300 kbit/s in digital-only mode. The first generation DAB uses the MPEG-1 Audio Layer II (MP2) audio codec which has less efficient compression than newer codecs. The typical bitrate for DAB stereo programs is 128 kilobit per second|kbit/s or less and as a result most radio stations on DAB have a poorer sound quality than FM does under similar conditions. Many DAB stations also broadcast in mono. In contrast, DAB+ uses the newer AAC+ codec and HD FM uses a codec based upon the MPEG-4 HE-AAC standard. Before DAB+ was introduced, DAB's inefficient compression led in some cases to "downgrading" stations from stereophonic to monaural, in order to include more channels in the limited 1 Mbit/s bandwidth. Digital radio, such as DAB, DAB+, and HD FM often have smaller coverage of markets as compared to analog FM, radios are more expensive, and reception inside vehicles and buildings may be poor, depending on the frequencies used. HD Radio shares most of these same flaws (see criticisms below). On the other hand, digital radio allows for more stations and less susceptibility for disturbances in the signal. In the United States, however, digital broadcast technologies other than HD Radio (such as DAB+) have not been approved for use on either the FM or AM bands. DAB is well suited to national broadcasting networks that provide several stations as is common in Europe, whereas HD is more appropriate for individual stations. HD versus DRM Digital Radio Mondiale (DRM 30) is a system designed primarily for shortwave radio with compatible radios already available for sale. DRM 30 is similar to HD AM, in that each station is broadcast via channels spaced 10 kHz (or 9 kHz in some regions) on frequencies up to 30 MHz. The two standards also share the same basic modulation scheme (COFDM), and HD AM uses a proprietary codec. DRM 30 operates with any of a number of codecs, including AAC, Opus, and HVXC. The receiver synchronization and data coding are quite different between HD AM and DRM 30. As of 2015 there are several radio chipsets available which can decode AM, FM, DAB, DRM 30 and DRM+, and HD AM and HD FM. Similar to HD AM, DRM allows either hybrid digital-analog broadcasts or pure digital broadcasts, DRM allows broadcasters to use multiple options: Hybrid mode (digital/analog) - 10 kHz analog plus 5 kHz digital bandwidth allows 5–16 kbit/s data