fcc – Page 3 – Engineering Radio

The AM HD all digital test, part II

Continued from part I:

In order to get to the root problems of AM (aka Medium Wave, or Medium Frequency) broadcasting, a bit of history is required. For the sake of brevity, here is the cliff notes version:

Early broadcasting services were entirely AM and heavily regulated by the FRC and later FCC
FM broadcasting was introduced in the late 1930s experimentally, then commercially circa 1947
In 1946 the FCC relaxed its regulations allowing many more AM stations to be licensed as both class II (currently class B regional) and class II-D, II-S, and III-S (currently class D) stations. Between 1946 and 1953 the number of AM stations more than doubled from 961 to 2,333
In spite of FM’s technical superiority, AM remained dominant until approximately the mid to late 1970s when the FCC forced FM stations to end simulcasting with co-owned AM stations
Broadcast deregulation came in small waves at first; programming rules, business rules, some technical rules, and operator license requirements were done away with, and enforcement of other rules became more selective
Deteriorating antenna systems, splatter, modulation wars, declining technical resources, and increased electrical noise created interference issues
The electrical noise floor gradually increases as more electrical appliances, street lights, fluorescent lights, and other intentional emitters increase
Radio manufacturers responded to consumer complaints by greatly reducing the audio bandwidth of their AM receivers
Broadcast deregulation greatly increased in the 1980s
The FCC voted in 1980 to limit skywave protection of clear channel (class I or A) stations to within 750 miles of the transmitter site allowing former daytime-only stations to stay on at night which increased interference
AM Stereo is implemented in 1982 to improve quality and compete with FM broadcasting. Competing systems are proposed, FCC does not mandate a standard, lets the market decide, and the technology dies off
The National Radio Systems Committee (NRSC) is formed and comes up with a standard (NRSC-1) that restricts AM broadcast audio to 10 KHz or less, mandates yearly measurements
Ownership rules are loosened somewhat in 1994, then greatly in 1996
The expanded AM band (1,610 to 1,700 KHz) is opened up in 1997 to existing AM broadcasters. Once stations are licensed to operate in the expanded band, they are supposed to surrender their former licenses, few do
The great radio consolidation takes place; from 1997-2004. Synergy is the word of the day, stations are overvalued in multiple transactions which created a debt bubble
Skywave listening is mostly depreciated as an acceptable communications method by the industry
The introduction of IBOC hybrid analog/digital broadcasting in 2002 greatly increased the adjacent channel interference issues. Sidebands out to ±10-15 KHz of the carrier are introduced with power levels of -16dBc. For a 50 KW station, this equals approximately 2,500 watts of power transmitted on each of the adjacent channels. Analog audio of stations transmitting AM IBOC is restricted to 5 KHz, background digital noise is often present in analog audio, further degrading the quality
Inside electrical noise greatly increases as compact fluorescent lamps (CFL) and LED lamps become popular energy-saving measures
Night-time operation of HD radio was permitted in 2007 creating greater interference problems to distant adjacent channel stations
There are 4,738 AM stations licensed, 89 are silent, approximately 210 transmit HD radio, and approximately 66 (mostly class A and B stations), transmit HD radio at night

There is not any one development that can be singled out as the smoking gun that killed the AM broadcast band, it is rather, a death from a thousand cuts. Because of heavy debt loads, technical, programming, promotional, and personnel resources are directed away from AM stations (and FM stations too). After the staff was reduced and news departments eliminated, AM stations became a dumping ground for mediocre satellite-syndicated talk programming. Eventually many also became a technical nightmare due to deferred maintenance.

There can be little doubt, AM broadcasting is a tough business to be in. In spite of all of that, however, there are several AM stations that are not merely surviving but thriving. What does it take to be a successful AM broadcaster in 2013? There seem to be several common threads, but the two most common are good technical operations and local programming.

Continued in Part III

The AM HD all digital test, Part I

After reading this article in Radio World it seems the all-digital AM testing completed last December was “nearly flawless.” This comes as no surprise considering that WBCN is owned by CBS, also an iBiquity investor. Could there really be another result? I think not. But let us examine the technical aspects of the WBCN test itself.

WBCN is on 1,660 KHz in the expanded part of the AM band. According to the FCC database, it transmits from a single 90.7 degree tower. As such, the tower is likely either broad-banded already or easily modified to be. Also according to the FCC database, there are eight other stations licensed to 1,660 KHz, all of which transmit with a power of 1 KW at night. This eliminates much of the interference issues found on the rest of the AM band. It can be further noted, the problem with electrical noise is most prevalent below 1,000 KHz. There is little wonder in the nearly flawless results.

