CEA-909

CEA-909 is the ANSI standard for 8VSB/ATSC smart antennas. The basic concept is that the smart antenna either physically rotates toward the signal, or is stationary, but has elements pointed in different directions and uses only those elements pointed toward the signal. This is accomplished by feedback from the control device, such as a digital-to-analog converter box, telling the smart antenna when the signal is stronger or weaker.

Not much information is publicly available about the CEA-909 specification, but some information can be gleaned from Texas Instruments' TVP9000 documentation.cite web
date = July 2007
url = http://focus.ti.com/lit/ds/symlink/tvp9900.pdf
title = "VSB/QAM Receiver Data Manual" (SLEA064A)
format = PDF
work = TI.com
publisher = Texas Instruments
accessdate = 2008-05-29]

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.

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.

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.

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.cite web
date = November 30, 2007
url = http://www.ce.org/PDF/2007-11-30CEAStandardsMonthlyUpdate.pdf
title = "CEA Standards Update"
format = PDF
work = CE.org
publisher = Consumer Electronics Association
accessdate = 2008-05-29] After editorial review, it was published in December 2007.cite web
date = December 2007
url = http://www.ce.org/Standards/browseByCommittee_2784.asp
title = "Standards Details - CEA-909-A (ANSI)"
work = CEA Standards
publisher = Consumer Electronics Association
accessdate = 2008-05-29] cite web
date = December 2007
url = http://www.ce.org/Print/Standards/ANSI_CEA-909-A_Preview.pdf
title = "ANSI/CEA-909-A Preview"
format = PDF
work = CE.org
publisher = Consumer Electronics Association
accessdate = 2008-05-29]

Official specs

The official specifications are available for purchase from Global Engineering Documents.cite web
date = December 2007
url = http://global.ihs.com/doc_detail.cfm?item_s_key=00414854&item_key_date=920531&rid=CEA
title = "Document Details: CEA-909, Rev. A, Date: 12/00/07"
work = Standards Store
publisher = Information Handling Services (IHS)
accessdate = 2008-05-29]

References

Further reading

* cite web
date = June 1, 2002
url = http://www.ce.org/standards/StandardDetails.aspx?Id=1418&number=CEA-909
title = "Standard Details - CEA-909"
work = CEA Standards
publisher = Consumer Electronics Association
accessdate = 2008-05-29

* cite web
date = January 31, 2007
url = http://www.ce.org/PDF/2007-01-31CEAStandardsMonthlyUpdate.pdf
title = "CEA Standards Update"
format = PDF
work = CE.org
publisher = Consumer Electronics Association
accessdate = 2008-05-29

See also

* DiSEqC and USALS, existing standards allowing control of satellite television rotors and switches via the same cable as the main signal.