CEA-909
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CEA-909 is the ANSI standard for 8VSB/ATSC smart antennas. Not much information is publicly available about the CEA-909 specification, but some information can be gleaned from Texas Instruments' TVP9000 documentation.[1]
Analog televisions generally give instant feedback as the signal gets better or worse as you move the antenna. Digital television antennas can be difficult to aim correctly because of the cliff effect and because of delays in decoding and displaying the signal. Smart antennas remove the burden of positioning the antenna for digital TVs and can make the tuning process easier than it was with analog television.
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[edit] Information from TVP9900 document
There are two basic modes of operation for a CEA-909 antenna, mode A and mode B. Mode A allows for communication only from the tuner to the antenna and Mode B allows for bidirectional communication. A 14-bit pulse-width modulation data stream is sent to the antenna and if the antenna is mode B a 10-bit data stream is sent back. The timeout period for a response from a mode B antenna is 100 ms. The system uses a single wire for communication, possibly similar to I²C.[1]
The 10 bits sent back from the antenna are largely unused. Only the first two bits are used with at least one of those being used for a transmission error flag; the remaining 8 bits are reserved. The contents of the 14 bits sent to the antenna are not revealed.[1]
[edit] Revision CEA-909-A
CEA-909-A is an update to CEA-909 that enables a single coaxial cable to connect smart antennas to smart antenna-capable DTV sets. A weakness of CEA-909 was that it required another control cable in addition to the coaxial cable. This revision was first approved by the Video Systems Committee on 6 June 2007 and ANSI public review closed on 1 October 2007.[2] After editorial review, it was published in December 2007.[3][4]
[edit] Official specs
The official specifications are available for purchase from Global Engineering Documents.[5]
[edit] References
- ^ a b c VSB/QAM Receiver Data Manual (SLEA064A) (PDF). TI.com. Texas Instruments (July 2007). Retrieved on 2008-05-29.
- ^ "CEA Standards Update" (PDF). CE.org. Consumer Electronics Association (November 30, 2007). Retrieved on 2008-05-29.
- ^ "Standards Details - CEA-909-A (ANSI)". CEA Standards. Consumer Electronics Association (December 2007). Retrieved on 2008-05-29.
- ^ "ANSI/CEA-909-A Preview" (PDF). CE.org. Consumer Electronics Association (December 2007). Retrieved on 2008-05-29.
- ^ "Document Details: CEA-909, Rev. A, Date: 12/00/07". Standards Store. Information Handling Services (IHS) (December 2007). Retrieved on 2008-05-29.
[edit] Further reading
- "Standard Details - CEA-909". CEA Standards. Consumer Electronics Association (June 1, 2002). Retrieved on 2008-05-29.
- "CEA Standards Update" (PDF). CE.org. Consumer Electronics Association (January 31, 2007). Retrieved on 2008-05-29.
