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Published byLizbeth Helena Kelley Modified over 9 years ago
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DRM update
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DRM Development Sep 96 – Informal meeting between 5 broadcast-related organizations Apr 97 – 1 st formal meeting of Digital Radio Mondiale TM (DRM TM ) Mar 98 – 20 broadcast-related organizations signed the MOU in Guangzhou, as a first step to the official inauguration
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DRM Development Apr 2001 – DRM's has gained approval by ITU-R's members. The recommendation is now referenced as ITU-R BS.1514 and under standardization process. Sept 2001 – the European Telecommunications Standards Institute (ETSI) published the technical standard for DRM’s on-air system. The document is called ETSI TS 101 980 V1.1.1
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DRM Development Nov 99 – Evaluation group carried out field test 2002 – DRM is an international consortium of 72 broadcasters, network operators, manufacturers 2003 – DRM is scheduled to launch
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Digital AM System iBOC –USA (MW) –In Band On Channel system, analog and digital Tx on same channel –Wider BW requirement than DRM –MPEG2 & OFDM
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Digital AM System DRM –Europe (LW, MW & SW) –Tx on same band, different channels. –Simulcast is underway –MPEG4, QAM & OFDM
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IBOC Spectrum Fig 1 – AM Hybrid IBOC Spectrum Fig 2 – AM All digital IBOC Spectrum
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IBOC Spectrum Fig 1 – AM Hybrid IBOC Spectrum
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IBOC Spectrum Fig 2 – AM All digital IBOC Spectrum
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DRM Spectrum
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DRM Field Test Phase 1 –Nov 1999 ~ Mar 2000, point to point SW and MF transmission. –Transmission path testing. Phase 2A –Jul ~ Aug 2000 –Audio quality and reliability test
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DRM Field Test Phase 2B –Dec 2000, broadcast in MF and LF bands. –2001, transmission from Canada to Madagascar (13000km)
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DRM Field Test Latest Test –12 June 2002, Long-term DRM tests from Deutsche Welle and Radio Netherlands Bonaire, Netherlands Antilles are continuing. –The latest phase involves simulcast (analog/digital) mode. –Carrier frequency: 15530kHz
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DRM Field Test Commend BBC – Compliance testing and specification validation Clear, Complete and Unambiguous
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Features Reinvigorate the use of frequency bands below 30 MHz – Short-Wave, Medium-Wave and Long-Wave Improve sound quality, FM-like with the AM reach Reduce interference by digital technique
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Features Wider coverage due to improved S/N Alternative frequency switching and Single Frequency Network Value added services: –Program labels –Text messages
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Impact Modification of existing transmission equipment is needed New digital receivers is needed Slightly reception improvement with existing output power Better sound quality
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Coming Up OFTA invite RTHK to conduct a DRM trial test in Peng Chau at 810 kHz
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Analogue Vs Digital
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DRM System Non proprietary, open standard uses existing AM broadcast frequency bands, 9 –10 KHz channel Support SFN Not support analog receivers Simulcast is underway
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Technical Info Audio: –MPEG4 Advanced Audio Coding (AAC) + Spectral Band Replication (SBR) compressed audio: 20kbps / channel RF: –QAM & ODFM (similar to DAB)
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Spectral Band Replication
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Digital Multiplex AudioDataControl signal MSCFACSDC Multiplex
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World wide field test
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Countries with DRM Members
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16 QAM Constellation Change in amplitude and phase
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MPEG-2 AAC a high quality audio coding standard for 1 to 48 channels at sampling rates of 8 to 96 kHz, with multi-channel and multilingual capabilities. AAC works at bit rates from 8 kbit/s for a mono speech signal up to 160 kbit/s for very high quality. Three profiles of AAC provide varying levels of complexity and scalability.
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MPEG-4 AAC Coding and composition of natural and synthetic audio objects at a very wide range of bit rates The representation for synthesized sound can be derived from text data or so-called instrument descriptions
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MPEG-2 AAC Vs MPEG-4 AAC MPEG-4 AAC has all the tools and functions of MPEG-2 AAC plus the Noise Substitution tool, a Long Term Predictor as well as extensions to support scalability
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Useful Web Site DRM: –official website: www.drm.org –www.ist-radiate.com IBOC: www.ibiquity.com MPEG: mpeg.telecomitalialab.com ETSI Web site: www.etsi.org
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