HD radio – Page 13 – Engineering Radio

IBOC update

Since the FCC approved a tenfold increase in the radiated power of the digital carrier, a progress report on the digital radio rollout is in order. The FCC report and order (MM Docket No. 99-325) give us some background:

An original goal of the developers of the hybrid FM IBOC DAB system was replication of FM analog coverage without adversely affecting either the host analog signal or adjacent channel analog FM operations. iBiquity and several independent parties conducted extensive field and laboratory tests. Based on the National Radio Systems Committee (“NRSC”) evaluation of those test results, iBiquity requested and the NRSC approved an FM Digital ERP of one percent of FM Analog ERP (20 decibels below carrier (-20 dBc)).

And (after paying gobs of license fees and installation costs):

Many FM stations promptly commenced hybrid FM IBOC operations. Despite the rigorous testing, it soon became apparent that hybrid FM IBOC digital coverage often did not replicate analog coverage, especially in mobile and indoor environments.

Therefore (Fox, here are the keys to the hen house, knock yourself out):

Based on the results of the experimental operations with increased FM Digital ERP and other studies, on June 10, 2008, a group consisting of 18 radio group owners that operate over 1,200 commercial and noncommercial educational (“NCE”) FM stations and the four largest broadcast transmission equipment manufacturers, identifying themselves as “Joint Parties,” requested (the “Joint Parties Request”) that the Commission generally increase maximum permissible FM Digital ERP10 from one percent of a station’s authorized analog ERP (-20 dBc) (1% FM IBOC Power”) to a maximum of ten percent of a station’s authorized analog ERP (-10 dBc) (“10% FM IBOC Power”).

Based on (We find these hens are delicious!):

NPR concluded that at 1% FM IBOC Power, the mobile, indoor and portable digital coverage achieved by most FM stations would not replicate analog coverage, but that at 10% FM IBOC Power most FM stations could achieve digital mobile, portable and indoor coverage levels which either met or exceeded comparable analog coverage levels.

And (in spite of numerous concerns by the public and other broadcasters) Viola:

73.404 Interim Hybrid IBOC DAB Operation.
(a) The licensee of an AM or FM station, or the permittee of a new AM or FM station which has commenced program test operation pursuant to § 73.1620, may commence interim hybrid IBOC DAB operation with digital facilities which conform to the technical specifications specified for hybrid DAB operation in the First Report and Order in MM Docket No. 99-325, as revised in the Media Bureau’s subsequent Order in MM Docket No. 99-325. FM stations are permitted to operate with hybrid digital effective radiated power equal to one percent (-20 decibels below carrier (dBc)) of authorized analog effective radiated power and may operate with up to ten percent (-10 dBc) of authorized analog effective radiated power in accordance with the procedures set forth in the Media Bureau’s Order in MM Docket No 99-325. An AM or FM station may transmit IBOC signals during all hours for which the station is licensed to broadcast.

Notice how they stuck AM nighttime operation in there too. Now I get to hear IBOC signals over riding adjacent channel stations that used to come in clearly via skywave. One tends to wonder if this interference is not deliberate. Crush the small operators with interference, make their stations worthless, drive them out of business…

To help things along, iBiquity has offered to reduce their licensing fees to ~~$5,000.00~~ (oops, its more like $10,500 – 12,500). These rules were put into effect on January 29, 2010. According to the FCC database, there are 1524 FM stations and 292 AM stations transmitting IBOC. That breaks down to 15% of the FM stations and 6% of the AM stations. I will post an update if there is a sudden rush to install IBOC. Still a pretty low penetration for a 10-20-year-old technology. It is likely these low numbers are the reason why both broadcast bands are still mostly listenable, at least from a technical perspective.

As the noise floor rises and the competing stations sink further and further into the mud, the audience will turn to non-static-filled technologies to listen to their music and other programs.

