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  1. #1
    satdoctor Teacher
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    Default Difference b/w DVB-S and DVB-S2 signals


    Hi chaps ! anyone here plz tell me whats the main difference btween signals of DVB-S and DVB-s2 ? i know that dvb-s2 are mpeg4 but i want to ask that can a reciever or dvb-s card can scan(or recieve) a signal of dvb-s2 transponder ?
    AIM

  2. #2
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    Cool DVBs and DVBs-2

    DVBs and DVBs2 are using different modulation. The content can be either MPEG-2 or MPEG-4 video or any data. DVBs use QPSK modulation and DVBs2 uses 8PSK or 16APSK or even 32APSK. You can't use DVB-S receiver for DVB-S2 because the difference in modulatio.

    So you can't use DVB-S MPEG4 receiver for receiving DVB-S2 MPEG4 channels.

    http://en.wikipedia.org/wiki/DVBS2 for more info

  3. #3
    satdoctor Teacher
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    Anish Thanks for kind info . One more question . It means i cant use my DVB-S Skystar 2 Card for watching DVB-S2 channels even if i cofigure the HD codec in graph file ? channels are not getting scaned so i must change my DVB card ? or can i get these signals on my DVB-S card with any other option for example if i use HD KU lnb? plz do inform me
    AIM

  4. #4
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    You can't get signal without DVB-S2 device, like skystar2 HD or other DVB-s2 receivers .
    Dream Box 800HD, Neotion 3000, SS2,
    12 Feet Motorized Dish 128 E to 3 E

  5. #5
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    Default thanks .

    Thanks rizwan for ur kind info
    AIM

  6. #6
    Member Teacher
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    I'm not master or teacher .. it's only share / infomations about this topic

    DVB-S2 is a second generation modulation and coding standard for Digital Video Broadcast over satellite. Standard number EN 302 307 was released in 2004 and is the first new satellite transmission standard since the DVB-S universal framework for transmission of MPEG-2-based digital television services was adopted in 1994.
    The DVB-S2 standard enables delivery of significantly higher throughput in a given satellite transponder bandwidth than DVB-S. It also supports a much wider variety of input data formats, including multiple transport streams, generic data formats and more.
    Using traditional standards, even premium subscription fees cannot support the satellite costs associated with HDTV’s bandwidth requirements. A new standard was needed to maximize bandwidth usage efficiency and ensure operator profitability.
    Much higher rates of channel efficiency than past standards are enabled by new channel coding schemes. Together with higher order modulation, this increases satellite transponder throughput by about 30% at a given transponder bandwidth and transmitted EIRP relative to DVB-S/DVB-DSNG.
    Differential error protection and modulation for service components or transport streams (e.g. SDTV, HDTV, audio, multimedia) are made possible by Variable Coding and Modulation (VCM). This further enhances bandwidth efficiency while maintaining desired quality. Satellite capacity for interactive and point-to-point applications may be increased by 100%-200% by combining VCM functionality with the use of a return channels to achieve closed-loop Adaptive Coding and Modulation (ACM). ACM improves channel protection and dynamic link adaptation capabilities and may potentially reduce service provisioning costs substantially.
    In areas with variable receiving capabilities or conditions, DVB-S2 can improve transmission quality substantially. Adaptive Coding and Modulation (ACM) varies the level of channel protection and modulation on an individual transport stream level, with dynamic adjustment to environmental conditions. A wide range of formats may be simultaneously transmitted on the same transport medium. Supported input data formats include continuous bitstreams, single or multiple MPEG transport streams and IP as well as ATM packets. This represents a substantial improvement over DVB-S and DVBDSNG, which support only MPEG transport streams. To a great extent, this ...ure-proofs DVB-S2.
    With DVB-S2 30% more content can be transported using the same bandwidth, for the same cost. Or the same content can be transmitted using 30% less bandwidth, for cost savings of 30%. Either way, network operators and broadcasters benefit. DVB-S2’s higher power efficiency results in additional savings. DVB-S2 signals require an average of 2.5 dB less link margin than a DVB-S signal with the same error protection overhead. This means smaller antennas, less unlink power and/or cheaper satellites DVB-S2 supports a wide range of modulation schemes, including QPSK (2 bits/symbol), 8PSK (3 bits/symbol), 16APSK (4 bits/symbol) and 32APSK (5 bits/symbol). These APSK modulation schemes provide superior compensation for transponder non-linearities than QAM.
    At the transmission site, a DVB-S2 modulator – either standalone or integrated in an encoder - is needed to modulate the content. Terrestrial and cable headends must be equipped with DVB-S2 receivers, while DVB-S2 settop boxes are required for DBS subscribers
    DVB-S2 provides both backward-compatible and non-backward compatible modes. The backward-compatible mode allows legacy DVB-S receivers to decode a portion of the transmitted bouquet and new DVB-S2 receivers to decode the entire bouquet. It provides somewhat lower bandwidth savings than the non-backward-compatible mode, but enables DTH operators to distribute the capital and labor expense associated with replacement of the installed base of set-top-boxes over a longer period. Direct transition to non-backward-compatible mode is most suitable for contribution solutions and distribution to terrestrial, cable and satellite headends. A number of video network equipment providers have developed encoder/modulators and receivers that simultaneously support DVB-S and DVB-S2. These devices are ideal for systems that are in the process of migrating to DVB-S2.
    DSNG applications benefit from the lower bandwidth requirements of DVB-S2 as well as from its superior link resilience. DVB-S2 advantages that are particularly critical for DSNG include narrower frequency slots for identical service bit rates or higher bit rates for the same frequency allocation; point-topoint or point-to-multipoint transmission; increased availability; and reduced uplink power requirements.

