Distribution Network
The Distribution Network was for the first 37 years of YSTV's history the only way to watch our programmes before the availability of content via our website. It mirrors the Contribution Network used to get video from around campus back to YSTV's studios for broadcasting major events around campus.
Original Network
Whilst the University was being built during the late 60s and early 70s, the decision was taken that a closed-circuit television broadcast system would be a good idea. After an early experiment with VHF distribution and a daisy-chain contribution system that formed a giant ring, the contract was given to the Rediffusion company, whose main business was in distributing paid TV and radio services to householders over wired networks.
A closed circuit system of Audio Visual (AV) distribution and contribution was installed, along the lines of a small urban area commercial system, but with a greater provision for sending video back from the various parts of the university to be broadcast. The system allowed up to 4 channels to be conveyed around campus on a multi-pair pair cable, with each channel dedicated to a separate pair. Further pairs in the cable allowed for up to 9 channels, 5 of them video and the other four audio-only. Video channels carried both the audio and video signals on a single pair in the cable. This was used to re-broadcast the (then three) terrestrial channels as well as carrying YSTV's output from it's inception.
The new Network
By 1994 the passing of the years had taken its toll on the system, and various colleges/buildings had been remodelled, leading to removal of the AV racks or cutting of contribution/distribution cables. The remaining televisions soldiered on, and when required were repaired by using parts from any spares that could cannibalised from the spares from the garage in Wentworth. Despite best efforts, picture quality was suffering, colour would turn to black and white and then back or various interference patterns could be seen on the screen.
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. The example circuit diagram seemed a remarkable simple solution, just one IC for transmitter and one for the receiver. 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. This lead to a plan to replace all the modulation equipment from the Rediffusion system with base-band video senders and receivers using the Maxim ICs, driving over the old contribution network cables to distribute video to the vent rooms, and then over the unbalanced video cables to the TVs themselves.
This was implemented as a test in Vanbrugh by Owain Davies, feeding the three TVs there, and worked very well. The problem of getting cables run from the vent rooms to the TVs was significant however, as it required cables to be run above ceilings and so on. Given that this would be needed for almost all the colleges, Rob Sprowson opted to do the whole job, and run new cable from LTC to the TV locations. The receivers could then be installed near the TVs, and the contribution cables (which anyway did not run to Langwith or Derwent) left alone. This was implemented using 3-pair screened cable, providing for stereo audio and balanced video to all the available or proposed TV positions.