New Broadcast Network - Revision history

Sprow: Spelling

2007-11-19T09:32:26Z

Spelling

← Older revision		Revision as of 09:32, 19 November 2007
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	The development effort for an all digital system was prohibitively long, and while the coaxial system had merits in bandwidth terms the cost of the cable ruled it out. The decision was made to select twisted pair cabling on the basis that getting some new cabling installed was the most important step: a digital system could always reuse any cable in the future following an initial analogue installation.		The development effort for an all digital system was prohibitively long, and while the coaxial system had merits in bandwidth terms the cost of the cable ruled it out. The decision was made to select twisted pair cabling on the basis that getting some new cabling installed was the most important step: a digital system could always reuse any cable in the future following an initial analogue installation.

	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 constructed 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		The six transconductance amplifier outputs were allocated as
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	On the whole, the university's use of wooden covered walkways made cable installation fairly simple with a few notable exceptions		On the whole, the university's use of wooden covered walkways made cable installation fairly simple with a few notable exceptions
	* The crossroads outside LTC and Central hall, massive bundles of other power cables, fire alarm cables, network and communications cables all met here and the walkway was completely full. A can of WD40 was used to grease the cables so that they could be dragged past this section		* The crossroads outside LTC and Central hall, massive bundles of other power cables, fire alarm cables, network and communications cables all met here and the walkway was completely full. A can of WD40 was used to grease the cables so that they could be dragged past this section
	* Central hall, an impenitrable concrete fortress not intended to ever have any wires added to it once ~~contructed~~		* Central hall, an impenitrable concrete fortress not intended to ever have any wires added to it once constructed
	* The under road tubing from Biology to Wentworth, the tubing had blue pull through ropes so laying cables was quite simple, but the area was infested with thousands of itchy biting flies		* The under road tubing from Biology to Wentworth, the tubing had blue pull through ropes so laying cables was quite simple, but the area was infested with thousands of itchy biting flies
	* Over Vanbrugh kitchens, through the high voltage substation, with a little supervision from Steve Stead in Estates department		* Over Vanbrugh kitchens, through the high voltage substation, with a little supervision from Steve Stead in Estates department
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	== Post fix additions ==		== Post fix additions ==
	=== Estates ===		=== Estates ===
	After the initial burst of activity in 1998, the remaining two years of [[Rob Sprowson]] and [[Chris Ward]]'s time was largely occupied chasing estates to add the remaining missing pieces of the jigsaw puzzle. Resourcing within Estates meant that new YSTV monitors ~~was~~ never a top priority.		After the initial burst of activity in 1998, the remaining two years of [[Rob Sprowson]] and [[Chris Ward]]'s time was largely occupied chasing estates to add the remaining missing pieces of the jigsaw puzzle. Resourcing within Estates meant that new YSTV monitors were never a top priority.

	=== Locations ===		=== Locations ===

Sprow: /* Locations */

2007-11-18T21:53:23Z

Locations

← Older revision		Revision as of 21:53, 18 November 2007
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	Some progress was made, though by graduation the network was still not as extensive as had originally been hoped. A number of small finishing off jobs remained, these were left for the following year's [[Network Engineer]] to complete.		Some progress was made, though by graduation the network was still not as extensive as had originally been hoped. A number of small finishing off jobs remained, these were left for the following year's [[Network Engineer]] to complete.
	* Alcuin - cables hastily retracted during nucleus demolition and left in a coil at the back door to the JB Morrell library, this work was conducted remotely after [[Rob Sprowson]]'s graduation while working		* Alcuin - cables hastily retracted during nucleus demolition and left in a coil at the back door to the JB Morrell library, this work was conducted remotely after [[Rob Sprowson]]'s graduation while working
	* Library - a power point was located, but had only a live connection and no neutral, internal wiring was added to the snack bar by [[Chris Ward]] early one morning due to noise restrictions, and a set briefly installed on a bracket. Due to the lean-to contruction of the snackbar the TV inched forward every time the door slammed shut and the TV was hastily withdraw when it fell and nearly injured a student drinking a laté. The socket was scheduled to be repaired in summer 2000		* Library - a power point was located, but had only a live connection and no neutral, internal wiring was added to the snack bar with [[Chris Ward]] early one morning due to noise restrictions, and a set briefly installed on a bracket. Due to the lean-to contruction of the snackbar the TV inched forward every time the door slammed shut and the TV was hastily withdraw when it fell and nearly injured a student drinking a laté. The socket was scheduled to be repaired in summer 2000
	* Vanbrugh - the snackbar television was modified to always turn on to YSTV rather than an off tuned terrestrial channel, and URY used the 4th output from the receiver, but otherwise Vanbrugh remained unchanged		* Vanbrugh - the snackbar television was modified to always turn on to YSTV rather than an off tuned terrestrial channel, and URY used the 4th output from the receiver, but otherwise Vanbrugh remained unchanged
	* Langwith - used annually for conference services, eventually the receiver was modified to have a BNC connector on it to allow the mute monitor to be easily added and removed each summer		* Langwith - used annually for conference services, eventually the receiver was modified to have a BNC connector on it to allow the mute monitor to be easily added and removed each summer

Sprow: /* Documentation */ Repetition

2007-11-18T18:42:21Z

Documentation: Repetition

← Older revision		Revision as of 18:42, 18 November 2007
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	To help with future work, a blue print of the university on A2 paper was obtained from Estates and marked with the new cabling routes along with joins to old Rediffusion routes and other similar annotations. This map was submitted back to Estates for inclusion on future drawings in the hope that this would avoid damage to cables.		To help with future work, a blue print of the university on A2 paper was obtained from Estates and marked with the new cabling routes along with joins to old Rediffusion routes and other similar annotations. This map was submitted back to Estates for inclusion on future drawings in the hope that this would avoid damage to cables.

