Radio World Engineer Extra - Oct 20, 2021

Welcome to the

Oct 20th, 2021

issue of Radio World Engineering Extra

I T ’ S A L L I N W H E AT N E T- I P

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In-depth technology for radio engineers

radioworld.com | October 20 2021 | $5.00

The joy of ferrite toroids Used properly, these donuts can give your gear some important extra protection.

New RFR rules

Stephen Lockwood on their implications for broadcast.

No weak links!

Audio performance testing on the cheap.

Simple solutions

Don’t jump to hasty, unsupported conclusions when managing a problem.

Vol. 45 No. 26 | Octobter 20 2021 www.radioworld.com FOLLOW US www.twitter.com/radioworld_news www.facebook.com/RadioWorldMagazine CONTENT Managing Director, Content & Editor in Chief Paul J. McLane, paul.mclane@futurenet.com, 845-414-6105 Senior Content Producer — Technology Brett Moss, brett.moss@futurenet.com Technical Advisors Thomas R. McGinley, Doug Irwin Technical Editor, RW Engineering Extra W.C. “Cris” Alexander Contributors: Susan Ashworth, John Bisset, James Careless, Ken Deutsch, Mark Durenberger, Charles Fitch, Travis Gilmour, Donna Halper, Craig Johnston, Alan Jurison, Paul Kaminski, John Kean, Peter King, Larry Langford, Mark Lapidus, Jim Peck, Mark Persons, Stephen M. Poole, James O’Neal, Rich Rarey, Jeremy Ruck, John Schneider, Dan Slentz, Randy Stine, Tom Vernon, Jennifer Waits, Chris Wygal Production Manager Nicole Schilling Managing Design Director Nicole Cobban Senior Design Directors Lisa McIntosh and Will Shum ADVERTISING SALES Senior Business Director & Publisher, Radio World John Casey, john.casey@futurenet.com, 845-678-3839 Publisher, Radio World International Raffaella Calabrese, raffaella.calabrese@futurenet.com, +39-320-891-1938 SUBSCRIBER CUSTOMER SERVICE To subscribe, change your address, or check on your current account status, go to www.radioworld.com and click on Subscribe, email futureplc@computerfulfillment.com, call 888-266-5828, or write P.O. Box 1051, Lowell, MA 01853.

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The right solution is often the simplest

Then if you can’t figure it out, proceed to the unknown

I

t’s no secret that I love all things aviation. There’s nothing better in my view than slipping the surly bonds of earth and launching into an azure sky of still, smooth air and watching the earth move beneath my wings.

Cris It should be no surprise, then, Alexander that I subscribe to a stack of aviation CPBE, AMD, DRB magazines.

Director of In AOPA Pilot a few months ago, engineering, columnist Natalie Bingham Hoover, Crawford writing about diagnosing and solving Broadcasting problems with general aviation aircraft, hit upon a principle that has great application in broadcast engineering.

Comment The writer asked her aircraft on this or any story. Email mechanic the secret to his ability to rweetech@ diagnose and isolate aircraft problems gmail.com. so quickly.

His response: “It’s simple. Always start with the easiest solution. And if you still can’t figure it out, then go from the known to the unknown.”

Those words just about jumped off the page at me.

They describe, in a nutshell, the process I have used for 40+ years in troubleshooting broadcast systems and equipment. Before I’d read that, if asked I would have been hard pressed to describe it so succinctly.

Train wreck Years ago, we had a young resident engineer living at the transmitter site of our Los Angeles radio station, which was a three-tower 10 kW directional AM. This young man had a good head on his shoulders but he didn’t have a lot of directional AM experience … okay, he didn’t have any. But he was willing to live alone at a transmitter site on an island off the California coast and keep an eye on things.

Please recycle. We are committed to only using magazine paper which is derived from responsibly managed, certified forestry and chlorine-free manufacture. The paper in this magazine was sourced and produced from sustainable managed forests, conforming to strict environmental and socioeconomic standards. The manufacturing paper mill and printer hold full FSC and PEFC certification and accreditation.

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THIS ISSUE THIS The right 3 ISSUE solution is

often the simplest

NEWS

Ferrite xxx xxx toroids can be an engineer’s best FEATURES pal xxx x Understand xxx 14 these new RFR BUYERS rules

x 8

GUIDE 19 x

xxx xxx Marketplace

OPINION Audio 20

xxx performance x testingxxx on the cheap

From the Tech Editor One day he called me and said that the whole directional pattern was screwed up. None of the parameters were anywhere close to correct. It was a train wreck. I could hear the near-panic in his voice as he conveyed the situation to me.

