HD Radio Receiver | HD Radio Stations
HD Radio is iBiquity's new and innovative brand of digital radio -record breaking technology for transmission and reception of unique and crisp sound that has been digitized and compressed into this innovative format. HD Radio Tuner technology allows for the digital hd radio to be transmitted throughout your home or office or car. The Federal Communications Commission selected HD Radio Digital as the standard for local area broadcast of signals within the United States, allowing for HD Radio stations to be developed in North America. It offers multiple programs on one channel and works on the same frequencies allocated to analog (FM and AM) radio stations. Supporters claim CD quality sound and reduced interference, and offer products such as the Car HD Radio, Digital HD Radio, and HD Radio Antenna technology so that you can listen to an HD online Radio..
Digital information is transmitted using COFDM, a modulation method that has been used in a number of different digital television and radio systems, including DVB-T. The audio compression algorithm was initially set to be PAC when iBiquity's standard was first approved by the Federal Communications Commission (FCC) in 2002, but the system was changed to the HDC codec in 2003. The change was made because the low-bitrate audio for AM stations was described by some as being "underwater", plus the fact that the partially in-house HDC format has newer patents that can be exploited for longer periods. HD Radio stations must pay royalties each year to iBiquity, plus the costs paid by the manufacturers of the transmitters which are then passed along to the stations that buy them.
In hybrid mode, the AM version can carry 36 kilobits per second of data for the main audio channel, while FM stations can carry information at 96 kbit/s. HD Radio can also be used to carry multiple distinct audio services, called multicasting but actually more like multiplexing. Secondary channels, such as for weather, traffic, or a radio reading service, can be added this way, though it may reduce the audio quality of all channels on a station. Datacasting is also possible, and RDS-like metadata about the program and station are included in the standard. Stations may eventually go all-digital, meaning they could no longer be heard on a regular radio.
HD Radio Station
Also notable is that in hybrid mode, a radio will lock onto an analog signal first, then HD Radio FM stereo, then try to find a solid digital one. If the digital signal is lost, it will blend to analog, the same way a car radio will blend from stereo to mono given a weak signal. Much of the success of this relies on proper synchronization of the analog and digital audio signals by broadcast engineers at the transmitter. This fallback may also be impeded by the use of multiple channels.
While iBiquity is responsible for the development of these standards, and the FCC for its regulation, the National Radio Systems Committee (NRSC) is the standards body for HD Radio. It is officially known as NRSC-5, with the latest version being NRSC-5-A.
HD Radio Receiver
As of June 2006, receivers are becoming less expensive, starting at around US$ 100-$150. The Kenwood Tuner, for use with Kenwood stereos is selling for about $100. Manufacturers have initially focused on making car stereos, BMW being the first with their announcement of HD Radio being an option for their 2006 7-series, 6-series, and 5-series models. Home listening equipment is currently available from few companies, in both a home tuner and a tabletop model. The Boston Acoustics Recepter is one common model cited in listener tests. DaySequerra produces a line of high-end equipment designed primarily for use by broadcast engineers.