From a technical standpoint, this is about as favorable a testing configuration as can be conceived for AM IBOC. If AM HD radio did not work under these test conditions, then it would never work at all. The actual data from the tests has yet to see the light of day and it may never be released. This is likely due to the same reason the NAB will not release its technical improvement study on AM; we simply won’t understand it.

Near the end of the article, someone (it is not exactly clear who) asks the NAB, “Why the opacity?” For which the answer given is “to get stuff done.” There is a fair bit of hubris in that statement. Is the NAB now the technology decider for the rest of us? I think not. Shutting out everyone but a very select few rightly causes suspicion, something that the Radio World article acknowledges.

Accurate, real-world testing involves more than using one technically favorable test subject. In fact, the tests should be run in the most technically challenged environment to present meaningful data points in real-world conditions. Stations like a six-tower directional on 580 KHz, a 190-degree tower with a folded unipole on 810 KHz, or pretty much any class C AM station at night time. These types of tests will represent at least a few of the existing antenna systems and stations. Will that happen? It depends on whether the FCC will hold somebody’s feet to the fire and demand meaningful testing.

Much ink has already been spilled by various trade publications debating the future of AM broadcasting. Most take the position that there are several technical issues that make AM broadcasting problematic if not downright untenable. There are indeed some technical issues with AM when compared with FM or IP-based audio distribution. There are also several ways that AM broadcasting is superior to both FM and IP-based audio distribution. The truth is that AM broadcasting’s issues are complex and involve technical, regulatory, and operational considerations.

These can be broken down as follows:

AM is prone to electrical noise interference
AM is prone to co-channel and adjacent channel interference
AM has inferior bandwidth and thus the audio quality
AM has poor signal quality
AM has a low or no market share

All of these problems conspire to make AM broadcasting unprofitable, or so the narrative goes. Does all-digital AM HD radio really solve any of these problems? From the WBCN test alone, the results are inconclusive.

Transmitting a signal in digital format does not make it immune to noise or interference. It simply masks the interference until the noise floor becomes too high causing excessive bit errors, at which time the receiver mutes. Thus, with AM HD radio in a noisy environment, the listener will not hear static, that much is true, they may not hear anything at all. Is this all-or-nothing reception an improvement?

AM broadcasting audio bandwidth problems are mostly self-inflicted. AM stations created loudness wars in the 60s and 70s, causing splatter and adjacent channel interference on older, cheap diode detector-type receivers. Receiver manufacturers responded by limiting IF bandwidths to 3-4 KHz, slightly better than telephone quality. The industry came up with the NRSC-1 standard which limited AM bandwidth to 10 KHz or less. For a long while, AM radio receivers remained very poor. This appears to be changing with newer receivers that are both more selective and more sensitive. My Toyota has a Pioneer radio which has good bandwidth on AM. Is it as good as FM? No, but it is certainly listenable, especially if no other station is playing that style of music.

That brings me to programming, which is the real crux of the issue. Continued in part II.

Three generations of emergency communications

Even before CONELRAD was introduced in 1951, radio broadcasting was a critical part of the emergency communications infrastructure. The government recognized early on the ability of radio to transmit data and information quickly, over large areas to the general public. It works when all other systems fail, as demonstrated repeatedly over the years, the last of which occurred during Hurricane Sandy last October. Massive destruction from flooding in lower Manhattan and shoreside Brooklyn rendered the electrical grid, telephone network, cellular network, and the internet out of order. Fortunately, enough radio stations stayed on the air and people used battery-powered AM and FM receivers to obtain information.

CONELRAD poster, circa 1950's — CONELRAD poster, circa 1950’s

CONELRAD served two purposes; first, radio stations either re-tuned their transmitters to 640 or 1240 KHz or switched off the air. Then, each station that was still on the air would transmit for ten minutes, after which, they turned off and the next station in the chain would turn on and transmit for ten minutes. This was designed to confuse the Soviet bombers flying over the north pole on their way to incinerate us. Secondly, the CONELRAD stations were to distribute emergency information during and after the said attack.

Recently, I found this CONELRAD receiver in a bomb shelter at a radio station. It dates to pre-1963, which is when CONELRAD was replaced by EBS.

EBS or the Emergency Broadcast System was a refinement of CONELRAD in several areas. EBS used a two-tone attention signal to unmute receivers and alert the public that something important may be happening. Initially designed as a national system to warn of an impending attack, in later years it was also used by state and local governments to warn of other emergencies like weather, etc.

The current system is EAS or Emergency Alert System.