I didn’t know that array well at the time. It was a 1952-vintage system and used a tank-type power divider with jeep coils, something I had no direct experience with.

But in an effort to calm the new engineer down, I started asking some questions: Is the station on the air?

Yes, it’s on.

What is the common point current?

It’s normal.

How is the transmitter behaving? What are the meters telling you?

It looks about like it always does.

With that short exchange, I began to get a picture of an array that seemed to be operating normally despite the antenna monitor indications.

I suspected a sample system problem, and because it was affecting the indicated parameters for all the towers,

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I thought that the problem might be in the sample for the reference tower.

To confirm this, I sent the engineer out with the field intensity meter to look at all the monitor points, not an easy task on that island. This job was a half-day affair with a lot of off-roading to interesting locations.

A few hours later, he called: monitor points normal.

That sealed it. The array was fine. We were dealing with a sample issue.

I grabbed some test equipment, caught a flight out to L.A., took a helicopter to the island and within a very short time had found the issue: a shorted (or mostly shorted) sample line to the reference tower.

“

When a problem erupts we tend to think the worst, but we have to discipline ourselves not to jump to a conclusion.

MEANS MORE

THAN EVER

BEFORE NATEHOME.COM

”

From the Tech Editor

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Above Pushing the reset button is a good place to start, a simple, easy step that just might solve the problem.

Fixing the problem took a lot longer than finding it and involved a lot of digging. But we did find the buried lines, identified the one with the problem and spliced in a new piece, replacing a 3-foot section that had gotten waterlogged. After that, all was well on the monitor.

When something like that happens, we tend to think the worst, and sometimes it is the worst. But we have to discipline ourselves not to jump to that conclusion.

We have to start with the easiest solution and work our way through to the harder stuff. We must eliminate the things we most easily can first and go from there. And whether or not a particular troubleshooting step identifies the issue, it is not wasted. With each step we remove one variable from the equation.

If, on the other hand, we jump to an unsupported conclusion and start turning knobs, we add a whole bunch of new variables … unless, of course, we get lucky and somehow manage to hit on the cause of the problem by accident. Hey, it happens.

Known to unknown But suppose that we have eliminated all the easy stuff and still haven’t isolated the problem. What then?

That’s where the “known to unknown” process comes into play.

If you can find a similar part, device or circuit that is working correctly and compare it to the one that’s not, you may well be able to figure out the problem.

It may be a matter of subbing in a known good part or board to see if that makes a difference. In the case of the directional array problem, it was a matter of comparing the TDR display of a known good sample line to that of the suspect line.

If it’s not possible to compare or substitute components or assemblies, another option is to compare voltages, currents, waveforms or impedances to known good values or examples.

In days gone by, manufacturers would often note such known good values on the schematic or in notes.

Experienced engineers, after completing a project, often record such values in a notebook, a log or even a note affixed to the end of a transmission line. Those benchmarks can help isolate a problem.

The point is that jumping to unsupported conclusions or performing troubleshooting steps out of order is a waste of time, effort and a psychological drain.

Going back to the aviation mag column, the writer concluded by saying that “with our airplanes, like so many things in life, the first step in solving a problem is simply believing we are capable. After that, a little common sense helps. And … remember that the right solution is often the simplest one.”

That has certainly been my experience over the years.

radioworld.com | October 20 2021

Tips & Tricks Writer

Ferrite toroids can be an engineer’s best pal

Proper use of ferrites can go a long way to protecting your equipment

Jeff Welton Sales Manager, U.S. Central, Nautel Ltd.

Below Ferrites, at bottom center, are seen in a transmitter installation.

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O

ne of the best tools in the engineer’s lightning protection toolbox is a tried, true and frequently underutilized friend, the ferrite toroid.

The principle is quite simple. If you have two (or more) conductors passing through a ferrite, such that the net sum of their currents is zero, then the ferrite is an inert object, just sitting there waiting for something to happen.

If, as in the case with a surge or lightning strike, the current on any conductor increases, such that the net current is no longer zero, then the ferrite core saturates, creates a magnetic field and attempts to induce an equal and opposite current flow in the other conductor(s) — in effect, trying to maintain the zero net total current.