	A technical reference manual, in the same style as produced for the [[Cub Conversion]] and [[Station Video Mux]] was also ~~produced~~, extending to 4 dense pages of A4 text plus copies of the schematics, stripboard layouts, and datasheets for the receiver units.		A technical reference manual, in the same style as produced for the [[Cub Conversion]] and [[Station Video Mux]] was also published, extending to 4 dense pages of A4 text plus copies of the schematics, stripboard layouts, and datasheets for the receiver units.

	== Contribution ==		== Contribution ==

Sprow: /* Post fix additions */ Docs

2007-11-18T18:41:54Z

Post fix additions: Docs

← Older revision		Revision as of 18:41, 18 November 2007
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	The second incident was while [[P/S/016]] was being redecorated, the decorators removed the fuse from the supply feeding the network box (as the box itself was hidden behind a wooden panel). A large 'DO NOT TURN OFF' label was added to help prevent a recurrence.		The second incident was while [[P/S/016]] was being redecorated, the decorators removed the fuse from the supply feeding the network box (as the box itself was hidden behind a wooden panel). A large 'DO NOT TURN OFF' label was added to help prevent a recurrence.

			=== Documentation ===
			To help with future work, a blue print of the university on A2 paper was obtained from Estates and marked with the new cabling routes along with joins to old Rediffusion routes and other similar annotations. This map was submitted back to Estates for inclusion on future drawings in the hope that this would avoid damage to cables.

			A technical reference manual, in the same style as produced for the [[Cub Conversion]] and [[Station Video Mux]] was also produced, extending to 4 dense pages of A4 text plus copies of the schematics, stripboard layouts, and datasheets for the receiver units.

	== Contribution ==		== Contribution ==

Sprow: Epilog

2007-11-18T18:35:52Z

Epilog

@@ Line 84: / Line 84: @@
 == Post fix additions ==
-Sigh.
+=== Estates ===
 == Contribution ==

Sprow: Contrib

2007-11-18T18:13:17Z

Contrib

← Older revision		Revision as of 18:13, 18 November 2007
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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.
	[[~~Image:Net2000Rough~~.~~png~~\|~~left\|thumb\|160px\|Schematic~~ of ~~1998 installation]]~~
			== 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.

Sprow: /* New cabling */ Cable reuse

2007-11-18T17:54:32Z

New cabling: Cable reuse

← Older revision		Revision as of 17:54, 18 November 2007
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	== New cabling ==		== New cabling ==
	In summer 1998 an ambitious 2km of 3-pair plus overall screen cable was installed, following an initial mixup which had seen 2km of 3 core mains cable delivered to the station instead.		In summer 1998 an ambitious 2km of 3-pair plus overall screen cable was installed, following an initial mixup which had seen 2km of 3 core mains cable delivered to the station instead. This would be joined to portions of known good Rediffusion cable, notably the thicker solid core contribution cables in reverse.

	~~The~~ three pairs were assigned		Where terminated to the three pairs were assigned
	* Red/black: video		* Red/black: video
	* Green/black: left or mono audio		* Green/black: left or mono audio

Sprow: /* Key equipment */ Gaffa

2007-11-18T17:52:44Z

Key equipment: Gaffa

← Older revision		Revision as of 17:52, 18 November 2007
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	* The long step ladder borrowed from the Drama Barn		* The long step ladder borrowed from the Drama Barn
	* An electric screwdriver and a bag of washers and screws - the walkways had lost many of their screws over the years		* An electric screwdriver and a bag of washers and screws - the walkways had lost many of their screws over the years
			* Gaffer tape

	=== Navvies ===		=== Navvies ===

Sprow: More words

2007-11-18T17:52:15Z

More words

@@ Line 12: / Line 12: @@
 == New cabling ==
 In summer 1998 an ambitious 2km of 3-pair plus overall screen cable was installed, following an initial mixup which had seen 2km of 3 core mains cable delivered to the station instead.
 Timing was opportune as this was the same summer that a private contractor was installing about the same amount of cabling for the one-per-room campus telephones for student's bedrooms. Often a route could be covered by following the private contractors while the covered walkway panels were removed, though sometimes they followed the YSTV installation too.
@@ Line 49: / Line 55: @@
 A service history sticker was added to the rear, but seldom used.
 == Post fix additions ==
 [[Image:Net2000Rough.png|left|thumb|160px|Schematic of 1998 installation]]

Sprow: Add words

2007-11-18T17:33:59Z

Add words

@@ Line 1: / Line 1: @@
-Audio driver used SSM2142/SSM2141.
+== System options ==
 [[Image:NetboxGuts.png|left|thumb|160px|Inside the new network receiver]]
-[[Image:WantToTurnMeOn.png|left|thumb|160px|Network prompt label]]
 [[Image:Net2000Rough.png|left|thumb|160px|Schematic of 1998 installation]]