
Limiting, therefore, trades off betweenloudness and listener fatigue. Technolo-gies deployed in late -generation pro -
Durso is chief engineer at KPBS-FM, San Diego. Respondvia the BE Radio FAXback line at 913-967-1905
molested must becontrolled by aclipper circuit.The clipper is po-tentially the mostdestructive of all
The Aphe.v Systems line includes a numberofseparate analog audio processing devices.Shown here (from top) are the Compellor,Aural Exciter Type III, Dominator II andDigicoder (a digital/analog hybrid stereo gen-erator).
audio circuits in aprocessor.
Meanwhile, an audio processor's com-pression (orleueling) section essentiallyreduces the dynamic range of the audiosignal by constricting the average levelby some set amount. The amount ofcompression applied is expressed as aratio of the modified transfer function.A compression ratio of 4:1 means thatthe input voltage must change by fourunits of measure in order for the output
voltage to change by one unit of mea-sure. This reduction in dynamic range isusually desirable when reaching alargely mobile audience, especially inan environment where multipath istroublesome. Given the high ambientnoise levels found in automobiles, com-pression serves to keep the signal au-dible over a wide range of listening envi-ronments and signal reception condi-tions. Some radio formats can tolerate areduction in dynamic range more trans-parently than others, however.
In addition to handling the discreteleft and right channel audio signals, most
broadcast audioprocessors(those that in-clude a stereogenerator) add ahighly stable,phase -accuratestereo pilot sig-nal at 19kHz. Thestereo compos-ite baseband as-sembled by suchprocessors in-cludes the mainchannel audio
(L+R) signal (processed and bandpass-limited to 15kHz), the stereo pilot at19kHz and the stereo difference (L -R)subcarrier at 38kHz (twice the pilot fre-quency). Some engineers also opt toprocess the L -R signal separately in or-der to achieve a widened stereo image.This technique is not required to main-tain modulation compliance, but mayhelp define the audio signature of thestation.
10 BE Radio July 1994
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To obtain an extra edge of loudnessas well as provide greater overmodulationprotection on highly processed signals,the technique of composite processinghas gained popularity. The compositeprocessor is the last element in the au-dio chain prior to the exciter basebandinput and, when properly adjusted, candeliver a few more dB of increased loud-ness. Careful attention must be paid toavoid clipping the stereo pilot, whichcould result in pilot modulation, a viola-tion of FCC rules. To avoid this,the stereo pilot is inserted afterthe composite processor.
Finally, many FM stations in-troduce additional signals in thebaseband subcarrier regionabove 53kHz. Any station usingsubcarriers must minimize spu-rious energy present in thissubcarrier region of the com-posite signal. In the absence ofadequate filtering in the audioprocessing chain, adjustments
ticular part of the spectrum. In manycases, a split -band limiting section isfollowed by a separate split -band com-pression section. Often, a wideband (i.e.,single -band) automatic gain control(AGC) section precedes the split -bandprocessing sections. This type of pro-cessor enables programmers to fine-tune the sound of a station more pre-cisely and process more aggressively.
Analog processors use conventionaltechnologies to perform the functions
The Audio Signature from Circuit ResearchLabs is a digitally controlled analog audioprocessor with setupmemotyand remote -con-trol capability.
made to the main channel sig-nal can have a profound negative effecton subcarrier services.
A station's audio processingserves two masters - the
chief engineer and the pro-gram director.
Processor typesFM audio processors generally fall
into three categories: analog, analog/digital hybrid and digital. In addition,processors are usually further dividedinto multiband or split -band types.
The multiband (usually a 2 -band) pro-cessor generally divides the audio sig-nal between the low frequency and mid/upper frequency bands. This allows theprocessor to treat the energy levels inthese bands separately and helps toreduce the pumping that results fromthe low -frequency band (the spectralarea that is generally predominant inmusic and speech) driving the overallgain of the system. To avoid excessivealteration of the audio signal's dynam-ics, an adjustment is usually providedthat determines how much the low -fre-quency band acts as the overall gain -reduction control. This approach canpreserve much of the original dynamicsof the program material.
A more competitive approach splitsthe audio spectrum up into a largernumber of bands (typically four or more)that are each processed and controlledindependently. Characteristics of eachband (such as attack and release times)can be adjusted to change the densityof the program or to emphasize a par -
of audio fil-tering, com-pression, lim-iting and pi-lot/stereosubcarrier
many aspects of the audio processorcan actually be problematic at times.Engineers and programmers must re-sist the temptation to make adjustmentsthat may result in a progression of er-rors. Many parameters must be adjustedproportionally and the setting of oneadjustment may quickly destroy the re-lationships that make up the sound of aparticular processing configuration.Digital audio processors will yield ex-cellent results when properly adjusted,especially when operated through a digi-tal air chain all the way to the exciter.
In most cases, digital processors alsoderive filtering, pilot and subcarriergeneration digitally. Because digital au-dio processors can so carefully controlthe content of the composite signal,stations transmitting subcarriers in theupper baseband region should notice
an improvement incrosstalk performance.
These digital pro-cessors are essentiallycomputers attached toDSP hardware undersoftware control.Therefore, processoroverhead also makesit easy to include pow-erful scheduling fea-
The Unity 2000i from Cutting Edge Technolo-gies is a single -box, multifunction hybrid pro-cessor that comes with remote PC control soft-ware.
generation.This is not to suggest that such prod-ucts lack sophistication. To the con-trary, modern analog audio processorscontain extensive state-of-the-art elec-tronics and can produce excellent sonicresults.