For this reason, ferrites are a very good tool in many ways, not the least of which is lightning protection. Used on a coaxial cable going out to the antenna system, they can also be useful for finding ground loops.

If you have a ground loop, such that not all of your return current is through the coax shield, the ferrite will saturate — and quickly (depending on the amount of the imbalance between feed and return) get physically warm … in extreme cases, I’ve even seen them explode!

Easy to install You want ferrite toroids at the output of the transmitter, preferably before the point where the coax shield is connected to the station reference ground (usually where the coax enters the building, but not always, so keep an eye

Tips & Tricks

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out). The photo in the image on page 6 was taken at an AM site.

In the course of the installation, ferrites can and should be placed on pretty much every current-carrying conductor, including AC lines, remote control feeds and audio/AES lines (don’t forget the STL antenna cable).

Nautel provides a handful with every transmitter that goes out the door, to ensure your installation isn’t held up for want of some basic protection. Talk to your sales rep if you think you need more.

For any cable where there is a safety ground connection (for example, the antenna feedline ground referenced above, or an AC mains surge protector), ensure the ferrites are installed between the ground and the equipment being protected. That makes the reference ground connection look like a better path than the equipment, by raising the effective impedance lighting or surge current has to overcome to get to the equipment.

The second photo is a 5 kW AM transmitter installation showing ferrites on control, monitor, RF sample and Ethernet cables.

Ultimately, for the purpose of common mode protection (trying to keep feed and return currents equal), size and permeability are somewhat less important than if we were making a choke by wrapping a single conductor around the toroid.

Another use for toroids is helping to reduce pickup (for example, the RF from your AM station getting onto the audio feed for your FM station). The principle is much the same as for lightning protection: The ferrite will help to

“

Above Ferrites, top left, are used on control, monitor and RF sample lines in this Nautel NX5 installation.

filter any signal that is not present in equal amplitudes in both the feed and return paths.

Nautel offers several ferrites that can help, and you can order them via our Parts Quotation Request form at http:// support.nautel.com/parts.

Some useful part numbers: LXP38 — this is a 3/4-inch inside diameter toroid, good for RF rejection and lightning protection on small signal cables.

LP23 — a 2-1/8-inch inside diameter toroid, good for most heavier AC cables and coax up to 1-5/8 inches (as long as the connectors aren’t already installed!)

In the course of LP32 — a 4-1/8-inch inside diameter toroid, good for the really big AC and RF cables (again, this won’t fit over a 3-1/8the installation, inch EIA flange, so keep that in mind when planning) ferrites can and LA52 — a small (1/4-inch inside diameter) clip on ferrite that helps to keep higher frequency (FM) RF out of control should be placed on pretty and signal wiring. Impedance curve shows 320 ohms at 100 MHz, so it wouldn’t be so good for an AM station, but much every current-carrying definitely useful for a higher power FM. Before being named sales manager for Nautel’s U.S. Central conductor.

Region, the author spent 16.5 years as a customer service technician for the company.

radioworld.com | October 20 2021

Regulatory Update Writer

Understand these new RFR rules

They don’t change exposure limits but you should understand their implications Stephen Lockwood P.E., PMP President, Hatfield & Dawson Consulting Engineers

T

he FCC recently adopted Docket No. 19226, “Human Exposure to Radiofrequency Electromagnetic Fields and Reassessment of FCC Radiofrequency Exposure Limits and Policies.” These new rules became effective May 3, 2021.

This rulemaking has three main parts. The first issue was the resolution of the notice of inquiry from 2013 that asked whether radio frequency exposure limits should be changed. The second was a report and order with new rules for RF exposure. The third was a Notice of Proposed Rulemaking for additional modification to the RF exposure rules.

The major takeaways:

• There have been no changes to the existing exposure limits. This process included input from more than 1,000 commenters and participation from other federal agencies including FDA and EPA). The conclusion: “After reviewing the extensive record submitted in response to that inquiry, we find no appropriate basis for and thus decline to propose amendments to our existing limits at this time.”

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• New rules have been adopted. The critical part of these rules that affect broadcasters is how to assess RF exposure compliance and how to communicate about RF hazards.

New and modified facilities must comply with these rules after May 3, 2021, and existing facilities will be given until May 3, 2023 to come into compliance.

• New rules are proposed to address changing technology that would extend the frequency range from 100 GHz to 3,000 GHz, localized exposure limits and assessment methods. These issues do not pertain to broadcasting.

