The standard FM channel in the United States, as defined by the FCC is 200 KHz (See CFR 47 73.201). The occupied bandwidth of an FM IBOC signal, as created by Ibiquity, Inc, is 400 KHz. See below picture:
HD radio trace on FSH3 Spectrum Analyzer
A picture is worth a thousand words. Engineering types will understand this without explanation. For non-engineering types, here is your thousand words (or so):
On the left hand side of the screen is the signal strength scale. Each vertical division is 10 dB. This is not absolute signal strength, it is referenced to -20 dBm. However, it gives a good relative signal strength for both the analog carrier and the IBOC carriers. The analog carrier is centered on the screen, it slopes upward like a steep mountain, peaking at -50 dBm relative. The IBOC carriers are on either side of the analog carrier, they are flat, approximately 75 KHz wide and peak approximately 20 dBm below the analog carrier (-20 dBc). For some reason, likely the bandwidth and/or impedance match between the antenna, high level combiner and the two transmitters, the left IBOC carrier is actually peaking around -14 dBc.
The span, as noted on bottom right hand side of the screen is 500 Khz. Each horizontal division is 50 KHz. The entire span of the measurable signal is eight horizontal divisions, thus 400 KHz.
As noted above, the allocated channel bandwidth is 200 KHz, thus this station is exceeding it’s allocated bandwidth by 100%. This is allowed under CFR 73.404, which is titled “Interim hybrid IBOC DAB operation.”
IBOC proponents will make the argument the FM radios work on something called “The capture effect,” which is to say that if two signals are on or close to the same frequency, only the stronger signal will be demodulated. Thus, the IBOC carriers have no effect on the adjacent channels that they are interfering with so long as the adjacent signal is stronger than the IBOC carrier. The argument is further carried forward by assuming that with a stations protected contour (60 dBu in most cases), the IBOC carrier will never exceed that analog carrier.
That is not necessarily true, especially in areas where terrain (and buildings, underpasses, unintentional directionality in transmitting antenna, etc) can attenuate signals close in causing the IBOC signal to become equal to or stronger than the adjacent analog signal. This effect causes picket fencing. Lower powered FM stations; class A, LPFM, etc, are especially vulnerable to this effect.
Further, even in areas where the analog carrier is stronger than the IBOC carrier, the noise floor has been moved from -100 dBm or so to -70 dBm, which is a 1,000 times greater. To assume that raising the noise floor by 1,000 times will have no effect is, as they used to say in the Navy, making an ASS out of U and ME. Mostly you, in this case. This effects the receiver by making it less sensitive, it will also add noise to the demodulated signal as the elevated noise floor will show up as background hiss. Even further still, higher IBOC carrier levels, as authorized by the FCC in January of 2010 can interfere with the stations own analog carrier.
According to the both Ibiquity and the FCC, which stated in the Notice of Proposed rule making, the reason for interim IBOC operations are:
iBiquity’s IBOC DAB technology provides for enhanced sound fidelity, improved reception, and new data services. IBOC is a method of transmitting near-CD quality audio signals to radio receivers along with new data services such as station, song and artist identification, stock and news information, as well as local traffic and weather bulletins. This technology allows broadcasters to use their current radio spectrum to transmit AM and FM analog signals simultaneously with new higher quality digital signals. These digital signals eliminate the static, hiss, pops, and fades associated with the current analog radio system. IBOC was designed to bring the benefits of digital audio broadcasting to analog radio while preventing interference to the host analog station and stations on the same channel and adjacent channels. IBOC technology makes use of the existing AM and FM bands (In-Band) by adding digital carriers to a radio station‘s analog signal, allowing broadcasters to transmit digitally on their existing channel assignments (On-Channel) iBiquity IBOC technology will also allow for radios to be ”backward and forward” compatible, allowing them to receive traditional analog broadcasts from stations that have yet to convert and digital broadcasts from stations that have converted. Current analog radios will continue to receive the analog portions of the broadcast.
Few if any of those goals have been met. As far as the forward/backward compatible thing, it just isn’t so unless a person actually owns an HD Radio. As noted in previous posts, few consumers have seen fit to purchase an HD Radio, nor have car manufacture’s taken to installing them en mass in new cars, so there is no forward compatibility. Instead, we have FM radio stations interfere with each other and themselves in an attempt to “modernize” the audio broadcasting business. This is a bigger problem for small, community radio stations that can neither afford to install the expensive, proprietary HD Radio system, or broadcast quality receivable signals with an adjacent HD Radio signal raising the noise floor by 1,000 times or more.