Digital/analog hybrid processors typi-cally use digital circuits for control whileaudio signals remain in the analog do-main. Digital control can provide greaterconsistency and allows easy storage ofmultiple parameter settings that can berecalled to change the action of theprocessor almost instantaneously. Thistype of flexibility is useful to stationsthat change programming with dayparts,or that simply want different amountsof processing for different times of theday (e.g., more compression duringdrive -time). Settings might also bechanged to conform to the needs of on -air talent. Another popular hybrid pro-cessor technique is the digital genera-tion of the 19kHz pilot and 38kHz stereosubcarrier signals. This method resultsin superior phase and frequency stabil-ity performance, which is critical formaintenance of optimum stereo sepa-ration.
Digital audio processors convert au-dio signals to digital form, and thenapply digital signal processing (DSP).DSP is controlled by software and givesthe user control over numerous param-eters of the processor. Control over so
tures that can accom-modate daypart programming. Digitalprocessors also may include digital in-puts and outputs that conform to theAES/EBU standard. It is possible todayto take the stereo analog signal from thebroadcast console (or other final studiosource) and convert it to AES/EBU (if it
Late -generation processorscan achieve high levels of
average modulation withoutobjectionable distortion.
is not already) for transmission througha digital STL. At the transmitter site, thedigital signal is returned to AES/EBUform and fed to the digital processor.The most recent development in thisarea now allows an AES/EBU output fromthe digital processor to be fed to a digi-tal FM exciter input. In this case, thestereo generator is part of the exciter,which feeds the digital baseband signalit creates to a numerically controlledoscillator (NCO) for deviation of the FMcarrier.
Control of hybrid or digital proces-sors may also be possible from a remotelocation, typically via PC and modem,using control/communication software
111he Radio Broadcast Data System(RBDS) has been a long time com-ing in the United States, but as itbegins in earnest, several new
service providers have begun to markettheir offerings to RBDS-equipped broad-casters. These providers operate asthird parties using a portion of an FMradio station's RBDS subcarrierdatastream to reach customers withinthe station's coverage area. The cus-tomers typically are outfitted withproprietary receiving hardware by theservice providers. In these respects, theapproach is quite similar to traditionaldata subcarrier leasing.
Where things differ with RBDS is inthe multiplicity of services that canshare a single subcarrier. First, you'llrecall that the primary function of RBDSis providing program associated data(PAD) to radio listeners. (See "Rx forNew Radio Profits," March 1992.) As asecondary function, auxiliary or trans-parent (i.e., inaudible/invisible to theradio listener) services such as thosediscussed in this article can be added.They serve users other than the radiostation's normal listeners and bring ad-ditional revenue to the station fromservice providers.
An interesting synergy evolves fromthis relationship. Because a station'sonly real cost of implementing RBDScomes at the initiation of the service(i.e., coder and monitor purchase andinstallation), station management isnaturally interested in seeing some earlyreturn on the investment. (See "Radio inTransition: Implementing RBDS," June1994.) Yet the promotional and sales -
New RBDS services
By Skip Pizzi, technical editor
As RBDS begins its deployment, a number of newservice providers and platforms have emerged.
enhancement value of RBDS's PAD ser-vices is limited in the short term by alack of RBDS-capable receivers in thehands of radio listeners. Significant pen-etration of this hardware will not beattained among general radio audiences
Broadcasters should becautious in their acceptance
of these services.
for several years. On the other hand,third party or "industrial" RBDS appli-cations can have a more immediate im-pact because the receivers are quicklyplaced in the hands of customers iden-tified by service providers. Marketing ofthese services also is handled by ser-vice providers -the broadcaster servesonly as a delivery conduit and can beginto reap financial benefits soon afterimplementation in many cases.
CaveatsSome industry observers advise
broadcasters to be cautious in theiracceptance of these services, however.The RBDS subcarrier's relatively low1.2kb/s data rate can only accommo-date a limited amount of this transpar-ent data before it begins to slow theoperation of both PAD and transparentRBDS functions. Signing long-term leasesfor substantial transparent data use ofan RBDS subcarrier may seem like agood idea today when so much of theRBDS datastream seems like excess ca-pacity. Yet, if and when RBDS PAD ser-vices become popular in the future, astation may regret the speed or capac-
ity penalty paid by burdensome trans-parent data carriage. As with anysubcarrier leasing, broadcasters mustbe fully aware of their spectral assets'value - both in current and projectedterms.
Also note that some of the servicesbelow also may require an increase ininjection level of the RBDS subcarrierfrom its nominal 2.6% to 5% or higher.This may affect the received quality ofmain -channel audio or other subcarrierservices.
New services and systemsAmong the first RBDS transparent
services to be established was paging.So far, only one company, Axcess USA,has implemented RBDS paging on a largescale. The company sells franchises tostations or third parties to operate localpaging systems. Axcess provides alpha-numeric RBDS pagers to subscribers.There is no national paging intercon-nection feature as yet with the service.
Sage Alerting has pioneered the useof RBDS for a similar addressable mes-saging service, but this one emphasizesemergency or other alerting features,again on the local level only. Sage alsohas proposed an RBDS-based system tothe FCC as a candidate for updating theEmergency Broadcast System (EBS).
Industry insiders report that the mar-ket for RBDS paging/alerting may openup soon as more companies begin tooffer services and receiver hardware.
The market for Differential GlobalPositioning System (DGPS) services isalso growing. These services increasethe accuracy of satellite -delivered GPS
14 BE Radio July 1994
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data to non-military users from a fewhundred meters precision down to afew meters or less. DGPS has been avail-able for some time via other deliverymethods (satellite or microwave) but athigh cost. Delivery of DGPS correctiondata via RBDS broadcast can greatlyreduce the cost of such service, makingit attractive to many new users. Differ-ential Corrections, Inc. (DCI) providesDGPS service as an RBDS application toproperly equipped or adapted GPS re-ceivers using the so-called RTCM-104standard. (See "Radio in Transition: Onthe Horizon," December 1993.)