Evaluation of RF exposure Right Denny Todd is shown on Black Mountain near Las Vegas, wearing a Euclid Garment RF suit, in an undated photo from the archives of Richard Tell Associates.

The FCC has adopted new methods to determine and demonstrate compliance to replace specific outdated and inconsistent rules.

There are three sections: • Exemption: This is for devices that are “so clearly compliant,” as demonstrated by a simple calculation to show compliance with the exposure rules, that they do not require further evaluation (i.e., operation at very low

power or large distance from humans). The former term for “exemption” was “categorically excluded.” Many devices that were “categorically excluded” will now be classed as “exempt.” The former rules were based on service, whereas the new rules are more calculations-based. Broadcast equipment exempted are likely wireless microphones, wireless video feeds, Wi-Fi, cellphones and other lower power devices used in broadcast production.

• Evaluation: This category is for devices or facilities that require some demonstration such as calculations, measurements or computational modeling to demonstrate compliance. For broadcasters, there are not many changes as most facilities required and will still require analysis of RF exposure. All broadcast transmitting facilities need to analyze the facility and need to include other nearby facilities, since compliance is for the site, not just on a perstation basis.

• Mitigation: Where evaluations show a possibility that the exposure limits are exceeded, mitigation is needed to control access to RF exposure. Mitigation is accomplished

radioworld.com | October 20 2021

Regulatory Update by signage, access control, training or other methods to assure that exposure limits are not exceeded. Clear specifications are now given for signage and communications. All facilities that have the potential of producing areas that exceed the exposure limits must have some method of restricting exposure. All areas that exceed the public exposure limits must have some access control to restrict public access to areas that exceed the limits.

Evaluation is performed using site-specific information such as power, frequency, antenna type, physical mounting locations and distance.

These are done by using standard electromagnetic modeling, calculations using the methods laid out in OET65, or use of the FCC’s FMModel program, as appropriate.

Mitigation

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The FCC has adopted four exposure categories that indicate RF exposure circumstances.

These are equivalent to the practices from “IEEE C95.72014 – IEEE Recommended Practice for Radio Frequency Safety Programs, 3 kHz to 300 GHz” and “IEEE C95.2-2018 - IEEE Standard for Radio-Frequency Energy and CurrentFlow Symbols.”

Access control, signage and training requirements generally align with existing industry best practices.

The categories from lowest exposure to highest exposure are as follows: • Category 1: Below the General Population Limit where there is no potential of exceeding the limits. No mitigation measures are required. Optional GREEN INFORMATION sign can be posted. This sign would contain specific language for each broadcast site. Shown is an example for AT&T sites. See Fig. 1. (The images shown are courtesy Richard Tell Associates, www.radhaz.com.)

Above Left Fig. 1: An optional GREEN INFORMATION sign for use in Category 1 situations.

Above Middle Fig. 2: A BLUE NOTICE sign and limited public access are required in Category 2 locations.

Above Right Fig. 3: A YELLOW CAUTION sign and limited access to both workers and the public applies in Category 3.

An example of this would be AM tower bases, where shock and burn hazards are present. See Fig 5.

Additional Mitigation Measures

• Category 2 (NOTICE): Signs, positive access controls such as locked doors, ladder cages, fences, on-site building security — appropriate training with supervision of transient persons.

• Category 3 (CAUTION): Signs, engineering controls, indicators such as chains, railings, paint, maps. Appropriate training, use of time-averaging, or personal protective equipment.

• Category 4 (WARNING): Signs, restricted access, power reduction, ceasing operation with lockout/tagout on controls.

The following information must be communicated: • All these signs must include the RF energy advisory symbol. See Fig. 6 on page 18.

• A description of the RF source (e.g., types of facility and transmitting antennas)

• Category 2: Above the General Population Limit and below Occupational Limit. Must post a BLUE NOTICE sign and limit public access to this area. See Fig. 2.

• Category 3: Above the Occupational Lim it but below 10x the Occupational Limit. Must post a YELLOW CAUTION sign and limit access to both workers and the public.

See Fig. 3.

• Category 4: Above 10x the Occupational limit. The ORANGE sign shown in Fig. 4 is required, and limit all access. Also must post a RED WARNING sign as discussed below.

A RED DANGER sign must be posted where immediate and serious injury potential exists, regardless of category.

Left Fig. 4: In Category 4 situations, this sign as well as the red warning sign are required, with all access limited.