I can think of no other greater threat to free over the air broadcasting than HD Radio and the degradation of AM and FM services that comes with it. The consumer has shown that they don’t care. If given the choice between free over the air broadcasting that has mediocre programming and is full of interference, and some type of paid internet streaming service that sounds reasonable with good programming, they’ll go for the latter.
In short, some cobbed together digital modulation scheme is the last thing that radio needs right now.
I have received an e-mail from occasional reader John, who comments that many of the Windy City AM’s have turned their buzz saws off. I note myself today, the same can be said for many of the NYC AM’s. WABC has had their’s IBOC turned off for quite some time. The latest to turn off is WNYC on 820 KHz. Several people have noted the loss of noise on their signal this morning.
According to Ibiquity’s own website, only six AM stations in the NYC market are currently using IBOC.
What does this mean?
Could it be that management is finally realizing that the cure is worse than the disease? The disease being alleged poor audio quality, and the cure being IBOC itself.
I found this picture of Bob Struble’s vacation last summer:
HD radio flagship
To the uninitiated, this might seem quite alarming; boat sinking, rigging all ahoo, this poor guy waiting rescue or certain death. But to understand what is going on here, you have to see the whole picture. Things are not what they seem, in fact, it’s designed that way:
The rest of the story
All this time, I have been lamenting the technical flaws IBOC, when really; its supposed to do that. Holy cow! All these years of wondering, “What the fuck are they thinking?” and decrying HD Radio, especially AM HD radio. Boy am I embarrassed. Makes me want to do this:
Baghdad Bob Bob Struble latest quote, brought to bold typed prominence on the pages of Radio World magazine: ”Consumers now expect to see album covers when they listen to music.” I think he means album art, but anyway.
You mean to tell me HD radio is failing because of lacking album art! Of all the Bob Struble quotes, to prominently feature this one in their article makes me think 1) the editors at Radio World have a sense of humor, or 2) they have a sense or irony, or both.
So anyway, there you have it: Album Art. The rest of the so called technical flaws are “design features” that will enhance HD radio in the long run. They’ve got us right were they want us.
If I had to pick, one of the most egregious things about HD Radio™ is the fact that it is a proprietary system. Ibiquity owns the licenses for the IBOC HD Radio™ technology. If the FCC were to force radio stations to convert to all digital transmission, like they did with TV, then one corporation would then own the modulation method for all of the radio stations in the country. It would also own all of the secondary (HD2 and HD3) channels by virtue of the password protected software and would, as current contracts are being written, be allowed to inspect the books any time they want.
This could lead to some very interesting situations, especially if Ibiquity chose to flex some muscle regarding programming content, formats, music, politics, news coverage, or what have you. Lets not forget, Ibiquity’s investors are large broadcasting companies like Clear Channel, Cumulus, Citadel, Univision, and so on. Smaller broadcasting companies could likely get caught in a go along to get along situation.
If you have never played with an HD Radio™ exciter, let me tell you, everything is locked down. Every function needs a password from Ibiquity and there is no way around it.
Ibiquity’s proponents dismiss this concern and continue to say “Just wait until the patent expires, then it will be an open system.” Except that the “patent” is not going to expire. Ibiquity owns 16 patents for their IBOC system. Only one patent needs to be in effect for the HD Radio™ system to remain proprietary. The last patent was issued on May 10, 2010. Ibiquity simply needs to make some small change, update, or tweak and they can file for a new patent, which will add another 10 years. This can continue indefinitely.
It has been about a month now, has anyone taken them up on this:
iBiquity Digital and Citadel Media announced a partnership which will enable stations to upgrade to digital while avoiding cash expenditure. Stations will have the opportunity to provide on-air inventory to Citadel Media in exchange for the HD Radio license fee and equipment supplied by Broadcast Electronics, Continental, Harris and Nautel.
I was sure that my former employer, now that I have left the company, would at least look into this. I know there are many other frugal like minded companies out there that look at trade as being “free.” Anytime I had a building project, like paving the parking lot or replacing the roof membrane, the first question asked was “Can we trade it?” I hated dealing with trade. Often, it would end up as a half paved parking lot and the general manager asking “Gee, what happened?”
I would be surprised if this iBiquity scheme didn’t generate at least some interest in the HD radio holdouts. Has anybody heard anything else on this?
