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New Broadcast Network: Difference between revisions
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Also, [[Owain Davies]] had contructed a 19" rack unit with 6 balanced line video outputs and matching audio drivers off his own back, so half of the transmission system was already built and tested. | Also, [[Owain Davies]] had contructed a 19" rack unit with 6 balanced line video outputs and matching audio drivers off his own back, so half of the transmission system was already built and tested. | ||
The six transconductance amplifier outputs were allocated as | |||
# LTC - Langwith - Derwent | |||
# LTC - Vanbrugh | |||
# LTC - Biology - Wentworth | |||
# LTC - Library - Alcuin | |||
# LTC - Central Hall - Physics - Goodricke | |||
# LTC - Unused | |||
the optional termination on the receiver boxes meant that extra receivers could be added to a chain as simply as looping a signal through a monitor, and moving the terminator to the last link in the chain. | |||
== New cabling == | == New cabling == | ||
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== Receivers == | == Receivers == | ||
The receiver units were all built by [[Rob Sprowson]] based on cloning the video receiver from Owain's Vanbrugh prototype, with the addition of an on board distribution amplifier to directly drive up to 4 sets. The audio driver used was an SSM2142/SSM2141 transmitter and receiver pair, again balanced line, with two copies of the circuitry present to allow for future stereo transmissions (only one half was populated to save money). | The receiver units were all built by [[Rob Sprowson]] based on cloning the video receiver from Owain's Vanbrugh prototype, with the addition of an on board MAX497 distribution amplifier to directly drive up to 4 sets. The audio driver used was an SSM2142/SSM2141 transmitter and receiver pair, again balanced line, with two copies of the circuitry present to allow for future stereo transmissions (only one half was populated to save money). | ||
[[Image:NetboxGuts.png|left|thumb|160px|Inside the new network receiver]] | [[Image:NetboxGuts.png|left|thumb|160px|Inside the new network receiver]] | ||
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In broad terms, although the heart had been ripped out of the Rediffusion system, at the start of Autumn 1998 the total network coverage was largely unchanged (Vanbrugh, Goodricke, Derwent, Langwith) except that now the images were in colour and on modern stereo sets. | In broad terms, although the heart had been ripped out of the Rediffusion system, at the start of Autumn 1998 the total network coverage was largely unchanged (Vanbrugh, Goodricke, Derwent, Langwith) except that now the images were in colour and on modern stereo sets. | ||
[[Image:Net2000Rough.png|left|thumb|160px|Schematic of 1998 installation]] | |||
== Post fix additions == | == Post fix additions == | ||
Sigh. | Sigh. | ||
[[ | |||
== Contribution == | |||
Originally the only anticipated contribution was to be the link, via Physics, to the star point at the centrally located Language Teaching centre. | |||
However, the move to Derwent of the student union elections for [[EN 99]] meant that some rapid cable tracing was required. A balanced line driver was placed in the ceiling void above D/016 which allowed (via a choc block in Langwith) pictures to be received in LTC which were then relayed {{unsure|somehow}} back to Goodricke. | |||
The system was extensively tested prior to the event by use of a BBC Micro generating a test pattern, also in the ceiling void, to a monitor in Goodricke. | |||
In spring 2000 the link was revisited and the last remaining traces of Rediffusion equipment ripped out of LTC, the new cables fed discretely into the 19" rack unit (wall mounted vertically on wooden blocks), and rubberised Rediffusion cables cropped and labelled where known into a choc block patch panel. In theory this meant that any known good links could be reused in the same way that Derwent was by simply moving links around, with Derwent to Goodricke being the default state. | |||