Right Fig. 5: A RED DANGER sign must be posted where immediate and serious injury potential exists, regardless of category.

radioworld.com | October 20 2021

Regulatory Update • Behavior necessary to avoid overexposure (e.g., access limits) • Up-to-date contact information (e.g., monitored phone number or email address connected to someone with authority and capability to provide a prompt response).

From the FCC

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Some observations We believe that the vast majority of broadcast sites comply with the FCC rules.

In most of the nation, on-tower work is the situation where RF exposure limits may be exceeded. The best practice is to cease operations when on-tower maintenance is being performed near the antennas.

The more dangerous issue for tower worker safety is the gravity field, and removing the RF field (which, unlike the gravity field, has an off switch!) is the better approach.

For multiuser sites, maintenance requires coordination between licenses and the tower crews.

Docket No. 19-226 specifically warns against oversignage. We note that many sites have conflicting signs, and many licensees have posted all available RF signs.

RF signs and other hazard signs such as HIGH VOLTAGE have been used in place of NO TRESPASSING signs, warning of hazards that do not exist. This is inappropriate as warning should only be given for real hazards — something about a boy crying wolf.

To comply with a misunderstanding of the RF exposure conditions and rules, some licensees have ordered all of the signs in the catalog and posted them all in hopes that one will be correct. We have noted that many sites have all of the signs posted. Some analysis is required for determining the correct signage for each site.

Site evaluation now mainly occurs during the licensing process or license renewal.

Above Fig. 6: The RF energy advisory symbol.

Middle Fig. 7: An inappropriate message and ionizing radiation symbol.

Right Fig. 8: An obsolete OSHA RF sign.

Below Fig. 9: Graphical representation of exposure categories and associated signage requirements

Range of Exposure Conditions (Not to Scale)

As part of this process, the FCC Office of Engineering Technology is revising OET Bulletin No. 65, “Evaluating Compliance with FCC Guidelines for Human Exposure to Radio frequency Electromagnetic Fields.”

This document provides the necessary methods to calculate RF exposure. The FCC provides the tool of FMModel to evaluate RF exposure from FM antennas quickly. All new and modified facilities must comply with the new rules. All other licensees must come into compliance by May 3, 2023. A review of the evaluation process and mitigation methods must be done for existing facilities to confirm compliance.

The first step in this process is to review what was represented to the FCC and ensure that it conforms with reality. Has the antenna been changed? Have new facilities been added to the tower? On an adjacent tower?

The most troublesome RF exposure sites are mountaintop sites that use short towers. Many of these sites present RF exposure environments that are above the FCC limits. Licensee must perform analysis to assure these areas are appropriately signed and managed.

Many sites have outdated signs or signs that are inappropriate. All signage at RF sites must be reviewed and revised to comply with these new rules. For many sites, the signs have been posted for 20 or more years and have faded.

Some examples of outdated and inappropriate signs are shown in Figs. 7 and 8 .

While these newly-enacted RFR rules don’t change the exposure limits for the frequencies in which broadcasters operate, they still affect broadcasters.

Going forward, we will have to perform new evaluations and update our signage. For existing facilities, the time to prepare for this is now, long before the 2023 deadline.

10x Occupational

Occupational Limit

General Population Limit

radioworld.com | October 20 2021

4 3 2 1

!

WARNING

!

CAUTION

NOTICE INFORMATION (optional)

Marketplace WideOrbit Releases WO Traffic v21.0

Cleanfeed Adds Features

WideOrbit announced a new release of its WO Traffic ad sales and commercial operations platform for broadcasters.

“The newest release of WO Traffic marks a significant milestone in the industry with the introduction of the Electronic Material Instructions module, the first automated solution to address the longstanding need to simplify and streamline the material instructions process,” it stated in a press release.

The graphic depicts the Electronic Material Instructions process.

The licensed module integrates with material instructions providers including ECN, PremiumMedia360, ITN Networks and SpotGenie. More integrations are planned, including Warren Lamb and vCreative.

“These integrations simplify the exchange of new and revised material instructions, helping broadcasters reduce errors (and costly makegoods) while increasing staff productivity,” the company stated.

Cleanfeed introduced an enhanced set of studio tools intended for the use of broadcasters and podcasters.

The tools are housed in the user’s browser, with no requirement for external hardware or software. They include enhancements to Cleanfeed’s Clips feature and a new Player for longer cuts of audio.