A similar DGPS service calledACCQPOINT is provided by Magnavox,in conjunction with Cue Paging. It is nottechnically an RBDS application, but in-stead is offered as part of Cue Paging's57kHz service. This established nationalpaging network can co -exist on the57kHz subcarrier with RBDS service. al-though some slowdown in response timeof both services may occur.
An interesting development thatmight find an RBDS application is Mile-stone Technologies' SATX system, a one-way binary file transfer protocol withthe robustness required for wirelessdelivery. This could increase the utilityof RBDS's TDC (transparent data chan-nel) or other functions. So far, RBDSdata has been limited to short text mes-sages or ASCII files. A one-way, wireless,binary file transfer function could allowserious computer data downloads; sucha protocol is critical to any future infor-mation superhighway "off ramp" or realdatacasting application for broadcast-ers. Although true wireless computingrequires a 2 -way, point-to-point link,there may be marketable uses for one-way, point-to-multipoint data -file down-loading, such as database updating ornavigational/mapping services.
A specific commercial application forRBDS data is the MusicBoard systemfrom Specialized Communications. Thisservice downloads the name of thecurrently airing song title and artist toan active billboard display promotingthe station. The billboard features alarge lighted display (similar to a time/temperature or news headline banner)set inside a huge, stylized car radio face-plate with the legend "Now Playing onMOM" During commercial breaks, thedisplay runs generic promotional text.
A company called Terrapin has de-veloped a different kind of locating re-ceiver that does not use GPS but insteadtracks the 19kHz pilot frequencies ofseveral FM stations in a given market,and triangulates a location based onreceived phase deviations. The system,called Position Information NavigationSystem (PINS) can obtain reasonablepositional accuracy, but is limited bythe frequency drift inherent in FM pilot
signals. Correction data to compensatefor this drift can be transmitted to PINSreceivers in a given market via the RBDSsubcarrier of one FM station in the mar-ket. With this correction data, positionalaccuracy down to 10m can be achieved.Other RBDS data also can be receivedby a PINS receiver, allowing it to com-bine location and text information on asingle display.
Unlike GPS, PINS can be used in urbancanyons and even indoors. Each re-ceiver is addressable, and a PINS mod-ule can be built into a portable phone toprovide Mobile 911 (M-911) service.Under this proposed system, a portablephone can automatically report its po-sition to emergency services when 911is dialed. Terrapin also foresees wire-less computing and IVHS applicationssuch as location adaptive databases(smart yellow pages), plus a number ofinteresting 2 -way services when com-bined with a mobile telephone (such asautomatic vehicle location, traffic con-dition reporting or paging with mes-sage -received acknowledgments).
Terrapin's approach is really a plat-form for RBDS rather than a service.Along the same lines, Modulation Sci-ences has developed a line of general-purpose RBDS receivers that can out-put the full RDS or RBDS data set. Thereceivers, called the RDS-X series, arefully addressable, or they can be made"pseudo -addressable" by only respond-ing to RBDS signals accompanied by anidentifying beacon (similar to the use oftone -squelch in 2 -way radio systems).The receivers can also provide FM au-dio output and diversity reception. Theyare targeted at the industrial market-place, and their availability may encour-age other new service providers to en-ter the marketplace using these receiv-ers as their customer platforms andconfiguring them as needed.
Nevertheless, at least some of theproposed services and systems de-scribed in this article may achieve suc-cess, and with it bring some early re-turns to FM broadcasters who haveimplemented RBDS.
For more information onRBDS services, circle thefollowing on Reply Card:
ACCQPOINT (74)Axcess USA (75)Coupon Radio (76)Differential Corrections (77)Milestone Technologies (78)Modulation Sciences (79)Sage Alerting (80)Specialized Communications (81)Terrapin (82)
Circle (19) on Reply Card
16 BE Radio July 1994
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RE: Radio
IIIhere is a new technology avail-able for AM directional antennadesign that can dramatically re-
duce land and capital equipment costs.Instead of using two towers, for example,many applications could simply use onetower and a hot guy wire. Theoretically,for a new station, this technique wouldrequire roughly half the land and halfthe number of towers compared to con-ventional design. It might also be usedwhen modification of an exist-ing pattern was required. Bytuning existing guy wire(s) or 79Madding a simple slant wire, astation might be saved from 73Mhaving to relocate its antennasite, as is often required for suchmodifications.
This hot guy wire technologyhas been proven outside of theUnited States, but the FCC hasyet to accept it. The commis-sion requires certain traditionalformulas to be used to calcu-late radiated fields. Althoughexceptions have been allowedin the past, additional measure-ments are usually required toprove that what the antennadesigner has predicted is trueif the standard formulas appearto be violated.
Studies indicate that betterskywave radiation predictionscould be obtained using suchmoment -method antenna designthan with the existing FCC for-
Bingeman is senior engineer at Continental Elec-tronics. Dallas. TX. Respond via the BE RadioFAXback line at 913-967.1905
Lower -costdirectional antennasystems
By Grant W. Bingeman
Hot guy wires can make AMDAs more cost-effective.
mulas. The moment -method is consid-ered superior because it makes fewerassumptions and simplifications of thecurrent distribution on the radiatingelements in a directional array. Thisimplies that less actual interference canbe expected at night from directionalantennas designed with the moment -method.
