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Petition for Declaratory Ruling and connected assignment applications granted

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The Media Bureau Announces a Freeze, effective immediately, on the following Filings (collectively, Filings)

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First I’ll tell what you already know. Back in the day, AM broadcasting was king and FM was commercial-free. Things changed in the 1970s as FM grew in popularity. Here we are 40+ years later with many AMs struggling. Some have gone away because they were no longer financially viable. To make matters worse, AM directional stations are more time-intensive and costly to maintain, especially when compared to FM stations.

On the positive side, I know a number of smaller AM/FM combination and stand-alone AM stations in Minnesota that are doing well. One town has a 1 kW AM with a 100 kW FM. The AM brings in 40% of the sales revenue because it has always been locally programmed with live announcers until 1 p.m., then is live again during afternoon drive.

AM radio isn’t supposed to sound bad. It can be a clean and pleasurable listening experience, even when there is only 3 kHz of audio bandwidth. On the other hand, AM can be ugly to the ear when there are maladjustments.

SCIENCE

Modulation is the process of adding audio to a transmitted signal. Amplitude modulation is aptly named. A station’s carrier (transmitter power) is varied by the station’s audio. Carrier power is depressed to zero watts to achieve 100% negative modulation. It increases to 1.5 times carrier power when 100% positive modulation is reached. That is why a thermocouple antenna ammeter reading rises with modulation. You read it during a programming pause to get an accurate measurement.

METERING

AM modulation monitors have –100% and +125% lights indicating overmodulation. You really don’t want those lights to come on. More is not better.

First, be sure to set the monitor’s RF carrier level control so the carrier meter needle is in the right spot, as per manufacturer’s instructions. A carrier meter misadjustment will result in inaccurate modulation monitor readings.

Fig. 1 shows an AM modulation monitor. The –100% and +125% lights are on and yet the analog modulation meter reads only 94%. It is normal for an analog meter to read lower than actual modulation. In fact, 85 to 90% is a more realistic meter display, because it cannot track peaks as lights do.

Fig. 1: AM modulation monitor showing overmodulation.

A monitor’s audio output will sound excessively bright or harsh if a de-emphasis audio circuit is not included. Monitors traditionally do not have this, but often a simple capacitor and resistor modification will do the trick. The idea is to undo the high-frequency boost that is a part of the audio processing, per the National Radio Systems Committee (NRSC) standard. As you probably know, the transmitted audio has increased high-frequency response to overcome high-frequency rolloff in most receivers. The goal is to restore flat frequency response to the listener. Some audio processor manufacturers are using non-standard pre-emphasis curves to suit their taste. That complicates getting a realistic feel for frequency response. At least they are trying to make the best of receiver frequency response roll-off.

ON A SCOPE

An article I wrote regarding the operation of oscilloscopes, “Your Scope Is a Tool for all Seasons,” appeared in the Jan. 13, 2013, edition of Radio World.

To refresh your memory, a scope has a display where a dot that travels from left to right is deflected up and down with voltage. In this case, we will look at a transmitter’s RF output.

Fig. 2: An AM RF carrier wave on an oscilloscope.

I’ll begin with Fig. 2. It shows an oscilloscope with a view of the transmitter’s carrier with the scope sweeping at high speed (0.2 microsends per horizontal screen division) to see the actual carrier wave of an AM radio station. By carrier, I mean the transmitter’s power output. What you see is an almost perfect sine wave at the station’s operating frequency.

 

Fig. 3: A carrier with no modulation.

Let’s zoom in to the scope’s screen. Fig. 3 shows the carrier when the oscilloscope is slowed down to view audio (0.2 milliseconds per division). No modulation was present at that instant. Fig. 4 shows a 1 kHz sine wave modulating the carrier 100% positive and negative. The positive parts are the top and bottom peaks. They are mirror images of each other. The negative modulation part is where the carrier is just pinched-off at zero power in the center of the screen. This sine wave is relatively clean/undistorted, with less than 0.5% audio harmonic distortion.

Fig. 4: A carrier modulated 100% with a 1 kHz sine wave.

Many receivers do not reproduce it that way. The last 5 or 10% of negative modulation, between 90 and 100%, is where receiver detectors have trouble faithfully reproducing what the transmitter is sending. The result is audio distortion. We all know that unwanted audio artifacts are a listener turnoff.

Fig. 5: 100% modulation with receiver detector output.