“The tools give podcasters and broadcasters the functionality of a professional radio studio, straight out of their laptop,” the company stated.

“Features now give users the opportunity to give their listeners and guests a finished production experience, including the ability to play intro and background music, host a panel show or quiz with sound effects, review music, have guests comment on interviews or even play voxes from the public.”

Cleanfeed promotes its product as providing highquality remote audio “as if you were in the same studio as someone else,” with low latencies and multitrack recording, controlled via a link in a browser.

Info: www.wideorbit.com

Info: blog.cleanfeed.net

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Audio Essentials Writer

Jeff Keith Senior Development Engineer, Wheatstone Corp.

Audio performance testing on the cheap

The on-air sound can never be better than the cheapest link

T

here’s nothing like a little audio performance testing to cap off a hectic week at the station, especially if you don’t have to haul out the heavy (read “expensive”) equipment to do it.

There are two main things I like to test: the flatness of the frequency response and the distortion added by equipment in the air chain. For this, you’ll need clean test signals and a way to measure those signals after they’ve passed through the air chain.

Measuring distortion 20

Top Right Fig. 1: Two sine waves at 1 and 2 kHz, equal amplitude.

Below Right Fig. 2: Undistorted spectrum of two sine wave signal.

Obtaining clean test signals is fairly easy. Most audio editing systems have the ability to synthesize lowdistortion sine waves and then save them to a file.

I generate and analyze test tones using some software tools written by Sebastian Dunst, available from http:// softsolutions.sedutec.de. Note that a license is required to use these tools in a “commercial” environment.

I use the SoftSolutions Multisine audio generator to synthesize single or multiple sine waves of any length or audio level, stereo or mono, and store them as a linear .wav file.

Fig. 1 is the waveform that has resulted from adding a pair of sine waves at 1 kHz and 2 kHz, both at equal amplitude, to create a test signal. Then, with the SoftSolutions AudioAnalyzer software, I can analyze audio saved as a .wav file and display the distortion parameters I’m interested in.

Fig. 2 is the spectral analysis of the waveform from the above example. This would be what we’d see if we had a perfect air chain.

If these two pure sine waves are fed through an air chain with no distortion (which isn’t possible, yet — all circuits

add distortion), the analyzer would show only the original two signals. As the spectrum analysis shows, the rest of the audio spectrum would be clean — no other signals would appear above the bottom of the display.

radioworld.com | October 20 2021

Audio Essentials

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But if there were distortion, what would it look like? It might appear similar to Fig. 3, showing many other signals in addition to the first two we started out with. The example is of a severe distortion problem — this air chain would sound horrible on the air!

Frequency response The same tools we just used to measure the distortion within the air chain can also be used to measure frequency response.

This time we’ll use the same software tools to generate a test signal that has many sine waves. By then sending this complex signal through the air chain and then looking at it on the analyzer, we’ll be able to see if the sine waves (at different frequencies) are coming back at equal levels.

Fig. 4 is the waveform of a test signal made up of sine waves at 20, 40, 80, 160, 320, 640, 1280, 2560, 5120, 10240 and 20480 Hz. In a perfect air chain, the analyzer would show all of the signals at their original and equal levels after passing through the air chain.

Top Left Fig. 3: Severely distorted spectrum of two sine wave signal.

Top Right Fig. 4: Waveform of 11 sine wave signal.

Above Left Fig. 5: Spectrum of undistorted 11 sine wave signal.

Above Right Fig. 6: 11 sine wave spectrum through an air chain with some problems.

Fig. 5 shows that all of the signals are present and that they all reach the same audio level. This represents “flat” (good) frequency response.

What would the analysis look like if there were a loss of low frequencies due to, for instance, dried out electrolytic capacitors in some part of an analog signal path?

It might look like the next display, shown in Fig. 6. Note how the signals at lower frequencies are quite a bit lower compared to the mid and high frequencies. This station would have a “weak” bottom end, no matter what they tried to do with the audio processing.

There are many tools available, both hardware and software, that can be used to quantify the quality of the station’s air chain. Remember that it is not important which tools are used but rather that they are used to check occasionally to see if the station’s air chain is healthy.

If the air chain isn’t up to snuff, it doesn’t matter what audio processor, transmitter, STL or exciter the station has, because the on-air sound can never be better than that of the weakest link.

radioworld.com | October 20 2021

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