    difference between DVB-S2’s DSNG professional mode
    The broadcast services mode of DVB-S2 is most suitable for Direct-to-Home (DTH) services, collective antenna systems and cable television headends. It supports only QPSK and 8PSK modulations and does not make use of very low FEC rates that are targeted to extremely difficult professional reception conditions. It supports constant coding and modulation (CCM) for transmission. Variable coding and modulation (VCM) may be applied to multiple transport streams requiring differentiated error protection for different services.
    The digital satellite news gathering (DSNG) mode of DVB-S2 is optimized for point-to-point and point-to-multipoint applications. It is targeted for low symbol rate, narrow band signals of usually less than 5 MHz. In order to transmit high quality video content with relative high bit rates in a low symbol rate, 16APSK and 32APSK modulations may be used together with synchronization pilots. 16K short FEC blocks, in addition to the 64K normal FEC blocks in the broadcast profile, may be used for low latency in the channel. In order to maintain reliable signal reception even in bad weather conditions and using small up-link dishes mounted on a DSNG truck, very low FEC rates may be used.
    Last edited by sarkaboulhtoo; 30th December 2010 at 10:58.

  7. #7
    Junior Member Master
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    but any different b/w ku and c band because my dm 800hd can tune all ku dvb-s2 signals but not c band for exp inelsat7/10 there are about 4 or 5 dvb-s2 frequencies my receiver can not tune them the kenyan mux tbc and primier tv my question here is it because of lnb or dish size am using 180 cm dish pls help

  8. #8
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    Quote Originally Posted by castro View Post
    but any different b/w ku and c band because my dm 800hd can tune all ku dvb-s2 signals but not c band for exp inelsat7/10 there are about 4 or 5 dvb-s2 frequencies my receiver can not tune them the kenyan mux tbc and primier tv my question here is it because of lnb or dish size am using 180 cm dish pls help
    My Strong 4910 can tune 3783 H Ten Sports and 3922V India TV. The others I Cannot tune because of signal level. You probably have a dish size issue.
    TBS 5922 USB,Skystar 2, STRONG SRT4910, Openbox S9. 2.4M Prime Focus PAS10 - CBand(68.5 DEGE)+Thaicom(78.5 DEGE)+IS902 (62 DegE), 120cm dish Ew3A( 7DEGE) side LNB Ew2A( 10 DEGE)+w2(16 DEGE) ,3.0M Mesh Motorised dish on arc (AM44 (11 DEGW) to AM33 (96.5 DEGE), 150 cm dish PAS 10 KU, 80cm dish Ew4/w7(36 DEGE)

  9. #9
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    Cool Signal Strength for DVBS-2

    One of the side effect of DBS-2 is, it need bigger dish than DVBS. I think it because of changes in modulation and FEC - may be it wrong. I have no DVBS-2 receiver for more experiments.

  10. #10
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    but it's ok on ku type .. may be happen on c type

 

 

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