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 1930’s 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 1970’s 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, operator license requirements were done away with, 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 manufactures responded to consumer complaints by greatly reducing the audio bandwidth of their AM receivers
  • Broadcast deregulation greatly increased in the 1980’s
  • The FCC voted in 1980 to limit skywave protection of clear channel (class I or A) stations to within 750 miles of 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, 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; 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 carrier are introduced with power levels of -16dBc.  For a 50 KW station, this equals approximately 2,500 watts 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 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, 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 staffs were 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 seems to be several common threads, but the two most common are a 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, or 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 test 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 which makes 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 audio quality
  • AM has poor signal quality
  • AM has 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, 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 60’s and 70’s, causing splatter and adjacent channel interference on older, cheap diode detector type receivers.  Receiver manufactures 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 music.

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

The NAB’s AM study

As has been widely reported in other places, the NAB (National Association of Broadcasters) has completed its study of AM Radio and recommendations to improve the service.  The NAB has taken a cautious, if not somewhat paternalistic approach of holding the report while they review their options.  It seems that the technical nature of such a document would not be understood by us mere mortals.

Some of the AM improvement options that have been bantered about in the past include:

  • Moving AM stations to the vacant frequencies of TV Channels 5 and 6, see this.
  • Reducing the number of AM stations on the band, see this.
  • Increasing transmission power of AM stations, see this.
  • Converting AM stations to all digital modulation, see this.

There may be a few other options considered also.

It does not take too much analytical prowess to deduce where the NAB’s proposal is going.  My prediction is that they will be promoting an all digital “solution” to the AM broadcasting issue using iBquity’s HD Radio product.  I base this prediction on the fact that all of the major radio members of the NAB (Clear Channel, Cumulus, CBS, et al) are heavily invested in the iBquity product.  For this reason, the NAB will find (or has found) that digital broadcasting in the medium wave band will solve all of the current perceived problems with AM and everyone should embrace the technology.

A few numbers to note:

  • iBiquity and the FCC data base reports that there are currently either 270 or 299 AM station licensed to operate with HD Radio. Other sources note that several of these stations have been turned off and the actual number using HD Radio is 215.
  • There are 4754 AM stations licensed by the FCC.
  • Currently HD Radio is transmitted 4-6% of the AM stations in the country.
  • It costs $25,000 US to license a single HD Radio station through iBiquity.  They are, however, discounting that to between $11,500 and 13,500 and have a convenient payment plan (limited time offer, expires December 31, 2012, FCC license fees are extra).
  • It costs between $75,000 and $150,000 to equip and or modify a single AM station with HD Radio gear.

Unless iBiquity drops all patent claims and licensing fees to use its product, an FCC mandate for AM stations to install HD Radio would be skating dangerously close to corporate fascism (AKA Mussolini Fascism or Corporatism) as one corporate entity would then control broadcast radio by licensing its modulation scheme.  And no, the patent is not going to expire.

Digital modulation schemes used in the medium wave band have their own set of technical issues.  HD Radio is not the panacea for AM broadcasting’s self inflicted woes.

Shocker: LPFMs have little or no impact on commercial FMs

The long awaited report, required by the NAB as a part of the Local Community Radio Act has concluded that LPFMs have little or no impact on commercial FM stations. No kidding?

The executive summary states that:

LPFM stations serve primarily small and rural markets and have geographic and population reaches that are many magnitudes smaller than those of full-service commercial FM stations. In addition, LPFM stations generally have not been in operation as long as full-service commercial FM stations, have less of an Internet presence, and offer different programming formats. We also found that the average LPFM station located in an Arbitron Radio Metro Market (“Arbitron Metro”) has negligible ratings by all available measures and has an audience size that lags far behind those of most full-service stations in the same market.

Followed by:

Although each of the stations differs considerably in its individual characteristics, the results of the case studies show that the selected LPFM stations generally broadcast a variety of programming continuously throughout the day, operate with very small budgets, rely on mostly part-time and volunteer staff, do not have measurable ratings, have limited population reach, and do not generate significant underwriting earnings. All but one of the station managers that we interviewed stated that the LPFM station is not competing directly for listeners with any specific full-service stations.

And:

We conclude that, given their regulatory and operational constraints, LPFM stations are unlikely to have more than a negligible economic impact on full-service commercial FM stations.

Forgive my excessive block quoting of the FCC report titled: Economic Impact of Low-Power FM Stations on Commercial FM Radio, I found those portions of text far better than anything that I could write on the subject.

The NAB is reportedly “reviewing” the results, which the cynical me thinks is just another way of stalling a potential LPFM window later this year.