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  1. #1
    Hifi Freak
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    Nov 2006
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    DAB vs DVB-H

    Leste dette http://www.tu.no/data/article107478.ece
    Nå ser det jo ut til at DVB brer om seg, det har jo funka på parabol i mange år, og nå kommer jo også bakkenettet. Man kan jo i og for seg sende hva som helst i datastrømmen, så det virker jo fornuftig å bruke det til å sende radio også.
    Er det noe hold i påstandene til Øyvind Nondal?
    Hippies, prepare to be punished!

  2. #2
    knutinh
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    DAB vs DVB-H

    Jeg er enig i argumentene om at Norge vil tjene mye på å følge samme standard som resten av verden. Vi vil sannsynligvis få bedre/billigere terminaler, og muligheten til å ta med mottaksutstyr på ferie.

    I tillegg har DAB (fortjent eller ikke) fått ganske mye negativ omtale, og man kan kanskje tenke seg at en standard basert på noe helt annet enn DAB vil få raskere utbredelse av denne grunn.

    Jeg forstår det slik at DVB-H benytter seg av kanal-modulasjonen i DVB-T og at denne er mindre egnet til å dekke et terreng som det norske for mobile mottakere i høy fart, mens den kan være utmerket for biler i f.eks Frankrike eller stasjonære mottakere i Norske boligstrøk. Dette vil kunne føre til høyere kostnad for sendernettet for en gitt dekning, alternativt dårligere dekning for en gitt kostnad. Som eksempel så har noen regnet på at samfunnsgevinsten for norge på at "vårt" alternativ for GSM ble standardisert var 2 milliarder - hvis frankrikes forslag (som hadde dårligere robusthet mot rugged terreng) hadde blitt vedtatt måtte vi ha bygd ut basestasjoner for ca 2 milliarder ekstra, en utgift som hadde dryppet ned på befolkningen i form av skatter og avgifter, eller ringekostnader.

    Hvis det er vedtatt at vi SKAL ha et DAB-nett (med helt annen dekningstype enn det digitale tv-nettet), og dette allerede er kommet godt i gang så kan man tenke seg at ekstra-kostnaden for å "slenge på" DMB er relativt lav, mens kostnaden for å bygge opp et urelatert nett med samme dekningstype men helt annen teknologi er høyere.

    Disse fire faktorene må vel balanseres mot hverandre.

    -k


  3. #3
    Hifi Freak
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    DAB vs DVB-H

    Og derr! var DVB-H offisiell EU standard for kringkasting til mobile enheter.

    http://ec.europa.eu/cyprus/news/mobile_tv_en.htm

    Hippies, prepare to be punished!

  4. #4
    knutinh
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    DAB vs DVB-H

    Jepp. Det kunne ha vært morsomt å være flue på veggen i Brussel og sett hva som foregikk i kulissene. Nokia har i alle fall god grunn til å glede seg, og det er antagelig bra for brukere og aktører at en standard blir ... standard.

    -k

  5. #5
    Hifi Freak
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    DAB vs DVB-H

    Selv om Nokia nok er mest glad, så er det veldig bra for alle at man vet hva man har å forholde seg til. Nå er det bare å sette igang å lage DVB-H mobiler, så tenker jeg ting løser seg av seg selv.

    Lurer på hvor lang tid det tar før det synker inn hos NRK.
    Hippies, prepare to be punished!

  6. #6
    KindOfBlue
    Guest

    DAB vs DVB-H

    Kryss i taket. Vi skal nok alle være glade for dette - suverent bedre format, video og audio i digital versjon, og med store muligheter for streaming. R.I.P. DAB.

  7. #7
    knutinh
    Guest

    DAB vs DVB-H

    Jeg har ikke satt meg inn i hverken Dmb eller dvb-h. Dette er hva wikipedia har å si:
    http://en.wikipedia.org/wiki/Digital...a_Broadcasting
    Digital Multimedia Broadcasting (DMB) is a digital radio transmission system for sending multimedia (radio, TV, and datacasting) to mobile devices such as mobile phones. This technology is an offshoot of Digital Audio Broadcasting which was originally developed as a research project for the European Union (Eureka project number EU147). DMB was developed in South Korea under the national IT project. And the world's first official mobile TV service started in South Korea in May 2005, although trials were available much earlier. It can operate via satellite (S-DMB) or terrestrial (T-DMB) transmission. DMB is based on the Eureka 147 Digital Audio Broadcasting (DAB) standard, and has some similarities with the main competing mobile TV standard, DVB-H. [1]

    Like DAB, T-DMB is made for transmissions on radio frequency bands band III (VHF) and L (UHF), for terrestrial. Because the United States and Canada still allocate the first band as for television broadcasting (VHF channels 7 to 13) and the United States reserves the L band for military applications, DMB is still unavailable in North America. Qualcomm's MediaFLO is a proprietary system used there instead. In Japan, 1seg is the standard, using ISDB.

