AM – Page 27 – Engineering Radio

I-Buzz

Rumor has it that iBiquity is going to release a software upgrade for the AM IBOC system they peddle. Allegedly it is going to improve the sound quality of the digital signal, allow the analog signal to increase its bandwidth to 10 kHz, and provide data such as song titles. No word on whether they will be providing software upgrades to consumers for the many HD radio^TM receivers out there.

I have been following a discussion on AM quality over the last few days. It seems many engineering types at least, acknowledge that analog AM can sound good, if not more natural than FM. The addition of IBOC hybrid mode on AM station has created more noise and further degraded the station’s main signal by reducing the bandwidth to less than 5 kHz.

Tonight I am listening to WWVA on 1170 kHz, and there is this horrific white noise/hash over top of the station. Same thing on 1190 kHz, all courtesy of WHAM 1180’s IBOC transmission. It is one thing to trash your own station, limiting the analog audio response to 5 kHz. It is quite another thing to trash the adjacent frequencies with noise making them unlistenable.

Here is a brief clip (recorded at 8:00 pm EDT, March 24, 2010):

The second clip, WWVA has faded out (recorded at 9:10 pm EDT, March 24, 2010)

The audio in these videos is adequate but not the best, still, it is pretty clear that there is a whole bunch of white noise on top of WWVA’s signal and on 1190 where no station is coming in. The only conclusion that I can draw is that WHAM is operating with their IBOC turned on. This was recorded at a location that is 197 miles from WHAM and 364 miles from WWVA. I have made several better recordings directly into the computer without the video frequency readout reference.

In 1990, the FCC mandated NRSC-2 (73.44) spectral mask on all AM stations, requiring them to put in brick wall filtering to limit the bandwidth to 10 kHz or less. They also require all AM stations to do “equipment performance measurements” (73.1590) to verify that the stations are complying with FCC regulations. This was done because of excessive sideband splatter by AM broadcasters creating interference to adjacent channel stations. I agree in principle with the NRSC-2 standard, I think it serves a purpose. Why then, are stations allowed to interfere with other stations with IBOC signals? Even though Ibiquity has put up a spectral mask that complies with NRSC-2, it still creates interference. Isn’t this a double standard? A station in Pennsylvania gets fined $4,000.00 for operating past its sign-off time (because operating after sign-off might create harmful interference), yet, WHAM gets to generate noise all night and drowned out adjacent channel stations that are hundreds of miles away.

In the meantime, if the FCC inspector shows up at a station that has not made the required “equipment performance measurements” they will get a fine too.

Am I crazy, or is it hypocritical bull shit to fine one station for potentially harmful interference, but then the FCC to ignores its own rules and allows another type of interference? Hint: I am not crazy.

I have recorded this in .wav format and I am sending it to the FCC with an interference complaint letter. It is about time somebody made some noise about this noise. Apparently, there are many engineers who feel the same way. Will Ibiquity listen, or will they keep doing CPR on a corpse?

History of the WGY broadcasting tower

To any who lives in the capital region, the WGY tower near the intersection of I-90 and I-88 in the town of Rotterdam is a familiar site. It is big, tall, and conspicuously marked with a huge “81 WGY” on the southwest face of the tower. At night the call letters used to be lit up by a spotlight but that may have been turned off in recent years.

In my time as chief engineer there, I found several file folders of memos and other materials about the building of the tower, which started in 1936. Prior to that, WGY used a T-top wire antenna, first from the General Electric plant in Schenectady (1922-25) and then from the current tower site in Rotterdam. Located with WGY were GE’s experimental shortwave stations W2XAF and W2XAD.

When the station increased power to 50,000 watts in 1925, many reports of fading were received from locations 20-50 miles away. WGY engineers studied the situation by doing a full proof on the antenna. They found an elliptical-shaped pattern with nulls to the north and south. This coincided approximately with the T arms of the T top antenna, likely due to the self-resonating effect of the support towers for the ends of the T.

NBC, then owners of WJZ (now WABC) in NYC had studied this problem for years and came up with a new antenna design for Standard Broadcast, the uniform cross-section guyed tower. Starting in 1935, WGY began to investigate installing such a tower in South Schenectady, as the transmitter site was then known. One report showed an efficiency gain of 430% over the T top antenna that was in use. The General Electric construction and engineering department raised several objects to the standard triangular tower then and now commonly used for AM radiators.

