New Broadcast Network: Difference between revisions

From YSTV History Wiki
Jump to navigation Jump to search
(content from main page)
 
(sumarise 1998 (full story has it's own page), ready to continue the story)
Line 1: Line 1:
This gradually replaced the [[Original Broadcast Network|Rediffusion]] system from 1996 onwards as it became increasingly hard to maintain and upgrade the old system.
This gradually replaced the [[Original Broadcast Network|Rediffusion]] system from 1996 onwards as it became increasingly hard to maintain and upgrade the old system. It broadly remains in use today, with various losses as further building work has been undertaken, and some re-working to accommodate extra outlets.


== Vanbrugh Upgrade ==
The first section to be constructed was the link to [[Vanbrugh Upgrade|Vanbrugh college]], which was undertaken in 1996 by [[Owain Davies]]. Whilst subsequently modified to bring it into line with the new work being done on the rest of the network, it remains the blueprint for the rest of the system.


During the summer holidays of 1995, [[Owain Davies]] visited the station and stumbled across a flyer from Maxim highlighting their MAX435/MAX436 video balanced line drivers and receivers.  
== [[Vanbrugh Upgrade]] ==
In 1996 a set of balanced line video drivers were constructed for installation in LTC, and a receiver unit to be installed in the Vanbrugh vent room with the existing Rediffusion equipment rack. These were linked using the Rediffusion video contribution cable, with audio being sent over the audio contribution cable. The unbalanced video cable from one of the contribution points to the Vanbrugh vent room was intercepted and connected to the TV next to the porter's lodge, where a video DA was installed to send unbalanced video to the local TV and those in the JCR and Bar areas. Audio was balanced from LTC to the porter's lodge where it was unbalanced for distribution to the TVs.


At this point, he did not know if he was return to York or not, however he took the flyer away to read at home. He had come across the benefits of balanced line audio earlier on in his Electronics degree and seen it in practice at YSTV where it was used to convey microphone signals down incredibly long pieces of dirty EM infiltrated cable and be amplified at the other end, resulting in crystal clear clarity. The example circuit diagram seemed a remarkable simple solution, just one IC for transmitter and one for the receiver. He returned to York in September of 1995, however he was not due to start his tenancy on a house in Osbaldwick for a week or so and therefore had temporary accommodation in Fairfax House. It was here that the prototype transmitter and receiver were constructed. Trials of the units were performed in the studio of [[G/046]] using twisted pair audio cable. This soon ran out with the units managing to successfully convey the signal, so he resorted any scrap of telephone cable, mains cable, or any cable he could lay his hands on. The signal did eventually deteriorate, usually with the picture going black and white due to a disappearing colour burst (in fact he was amazed by how much the colour burst could reduce in amplitude and colour in the picture remain). He experimented with different resistor and capacitor networks on the feedback loop of the receiver amplifier in an attempt to equalise the high frequency loss of the cable. It was demonstrated to various members of the station using two monitors, one showing before transmission and the other reception with a sea of cable of the floor. The subject under test was given the challenge to determine which monitor was showing the picture that had gone down the various different types of cable. At this point it was decided to inform AV of the idea, since they were the other stakeholder in the network. A meeting was held and they seemed quite interested in the idea and they offered to {{unsure|loan}} the electrical fix installation plans for the University. Their collection was quite comprehensive covering most of the University's buildings, from the colleges down to the VC's bungalow. On these plans were marked the locations of the various contribution points, AV racks and routing information of the cables linking the two.  
This provided a concrete proof that the system worked, and that base-band distribution over inexpensive twisted pair cables could offer picture quality equal to much more expensive coaxial cable, thus making a wholesale replacement of the old Rediffusion system viable.


Owain had found in LTC the composite output from the contribution feed from Physics. The picture was in good condition, meaning the interference problems were occurring on the distribution side of the network only. Armed with the knowledge from the plans, LTC began to make more sense. Three things came out from this visit
== The 1998 scheme ==


* LTC could act as the distribution for the new network since the composite was good.
== Current Status ==
* Since the composite was good, a lot of the wiring must be good and therefore could be reused.
 
Audio driver used SSM2142/SSM2141.
 
== Beyond Vanbrugh ==

Revision as of 22:58, 19 July 2007

This gradually replaced the Rediffusion system from 1996 onwards as it became increasingly hard to maintain and upgrade the old system. It broadly remains in use today, with various losses as further building work has been undertaken, and some re-working to accommodate extra outlets.

The first section to be constructed was the link to Vanbrugh college, which was undertaken in 1996 by Owain Davies. Whilst subsequently modified to bring it into line with the new work being done on the rest of the network, it remains the blueprint for the rest of the system.

Vanbrugh Upgrade

In 1996 a set of balanced line video drivers were constructed for installation in LTC, and a receiver unit to be installed in the Vanbrugh vent room with the existing Rediffusion equipment rack. These were linked using the Rediffusion video contribution cable, with audio being sent over the audio contribution cable. The unbalanced video cable from one of the contribution points to the Vanbrugh vent room was intercepted and connected to the TV next to the porter's lodge, where a video DA was installed to send unbalanced video to the local TV and those in the JCR and Bar areas. Audio was balanced from LTC to the porter's lodge where it was unbalanced for distribution to the TVs.

This provided a concrete proof that the system worked, and that base-band distribution over inexpensive twisted pair cables could offer picture quality equal to much more expensive coaxial cable, thus making a wholesale replacement of the old Rediffusion system viable.

The 1998 scheme

Current Status

Retrieved from ‘https://wiki.ystv.co.uk/index.php?title=New_Broadcast_Network&oldid=5151’