The Emergency Alert System was an advancement of the EBS in several areas. Using SAME protocol in the message headers allowed stations to automate alert message relays. This was driven by the desire for unattended operation. The use of SAME also allowed many different types of messages to be filtered by alert type and area. Each EAS unit also had an internal voice recorder. All of this was upgraded in 2011 with the introduction of CAP, which would take email messages and generate computer voice alerts to be sent out over broadcast stations.

Three generations of emergency communications equipment found at one facility.

The main problem with EAS CAP is it violates the engineering principle of KISS (Keep It Simple, Stupid). It is an overly complicated system that relies on the internet, e-mail servers, the public telephone system, and other infrastructure that may not survive natural or man-made disasters, enemy attacks, or other disruptions. Even something as simple as a national test proved to be problematic in 2011.

For a real emergency information network, the idea of WGU-20 has some merit. Two or more well-positioned medium to high-powered LF stations could serve as a PEP distribution network and reliably cover the entire country. With such a system, every broadcast station, cable head end, and NOAA radio transmitter could monitor the LF stations directly, thus replacing most of the over-the-air daisy chain and or FEMA leased lines. The advantages of LF is that it is fairly immune to HEMP, it goes a long way reliably, can have multiple redundant transmitter sites located within secure areas like military bases, and uses time-proven technology. That would be a real, cold war solution. But no, let us instead rely on a hodge podge of ISPs, TELCO leased lines, 3/4G wireless networks, SMS, satellite links, e-mail servers, and the like, because: Hey! It’s the digital age, we don’t need none of that stinking broadcasting crap.

Opportunity

My son and daughter are playing ice hockey this winter. This means that every Saturday morning I have to get up very early and haul them off to the rink for practice and a game. It is actually a lot of fun because I love watching them play. Having played a certain version of pond hockey in my youth, it brings back good memories.

In any case, last week, after they finished their game and changed out of their hockey gear, my son wanted to watch the older kids play. Thus, we sat down in the bleachers for a few minutes to watch the 12-15-year-olds play against a traveling team. Most hockey leagues are mixed, that is to say, girls and boys play on the same team. Not to put too fine a point on it, but the girls can be decerned not only by their ponytails but also the pink stake laces or pink hockey gloves. I also noticed that the girls seem to play a more cerebral version of the game, which is a joy to watch.

Not soon after we sat down, a fast break play developed at mid-ice. It was truly a thing of beauty. A player from the home team intercepted a pass from the opposing team and took off down the ice. She was followed closely by another player from her own team. As they crossed the opposing red line, the other team closed in. I watched the lead player move fast toward the goal and then fake out the goalie, lifting her stick oh so much as she made the shot. The goalie was completely fooled and dove for the non-existing puck, which was left on the ice for the following player, who neatly scooped it into the goal under the goalie’s leg. It was over in a flash of white jerseys and pink laces. I thought to myself; these are kids are great! You do not have to watch an NHL game to see good hockey and sometimes the so-called “professional” sports are overrated anyway.

Which got me thinking about LPFM. How many budding journalists, play-by-play announcers, DJs, and presenters are out there waiting for an opportunity to show their stuff? An opportunity that they may never get because most commercial and many public radio stations are locked into an increasing automation loop. Locally originated programming is constantly being cut and replaced by satellite-syndicated formats and or out-of-market voice tracking. It is truly a shame because the strongest leg that terrestrial radio can stand on is localism.

LPFM can be that opportunity to return the radio to its community of license. It will not be easy, clearly, the rules were written to prevent LPFM from ever competing with commercial or even public radio stations. Restrictive power levels, odious interference rules, and limited fundraising capability will keep all but true believers and perhaps ignorant souls from attempting for a license. It will be hard, but not impossible, and true believers will make a go of it. The October 15th, 2013 filing window will very likely be the last opportunity for community organizations to establish a local radio station. After that, the remaining spectrum crumbs will be divided between translator aggregators to create ever larger networks of mostly redundant content.

Terrestrial radio may well go through an evolutionary change. As more and more broadcasters are finding out, once a license is owned, there is a great deal of expense in operating a station. Things like employees and office supplies can be cut, however; towers need to be maintained, transmitters and antennas need to be replaced periodically, electricity bills must be paid, etc. The larger the station, the more operating costs are involved. Another serious economic downturn like 2008 and the crazy train will be off the rails. The inexpensive-to-operate, volunteer-run local LPFM may indeed be the last radio station(s) standing. I have heard many decry this type of station as “amateurish” or “not professional.” Here is what can happen if you give a bunch of amateurs a free hand:

Good stuff. Big picture stuff.