China_Multimedia_Mobile_Broadcasting Knowpia

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.

References edit

^ ^a ^b "China releases mobile TV industrial standard" (Press release). Interfax China. 2006-10-25. Retrieved 2007-04-14.
^ "TiMi Technologies Co. Ltd". Academy of Broadcasting Science. 2008-01-31. Archived from the original on 2009-02-25. Retrieved 2008-06-08.
^ ^a ^b ^c Mike Clendenin (2006-12-18). "China's mobile-TV spec similar to Europe's". EETimes. Retrieved 2007-04-14.
^ "China releases first mobile TV chip based on CMMB standard - SARFT official" (Press release). Interfax China. 2007-03-28. Retrieved 2007-04-14.
^ Cai Yan (2007-03-29). "Chip supports China's CMMB mobile TV". EETimes. Retrieved 2007-04-14.
^ Rohde & Schwarz. "CMMB Information". Retrieved 2010-01-29.
^ Siano. "SMS1186" (PDF). Retrieved 2010-01-29.
^ Rohde & Schwarz. "Test signals for the new CMMB and DVB-SH mobile TV systems" (PDF). Retrieved 2010-01-29.
^ "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 2010-06-14. Retrieved 2010-06-21.