While the Philippines are still awaiting for the release of Implementing Rules And Regulation for the commercial rollout of ISDB-T DTTV transmission and set-top-box receivers before the December 31, 2012 analog TV transmission switch-off (ASO), there were an additional rollout of digital media that would replace the current analog FM and analog AM radio transmission and receivers using the U.S.-based digital radio platform, in order to attract many people that often bored of limited analog audio radio transmission for the past few decaces.
High definition digital radio, or branded as HD Radio, is a next generation digital radio platform developed from United States Of America (U.S.A.) assigning on both the former analog U.S.-based FM band (88-108 MHz) and the former analog AM band (522-1620 KHz) (also known as CAM-D, an AM band HD Radio) and surpasses other platforms such as European DAB (digital audio broadcast) that assigns only FM band, Digital Radio Mondiale (DRM) that uses Band-II short wave frequency (SWF), DTMB Sound Broadcast in mainland China that assigns only UHF TV band, and ISDB-Tsb that assigns only UHF TV band. The term HD is currently mean as “hybrid digital” mainly due to the combined analog and digital radio transmission, but with separate carrier signal of assigned radio frequency to prevent from interference of both analog FM/AM radio receiver and HD digital radio receiver. HD Radio uses a standard IBOC or IBAC modulation beside a separate 15 KHz analog FM carrier channeling and 9 KHz analog AM carrier channeling, with a rate of about 64 kbps to 128 kbps of HDC audio codec format. If analog FM/AM broadcasting would discontinue in the near future, it would generate at about 300 Kbps carrying 128 kbps to 256 kbps AAC format for optimal CD sound quality.
The digital radio transition using HD Radio as well as other types of digital radio platform may not be easy. There were many factors about possible disadvantages of adopting it on both the radio broadcasters and the consumers, mainly due to lack of promotional and informative activities, as well as its possible defects on both transmission and receivers. Firstly, if analog radio broadcasting would discontinue, then most low-budgeted veteran analog radio stations and their engineers would lose their job if they did not re-educate to know how to operate HD Radio transmission. Secondly, most consumers may not able to buy HD Radio receivers due to high-price of its fewer advanced digital circuitry compared to cheaper-priced analog radio receiver unit. And thirdly, the digital sound volume of AAC audio codec content streaming on HD radio was only limited, so therefore most HD radio unit must have an extra volume control in order to boost loudness, aside for adjusting a volume control on most stereo audio unit.
And while there is no specific date on when it will shut down analog FM and analog AM broadcast in the future even when the platform would change to a new specs regarding VSB-based (not OFDM) digital aerial modulation and AAC audio codec prototype, HD Radio is initially available to broadcast across United States and Canada, but there is no plan to adopt the U.S.-based digital radio platform across the country outside the two countries (I don’t know—in my thought—whether Mexico and the rest of Central Latin America, South Korea, and Taiwan have had also already rollout HD Radio) as mentioned above as a substitute to DAB, DRM, DTMBsb, and ISDB-Tsb. Various U.S.-based electronic consumer companies have decided to manufacture HD Radio receiver—both portable and handheld—and release through most U.S. and Canada stores for many consumers.
In the Philippines, FM radio station DWKC 93.9 MHz in Manila owned by Radio Mindanao Network (RMN) was the first station to experiment the platform to broadcast across Metro Manila started in mid-decade 2000s. DWRR 101.9 MHz FM Manila owned by ABS-CBN was followed suit for HD Radio test broacast in 2009, and later DWDM 95.5 MHz FM Manila owned by Eagle Broadcasting Corporation (a known subsidiary of Iglesia Ni Cristo Network Incorporated) for HD Radio test broadcast in 2011. The commercial rollout of HD Radio broadcast and HD Radio receiver in the Philippines would be available only if both analog FM and analog AM radio broadcast will shut down (even if those stations have a qualified graduating ECE students to operate an installed HD Radio unit) following the analog TV broadcast switch-off on December 31, 2015.