There is now some regulatory activ-ity on this front. A Notice of Inquiry has
been issued under MMDocket No. 93-177
under which theFCC may even-
tually accept
IGH-VOLTAGE moment -INSULATORS method
a n -
tennade -
TUNINGCAPACITOR
65m
---20 #10 GND RADIALS.°
50m LONG
signs in place of the old sinusoidal cur-rent distribution designs. Meanwhile,consultant Clarence Beverage has stud-ied hot guy wire antenna designs forimplementation at WXCT, Hamden, CT.As a result, a Proposal for Rule Makingrecently has been filed specifying thetechnical characteristics of the activeslant wire antenna.
South of the borderThis type of antenna has already been
implemented outside of the UnitedStates. Consider the case of XEWB, a50kW station that desires maximumcoverage in and around Veracruz,Mexico, while reducing signal strengthtoward sister station XEW in MexicoCity (both at 900kHz). To this end, adirectional pattern with a minimum tothe west and a maximum to the south-east is desired. The original 2 -tower ar-ray was at the end of its useful life andwas replaced by a single tower with a
hot guy section. This was achieved bytuning a portion of the northwest
guy wire as a reflector. A variablecapacitor was used near the guy
anchor to adjust the electri-cal length of the guy wire.
(See Figure 1.)XEWB is located north-
west of Veracruz on sandysoil close to the ocean.Comparison of the (hotguy) directional to thenon -directional mea-sured field intensitiesshows a reduction in gaintoward the west of 4dB to5dB, depending on exact
Figure 1. Section view of XEWB tower, showing tofi twp northwest guywires used as directional reflectors.
18 BE Radio July 1994
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bearing, and a maximumincrease of 3.5dB towardBoca del Rio, southeast ofVeracruz. (See Figure 2.)
Thus, the creation of a2 -element directional ar-ray out of a single towerby exciting a guy wire as aparasitic element is a vi-able and economicalmeans of doubling radi-ated power in a particulardirection, and providingprotection on one or twoother bearings. Of course,if the guy wire was fullydriven (via transmissionline, power divider andphasing networks), so thatindependent currentphase and ratio controlwere provided, additionalpattern control would beavailable if needed.
InstallationSome of the following
details of the modificationfrom a 2 -tower to a 1-tower/hot guy configura-tion emphasize currentand voltage concerns because of the high power of XEWB. These would be
moot in thecase of a signifi-cantly lower -power station(5kW or less).
Conversionof the quarter -wave tower todirectional op-eration en-tailed addingjumpers acrosssome of the ex-isting guy insu-lators, replac-ing the remain-ing guy insula-tors with largersizes having ahigher voltagerating, laying20 ground radi-als each 50meters longaround the guyanchor, addinga tuning ca-pacitor be-tween thenexus of thesenew radialsand the bottomof the hot guywire, and ad-justing thetower imped-
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Figure 2. Predicted patternfor XEWB after installationof hot guy wire system. Sub-sequent tuning adjustmentsreduced rear lobe.
ance matcher for the re-duced base resistanceand increased base re-actance.
80 The choice of whatappears to be too smalla number of ground ra-dials bears some expla-nation. The minimumnumber of ground radi-als can be determinedby knowing the RF cur-rent rating of the size ofwire used for the radi-als. For example, if thewire can handle IA with-out undue temperaturerise, and you have 20amperes at the bottomof the guy wire, then youknow that you need at
140 least 20 radials.The second consid-
eration is a compromisebetween efficiency and
cost. An effective empirical approachto this question is to measure the self-
base impedance of the active guy wirewhile radials are added to the circuit(the tower is detuned in the usual man-ner). When the self resistance no longerdrops significantly with increasing radi-als, you have a good compromise. Keepin mind that the existing radials fromthe tower can assist. Thus a "standard"ground system of 120 long radials andanother 120 short radials would clearlybe overkill in this particular hot guywire situation.
For 50kW XEWB, it was decided thatthe guy current was better shared be-tween two guy -wires, so the top twonorthwest guy wires were excited simul-taneously. They were simply jumperedtogether near the anchor and receivedthe same insulator modifications. (SeeFigure 2.) It is important to note that thevoltage gradient at the top of the hotguy wire can be quite high, and requirescareful corona treatment. The insulatorneeds to be a high -voltage type withcorona rings for all but the lowest powerstations. Experiments at XEWB deter-mined that a closely spaced string oflarge (8 -inch long) egg insulators is ad-equate for no more than 10kW withmodulation for the given tuning. Otherpatterns and guy wire configurationsmay limit this to 5kW.
Theoretical antenna analysis indicatesthat a reflector configuration is pref-
Continued on page 22
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Circle (7) on Reply Card
1' 11:l I'rocc'.c.sing continued from page 12RE: Radio continued from page 20
erable to a director arrangement, based on current/voltagestresses and bandwidth. Nevertheless, if a director is re-quired, it can easily be produced by adjusting the guy wiretuning reactance, or using a shorter portion of the guy as theactive element.
Application notesA weatherproof tuning box and a fence need to be erected
around the hot guy wire anchor, because considerable volt-age may be developed across the guy wire's bottom insulator.It is a good idea to provide an RF ammeter in series with thetuning reactance, and sampling for the antenna monitor.
In general, in order to avoid uncommonly high voltages andcurrents, and possible bandwidth problems, it is good prac-tice to keep the guy wire base current below the level of thetower base current. At XEWB, guy wire current was about 80%of tower current. More gain can be obtained with highercurrents, but the cost of increased insulation, bigger compo-nents or bandwidth treatments may not be justified for a tewtenths of a dB higher gain.
Using a guy wire as a radiating element in a directional arraywill require fewer towers and thereby shrink an antenna site'srequisite dimensions. The consequent reduction in capitaloutlay and debt service for land allows more room for profitat the radio station.
