Digital Braodcasting Symposium 2012
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DBS Attracts System Proponents
DVB Asia Review Meeting
The DVB hosted Asia Review meeting on 7 March was attended by a host of Asia-Pacific broadcasters together with Philip Laven, Chairman DVB, and John Bigeni, DVB representative for Asia. An update on the take-up of DVB-T/DVB-T2 systems around the world and specifically in this region was provided, sharing experience gathered from the recent trials in many countries.
DRM hosts Asia Group Meeting
The DRM Consortium had its Asia- Group meeting on 8 March, attended by its partners and Asia-Pacific broadcasters at the DBS. Ruxandra Obreja, DRM Chairman and DRM members conducted the meeting. Briefs on the progress of the DRM standard and of receiver availability were provided. The meeting highlighted prospects of major DRM implementations in Russia and India.
ISDB-T: Demonstration and Open-day
The Japanese digital broadcasting standard, Integrated Services Digital Broadcasting (ISDB) had an open-day demonstration of its technology and its applications in terrestrial and mobile broadcasting. The full day open-house had on display, ISDB-T set-top-boxes displaying SD and HD services, mobile devices with integrated ISDB-T capabilities and a demonstration of the Emergency Warning Broadcasting System (EWBS) on ISDB-T networks. ISDB-T experts explained the technology to the participants and provided up-to-date information on its progress. The demonstration also included the new ISDB-Tmm devices, the mobile multimedia broadcasting standard based on ISDB which will start its services in Japan later this year.
DRM to FM re-broadcasting is a technique used to provide more coverage for existing radio broadcasts. The DRM signal is transmitted with two audio services to a target area over hundreds of kilometres away. It is received by a single DRM receiver feeding two different FM transmitters and re-broadcast. This method can be used for programme distribution without the need for satellite links and for standalone solutions for remote areas, using solar energy and batteries.
The DAB+ rollout in Hong Kong is being carried out by a consortium of four broadcasters and will carry 18 digital radio services. Seven main transmitter sites have been identified and six are already in operation. Four additional gap fillers are planned for 2012. At the end of 2011, 13 channels were available on the network. Promotional activities are being carried out by the consortium to educate the public on digital radio.
The propagation model for digital radio network planning may present a dilemma for engineers as it has to be carefully chosen. Deterministic (or geometrical) models estimate the field strength directly from the path profile and require a detailed knowledge of the terrain. Empirical (or statistical) models provide estimations of field strength where there is insufficient knowledge of the terrain profile. Data is obtained from extensive measurements in different environments and this choice requires only medium rather than high resolution cartography.
Digital Radio DAB+ has just being introduced in some European countries to replace the terrestrial FM radio transmission. DAB+ networks in VHF Band III require wideband and high power transmitting antennas in order to maximize the number of programmes and coverage. The antenna solutions should be flexible to fit to various different installation requirements on loaded antenna towers and masts.
DAB was initially launched in Germany in 1995 but due to limited resources, no indoor coverage and lack of programmes it did not make much progress. When the DAB+ standard was introduced in 2010, the antenna requirements for DAB+ rollout changed, one of the main factors being the space allocation on existing masts. A broadband double-dipole antenna design was used to meet this requirement. It was especially suitable for round towers and could handle the high power required. The second type of antenna used was log-per antenna which was very low in weight and ideal for transmission along railways and highways.
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