Why am I not surprised

NPR and iBiquity have come to an agreement to screw the rest of us out of radio spectrum with a fourfold increase in HD Radio^TM power levels. Here comes the interference.

But hey, it’s the future, that digital stuff, because it’s better. And if you are not on board, then you are a narrow-minded backward thinker not worthy of consideration.

The funny thing is, all of the bells and whistles and whiz-bang digital do-dads, Ipod song titles, and fancy acronyms do not add up to a nano fart. If there is nothing compelling listeners to buy the HD Radios,TM it is a dead technology. Here is a news flash, when it comes to radio listenership,

IT’S THE PROGRAMMING, STUPID.

That has to be fixed, then the other stuff will start to make sense.

What do I know? I’m going to go have a cold beer and put my feet up.

The lesser of two evils

If I had to pick between allowing HD Radio^TM a 6 dB increase or removing the third adjacent protection for LPFM stations, I’d choose LPFM.

In tests performed by NPR, Ibiquity’s In Band On Channel (IBOC) digital radio scheme created significant interference to the first adjacent channel when running with 6% of the analog carrier power (-14 dB referenced to carrier) vs. the 1% (-20 dB referenced to carrier) currently allowed. The NAB would like to see -10 dB referenced to the carrier or 10% of the analog carrier power.

Remember Bill Clinton’s sign during his first election, something about the economy, stupid. In this case, it’s the Bandwidth, Stupid. In the US and Canada, FM stations are allowed 200 kHz of spectrum to transmit their analog signals. Analog signals include main channel mono (left plus right), and sub channels for stereo pilot (19 kHz) stereo matrix (left minus right), RDS (57 kHz), and any subcarriers in the 67-92 kHz range.

HD Radio^TM radio requires 400 kHz of spectrum to transmit its digital carriers. Here come those laws of nature again, you can’t fit 400 kHz bandwidth into 200 kHz of spectrum.

Ibiquity decided to try it anyway, contravening the FCC’s rules about FM broadcasting bandwidth channels which had been in place since the advent of FM broadcasting in the early 1940s. What they attempted to do was make the power level on the adjacent channel so low that most analog radios would not have a problem with it while there was a strong signal from another station present. (hey buddy, how about a little of this new thing called crack?) This is known as the capture effect.

Now, Ibiquity created this whole thing to make some money. Nothing wrong with that, this is a market economy after all. They marketed the hell out of HD Radio^TM radio, I saw them at various trade shows, they had full-page advertisements in all the trade magazines, they hit the phones, it was a full-court press (it’ll make you really cool, you’ll be able to do things you can do now and you’ll feel really good). They would even reduce or waive the license fee (here, just take a little rock, try it, on me, you’ll see).

So they were able to sell a very expensive system that has significant coverage issues because of the low power levels needed to satisfy the FCC’s concerns about adjacent channel interference. The NAB and many of the big radio groups bought in to it (gotcha, crackhead, you’re mine now).

Now, of course, those that bought into HD Radio^TM radio want their investment to work, (which it doesn’t right now) so all the talk of power increases and hey, lets just disregard that pesky interference issue. If you ignore it, eventually it will go away (along with the entire FM band).

The problems with HD Radio^TM radio are:

Inadequate building penetration at the current power level (1% of carrier power)
Bandwidth that exceeds current channel assignments on both AM and FM frequencies.
The proprietary nature of HD RadioTM’s CODECs and licensing for second channels give Ibiquity too large a role in saying how radio is broadcast in the US. Remember, radio station licenses are granted in the public interest, the owners are trustees of the public
Complete lack of public awareness.
It doesn’t really improve anything anyway.

By the way, shame on NPR (again) for their corporate stance contrary to maintaining good quality radio and serving the public interest.

Compared to that, LPFM is a very minor thing. As I said before, removing the third adjacent protection will raise the noise floor in the FM band and by default cause more interference. However, I’ll take a little more interference created by community radio stations over the complete rack and ruin of the FM band.