Engineering Radio – Page 27 – One Hundred percent Human Generated Content for your Reading Enjoyment

Doing it with sound AND pictures

AKA: Television!

I am talking about the type of TV you need an antenna for. I have been installing a few of these low-power digital TV transmitters at various places and it is good work.

Anywave MPTV 2.2 KW digital TV transmitter, WCRN Boston

LPTV antenna side mounted on tower in Quincy, MA ERP is 15 KW.

Anywave MPTV unpacking, rolling into the building, Ellenville, NY

This transmitter’s dry weight is about 500 pounds, which was a little bit too much for our appliance hand truck, so we built a ramp. They have a nice set of wheels on the bottom, so they roll into place.

Carrier power after pre-correction files updated

There are a few differences in the way things are done. First of all, there is a different set of acronyms:

ASI- Asynchronous Serial Interface, format for MPEG transport stream, max speed 270 Mbps.
SDI – Serial Digital Interface – Similar to ASI but can run much faster, up to 12 Gbps.
TS – Transport Stream, Encoded video and audio streams into the exciter. Same idea as composite audio input on an FM exciter.
TSID – Transport Stream ID, a unique number assigned to each DTV station and encoded with the transport stream.
PSIP – Program System Information Protocol, carries program and system data about the transport stream.
ATSC 3.0 – recently updated ATSC standard that allows TV stations to do more with their transport streams than before. Will also change the modulation from 8VSB to COFDM.

Then, some things that look familiar are called by different names, BNC cable vs ASI cable… I am a neophyte in the TV world, so there are still many things to learn.

EAS is still EAS, but now there is a locally generated video to go along with the audio.

A while back, some fool wrote their congressman because THE COMMERCIALS ON THE TEE-VEE WERE TOO LOUD, so there is something called CALM Act compliance.

However, at the output connector on the exciter, through the amplifier, filters, directional coupler, etc; it is RF and behaves like RF. Even more interesting; Mr. Doherty’s name is used to describe the RF amp. Doherty amplifier or Doherty modulation was designed by William Doherty for Western Electric in 1936. It was not until Continental Electronics began using it in their AM (317B) and Shortwave (420A) transmitters that it became known broadly. Old things are new again:

Continental Electronics 420A 500 KW Shortwave transmitter, Greenville site B

That picture is from my visit to Greenville, NC in 2017. This is the control console, the transmitter is behind the glass and takes up half the building. It was installed when the site was built in the early 1960s. The new Doherty UHF amplifiers use LDMOS devices, notably the BLF888E in the Anywave units.

Antenna sweep, channel 30 UHF slot antenna, WCRN Boston

Antenna with channel band pass filter, Channel 30 WCRN Boston

The Channel Band Pass Filter is required by the FCC, basically, it ensures that the TV transmitter is staying in its allotted 6 MHz channel. They add phase rotation, as noted above. This is why pre-correction is needed to keep the ATSC signal linear across the entire 6 MHz bandwidth. RF is RF and we like RF.

All Digital AM?

I have been reading, with interest, the saga of HD Radio on the AM (AKA Medium Wave) band. First question; if it goes all digital, will we still call it AM? Of course, there are other questions and concerns:

The proprietary nature of HD Radio, AKA MA3 or NRSC-5D as they are now calling it, is problematic. Xperi, the latest patent owner, currently (their word) has agreed to waive licensing fees for AM station owners who install their system. Is this a limited-time deal for early adopters or in perpetuity for all stations?
The NRSC-5D tests on WWFD, Fredrick, Maryland are hopeful, but as I pointed out before, it is one station with a well-functioning antenna system. Many AM antenna systems are defective either in design or due to deterioration. Is the FCC going to start policing the AM band again to cure these self-inflicted wounds?
Of course, the NAB wants zero oversight on the entire adventure. Under their proposal, small ownership AM stations would have a difficult time remediating interference issues from all digital co-channel stations by eliminating any required notification period, as proposed by the SBE.
The NAB also wants to nix a 1 Hz carrier frequency requirement, which would help with both the analog and digital interference issue, saying it would be too expensive. I disagree. In this day of universal GPS timekeeping, it would be easy to implement this on all modern transmitters, especially if they were already installing an HD Radio exciter.
Denis Jackson’s Radio World Article states that reliable coverage can be had out to 0.1 mV/m. This seems very, very optimistic given that ambient electrical noise (non-broadcast related) on the AM band is at very high levels and still climbing. Further, once the all-digital conversion starts, more and more co-channel digital interference will happen, likely cutting down that contour to a great extent. It works now but may not work later. These types of statements seem naive or perhaps disingenuous. Again, WWFD is one digital signal in a vast ocean of analog carriers.

While I am skeptical of some of the statements made in various articles and comments before the FCC, I do believe that converting the Medium Frequency band to all digital will have benefits. The BBC DRM tests carried out in 2007 (The Plymouth DRM long term trial) show that digital on MF can work. DRM has been implemented in various countries with good results.

Getting rid of the hybrid IBOC/Analog is a step in the right direction.

My concerns are the small owners who are still making a go of it on AM. Those guys still doing community radio and serving the public interest. If they choose to wait, are they going to get buried under a digital dog pile and then have to pay the full license fee later? Something like that might be the end for them.