Much mechanical planning and effort went into the design of the tower, which is a square tower, a 9-foot face, 625 feet tall. During the planning phase, KDKA was installing a similar tower, which collapsed when it was being erected in 1936. An analysis of the failure showed that one of the guy anchor cable sockets pulled out of the concrete (which was improperly poured). This may also be the reason why the KDKA tower collapsed in 2003, although I never read the engineering report on that failure. Nevertheless, GE Engineering felt that forging the members of a triangular tower weakens them and was too risky, thus, a square tower was the solution.

Further, every component of the tower was tested individually. Often, two of a type were build, with one being tested to destruction. Two base insulators were made for this specific tower. The first was tested to destruction at the National Standards and Institutes laboratory in Washington DC. It was found that the insulator withstood slightly more than 1,200,000 pounds of pressure. The working load (tower dead weight) of the base insulator is calculated to be about 430,000 pounds, thus almost a 3:1 safety margin.

The wire rope used for the guy wires was also tested to destruction. The working load on the upper guy is about 24,000 pounds, the wire rope broke at nearly 120,000 pounds. The concrete, guy anchor sockets, T bars, and all other parts were likewise tested.

Base insulator, WGY 625 foot square faced transmitting tower

Electrically, the tower is 186 degrees (it was 180 degrees on 790 kHz, the former WGY frequency). It had a 40 X 40 foot ground mat with 120 buried ground radials. The ground radials were #4 hard drawn stranded copper. When we investigated the system in 1999, it was complete and unbroken. The radials, ground screen, strap and all other metal component showed no signs of deterioration. It helps that the soil surrounding the tower is a sandy loam and well drained.

WGY open transmission line between transmitter building and tower base

The tower was fed with 600 ohm open transmission line, 180 degrees long. Initially, the system had been designed for high power operation up to 500 KW. However, when the transmitter was replaced in 1980, a new Harris ATU was installed, which can only handle 50 KW. I recall the base resistance to be 192 ohms with -j85 reactance.

A concrete wall surrounds the base insulator. This was installed in early 1942 to prevent the base insulator from being shot out by sabbators during WWII.

When I worked there, the station had a Harris MW-50B transmitter. This unit was in slightly better shape than its counterpart at WPTR across town. I did find some of the same quirky things with it, however. Our consulting engineer had a good line, “Harris, where no economy is spared…”

The site had a FEMA owned backup generator installed in the 60’s. This was an Onan 225 KW diesel powered unit. 225KW is likely a conservative estimate as those units were way overbuilt. The original fuel tank was buried out behind the building. FEMA contracted for it’s removal in 1995 because of concerns of leaks and soil contamination. When they dug it up, the primer was still on the tank. After getting the tank out of the ground, the contractor cut a large hole in it and lowered a person into the tank to clean it out. Something that should be profiled on the Dirties Jobs TV show.

Backup generator fuel tank — 5000 gallon backup generator fuel tank

The new tank was installed in the old outdoor transformer vault. It is a 5000 gallon double walled above ground tank with monitoring system.

It has been several years since I have been to this site. I know they installed a Harris DX-50 sometime in 2001 or so. They also may have replaced the open transmission line. WGY now transmits in HD radio, which they are able to do because the tower was well designed and installed.

Future of AM radio

It is clear to me that radio is changing, in some ways, it is changing for the better, and in many ways, it is changing for the worse. In spite of many bad business decisions made by overpriced MBAs, large consolidated radio groups seem to be hanging on, if only by their fingernails. It is very likely that the investment banks, who have the most to lose, are not interested in seeing their loans written off in a bankruptcy proceeding. As we all know, the consolidators that paid multiples of 15 to 16 times cash flow for stations, way overextended themselves. There is no hope that values will ever return to those levels, so the banks are now in the radio business.

Sure, the banks are not the owners of record, and the FCC never would consent to transfer all those licenses to so many investment banks. However, they are calling the shots, making “suggestions” on how best to run things. Offering perhaps a 1/4 percent reduction in an interest rate if the expenses can be reduced below a certain level. Unfortunately, for the communities like Ellenville, NY, their local radio station means nothing to the banker living in Manhattan. It is a number, and more than likely, a negative number on a spreadsheet. It means nothing to the group owner in San Antonio, other than some miscellaneous real estate assets. The same can be said for all the radio stations in the Hudson Valley if not the entire country.

Why is this important? I mean, who really cares? The apparent answer is no one seems to care. Local news, or what used to be local news such as town board meetings, high school sports scores, police blotter, and all of the many other small town things do not get the hearing they used to. Town boards; well if no one shows up for the meeting to pass the new zoning laws, so be it. School boards; sure, raise the taxes, most homeowners will just pay the new higher amount and not say anything. It is for the children, after all. Seems that the local constabulary is spending more time at the Dunkin Donuts than out walking around checking doors. That’s the way it goes. With the demise of local newspapers, detailed in a previous post, who is keeping an eye on things? Who lets the community know when something doesn’t pass the smell test?

