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THE RADIO OF THE FUTURE

THE RADIO OF THE FUTURE. DRM - Digital Radio Mondiale. Natarajan.P No. 17 S7 Electronics & Comm. PTDC. College of Engineering, Thiruvananthapuram. DEFINE DRM

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THE RADIO OF THE FUTURE

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  1. THE RADIO OF THE FUTURE DRM - Digital Radio Mondiale Natarajan.P No. 17 S7 Electronics & Comm. PTDC College of Engineering, Thiruvananthapuram

  2. DEFINE DRM DRM is the world’s only non-proprietary Digital AM Radio Systems for SW,MW, and LW with ability to use existing frequencies and bandwidth. DRM covers the broadcasting band below 30 MHz. College of Engineering, Thiruvananthapuram

  3. TRANSITION FROM ANALOGUE • Fairly easy to start digital broadcasting • Difficult to stop analogue broadcasting (because of the many millions of analogue radio and TV sets owned by consumers) • The real benefits of spectrum efficiency can be achieved only when the analogue services stop • As many countries have introduced digital TV, plans are being made for analogue TV switch-off • Analogue radio switch-off will take a long time • starting DIGITAL services early is the best mechanism for stopping ANALOGUE College of Engineering, Thiruvananthapuram

  4. DIGITAL BROADCASTING is important because: • it uses the spectrum much more efficiently than analogue broadcasting • digital transmitters operate at lower power • the number of radio & TV services can increase • it offers improved quality, especially on mobile and portable receivers • it offers new features, such as interactivity College of Engineering, Thiruvananthapuram

  5. DRM & DAB • Two digital radio systems: • DRM for use in the AM bands (LF, MF & HF) • Eureka 147 DAB for use in VHF & UHF bands • The EBU has endorsed both systems because they are complementary • DRM is designed for use in the narrow channels currently used for AM radio • DAB is a broadband system carrying multiple radio services (and video services) • Some broadcasters will use DAB or DRM • others will use both DAB and DRM College of Engineering, Thiruvananthapuram

  6. ADVANTAGES OF DRM • DRM signals fit within the 9 kHz or 10 kHz channels used by traditional AM signals • simplifying frequency planning • permitting existing AM transmitters to be reused for digital radio services with relatively minor modifications • Broadcasters are attracted by the re-use of expensive hardware, such as high power transmitters and transmitting antennas College of Engineering, Thiruvananthapuram

  7. DRM .. advantages • Large coverage areas • Four operating modes for reliability:- Ground wave mode, Sky wave mode, Highly robust modes 1 and 2 • Superior sound quality with AM reach • No change in listening conditions • Easy receiver tuning : by frequency, station name or program College of Engineering, Thiruvananthapuram

  8. DRM Features • Non proprietary standards • Compatibility with existing AM channels • Workable migration from analog to fully digital • Multi mode operation depending propagation • Provision for Data broadcasting • SFN capability College of Engineering, Thiruvananthapuram

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  11. DRM System Architecture MSC Audio data stream Source Encoder(s) Energy dispersal Channel encoder Cell inter- leaver Multiplexer Data stream Source Encoder(s) Signal Out OFDM cell mapper Pilot generator OFDM Modulator FAC information Coder,interleaver Energy dispersal SDC information Coder,interleaver Energy dispersal College of Engineering, Thiruvananthapuram

  12. DRM Multiplex Up to 4 Audio +Data MSC MULTIPLEX Channel parameters, Spectrum,modulation interleaving…. FAC To OFDM Multiplex,CA,freq, schedule,time/date, region, coding,SBR, PAD,Mod etc SDC College of Engineering, Thiruvananthapuram

  13. Source Coding College of Engineering, Thiruvananthapuram

  14. Frame structure 1 2 3 College of Engineering, Thiruvananthapuram

  15. For this, there are the following properties: Frame length: 40 ms AAC sampling rate: 24 kHz SBR sampling rate: 48 kHz AAC frequency range: 0 – 6.0 kHz SBR frequency range: 6.0 – 15.2 kHz SBR average bit rate: 2 kb/s per channel College of Engineering, Thiruvananthapuram

  16. DRM-Modes College of Engineering, Thiruvananthapuram

  17. Guard Interval for different Services • System immunity against Fading, Doppler effect • For SFN Operation College of Engineering, Thiruvananthapuram

  18. Implementation • Need a DRM exciter to generate QAM-COFDM symbols, in I and Q Channel • Need a Digital Frequency Synthesizer to phase and amplitude modulate the carrier • Linear amplifiers can take these signals directly • Non Linear older transmitters need to be linearised or are to be modulated separately in amplitude and phase • New MW transmitters using digital modulation techniques can easily take DRM. College of Engineering, Thiruvananthapuram

  19. Implementing DRM in Linear Transmitters Linear RF Amplifier Audio + Data To Antenna Output RF Circuits RF Amplifier Phase and Amplitude Modulated RF DRM Digital Modulator Pre-amplifier I Q Digital RF Synthesizer College of Engineering, Thiruvananthapuram

  20. Implementing DRM in Non-Linear Transmitters To Antenna Audio + Data Modulated HV High Level Modulator Output RF Circuits Corrected Amplitude RF Amplifier Corrected I I DRM Digital Modulator Digital Pre-correction Digital RF Synthesizer Q Corrected Q I Demodulated I Q Q Demodulated Digital Demodulator Digital RF Synthesizer Modulated RF Sample College of Engineering, Thiruvananthapuram

  21. Other implementation issues • Flat Spectrum response of the output circuit of transmitters • Non uniform Phase change in amplifiers • Antenna Tuning unit band width • Band width of antenna( wide-band/dual band) • Matching system / VSWR College of Engineering, Thiruvananthapuram

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  29. ADVANCEMENT • The DRM consortium voted in March 2005 to begin the process of extending the system to the Broadcasting Bands up to 120 MHz • The design development and testing phase are expected to be completed by 2007 – 2009 College of Engineering, Thiruvananthapuram

  30. CONCLUSIONS • Digital Radio Mondiale has achieved great technical success in developing the DRM system • Synergy between DAB and DRM must be exploited • The big challenge is now to achieve successful implementation • persuading broadcasters • persuading regulators • persuading receiver manufacturers • persuading consumers College of Engineering, Thiruvananthapuram

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