Acknowledgment: The author wishes to thank Sr. Miguel Barrientos of &sterna Radiopolisand Sr. Aguilar and his staff at XEWB. Thanks also to the Secretaria de Comunicacionesy Transportes (Mexico's FCC) for their cooperation and foresight.
Editor's note: For further technical information see "An Economical Directional Antennafor AM Stations." 41st Annual Broadcast Engineering Conference Proceedings (NAB1987).
BE RadioReader FAXback
We want to know what you think. Faxyour comments to the BE Radio editors
at 913-967-1905
provided by the processor manufacturer. This allows engi-neering and programming staffs to adjust a processor lo-cated at the transmitter site while listening in a controlledenvironment at the studio (or elsewhere).
Implementation issuesInstallation of FM audio processors varies, depending upon
a number of factors. When the studio and transmitter are co -located, the processor is generally placed in a rack adjacentto the exciter/transmitter. The cable run containing the com-posite signal should be kept as short as practical between theprocessor and exciter input. Where long runs cannot beavoided, a composite signal distribution amplifier may berequired, along with use of the exciter's balanced input or anexternal isolation transformer (to maintain signal levels andguard against the introduction of ground loops).
Some radio formats can tolerate a reduction indynamic range more transparently than others.
When the transmitter site is at a remote location, a studio -transmitter -link (STL) must be employed, using either an RFpath or leased telephone circuit(s). Either analog or digitaltransmission can be implemented, and signals may be deliv-ered to the transmitter as discrete left audio, right audio andsubcarriers, or as a composite signal ready for transmission.
With analog aural STLs, a discrete system will yield bettersignal-to-noise performance at greater distances than a com-posite approach because less bandwidth is required. Thismeans that audio processing equipment must be located atthe transmitter site, making the comprehensive (PC/modem)remote control available in the latest generation of audioprocessors all the more valuable. Subcarrier equipment,including RBDS, must also be located at the transmitter underthis scenario. In addition, some peak protection or prepro-cessing must be placed in front of the STL transmitter toprevent overdeviation of the STL system. Similar concernsexist with equalized telco STL circuits.
A composite analog RF system allows all processing equip-ment to be kept at the studio, which can be advantageous,assuming that the STL signal-to-noise is still acceptable.Composite digital transmission is possible using T1 telcocircuits or 23GHz RF links. The bandwidth limits of 950MHzaural STLs will not allow composite digital signals. In fact,they can only allow transmission of discrete digital signalswith the use of bit -rate reduction via perceptual codingtechniques.
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The processes of digital conver-sion, processing and rate reductionall generate delay in the audio path.Although this throughput delay isrelatively low, some operators mayfind it annoying. Of course, it is onlynoticeable when the operator is an-nouncing on -air because that is theonly time when a real-time refer-ence is available. To solve this prob-lem, a matrix can be built that is fedby both the off -air signal and a con-sole program output (the latter mayinclude audio processing). The ma-trix is activated and steered by theconsole microphone logic output.
Continued on page 28
22 BE RadioCircle (9) on Reply Card
July 1994
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However, if you just want to get practicalabout the whole thing, you can look at it this way, too. The CD Autochanger makesaudio programming so absolutely efficient and error -free that your life will be made
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Circle (8) on Reply Card
Anew home forMJI Broadcasting
By John Storyk, R.A.
The Bottom Line: A radio production/syndication house requires a hybrid facilityproviding efficient and high -quality output from parallel administrative and technicaloperations. Its geographic location affects its success, as well. But building any newaudio facility today also calls for some tough decisions on design philosophy, as theindustry teeters on the brink of a virtual digital production environment. Balancingthese diverse elements provided the challenging context for this project.
113 n 1980, MJI Broadcasting debutedRock Quiz, its first syndicatedradio show. Soon thereafter, the
company established itself as one of thecountry's leading suppliers of innova-tive radio programming. By 1992, MJIwas the second largest radiosyndicator in the UnitedStates, carrying 13 programs(including The GrammyAwards and The Country &Western Awards) fed to morethan 2,000 stations with a to-tal of 20 million listeners.
That same year, MJI movedto its new 15,000 -square footheadquarters in New YorkCity. Every media facility pre-sents design challenges, andthis one was no exception.
As usual,not enough space
Several months were spentoutlining the exact programrequirements for the new of-fices and production facili-ties, and simultaneouslysearching for a suitable newlocation. Like many success -
years to accommodate MJI's projectedgrowth.
As is often the case, the best physicalpiece of real estate is not always thebest financial deal. The search resultedin the selection of an approximately
Control rooms at allow simple reconfiguration for integration offuture technologies.
ful companies, MJI's growth had oc-curred during its previous 12 years witha minimum of attention paid to physicalneeds. At last there was an opportunityto plan intelligently for the future. Ex-pansion forecasts indicated that be-tween 16,000 and 20,000 square feetwould be required during the next five
Storyk is principal designer at Walters-Storyk Design Group,Highland, NY.
15,000 square feet parcel at 1290 Av-enue of the Americas, one of Manhattan'sbest mid -town addresses for the enter-tainment business (home of RollingStone,Atlantic Records and SBK Records).
Analyzing MJI - the businessAn important starting point for any
design is a block diagram of the space.MJI operates in several business areassimultaneously, so diagraming its func-
tions and programming the space waschallenging.
MJI's producers create shows by read-ing, phoning, writing, and then ultimatelyrecording and post -producing them inradio production studios.
The technical staff workswith producers to create theshows as well as edit, recordand produce all aspects ofthe finished programs. MIhas a number of differentshow formats, each withslightly different recordingrequirements. Four com-pletely isolated radio pro-duction studios were in-stalled, and the basic wallswere erected for a futurefifth suite (to be completedthis year). Analysis of exactprogramming needs re-sulted in only two of the fivesuites requiring voice-overbooths.