In Fig. 5, I’ve switched the oscilloscope to dual trace mode. It shows the transmitter at 100% modulation on the top trace. The bottom trace was sampled at the receiver’s detector. I made the measurement there so it rules out additional audio harmonic distortion, which might be added in the output stage. By definition, harmonic distortion is where this 1 kHz audio tone will have unwanted audio products at 2 kHz, 3 kHz, 4 kHz etc. because of non-linear system performance. In this case, distortion from transmitter through the receiver detector measured 5.1%. It was only 3.1% at 90% modulation.

Fig. 6: 125% positive modulation, 100% negative modulation with receiver detector.

Fig. 6: Traditional analog audio processing used diodes to clip the negative side of audio before it went to the transmitter so it would not attempt to overmodulate the negative modulation while allowing positive modulation to go to 125%. The downside is that it added as much as 6.5% harmonic distortion in the process. Add the receiver’s problems to the mix and you have a whopping 10.2% distortion. Ouch! You’d never allow that on FM.

Newer digital processors reduce but may not eliminate the problem. Yes, the station can be a bit (about 0.9 dB) louder on the dial, but it is irritating to many listeners. They don’t know how to describe it, but oops, there goes another tune-out! Again, some people hear it and some don’t. Best not to penalize the station with high modulation.

Fig. 7: The transmitter is being badly over-driven at 100% negative modulation.

Fig. 7 shows the transmitter being modulated at over 100% negative modulation. I’ve moved the scope’s trace up a bit so you can see detail. Negative peaks go flat to the center, which is no carrier at that instant. Modulation like this will not pass the required NRSC occupied bandwidth nor will it pass my ear test for listenability. It is tiring to hear.

Fig. 8 is where you want to be. No more than 95% negative modulation, the sweet spot between loudness and listenability.

Fig. 8: 95% program modulation of the carrier.

It is a shame to lose listeners for that last 5% (about 0.5 dB) of modulation. Few if any will hear the loudness difference. Likely most will hear grit in the audio of transmitters modulated to the max. You can make up much of the modulation percentage difference with careful adjustments of the audio processing, before it goes to the transmitter. Software-defined receivers eventually will solve much of this problem, but we need to deal with today’s radios.

When I was installing AM stereo years ago, negative modulation was usually set at 95% and positive modulation at 95% for stations to sound clean. It was positive +125% if the client preferred it. That extra positive modulation comes as “forced asymmetry” where the negative audio peaks are soft clipped so the positive peaks can go higher. Ouch!

Surprisingly, bad-sounding audio with less than 100% modulation will usually fit into the NRSC occupied bandwidth mask, in the FCC required annual measurement. That is because of the required 9.5 kHz low-pass filter in audio processing.

AM stations competed in loudness wars to beat the other guy years ago. Now it is time to give listeners a pleasant experience with natural-sounding audio. Don’t drive them away.

I grew up in a broadcasting family that owned two AM stations and no FM. Success was dependent on keeping listeners. Loudness was not the answer.

Comment on this or any article. Write to radioworld@futurenet.com.

Mark Persons, WØMH, is an SBE Certified Professional Broadcast Engineer. He recently retired after more than 40 years in business. His website is www.mwpersons.com.

The post Find Your Modulation Sweet Spot appeared first on Radio World.

The BBC has announced that its two flagship radio programs for Afghan audiences will now be carried live by Radio Television Afghanistan, the country’s national broadcaster.

BBC News Dari

“Majale Shamgahi,” which is broadcast in Dari, and “BBC Naray Da Wakht,” broadcast in Pashto, will have the first half of its hour-long evening news programs every day on RTA’s FM networks in all 34 provinces of Afghanistan, as well as on medium wave.

The BBC programs examine key local and international issues with daily reports, interviews and analysis.

“A partnership with the BBC further reinforces RTA’s mission of informing the Afghan nation,” said RTA Director General Ismail Miakhail.

Pictured from left to right are Diva Patang, RTA presenter based in London; Ismail Miakhail, RTA director general; Jamie Angus, BBC World Service director; and Ismael Saadat, planning and commissioning editor, BBC News Afghan.

“Adding BBC programming to our output will contribute to the provision of trusted and impartial news about Afghanistan and the wider world.”

[Read: Radio TechCon Opens Registration]

BBC News Pashto

“We are delighted that the new partnership with RTA will allow our content to reach more people in Afghanistan, on channels they already know,” added Jamie Angus, BBC World Service director.

Miakhail also said that the RTA Academy would use the BBC as an example as it looks to train its country’s journalists on ethical journalism.

“Majale Shamgahi” will air from 6:30–9:30 p.m. Kabul Time, and “BBC Naray Da Wakht” will air from 3–4 p.m. Kabul Time.

 

 

The post Radio Television Afghanistan Rebroadcasting BBC Radio Programs appeared first on Radio World.

