|
DVB-SH ("Digital Video Broadcasting - Satellite services to Handhelds") is a physical layer standard for delivering IP based media content and data to handheld terminals such as mobile phones or PDAs, based on a hybrid satellite/terrestrial downlink and for example a GPRS uplink. The DVB Project published the DVB-SH standard in February 2007.〔(dvb.org: DVB approves DVB-SH specification )〕 The DVB-SH system was designed for frequencies below 3 GHz, supporting UHF band, L Band or S-band. It complements and improves the existing DVB-H physical layer standard. Like its sister specification (DVB-H), it is based on DVB IP Datacast (IPDC) delivery, electronic service guides and service purchase and protection standards. DVB-SH specifies two operational modes: * SH-A: specifies the use of COFDM modulation on both satellite and terrestrial links with the possibility of running both links in SFN mode. * SH-B: uses Time-Division Multiplexing (TDM) on the satellite link and COFDM on the terrestrial link. == Comparison with DVB-H == The DVB-SH incorporates a number of enhancements when compared to DVB-H: *More alternative coding rates are available *The omission of the 64QAM modulation scheme *The inclusion of support for 1.7 MHz bandwidth and 1k FFT *FEC using Turbo coding *Improved time interleaving *Support for antenna diversity in terminals Recently, results from BMCO forum ((Alcatel April 2008 )) shows a radio improvement of at least 5.5 dB on signal requirements between DVB-H and DVB-SH in the UHF frequencies. The improvements to signal requirements translates to better in-building penetration, better in-car coverage and extension of outdoor coverage. DVB-SH chipsets are being developed now by DiBcom and NXP Semiconductors, and are expected to be available in beginning of 2008. Initial specifications show that the chipsets supports both UHF and S-Band and are compatible with DVB-H. DiBcom has announced a DVB-SH chip with availability in 2008 Q3. (Dibcom DVB-SH 2008 Q3 ). The chip "has dual RF tuners supporting VHF, UHF, L-Band and S-Band frequencies". 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「DVB-SH」の詳細全文を読む スポンサード リンク
|