I have been working on an HD Radio installation these last few days. This particular installation was manufactured by Broadcast Electronics. Some 13 years into the HD Radio development cycle and the implementation still seems like a kluge to me. To get some idea; to transmit a digital HD Radio with added sub-channels, the following equipment is needed:
- HD Data importer, off the shelf computer with a sound card and specific software from iBquity. This is used to import the audio for the HD-2 and HD-3/4 channels. Runs on Windows (Win 7), Linked to the exporter via IP ethernet
- HD Radio exporter, another specialized computer with a sound card. Frames the HD Radio data and adds PID, etc. Runs on Mandrake Linux, communicates with the exciter via data connection.
- HD Radio exciter; like other exciters, generates RF and modulates it.
- HD Radio transmitter; essentially an FM transmitter designed to run as a linear amplifier.
The HD Transmitter part can come in several configurations, including low level combining, high level combining or using a separate antenna for digital and analog signals.
None of this is news, of course. My point is, after ten years, there does not seem to be any further development in HD Radio technology. In the mean time, competitors are not standing still. The mobile wireless industry has evolved several times during the same time period; 3G, 4G and LTE have been successfully deployed and widely adopted by mobile phone users. Truly, mobile data is the real competition to terrestrial broadcasting.
The HD Radio transmission process is an overly complicated patchwork of hardware and software. The importer in particular seems substandard. It’s function is to run a bunch of small programs, each doing some small part of the importing process. The web-admin used Internet Explorer, who uses Internet Explorer anymore?
Since the HD Radio inception, little or no further development seems to have taken place. There are features, such as album art, program data, traffic data, etc but the system interface is weak, the hardware clunky, the data paths fragile, the operating system outdated, the typical installation is a compromise between cost and available floor space at the transmitter site.
HD Radio is also expensive to deploy and proprietary. There is little compelling reason to listen to HD-1 channels because the programming is identical to the main analog channel. HD-2, 3 and 4 channels seem to be mostly used to generate translator feeds, which again, are available with an analog radio. This use of HD Radio actually damages uptake because, If all the HD Radio sub channels are available on FM analog frequencies, then why even bother with an HD Radio receiver?
Thus the forces at work in the development of HD Radio seem to have reached equilibrium:
Consumer apathy + expensive deployment = 16% uptake on FM and 6% uptake on AM1
The digital radio roll out has been stuck at those levels for many years. Unless something changes, FM HD Radio will be limited to translator program origination and distribution. AM HD Radio will go the way of AM Stereo.
1: FCC data on HD Radio deployment; 1,803 of 10,727 FM stations and 299 of 4,708 AM stations have installed HD Radio as of December 31, 2014.