Announces auction of FM broadcast construction permits and seeks comment on auction procedures

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A Virginia licensee has been handed a $15,000 forfeiture — in addition to receiving a shortened license renewed term — after allegedly failing to keep proper issues and program files updated in the FCC OPIF database.

The Media Bureau at the Federal Communications Commission ruled in a combination order/notice of apparent liability that Seaview Communications, which is licensee of WPEX(FM) in Kenbridge, Va., apparently violated several sections of FCC rules.

[Read: AM Station Hit with $15,000 Forfeiture After Public File Lapse]

According to the bureau, the station allegedly failed to prepare its set of quarterly issues and programs lists and it failed to upload this information into the station’s online public inspection file. FCC Rules require that commercial broadcast radio stations place issues and program lists — which detail programs that he station has covered over a three-month period — every quarter . Those files must include a quick briefing of the issues addressed as well as lay out specific details such as the time, date, duration and title of each program. Stations must then upload certain public file documents to the FCC’s OPIF public inspection file database. As of March 1, 2018, all broadcast stations are now required to post public file info (except political file material).

When Seaview began the process of prepping its license renewal application, it answered “no” when asked if it has placed the required documentation into its public file. The station explained that it had difficulties in navigating the new on-line public inspection file. “As such, certain deadlines were not meet with respect to the ‘upload’ of issues/programs lists,” the licensee said, though Seaview said it had begun working with the FCC counsel and plans to resolve the public file upload problems.

However, this explanation does not excuse or nullify the violation, the bureau said. The commission has the authority to hand down a base forfeiture of $10,000 to those licensees who fail to maintain their public file and an additional $3,000 for failing to upload the required documentation.

The commission can also raise or lower those forfeitures based on the circumstances. In the case of WPEX, the FCC handed down a $15,000 forfeiture, saying that even though Seaview admitted to its violations, it did so only when compelled to answer via its renewal application. Moreover, the bureau found the violations were “extensive” and apparently encompassed the entire license term.

The Media Bureau also found that the licensee’s conduct fell short of the standard of compliance that the FCC uses when handing out a routine license renewal. “The issues and programs lists are a significant and representative indication that a licensee is providing substantial service to meet the needs and interests of its community,” the bureau said. As such, it concluded that a short-term license renewal of two years was warranted. “This limited renewal period will afford the commission an opportunity to review the station’s compliance with the [Communications Act] and the FCC’s rules and to take whatever corrective actions, if any, that may be warranted at that time.”

Seaview has 30 days to pay the forfeiture or respond seeking reduction or cancellation of the proposed forfeiture.

 

The post Virginia FM Handed $15,000 Forfeiture for Alleged Filing Violations appeared first on Radio World.

It’s time for broadcasters to confirm that their stations are up and running with the latest in EAS updates.

As it stands today, EAS participants are required to not only receive Common Alert Protocol messages from IPAWS but also configure their systems to reject all CAP-formatted EAS messages that include an invalid digital signature. Now, an effort to maintain compliance with commonly accepted security standards, FEMA is also taking the next step of removing support for older methods by requiring the use of an updated TLS 1.2 protocol to access FEMA’s IPAWS server, said Sage Alerting Systems and the Society of Broadcast Engineers. TLS, or Transport Layer Security, is cryptographic protocol providing communications security over networks and is often used for internet communications.

To acquire and verify IPAWS CAP alerts, a broadcaster’s EAS alerting equipment must be upgraded with the TLS 1.2 update prior to Nov. 8, 2019.

[Read: California LPFM Asked to Explain Alleged Transmission, EAS Violations]

The move is one of several rule changes put in place by the Federal Communications Commission and the Federal Emergency Management Agency to improve EAS security to ensure that messages are received smoothly and accurately.

According to Sage, the TLS 1.2 protocol is now part of a September 2019 update called Rev95. Certain ENDEC systems qualify for a free update; older systems will need to purchase an update via a distributor.

SBE cautioned in its blog that after the switchover on Nov. 8, older versions of the ENDEC software will not be able to receive CAP messages from IPAWS. “This will render the station in violation of FCC rules concerning EAS monitoring and logging,” the SBE said.

For Gorman-Redlich systems, the SBE reported that stations operating with E-prom V 9.5.8 will remain compliant with the changes. For Digital Alert Systems DASDEC/One-Net systems, those units operating with software versions 3.1 or 4.0 will remain compliant.

In addition to the CAP format changes, the SBE said the FCC also recently changed EAS rules to refine the time window within which an alert message is valid and added a new false EAS alert reporting rule.

 

The post Broadcasters Need to Keep Eye on Latest EAS Updates appeared first on Radio World.