    T-DMB uses MPEG-4 Part 10 (H.264) for the video and MPEG-4 Part 3 BSAC or HE-AAC V2 for the audio. The audio and video is encapsulated in MPEG-2 TS. The stream is RS encoding and the parity word is 16 bytes length. There is convolutional interleaving made on this stream, then the stream is broadcast in data stream mode on DAB. In order to diminish the channel effects such as fading and shadowing, DMB modem uses OFDM-DQPSK modulation. A single-chip T-DMB receiver is also provided by an MPEG-2 transport stream demultiplexer. DMB has several applicable devices such as mobile phone, portable TV, PDA and telematics devices for automobiles.

    T-DMB is an ETSI standard (TS 102 427 and TS 102 42. As of December 14, 2007, ITU formally approved T-DMB as the global standard, along with three other standards,like DVB-H, OneSeg, and MediaFLO.[2]
    http://en.wikipedia.org/wiki/Dvb-h
    DVB-H (Digital Video Broadcasting - Handheld) is one of three prevalent mobile TV formats. In other words, it is a technical specification for bringing broadcast services to mobile handsets. DVB-H was formally adopted as ETSI standard EN 302 304 in November 2004. The DVB-H specification (EN 302 304) can be downloaded from the official DVB-H website.[1] DVB-H is officially endorsed by the European Union.[2][3][4] The major competitor of this technology is Digital Multimedia Broadcasting (DMB). DVB-SH (Satellite services to Handhelds) now and DVB-H2 in the future are possible enhancements to this technology, providing improved spectral efficiency and better modulation flexibility.

    Technical explanation

    DVB-H Frame structureDVB-H technology is a superset of the very successful DVB-T (Digital Video Broadcasting - Terrestrial) system for digital terrestrial television, with additional features to meet the specific requirements of handheld, battery-powered receivers.

    DVB-H can offer a downstream channel at high data rates which can be used as standalone or as an enhancement of mobile telecommunication networks which many typical handheld terminals are able to access anyway.

    Time slicing technology is employed to reduce power consumption for small handheld terminals. IP datagrams are transmitted as data bursts in small time slots. Each burst may contain up to two megabits of data (including parity bits). There are 64 parity bits for each 191 data bits, protected by Reed-Solomon codes. The front end of the receiver switches on only for the time interval when the data burst of a selected service is on air. Within this short period of time a high data rate is received which can be stored in a buffer. This buffer can either store the downloaded applications or playout live streams.

    The achievable power saving depends on the relation of the on/off-time. If there are approximately ten or more bursted services in a DVB-H stream, the rate of the power saving for the front end could be up to 90%. DVB-H is a technical system which was carefully tested by the DVB-H Validation Task Force in the course of 2004 (see ETSI Technical Report TR 102 401). DVB-SH recently improved radio performances and can be seen as an evolution of DVB-H.

    DVB-H is designed to work in the following bands:

    VHF-III (170-230 MHz, or a portion of it)
    UHF-IV/V (470-862 MHz, or a portion of it)
    L (1.452-1.492 GHz)
    DVB-SH now and DVB-H2 in the near future are expected to expand the supported bands.

    DVB-H can coexist with DVB-T in the same multiplex.
    Google-søk gav meg denne sammenligningen:
    http://www.digitalradiotech.co.uk/dv...ld_Replace_DAB

    http://www.mobilegadgetnews.com/inde...howtopic=11567
    Wireless: Carving up big market for tiny televisions
    Eric Sylvers International Herald Tribune
    TUESDAY, MARCH 21, 2006
    ...
    Datamonitor forecasts that in 2009, 90 million DVB-H phones will be shipped, compared with 28 million DMB, 30 million MediaFLO and 18 million with the Japanese standard.
    ...
    Some favor DVB-H because it can be used while a viewer is in motion in cars and trains. Like DMB, it makes use of existing TV infrastructure, holding down costs. But most important, DVB-H uses less battery power than DMB and can handle higher bandwidth and thus potentially more channels - about 50, compared with about five on DMB.

    "DMB is likely to have problems competing with DVB-H because DMB uses much lower bandwidth," said Eino Kivisaari, a researcher with the Helsinki University of Technology.

    DVB-H saves power by sending transmissions in bursts, which lets the tuner switch off between bursts. This cuts power consumption by as much as 95 percent, Datamonitor says. But DVB-H takes longer to change channels, almost 20 seconds in some trials. That will improve, but analysts say it will not go much below five seconds.

    DMB can change channels in a few seconds, and it has the advantage that it can be broadcast on frequencies that have already been allocated by most governments, according to the Datamonitor report. But this advantage will be disappear as DVB-H frequencies are allocated.
    ...

  8. #8
    Hifi Freak
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    DAB vs DVB-H

    Hvordan går det med DAB'en i Storbritania?
    Players win, players loose, players prepare, players practise, players get hurt but players always get up. No matter what the outcome is, players play!

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