Digital audio broadcast in Hong Kong and issue of bandwidth allocation

Digital radio and allocation of bandwidth

Digital audio broadcast is a technology that applies computers to ‘compress’ sound waves into digital signals, which occupy smaller volume of bands and transmit in the air with high fidelity and longer distance because the signals can be re-arranged in the decoders in radio receptors.
Because of smaller band volume being occupied under digital audio broadcast, 100 bands can be placed within a range of band while the band can accompany 10 to 50 bands under analogue radio broadcast. In addition, analogue broadcast is constrained by the landscape because hills or high buildings can block the transmission of radio signals and the power is often smaller. Thus a radio band can only cover smaller areas and some different bands are applied by one channel, especially in hilly regions like Hong Kong, Taipei and Auckland, New Zealand.
For example, FM bandwidth ranges from 88MHz to 108MHz and intervals between bands are 0.4 MHz. But due to diffraction by hills and destructive interference, more bands is occupied by the same channel (in Hong Kong, 7 bands are allocated by the same channel). Meanwhile, there are 10 to 40 AM bands available in Hong Kong SAR and it needs 2 to 3 bands for a channel to cover the whole region. However, the reception quality of AM broadcasting is sometimes poor because of interference and low power. Therefore AM broadcasting has not been popular in past three decades. So not much channels apply AM broadcasting. Thus shortage of broadcasting bands occurs.
But Wave Radio, a new Hong Kong radio station that will operate in second half year of 2009, will introduce digital technology to improve the audio fidelity. It may be the hope of utilizing AM radio bandwidth. But it can still not relieve insufficiency of bandwidth. In recent years, some Hong Kong pro-democratic politicians opened pirate radio channel to resist existing public and commercial channels, but they faced strong suppression by the government.
In Taiwan, some non-Kuomintang politicians have also opened pirate radio broadcast to promote their views and they also faced forced closure by Kuomintang (Nationalist Party) government. However, pirate channels are mushroomed all over the island and several interference cases are reported. Those channels often promoted medicine with poor quality at high price and the presenters often propagandize demagogic political points of view.
Therefore, digital audio broadcasting should be introduced and promoted forcefully by the governments to provide more bandwidth and reduce the chains on audio broadcasting applications. Reducing those restrictions can create better environment to promote science, technology and traditional culture like classical music, opera. To manage the radio resources properly, quasi-official organizations should be set up and lease the periods for different organizations at affordable rate in order to allot time and channels for broadcasting and promote the quality of radio equipments.
AM radio theories: http://www.howstuffworks.com/radio-spectrum.htm
Introduction of AM broadcasting: http://www.economicexpert.com/a/AM:radio.htm

The original text was distributed on 7:29pm, 28 May 2009.

Digital Audio Broadcast and opening of radio and television channels

In the previous essay, we mentioned that Digital Audio Broadcast can reduce the bands required to broadcast due to combination of several audio streams. In fact, the band volume occupied by one analogue radio channel can transmit 10 digital signals. In Hong Kong SAR, there are seven radio channels transmit in FM and each of them occupies 7 band widths to service different areas. Transmission stations in Hong Kong SAR are often built 10km to 40km apart and one band can broadcast two to three channels from different stations due to reflection of signals by hills and variation of power of waves. 14 analogue radio channels or 140 digital channels can be transmitted through FM bands over Hong Kong SAR when band division is adopted.

Digital terrestrial television has been launched in Hong Kong at the end of 2007 and about 30% of residents have received television service in such way. Five bands are reserved for digital terrestrial television and each band can accommodate four to five channels. After the existing analogue broadcasting being withdrawn, there will be additional bands for additional television channels or amateur radio. But until now, only three bands that consist of ten channels provide service. The other two bands still have not been allocated yet and eight television channels are empty.

There are a lot of people find that the existing radio and television channels in Hong Kong cannot satisfy the needs of the public and the number of channels is not adequate, compared with Taiwan and most of developed countries. Moreover, the license issuing procedure of Hong Kong government is very strict and that inhibits merchants and public to apply for new broadcasting service. For example, only Wave Radio, operated in 2008 by Albert Cheng King Hon, a publisher and former radio host and councillor, applied for new radio licence successfully since 1991. Meanwhile, a pirate radio station operated by some democrats has been run irregularly.
In order to respond the concern of Hong Kong citizens, the pressure groups should urge the government to relax the conditions of licences for broadcasting and change the procedures. The guarantee deposit for audio broadcast should be reduced to $100000 to $5 million, depending on the size of staff, power and reception population. Licences issuing process must be supervised by the Legislative Council. Broadcast licensing authority should include independent academics or experts in cultural field, legislators and district councillors without politic connections. The period for applying low power broadcast licences by education institutions should be reduced to about three months. The change will be conducive to setting of campus radio and media for community services and promote participation of community services. The government and civil groups should be active on setting public television channels, in order to provide a platform for effective communications between government and different parties, promoting messages from non-government organizations, or even providing more educational programmes. In addition, civil groups should also urge the existing broadcasters to invest more on digital broadcast and launch more services immediately and the government should draft a plan to subsidize low income households to buy digital radio and television set and recycling of old appliances to reduce the harmful effect of mass dumping.

The original text was distributed on 10:19pm, 31 May 2009.