Architecture of the iTV trial The Cambridge Digital Interactive Television Trial started in September 1994, with ten users connected in the first phase. ATM networking technology is employed throughout the system, with two-way digital data being carried alongside cable TV signals over fibre optic links. In phase two, begun in March 1995, the network and the content server facilities were substantially enhanced, and the number of user sites (homes, schools and businesses) was increased: by January 1996 it approached one hundred. T1/E1 G.80x ATM Line Card These cards were used in the set-top boxes of the Cambridge Interactive Television Trial (iTV Trial). Nearly 100 such were installed in homes and schools in Cambridge. We used an E1 baseband signal running on the CATV feeder coax from the street cabinet to each home. The analog CATV occupied the upper frequencies as usual. I designed this card using two Xilinx devices because each device had two global clock networks and I needed a total of four clock domains.

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