HD Radio in and of itself is not the panacea for the AM band. Other things have to happen to make it work right. The SBE speaks extensively about ambient noise on the MF band. They are entirely correct. In addition, there are many, many AM stations that do not have compliant antenna systems. There are stations operating a DA-2 system full-time on the night pattern. There are stations operating a DA-2 full-time on the daytime pattern and power. There are stations that are supposed to turn off at night, which stay on 24/7. There are stations not reducing power to nighttime levels. The list goes on. Simply putting digital carriers on everything will not reduce station-to-station interference, especially at night.

I am cautiously hopeful that the FCC will look into the ambient noise problem, which simply cannot be over-emphasized. They would also need to re-invigorating the Enforcement Bureau. Since they closed down most of their field offices, it has been kind of a free-for-all out here.

In this time of COVID-19

As most of you may know, I live in New York State (Hudson Valley region). This is very close to the COVID-19 outbreak in Westchester County. There has been one confirmed case in my town. As such, we are experiencing the outbreak ahead of the curve from the rest of the country. School has been canceled for at least two weeks and perhaps indefinitely. All public gathering places are closed; restaurants, bars, movie theaters, malls, churches, etc. As a radio engineer, the COVID-19 virus has several implications:

Things are still going to break and will need attention. The good news is that most transmitter sites are unmanned. The only social interaction may be during the travel phase (getting fuel, food, etc).
Many studios and offices are being abandoned as well. Over the last few days, we have set up DJs to operate from their houses. Most sales and office staff have been told to work from home.
Broadcasters have been designated critical communications infrastructure, and The Department of Homeland Security has issued letters that allow travel and procurement of fuel during the national emergency for critical personnel.
I managed, prior to the store shelves being emptied this weekend, to procure some PPE. I don’t know how effective it will be, but anything is better than nothing.
Since Hurricane Sandy, I have had in place many emergency supplies and equipment needed to restore service in the event of a long-term interruption of basic services.

There are many long-term economic implications. For commercial radio stations, the loss of income is going to be extreme. As the virus has spread, businesses have canceled pretty much all advertising. During past disasters, radio was often the only means of getting information to the general population. I am not sure if this is still the case. How relevant is radio these days?

Automation Systems

Radio Automation Systems are nothing new under the sun. As Marconi tapped out his famous S, he was likely thinking “We should get a machine to do this…”

Broadcast stations have been installing different types of automation since the mid-1950s and early 1960s. It was touted as a way to free up announcers so they could do more important things.

While cleaning out an old studio/transmitter building and getting things ready for demolition, I found a stash of old product brochures for various automation systems from the 60s, 70s, and 80s. It looks like the previous owner used to go to the NAB every year. How many radio guys got their start on the overnight shift changing out reels? I know a few.

Gates automation system brochure, circa 1965

The Gates Radio Corporation had a fairly standard reel-to-reel system in three different configurations. These systems were pretty pricey in their day. According to the 1966 price list:

The Automate 244 cost $7,275.00 ($58,837.00 in 2020)
The Automate 484 cost $12,210.00 ($102,946.00 in 2020)
The Automate 1007 cost $17,150.00 ($138,799.00 in 2020)

Those are for stereo systems, mono systems cost about $500.00 less. Each one of those systems ran one station.

The larger the system, the more events it could trigger. I have never run into one of these in the wild.

Long-form satellite shows began to surface in the early 1980s. Things like all news formats and overnight talk shows. I have had nightmares where everyone walks around saying “This is Larry King, you’re on…” while UFOs fly overhead and next-door neighbor, Jim Hightower, buries PCBs in his backyard not more than 200 feet from his house.

Broadcast Electronics Control 16 radio automation system

Broadcast Electronics had the Control 16 system in the 1980s that ran off of a very basic computer system that could handle 3,000 events with the standard RAM configuration and up to 9,999 events with additional RAM. This was ideal for multiple program sources; music on reel machines, satellite syndicated talk or music formats, etc. No longer were these machines simply running the overnights.

Schaffer 901 radio automation system — Schafer 90x radio automation system

Schafer is perhaps the most known analog tape automation, at least to me. I know of several of these systems that were in operation through the mid 1990s. By this time, long-form satellite music formats had become the rage. However, there were still a few stations using reel-to-reel music services.

I particularly like this flyer from IGM:

IGM (International Good Music) brochure, circa 1971

By the mid-1990s, these tired old dinosaurs were being removed. Still, the mechanics of the operation were a thing to behold. It was nice because you could hear the relays snap shut after decoding a 25/35 Hz tone or one of the Mutual Radio be-doops. The cart-o-matic would chug through the break until the liner fired and then back to the bird. If there were any issues, one simply needed to stand there and watch which part of the machine malfunctioned.

Schaffer logging system — Schafer logging system

Computer-based systems like Computer Concepts DCS, Arrakis Digilink, and Audio Vault came along, which got rid of the analog tape. Instead, they stored audio on hard drives. In those early systems hard drive space was a premium, so usually, at least 3:1 compression was needed to fit all the commercials onto the drive space available.

My first brush with Audio Vault was in 1994 at WGY in Schenectady, NY. It was a pretty good system if you could understand the .ini files. As the BE tech support guys used to say “You can program it to turn the coffee pot on if you wanted to.”

Nowadays, what used to be a studio location is more akin to a content distribution node. This rack combines music and commercials stored locally on hard drives with out-of-town voice tracks and serves as the program source for eleven radio stations.

It works remarkably well, as long as the windows operating system stays functional.