Receiver tuned to local AM station playing good sounding music — A receiver tuned to a local AM station playing good-sounding music

A small AM radio station can be made profitable, just not at the margins expected by the big boys. There is a niche for perhaps a 1 KW or 5 KW non-directional station with its own real estate that is not in too bad shape and can be turned into a community radio station. Those types of stations are fairly low maintenance, most have some type of PSRA and PSSA to keep them on at least during drive times if they are daytimers. Others have minimal amounts of nighttime power. Almost all of them cover their city of license, even with small nighttime powers.

I have been looking into good quality AM radio receivers and there are a few out there which are not too expensive. Most GM car radios and older Chrysler radios have good AM radios. A group formed to promote AM radio, ensure that automakers install radios that are at least as good as their older versions, and work with manufacturers to make better small tabletop receivers and such would go a long way to improving the unjustly bad reputation that AM broadcasting has received. Further, working with the ARRL (amateur radio) to reduce and keep noise levels from things like BPL and other noise-making technologies that do not comply with current FCC regulations would also help. It is true that our environment has become electrically noisier, one might not be able to listen to the 50 KW clear channel station 500 miles away, but the local station should come in well enough to enjoy, especially if the programming is good.

FM radio is becoming crowed with translators, adjacent channel HD radio interference, LPFMs, and whatever else can be shoehorned into the band. The quality of FM is set to decline precipitously in the next few years. It seems that with the right combination of good local programming, good receivers, and radio station owners/operators that are not looking to get listed on the NASDAQ, small AM stations could survive, if not thrive in the business that the big stations turn away.

There are a number, a small number, of stations already doing this. As long as there is free local news and free quality programming, people will listen, no matter what band it is being broadcast on. Free trumps paid any time, any day.

AM radio

When I was a young lad, still impressionable I might add, I would listen to the big AM powerhouses at night with my little transistor radio. I have eluded to this in previous posts. I have also written an article for Radio World in which I suggest turning AM transmitter off at overnight hours to save money, with certain caveats. I still listen to AM radio quite often. I have a Kenwood R-2000 MF/HF receiver which, while not the best technical receiver, is the best-sounding AM receiver I have ever heard. Its wide AM IF bandwidth is 6.5 kHz, which seems to work very well with the high-end pre-emphasis curves most good AM processors employ. Music, especially oldies, which were recorded in AM’s hay day sounds spectacular. There is no other AM radio that sounds as good as this unit. Right now, the sun has just set and I am listening to WFED 1500 KHz in Washington DC. They are airing a VOA program called “Issues in the News.” It’s real red-meat radio. We are 250 air miles from the transmitter site.

I think there is a place for AM stations, not just merely being satellite repeaters, but making a meaningful contribution to their communities of license. Unfortunately, I am one of the few that thinks so. For as long as I have been in radio, AM has been declining. It is a matter of economics, most GMs would tell me. That being said, the two three-letter call signs that I worked at were consistently in the top four in the rating book. Clearly, live local programming was the key to this success.

The notion that they sound bad may or may not be true. An AM station that has a properly tuned and matched antenna can sound very good. Using a good receiver, one that has good fidelity, good selection and sensitivity can also increase listening pleasure. Unfortunately, almost all AM radios being sold today have an IF bandwidth that is only slightly better than a telephone around 2-3 kHz. This is because… I don’t know. Originally receiver manufacturers began limiting bandwidth to reduce interference. NRSC-2 was supposed to limit interference by reducing out-of-bandwidth splatter. Apparently, the manufacturers didn’t get the word.

Who knows, as the FM band gets filled with shit (interference from adjacent channel IBOC, translators shoehorned in, LPFM’s on third adjacent channels) AM radio might be viable again.

Once the moneymen got a hold of the broadcasting industry, everything was geared toward making money. Not that making money is wrong, it is certainly good to make a profit, however, with the margins on the FM stations, usually between 25-50%, AM stations were relegated to second place because their margins were much less than that. Even so, many AM stations were initially profitable during the consolidation and still had some ratings. Not so anymore. AM stations also require more maintenance, because of directional antennas and all that is associated with those systems. What a banker or an accountant sees when he looks at an AM radio station is a money pit. And, if the station has been run into the ground, it is a money pit.

Still, a small AM at a fire sale price might be fun to rehab. Launch some type of community radio format, put AM radio back where it was 30 years ago, solidly in the community. It might be fun.