> There are a few, Crutchfield sells the Kenwood
> tuner for the cars. Boston Acoustics has a
> table radio, it's pretty pricy at $ 299.
> Hopefully this will take off and the prices
> will come down.
Or it may go the way of AM stereo. The technology leaves MUCH to be desired and the business model used by the iBiquity people is atrocious.
1. Technical considerations. Since this thread involves an FM station, I will limit my discussion to the FM version of the so-called "HD Radio". In FM IBOC, the digital information is encoded onto multiple carriers that "bracket" the analog FM signal. If common amplification is used, the IPA and PA stages of the transmitter have to be linearized by changing the grid bias of the tube(s) or the biasing of the power transistors. Otherwise, all kinds of problems result with the transmitted digital component, including spurious products falling well outside of the assigned channel. A linear amplifier has much lower efficiency than does the Class C amplifier used for analog FM. Separate amplification avoids the problems associated with having to modify the transmitter (assuming that it would still meet FCC type acceptance), but considerable power is wasted in the combiner and reject load. Some stations have received permission from the FCC to use "interleaved" antennas, with some bays fed by the analog transmitter and others by the digital transmitter. All of this is a big expense for the station converting to "HD Radio".
2. The business model. Unlike other technological advances, implementation of "HD Radio" by a broadcaster requires that broadcaster to pay annual royalties to iBiquity, in addition to the royalties paid by the manufacturers of the "HD Radio" equipment that were passed along to the station purchasing that equipment. This is double dipping. If the inventors of FM stereo (GE and others) or NTSC color television (RCA) did this, most FM stations would probably still be broadcasting in mono and most TV stations would still show us black and white pictures.
It seems that multicasting will be the "killer app" of "HD Radio". However, there is an alternate means of broadcasting multiple program streams over FM stations: the FM Extra system. This system uses SCA subcarriers with digital encoding. While analog SCA sounds terrible (5 kHz audio bandwidth), FM Extra provides up to three channels of full-fidelity audio. It does not require additional transmitters, exciters, or combiners, as it works with existing FM equipment. There are also no annual royalty fees for broadcasting with this system and no special FCC authorization is required. The downside of FM Extra is that receivers are not yet available on the retail market. Stations using this system should make sure that their transmitters are tuned for minimum AM noise, as is the case with any kind of SCA system.
Stations using either system should beware of concatenation artifacts, caused by multiple analog-to-digital or interformat digital conversions. Each time a signal is converted to digital or changed to a different digital format, information in the original audio waveform is discarded by the sampling and coding algorithms. This sounds horrible. The best way to avoid this is to run an AES/EBU plant all the way from the console to the STL and exciter, minimizing any interformat conversions in the studio.