Or, it could also be phrased “A solution that causes more problems.” Radio World, once again, has a good article on the consequences of increasing IBOC power of the FM hybrid system. Especially telling is figure 24, a fuzzy 400 Hz sine wave showing how much distortion is added to the analog signal by a mere 4% HD signal. I’d be especially interested to see the results of the full 10% now allowed.
Naturally, HD proponents will cry “But this is only temporary! Wait until the transition to all digital!”
Bunk.
If HD radios were indeed flying off the shelves as iBiquity claims, and if the public expressed interest, okay, maybe. Clearly, that is not the case. The only thing that HD radio is doing is creating more interference. Period. More interference to the parent station and more interference to the adjacent channels all for an audience that does not exist. Another way to put it: NOBODY IS LISTENING. One of the station that I service had a Harris Deathstar go off line for four days. NOT ONE PHONE CALL, NOBODY CARES!
The public did not perceive a technical problem with analog FM broadcasting. Of course, that can always change as the band gets filled with interference.
Lets see where FM IBOC stands:
Rolled out with 1% digital power vs analog carrier, the system was found to lack building penetration and generally performed poorly in mobile listening environments (NPR labs study, Nov 24, 2009)
FCC allows up to 10% digital power vs analog carrier to overcome these problems, a few stations implement some type of power increase
The shows that self interference is the largest problem IBOC needs to fix, one that is un-fixable due to the laws of physics
The public yawns, turns on their iPod
IBOC is a failure, both in AM and FM bands.
We are watching the self destruction of radio broadcasting in the US.
I see this statement being made on various forums, blogs and other places. As some would like to believe, the problem with HD radio is that people don’t like change. A Look at the early days of FM radio in the 1950′s is a good example of this. FM radio took decades to catch on, HD Radio is no different. Currently, HD Radio is experiencing “growing pains” and the occasional “bump in the road.”
Except; no, not really.
Here is a side by side comparison:
Problem/issue
FM radio 1950
HD radio 2010
Implementation of technology
A new band was created and new radios containing the old (AM) and new FM band were manufactured. During the experimental phase (1937-47), the frequencies were between 42-50 MHz. This changed to 88-108 MHz in 1947. Uptake on new radios was slow due to a frequency shift.
Existing AM and FM frequencies were utilized using “Hybrid” mode. This entailed changing existing channel bandwidths arbitrarily
Funding
FM radio was implemented by broadcasters who, for the most part, bore the brunt of the costs themselves.
The CPB has granted millions of tax payer dollars to public radio stations to implement HD radio with most of that money going to one company, the owner of the proprietary technology. To date, NPR stations are the single largest user segment of HD radio.
Creation of interference
FM broadcasting created no interference to any other broadcasting station when it was rolled out
HD radio has created many interference problems, especially on the AM band at night, where skywave propagation makes adjacent channel stations bear the brunt of exceeded bandwidths. FM is prone to co-carrier interference from higher digital power levels created to solve poor reception issues in addition to adjacent channel interference to adjacent FM broadcasters from exceeded bandwidths.
Lack of consumer awareness or interest
Consumers were generally aware of FM radio, however, the FCC created a major stir when forcing FM broadcasters to move from their original frequency band of 42-50 MHz to 88-108 MHz. This move rendered obsolete many FM radios and caused hard feelings amount early FM radio fans.
Consumers generally unaware of HD. Those that are become disappointed with the lack of additional programming choices and poor receiver performance
Technical reception problems
FM stations began broadcasting with low power levels and horizontally polarized antennas. Radio was not yet a mobile medium. Many FM listeners needed to install outdoor antennas on their homes to get reception. Radio listeners were willing to undertake this for good reception.
HD power levels are less than needed to have reliable reception in buildings and mobile listening environments. A 6 to 10 dB increase has not effectively been implemented nor solved the problem
Audio quality
FM broadcasting is markedly superior to AM broadcasting in the areas of noise reduction and fidelity.
HD radio offers a slight improvement to “CD quality” which is hard for the average listener to tell apart from typical analog FM. AM offers increased audio quality over analog, however, due to reception problems, AM receivers often loose data synchronization and return to the analog signal, creating up/down listening experience most find annoying.