Maximizing pre -produc-tion functions enabled MJIto achieve an exceptionallyhigh yield of shows per re-cording/production suite.
In previous MJI facilities, pre -produc-tion has always ended up in windowlessback rooms or even corridors on occa-sion. The new space allowed this criti-cal staff function to be situated in a farmore pleasant environment.
MJI's libraries had been scatteredthroughout spare corners of their ear-lier facilities. Over the years, interviewsand programs had accumulated (at arate of about 30 per week), along with a
24 BE Radio July 1994
large record, tape and CD collection.This material is one of the operation'smost valuable assets. Today, a profes-sional librarian administrates this col-lection in one central room.
Traffic flowNothing happens in business without
sales. MJI is in the barter syndicationbusiness - they "trade" completed ra-dio programming for portions of eachstation's advertising time. Monitoringaffiliated stations and sales of the MJI-produced radio shows essentially hap-pens in a telemarketing environment.
It is to the company's credit that ex-ecutive and administrative space occu-pies so small a percentage of the entirecomplex. M.11 president Josh Feigenbaumhas the classic Manhattan high-rise cor-ner office with windows facing the cel-ebrated Museum of Broadcasting acrossthe street.
MJI's programs are created by pro-ducers working with pre-recorded ma-terial and numerous in -studio inter-views. These efficient ("one take") inter-views take place in one of three studios.Guests rarely visit MJI's "back rooms"(usually there is not enough time intheir schedules). The interview roomsand the handsome conference roomhave become a core of the facility.
All flow in and out of MJI takes placehere - guests, deliveries, and so forth.Groupedwith thesespaces area smalllounge,kitchen.mail room.traffic andother sup-port rooms.
Designconsid-
er-ationsAfter
Figure 2. Plan view of control room 2, with raytrace analysis. Note that operator position isfree from first- orsecond-orderspecularreflec-lions caused by vertical room boundaries.
was one reason for selecting this par-ticular site. Most of the offices alonginternal corridors have overheadclerestory lights (interior -wall win-dows) to allow daylight into the non -perimeter spaces of the facility. In thepre -production area, even more inte-rior wall glass is used making thespace more open and providing apositive effect on operations. Theexceptions are the studios for whichMJI engineers preferred not to have
DIFFUSORS(RPG)
L
Figure 1. Section view of control room.
some time, the transformation of a spaceflow diagram into an actual buildingfloor plan took place. Several underly-ing design considerations were agreedto early in the development stage:
1. The need for efficient work spaceswas predominant.
2. Technical considerations should bemerged with creature comforts in stu-dio suites and interview rooms. Workat MJI is intense at times, so a relaxedworking environment provides a wel-come counterpoint.
3. As much natural daylight for as manystaffers as possible was desired. This
daylight. Isolating radio productionsuites on a New York City exteriorbuilding wall is possible, but not with-out considerable expense.
MJI's design offers a combination of richwoods in the public areas along withmore technical finishes in the produc-tion and technical areas.
Technical production roomsMJI's radio production suites are as
interesting a challenge in acoustical andarchitectural design as would be ex-pected for a project of this scale. Afterdeciding not to have natural daylight instudios and control rooms, their loca-tion in the master plan was determined
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July 1994 BE Radio 25
quickly based on functionality. Theywould be close to production and thelibrary.
All of the control rooms are identical,both ergonomically and acoustically.For the past 10 years, MJI has producedshows by assembling mostly V4 -inchtape elements and integrating them withvinyl, or more recently, CD recordings.All rooms were configured for this equip-ment: up to four '/4 -inch tape recorderssurround a mixing console with easilyaccessible, built-in processing equip-
ment racks and mid -field monitors.All electric power for the production
area comes from a 30kVA isolation trans-former. Low -voltage wiring for the roomsis surface -mounted in troughs aroundthe front and side walls. Therefore, allequipment and associated wiring canbe installed and modified quickly. It wasimportant that the production suitedesign accommodate anticipated digi-tal workstation installation in the nearfuture. The surface -trough system forlow -voltage wiring ensures the efficiency
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of this changeover.Two of the recording suites have iso-
lated recording booths with Kineticsroll -out floating floors. (See Figure 1.)Used only for voice-overs, the boothsare non -reverberant.
Each control room employs near/mid-field monitoring with an expansive ceil-ing configuration. The rear walls arediffusive. Front and near side walls use2 -inch high -density, cloth -covered fiber-glass panels. Figure 2 shows the raytrace diagrams for a typical suite. NoiseCriteria ratings for all recording andlistening rooms are NC25 or better.
Building in New York City -always a thrill
Everyone has heard stories aboutconstruction in Manhattan. For the mostpart, they're true. In this case, a fewother elements presented an evengreater challenge:
I. Union construction crews were re-quired in this building - one ofManhattan's most prestigious mid-town locations.
2. MJI gave the builder 12 weeks to com-plete the entire job.
3. Relatively strict background/environ-mental noise and room -to -room soundisolation requirements were made forthe technical spaces, particularly dif-ficult in midtown, high-rise construc-tion.
I. By New York City standards, theproject had a tight budget, at lessthan $60 per square foot.
MJI was truly a fast track project.Some early site -preparation and con-struction work began even beforecompletion of final design drawings. Areal team effort was required to sur-mount the many challenges posed bythe project.
Design team:
Architectural/Acoustical Design:Walters-Storyk Design Group, High-land, NY. John Storyk, Beth Walters.
Electrical/Mechanical: RobertWolsch & Marcy Ramos, Engineers,New York, NY.
