Testing requires an HD Radio exciter, which can be had from transmitter manufacturers Broadcast Electronics or Harris. Also, iBiquity can supply information about its testing and certification program.
One of the main issues these radios face is the EMI problem caused by the DSP and embedded processors. To reduce the interference with sensitive RF receiver circuits and to meet FCC class B radiation tests, most manufacturers must spend time designing a board layout that minimizes EMI. Filtering eliminates most of it, but in some cases, shielding is required.
So far, iBiquity has blessed the Radiosophy MultiStream HD desktop radio. It uses Alps' tuner and TI's chips. FM signal-to-noise ratio is 78 dB, and AM's is 50 dB. The MultiStream's multicast capability lets uers select multiple streams from the FM signal. The AM and FM antennas are built in, with connections available for external antennas. Audio comes from dual-channel 8-W amplifiers with 4-V speakers. The 128-by 64-pixel backlighted LCD display shows time, frequency, and scrolling messages as stated in the HD standard.
Other interesting features include a stereo headphone mini jack and a USB port that will upload software upgrades into the DSP via the Internet and a PC. It also integrates RCA phono jack outputs in Sony/Philips Digital Interface (S/PDIF) digital format. An S/PDIF Toslink optical output jack sends the digital audio directly to an external stereo amplifier with larger speakers.
THE FUTURE
HD Radio is here. Unfortunately, only a handful of people have it, and not many more are even aware of it—despite the fact that it's present in multiple stations in most areas.
Recognizing this, major broadcast corporations have joined together to form the HD Digital Radio Alliance. This organization is devoted to publicizing HD Radio and lobbying auto manufacturers to add HD to their standard radio offerings. With more home radios on the way, users will soon be able to sample multiple new programs and services.
HD Radio was born with the initial goal of improving radio audio quality and reception reliability, which has been achieved. But with the new multicast capability (called HD2), stations are lining up lots of new shows and programs, such as specific music channels as well as talk shows.
Once they're in place, HD Radio will give satellite radio a run for its money. HD won't replace satellite radio, with its hundreds of channels of programming. But it will offer far more local programming choices, all for the price of a new radio. Look for high-defintion to explode once the word gets out and radios become affordable.
For more, see "Few Radios, Yet" at Drill Deeper 12192, "100 Years On The Air" at Drill Deeper 12193, and "Need More Information?" at Drill Deeper 12213 at www.electronicdesign.com