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Originally featured on BroadcastEngineering.com
Nov 15

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11/15/2010 7:35 AM  RssIcon

q-down-at-3g.jpgNew from Crystal Vision is Q-Down-AT 3G, a broadcast down converter and distribution amplifier which incorporates special features to allow it to meet the challenge of down converting material containing timecode or closed captions, making it the ideal down converter for ‘big system’ users or the US market.

Q-Down-AT 3G is the latest addition to Crystal Vision’s most successful range of products, the Q-Down family of down converters. Alongside its ability to transport timecode and closed captions between different definitions, Q-Down-AT 3G can down convert 1080p, 720p, 1080i and SD at both 50Hz and 59.94Hz, and gives very flexible outputs with up to eight reclocked loop-throughs of the 3Gb/s, HD or SD input along with three video outputs that can be configured as mixtures of digital and analog (composite, Y/C, YUV and RGB).

Using Crystal Vision’s propriety processing, Q-Down-AT 3G provides a unique level of image quality in its price range – avoiding aliasing while retaining picture sharpness. Its short processing delay eliminates the need to compensate audio or other signals for the video delay which makes a system design much simpler, while for those that want to match other equipment delays there is a fully flexible variable video delay. It can pass four groups of embedded audio, features HD to SD aspect ratio conversion including AFD insertion and reading, and offers signal probe functionality. Q-Down-AT 3G can be given integrated fiber connectivity and still use only a single frame slot simply by fitting the FIP input or FOP output options to the board.

When down converting it can often be a challenge to transfer information from the HD signal into the SD signal, especially where different formats are involved – as is the case with timecode and closed captions. Timecode is carried in the vertical blanking and gives every frame a time label which provides a useful time reference for those engineers that need to trigger edits, associate audio signals or keep track of when video was acquired. When performing a down conversion Q-Down-AT 3G takes the HD timecode information (Ancillary Timecode or ATC, to SMPTE 12M) and translates it to the Standard Definition timecode format (Digital Vertical Interval Timecode or DVITC, to SMPTE 266M). DVITC is inserted on two adjacent video lines, one in each field. Q-Down-AT 3G can also insert HD Ancillary Timecode into the outgoing SD – which saves the engineer having to decode the DVITC if he up converts again at a later stage. Q-Down-AT 3G can also help with system timing by using the ATC data to correct the interlace phasing when down converting from the progressive 1080p or 720p formats to an interlaced output – reducing the need to adjust it later using a synchronizer.

Closed captions provide additional or interpretive information to viewers who wish to access it, such as subtitles, audio description or an alternative language and are mandatory under US Federal Law. When down converting 59.94Hz video, Q-Down-AT 3G takes the HD closed captions (to the CEA-708 standard) and extracts the data it needs to insert the corresponding SD closed captions (to CEA-608) into the SD output stream. With closed captions normally inserted on line 21 in the vertical blanking, Q-Down-AT 3G has the flexibility to insert closed caption information on any lines between 12 and 21 – allowing the popular line 21 to be used for other data instead.

Explained Crystal Vision’s Managing Director, Philip Scofield: “The processing of timecode and closed captions in such a high quality, yet economical, down converter has made this product popular in critical applications with some of the biggest broadcasters throughout the world”.

Q-Down-AT 3G is a space-saving 4 x 10.5 inches module which is housed in the standard Crystal Vision frames – available in 4RU, 2RU, 1RU and desk top box sizes. The inputs and outputs are accessed by using the RM41 frame rear module or the RM57 for fiber input or output applications, while control can be from board edge switches, an active front panel on the frame, a remote control panel, SNMP and the Statesman PC software.

Q-Down-AT 3G is shipping now.

Based at Whittlesford near Cambridge in the UK, Crystal Vision provides digital keyers, picture storage modules and a full range of digital and analog interface equipment including converters, synchronizers, distribution amplifiers and audio embedders to the professional broadcasting industry worldwide.

www.crystalvision.tv

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