China Multimedia Mobile Broadcasting
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China Mobile Multimedia Broadcasting (CMMB) is a mobile television and multimedia standard developed and specified in China by the State Administration of Radio, Film, and Television (SARFT).[1] It is based on the Satellite and Terrestrial Interactive Multiservice Infrastructure (STiMi), developed by TiMiTech, a company formed by the Chinese Academy of Broadcasting Science.[2] [3] Announced in October 2006,[1] it has been described as being similar to Europe's DVB-SH standard for digital video broadcast from both satellites and terrestrial repeaters to handheld devices.[3]
It specifies usage of the S-band/U-band and occupies 25 MHz bandwidth within which it provides 25 video and 30 radio channels with some additional data channels.[3] Multiple companies have chips that support CMMB standard - Innofidei who was the first with a solution 28 March 2007.[4] [5]
Other manufacturers, such as Unique Broadband Systems, were quick to enter the race and grab a share of the handheld broadcasting market with their hardware platform supporting both CMMB and DTMB (as well as others) standard waveforms.
RF Details
[edit ]CMMB uses frequencies in the range 2635 - 2660 MHz (S-band) for satellite and "gap-filler" terrestrial broadcast, with additional terrestrial broadcast in the UHF band 470 – 862 MHz.[6] [7] The channel bandwidth can be either 2 or 8 MHz, depending on data rate.[8]
Coverage
[edit ]China Satellite Mobile Broadcasting Corporation (CSMBC), as of 2 June 2010, had completed CMMB network coverage in 317 prefecture-level cities.[9]
Versus DTMB
[edit ]- The CMMB is not a Chinese national standard (GB), but the DTMB is GB 20600-2006.
- The CMMB uses QCIF or QVGA, so can not broadcast the HDTV (1080i/1080p), but the DTMB can.
- The CMMB is intended for use on small screen devices (such as GPS, PDA, or smartphone...) in a mobile scenario, while DTMB is intended for use on large screen devices (such as PC, LCD TV, PDP TV...) in a fixed scenario.
See also
[edit ]- DTMB
- Digital Multimedia Broadcasting
- DVB (Digital Video Broadcasting)
- DVB-T (Digital Video Broadcasting - Terrestrial)
- DVB-H (Digital Video Broadcasting - Handheld)
- International standard
References
[edit ]- ^ a b "China releases mobile TV industrial standard" (Press release). Interfax China. 2006年10月25日. Retrieved 2007年04月14日.
- ^ "TiMi Technologies Co. Ltd". Academy of Broadcasting Science. 2008年01月31日. Archived from the original on 2009年02月25日. Retrieved 2008年06月08日.
- ^ a b c Mike Clendenin (2006年12月18日). "China's mobile-TV spec similar to Europe's". EETimes. Retrieved 2007年04月14日.
- ^ "China releases first mobile TV chip based on CMMB standard - SARFT official" (Press release). Interfax China. 2007年03月28日. Retrieved 2007年04月14日.
- ^ Cai Yan (2007年03月29日). "Chip supports China's CMMB mobile TV". EETimes. Retrieved 2007年04月14日.
- ^ Rohde & Schwarz. "CMMB Information" . Retrieved 2010年01月29日.
- ^ Siano. "SMS1186" (PDF). Retrieved 2010年01月29日.
- ^ Rohde & Schwarz. "Test signals for the new CMMB and DVB-SH mobile TV systems" (PDF). Retrieved 2010年01月29日.
- ^ "开通CMMB的317个城市及频道列表 — 中广互联 - SARFT.net | 中国广电第一门户 | 数字电视行业第一门户". Archived from the original on 2010年06月14日. Retrieved 2010年06月21日.