General Contractor: OD&P Con-struction, New York, NY.
Et,Circle (23) on Reply Card
. u BE Radio July 1994
1.
W understand whybroadcast engineers havea wait -and -see attitudeabout new products. Yourstation (and job) depend onrock -solid reliability andperformance you cancount on.
We'd like to introduceyou to Mackie Designs.Over the last six years,we've gained a seriousreputation for buildinghigh -value, trouble -freemic/line mixers withlegendary head-room, ultra -lownoise and uniquefeatures.
Mixers so goodthat they're regularly usedto create major labelcompact discs, featuremovie soundtracks, andmore commercial produc-tion work than you canshake an RE20 at Forexample, our CR-1604 16-
ch. micnine mixers areused nightly on the TonightShow, Conan O'Brian andDavid Letterman Shows'.
As for use at broadcastfacilities, well, we're nottotal newcomers. Over 70U.S. radio stations alreadyhave Mackie micflinemixers in place.
Does that mean youfolks aren't quite asconservative as everybodysays? If so, call yourfavorite broadcast supplyhouse, or dial us toll -freefor complete informationon Mackie's line of mixers.
If you are conservative,keep an eye on us, anyway.We want your businesseven if we have to waitfive years.
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Individualchannel signalmetering via solofunction.
7 AUX Sends from 4 knobs.AUX 1 doubles as a headphonemonitor cue via the MONSends 3 & 4 become A UAS5 & 6 via the SHIFT. button.
Two extra buses. Mute buttonsroute the channels' signals to.. nextra stereo bus called A LT 3/4Route it to the headphones, formonitoring advance audio cuesPreview a signal that hasn't beenbrought up in the mix yet...then add it by unmutingthe channel.
UnityPlus gain structure gives highheadroom and low noise at the sametime. Set the fader to center -decentUnity Gain, press channel solo tomonitor the channel via theCR-1604's LED meters, adjust theinput trim ONCE, and you reready. because there's 20c1f3MORE gain available on thefader, you won't need toconstantly re -adjust the trim. r
Maximum RF protection. Bothmixers use metal jacks and washersplus a shunting capacitor to de -railRF before it gets to any circuit,traces.
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Better -than -digitalspecs and /1! artroostBoth the 16-ch. CR.1504and 12-ch. M51202 have adynamic range of 105d5 and aninternal 5//4 ratio cf -116d5. You'regetting a rrixerthat can handle theoutput of cl:gital workstations,COs and DAT tapes withoutoverload.
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Circle (24) on Reply Card
FM Audio Processing continued from page 22
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When the microphone is off, the operator monitors off -air,but when the microphone is on, the operator hears a (pro-cessed) non -delayed program signal. It is desirable to includeaudio processing on the non -delayed feed so that the opera-tor can make mixing judgments while listening to a sound thatapproximates the on -air processing.
Some final pointsWhile a single box that does all has been assumed for the
purpose of this discussion, it is by no means the only solution.Multiple complementary pieces of equipment can also beused. Particularly in analog systems, stand-alone limiters,compressors, special -effects processors and stereo genera-tors are offered. Even with a single -box audio processor,some special-purpose outboard devices may still be useful,such as composite processors and filters or stereo -imageprocessors.
Without careful attention to the entire airchain, even the best processors will fail to
perform at their peak.
Also remember that audio processors are not the onlydeterminant of the radio station's sound. Without carefulattention to the entire air chain, even the best processors willfail to perform at their peak. Interfacing between devices isalso important, and the audio response of the entire systemmust be as linear as possible below 10Hz to minimize over-shoot. (When overshoot is present in the system, the proces-sor must be operated more aggressively to maintain peak
control, and so begins the spiral toward overprocessedsound - ultimately destroying the original intent of usingaudio processing in order to stand out on the dial.)
With so many choices available today it may seem adaunting exercise to settle on the right audio processor(s)for your station, but it can be done. Remember that formfollows function, so consider all the influential elements -the station's format, its transmission system, the process-ing features required, and, of course, the station's budget- when making your decision. The right processor choice,its proper installation and smart operation will guaranteea great sound that stays legal, keeping both the engineerand the programmer happy.
For more information on FM audioprocessors, circle the following numbers
on Reply Card. See also "DynamicsProcessors," p. 54 of the BE Buyers Guide.
AEV SNC di Vaccari G.& C. (66)Aphex Systems (67)Circuit Research Labs (68)Cutting Edge Technologies (69)Gentner Communications (70)Inovonics (71)Modulation Sciences (72)Orbzn Associates/AKG Acoustics (73)
Circle (25) on Reply Card28 BE Radio July 1994
EW PRODUCTS
RDS/RBDS decoder/monitor/analyzerModulation Sciences PRD-3000: PC -based RDS/RBDS monitor that checks andanalyzes all aspects of a station's RDS transmission. Accuratelymeasures RDS injection level and decodes and displays allRDS/RBDS data. Supplied with software that runs on any com-patible PC and features advanced analyzer functions, select-able error detection, and easy operation with menus andmouse support.
Circle (150) on Reply Card
Improveddigital audioworkstationDigidesign Software version1.5 of the Session 8PC: integrates ran-dom access 8 -chan-nel direct -to -diskdigital recording,multichannel digitalmixing and sequenc-er -style digital audioediting; featuresstrip silence, regionbin auditioning with a mouse click, shufflemode in the edit interface, backup capabil-ity, the ability to use locate points as gridand the ability to trim regions with themouse even if handles lie outside the waveview; interfaces with popular Windows MIDIsequencers; compatible with MPU-401 stan-dard MIDI interfaces.