Auxillary services, additional channels
FM broadcasting did not have any such features in 1950
HD radio offers the choice of 2 additional channels for programming. These channels are taken from the existing bandwidth/bit rate of the digital carrier and are a lower quality than the main channel. In addition to that, there is a data channel that can be used to display song titles and such
Programming
FM broadcasting began by offering programming unique from AM stations. The programming often consisted of classical music networks, educational programs, news programs and other such things. Additionally, commercial FM broadcasting often had fewer commercials than it’s AM counterpart
HD radio main channel is the exact duplicate of its analog signal. HD-2 and HD-3 channel offer a variety of programming choices including simulcasts of AM stations, retransmissions of co-owned out of market stations, syndicated satellite programs, and occasionally a niche format.
Electronic Media availability
During the early FM development and implementation the only competing electronic medium was AM radio
The choices of electronic media are wide and diverse. These include TV, satellite radio, internet, 3G wireless, mp3 players, AM and FM radio
Regulatory environment
The FCC staff was filled with ex or future RCA employees, who were interested in the status quo, thus keeping FM from becoming too big too fast and competing with the roll out of RCA’s television technology. Therefore it was hobbled with low power levels and a bizarre station class structure
HD radio has enjoyed a rubber stamp environment where large businesses and the FCC work together to re-write interference regulations with no regard for technical consequences.
The FM roll out in the late forties and early fifties is vastly different from the HD Radio rollout in the zero zeros. Due to fear of competition and patent disputes, RCA in conjunction with the FCC did all they could to squash the new technology. That is why FM radio took so long to be accepted by the general public. For those not versed with the history of FM development and FM broadcasting in the US, see Empire of the Air, by Tom Lewis. See also: Edwin H. Armstrong. It is a good read for those radio obsessed.
HD Radio is failing because the consumer is not buying it, I see little to change their mind.
Could be. Digital Radio Mondiale, or DRM, is a modulation scheme that a group of broadcasters and transmitter manufactures have been working on since about 1997 or so. There are numerous shortwave broadcasters; the BBC, the CBC, Deutsche Welle, Radio France Internationale, the VOA, and others have been using DRM on shortwave for several years now. I can state that the shortwave DRM system works well, I have a software decoder and use the sound card input on my computer to decode and listen to DRM shortwave broadcasts.
The goal of DRM is to establish a world wide open standard for digital broadcasting in the LF, MF, HF, and VHF bands. In the early years of development, DRM was designed for digital broadcasting on the bands below 30 MHz. This system is now known as DRM30. Since then, the DRM consortium has expanded that to the VHF band (up to 174 MHz) as well (meaning where the current FM band is located) and have called that system DRM+.
DRM uses COFDM (Coded Orthogonal Frequency Division Multiplex) modulation, which is the same as IBOC HD radioTM. This is a robust modulation system that employs multiple carriers at lower power (than an analog carrier) spread across the entire alloted bandwidth.
One of the claims is DRM transmits less power and is more energy efficient. In general, digital radio modulation does transmit less power, that is true. However, transmitters have to be run more linear for digital due to the increased bandwidth. This may not translate to greatly increased efficiency from the AC mains to RF standpoint. Because of that, there is more waste heat, and thus more air conditioning is needed to cool the transmitter room.
Some of the advantages of DRM over Ibiquity’s HD radioTM are:
Open source system. Royalties are paid by the transmitter manufactures only (and do date, most major US transmitter manufactures have already paid these). There is no royalties paid by the broadcaster to install DRM or by the consumer when purchasing a DRM capable receiver. One company does not own the rights to the modulation system for all the broadcasters in the country.
Universally standard; accepted by the European Telecommunications Standards Institute (ETSI), International Electrotechnical Committee (IEC), and the International Telecommunications Union’s (ITU).
The CODEC is HE-AAC 4, which is widely used world wide.
DRM30 and DRM+ fits into existing band plans and will not interfere with other users on adjacent channels. DRM30 is designed for 9 KHz channel spacing and DRM+ is designed for 100 KHZ channel spacing, all of which comply with existing FCC regulations.
Standardized receiver profiles, things that must be included in all DRM receivers. There are several advanced options as well, such as a media rich system that includes video.
DRM+ has several added features: DRM text, which is similiar to RBDS. EPG or electronic programming guide, which shows what is coming up next and a searchable schedule of when programs may be heard out to seven days. Some DRM+ receivers will have a TIVO like recording device that allows the user to record programs and play back later.
Traffic reporting and routing
In addition to that, DRM30 station have the ability to transmit low frame rate H. 264 video. This is a distinct advantage for short wave stations that are seeking a way around fire wall blocking. The video image is small, 176 x 144 pixels, and it is 8 frames per second, which is about as good as can be expected using a 9 KHz channel.
