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HD Radio

WEMU began broadcasting with HD Radio™ technology on Wednesday April 7, 2004 at 11:00 a.m.

HD Radio™ technology combines historical analog signal generation and digital transmission at the same time on the same frequency.

To receive the new digital signal, a listener will need a receiver that is HD Radio™ capable.

The technology, developed by iBiquity, has been ten years in the making. The system was extensively tested for both AM and FM stations with FM stations being approved for 24-hour use of the technology in October of 2002. AM stations were approved for daytime use only.

Commercial and public radio stations in the top 13 U.S. radio markets (covering 60% of the U.S. population) were encouraged to convert to HD Radio™ technology as soon as possible. Detroit is one of those markets. Several Detroit commercial stations have already converted to the HD Radio™ system.

The Corporation for Public Broadcasting also encouraged public stations in these markets to make the conversion by providing equipment grants. In the Detroit market, WEMU, WDET, WUOM and WKAR-FM have received funding. WEMU is the first public station to begin broadcasting using HD Radio™ technology in Michigan.

WEMU used CPB grant funds ($75,000), plus revenue received from renting its tower to cell phone companies to pay for this conversion. No fundraising money was used to convert WEMU to HD Radio™ technology.

In addition to WEMU’s conversion to HD Radio™ technology, WEMU reinforced its transmitter site to be able to provide an uninterrupted broadcast signal in case of an emergency similar to that experienced in August 2003. This includes uninterrupted supplemental power for both transmitter and studio locations. This is also funded by rental income. No fundraising money was used to secure uninterrupted power.

Characteristics Today

With an HD Radio™ capable receiver, listeners, when tuning to a station broadcasting with HD Radio™ technology, will hear the first eight seconds in analog, then the signal will transition to digital. The difference is perceptible. Further, on the outside fringe of our signal, as a listener leaves the coverage area, the signal will transition from digital back to analog.

HD Radio™ technology does not increase a station’s coverage area. However, it will greatly improve a listener’s reception within the current coverage area. The effects of tall buildings, valleys, and other situations which create interference/multi-path in analog are negated by HD Radio™ technology.

The sound of WEMU’s broadcast in HD Radio is louder on an HD Radio with a broader frequency range. There is a sense of “openness” in the sound. However, WEMU’s sound on an analog radio is stronger, clearer, and more brilliant than previously available in analog.

WEMU will not be 100% digital until the audio control consoles in the studios are replaced in the near future. However, the effect is discernable today.

The Future of the Technology

The possibilities for the features offered through HD Radio™ technology are limited only by the imagination in the industry. Among services being developed are:

  • Secondary Audio. The FCC is expected to rule in the near future to permit the use of digital technology to provide or MORE radio stations on the same frequency. A listener would have a choice among WEMU-1, WEMU-2, and perhaps WEMU-3. Three separate services all on 89.1 FM.
  • Radio TiVo™. Quickly and easily record for later listening, material you might otherwise miss, operating much like the television version of the technology.
  • Information Scroll. News reports, CD information, traffic information, weather, and news headlines are only a few of the text services that stations could offer. On a car radio, the text would scroll slowly when the car travels at higher speeds. It would scroll quickly when the car is stopped.
  • GPS Traffic Information. Traffic information tailored to your car’s location through the use of a GPS system combined with new traffic alert technology.

These are only a few examples of the possibilities on the horizon for HD Radio.


HD Radio™ capable receivers designed for the current technology are or will be available at local select electronic retailers in this area. They are also available on-line at various web sites. Automakers will be offering HD Radio™ capable radios in the immediate future. As the technology develops, the technology of consumer products will also adapt to the new features offered.