Circle (152) on Reply Card
RDS/RBDS data receiversModulation Sciences RDS-X series: a complete RDS/RBDS data receiver that receives and outputsany and all RDS or RBDS data groups along with composite baseband anddemodulated audio. The receiver can be used to feed billboards and signs infixed and mobile applications, control lighting in remote locations. providereturn telemetry, manage power line loads, and distribute emergency mes-sages and data. Features addressability, beacon tuning, alternative frequen-cy switching and group filter capabilities.
Circle (151) on Reply Card
Digital audioworkstationTimeline
StudioframeDAW-80: uses tech-nology based onthe industry stan-dard Intel/Win-dows platform; offers 8 -tracks of recording andediting capability, which will be expandable to a 32 -track system; features icon -driven editing, which isinterfaced into multimedia production and post -production.
Circle (154) on Reply Card
_.ea- I
crownIND
I.
Integrated transmission systemCrown Broadcast FM200: a user -adjustable 20-200W low -power FM trans-mitter; provides built-in audio processing, stereo gener-ation and reliable backup transmission capabilities;suited for network a 3plications; user -selectable in the87-108MHz range and offers an optional range of 65-73MHz; powered by 100/120VAC, 220/240vAC or 36-48VDC power with a built-in power regulator; availableas transmitter only, :ransmitter with sterec generatorand transmitter with stereo generator and audio pro-cessing; features laser -trimmed analog multipliers, dig-itally synthesized subcarriers and crystal -controlledswitched capacitor filters; offers frequency stabilitybetter than +/-250Hz from 0'-50'C; automatic controlcircuitry provides p,otection.
Circle (153) on Reply Card
July 1994 BE Radio 29
New Products Continued...
Broadcast audio consoleOtari B-10: a small audio mixer designed for broadcast and audio post-production facilities; 18 -bus console uses narrower (30mm) inputmodules; features channel grouping up to four groups for flexibleconsole configuration, enhanced talkback functions with a total offour talkback outputs and talkback output routing to the program buswhen not in the on -air mode; the high-level input on the group moduleprovides cascade connections with other mixing consoles; directoutput from the group module allows for 8 -track recording; includeseight VU meters and a correlation meter, high -reliability XLR connec-tors and a 2 -way power supply.
Circle (155) on Reply Card
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here are moments in the course of a manufacturingCompany's life that become historical milestones, not only
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over to contact its Dealers for detailed information,as well as to verify, in the course of a hands-on
demonstration, the meaning of the word "extraordinary".
Digital cartridge machinesFidelipac Dynamo( DCR1000 series: the record-er offers selectable sampling rates, sec-ondary and tertiary cues, start on audioand direct digital dubbing from CD viathe standard AES/EBU digital inputs; aPC keyboard is included for titling andediting.
Improved version incorporates a new25MB floppy disk drive from NEC; it isbackward compatible; can play andrecord the 13MB and 2MB floppy disksused previously in the DCR1000 series;the disks can store more than 10 minutesof stereo audio with a 15kHz bandwidthon a single disk; disks can be recordedwith up to 99 cuts per disk.Another new version incorporates a
Magneto -Optical (MO) disk drive using31/2 -inch MO diskettes; the 128MB dis-kettes are recordable and erasable andcan store more than one hour of stereoaudio; will be available in the fall with anoptional 230MB drive.
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Upgraded audio analyzerPotomac Instruments AA -51: features automatic total har-monic distortion measurements, shield-ed active balanced inputs, a frequencycounter, a 0.03% (full scale) S+N/N mea-surement range, a noise floor less than-92dBm, a reference set level control, 0.1%wow and flutter sensitivity, switchablehigh-pass and low-pass filters and head-phone and scope input monitor jacks.Owners of AA -51 audio analyzers havethe opportunity to upgrade the hard-ware on their instruments for half thecost of a new one.
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HeadphonesDeno', AHD -950: an over -the -ear, closed -typeheadphone; driver system uses 50mmvaporized diamond diaphragms driv-en by 6N-OFC (oxygen -free copper)voice coils that are 99.9999% pure andhoused in Neodymium; the driver hous-ings are made of a rigid yet dampedplastic with high specific gravity; the10 -inch connecting cord is made of thesame wire as the voice coils; offersfrequency response of 2Hz to 31kHz,30f1 impedance, sensitivity of 106dB/mW and power handling of 1,500mW. AHD -750: an over -the -ear headphonewith non -resonant body housing andultrasoft oval ear pads; has 50mm diameter diaphragmsmade of vaporized titanium; offers frequency response of2Hz-30kHz, 3011 impedance, sensitivity of 106dB/mW andpower handling of 1,500mW. AHD -650: closed -type headphone with non -resonanthousings and large, oval ear pads; has large 50mm dia-phragms; features Neodymium magnets and high -purity,linear crystal oxygen -free copper voice coils; offers fre-quency response of 3Hz-29kHz, 3511 impedance, sensitiv-ity of 106dB/mW and power handling of 1,200mW.
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RDS tunerDenon TU-65ORDS AM/FM tuner 8 -characteralphanume-ic display shows call lettersor ID/logo. providirg instant verifica-tion of tralsmitted codes and messag-es. Program Type (PTY) codes are usedfor search-:uning based on a user -se-lected typE of programming. Also dis-plays acctaate clock time as broadcastby the station and features FM IF band-width switch for higher selectivity un-der crowded dial reception conditionsor lower d.stortion when stations arcmore widely separaed.
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IT'S NEW!BE Radio's
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EUIPMENT WANTED
WE NEED YOUR HELP!Non Commercial - Non ProfitChristian Music Radio Station
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CONTACT: RANDALL CHRISTY(405) 265-4392
P.O. Box 1343, Ada, OK 74820
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