In some cases, DRM is capable of a hybrid mode (ed note: DRM calls this “Simulcast mode”), but what have we learned about hybrid mode digital radio: It doesn’t work very well. In short, it would be better if DRM were employed in the digital only mode. To many, this is a distinct disadvantage, but I don’t see it that way. There have been many that have made the IBOC roll out/FM broadcasting roll out annology. Frankly, those arguments don’t hold water. When FM was introduced, no attempt was made to shoe horn it into the existing AM (Standard Broadcast) band, it was not designed to interfere with other stations or itself, power levels were sufficient for good reception using existing technology, quality over AM was markedly improved and programming was often separate (simulcasting with existing AMs did not start until later). My point here is that any digital broadcasting should be introduced on a separate set of frequencies. Some have proposed using TV channels 5 and 6, which makes some good sense. Whatever the outcome is, we have learned, the hard and expensive way, that hybrid digital broadcasting does not work well.
A brief video about DRM30.
Currently, DRM30 is only allowed on shortwave broadcast frequencies in the US. I asked a product development engineer from a major reputable broadcast transmitter manufacture about this, his response was:
Medium wave broadcasting in the US already has HD radio, so the FCC would be disinclined to allow a new standard
One might be able to apply for an experimental license to broadcast DRM, but it would likely have an expiration date
It is possible to operate DRM in a hybrid mode on the AM band and occupy the same bandwidth as HD radioTM (30 Khz), it might also be possible to squeeze that down to 20 KHz.
Most modern (read: solid state) AM broadcast transmitters should be able to transmit DRM without modification (antenna systems may be a different matter).
It might be fun to apply for an experimental license to broadcast somewhere in the 1600-1700 KHz range with DRM30 only and no analog modulation, except for an hourly station ID in morse. A 1/4 wave tower in the middle of that band would be 141 feet tall. With use of a skirt, a grounded tower can be employed. That and a few above ground radials and the system would likely be pretty efficient. Part of the experiment would include driving around and taking signal strength readings while recording the programming material. This would give some real world testing on how the system would perform in wide spread use.
Of course, this would require a major about face by the FCC, which is not likely unless someone there grows or somehow acquires a back bone.
Some people question the need to do any type of digital broadcasting. I am a realist, in one way, shape, or form, digital radio broadcasting will (or already is) take(ing) place. It would make the most sense if the best system were used, which is not necessarily the first system proposed. The big question is, will today’s terrestrial broadcasters be involved, or out of business.
A little bit of information on what an AM HD Radio exciter looks like:
IBOC exciter, AM HD Radio
That is a Nautel version. The Harris version is called the “Dexstar,” Which has been nicknamed the “Deathstar” by those that work in the field. I was calling it the Harris Disaster, but found that nick name to be ambiguous.
Far better than I could ever explain it, Dave Hershberger, of Continental Electronics explains some of the potential problems with increasing the IBOC carrier(s) in an FM HD Radio system. If you have not already read it, read the entire article, it sheds some interesting light on the IBOC system and how it works.
Transmitting more digital power will certainly increase the digital coverage area and reduce digital dropouts. However, there may be some unintended consequences, which every broadcaster will have to evaluate before increasing digital power.
It is all right there. What amazes me is that the IBOC proponents do not acknowledge the system’s problems. Perhaps the above article is a bit over the head of the average general manager, or group VP, whatever the title dejour is. Engineers should understand this. Engineers should be able to explain this in an understandable way to managers and owners. It is the owners or whoever is holding their paper that have the most to loose in this scheme, which is to say, everything. Forget the FCC, they are in the pockets of their corporate sponsors anyway. Radio station owner’s and the bankers that control them should take a real hard look at this and see for themselves that they are writing their own epitaph.
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
~1st amendment to the United States Constitution
Any society that would give up a little liberty to gain a little security will deserve neither and lose both.
~Benjamin Franklin
...radio was discovered, and not invented, and that these frequencies and principles were always in existence long before man was aware of them. Therefore, no one owns them. They are there as free as sunlight, which is a higher frequency form of the same energy.
~Alan Weiner
Everyone has the right to freedom of opinion and expression; this right includes the freedom to hold opinions without interference and to seek, receive and impart information and ideas through any media and regardless of frontiers
~Universal Declaration Of Human Rights, Article 19
Heard in the clear