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What is Multicasting?

At a minimum, multicasting can double the number of choices available on free digital FM radio.  HD Radio technology enables an FM broadcaster to offer more than one program stream on its existing spectrum.  As of April 2006, more than 200 HD Radio stations across the United States offer two to three additional channels above and beyond their analog and main digital channels, with many more expected to go on the air this year.   Stations are using their HD2 multicast channels to  experiment with new music and news formats, showcase young artists and local bands, offer non-English language programming, and more. To see a comprehensive list of multicast formats, click here.

Finding an HD2 Channel on the Radio Dial

While multicast channels today are commercial- and subscription-free, consumers do need an HD Radio receiver that can receive multicast channels. For the most part to find a new HD2 channels, listeners tune up the dial from channel to channel in the same manner that they have always tuned in their favorite radio stations.  HD Radio products detect digital and multicast station availability and tune to these stations automatically.  (Tuning techniques vary by manufacturer.  As a result, some products may tune slightly differently.)

The Technology

FM stations have 150 kilobits per second (kps) of bandwidth available with HD Radio technology, of which 96 kps is typically used for digital audio programming.  In addition to offering superior sound quality, this 96 kps “bit rate” can also be carved into separate program streams (e.g., 93.7-HD2, 93.7-HD3, etc.) allowing FM broadcasters to expand their content offerings without requiring additional frequencies or spectrum.  For more details on HD Radio technology, visit the broadcast implementation section of this website. 

Multicast Content

Some examples of the innovative ways broadcasters are using multicasting today are:

• Clear Channel has been one of the most aggressive broadcasters when it comes to rolling out HD2 multicasting.  More than 100 of the group’s FM stations now offer HD2 programming, featuring a range of diverse formats.  Examples include: WKTU-FM’s HD2 channel features the only country music station in New York City; WMXD-FM’s HD2 Channel offers Detroit listeners Gospel music; and Albuquerque’s KABQ-FM HD2 Channel plays Spanish Oldies.
• CBS Radio’s 97.1 “Free FM” is airing Los Angeles Dodgers baseball games from sister station KFWB News 980 AM on its HD2 channel.  KFWB has been the radio home of the Dodgers since 2003 and continues to broadcast games, meaning HD Radio receiver owners in LA now have the option of listening to the hometown team on either side of the dial.
• Greater Media has launched three multicast channels in Detroit, including Riff2, a multicast channel of it legendary rock station WRIF-FM that features a steady diet of local music.  As an example of its commitment to local music, Riff2 featured an all White Stripes Weekend to celebrate the band’s series of hometown concerts. 
• Beasley Broadcast Group’s WKIS-FM in Miami offers Gretchen 99.9 HD2, inspired by country music sensation Gretchen Wilson. The southern rock-flavored format on ‘Gretchen’ complements the mainstream country programming on WKIS’s main channel.  The station also features an HD3 channel that streams weather information from the National Oceanic & Atmospheric Administration (NOAA).
• National Public Radio is offering its member stations programmed music formats for their multicasting channels, including classical, jazz, electronica, triple-A and folk.  Nearly 400 NPR member stations are in the process of upgrading to HD Radio technology.