| 摘要 |
PURPOSE: An apparatus for selectively connecting data channels is to allocate the data channels only when a subscriber demands, thereby utilizing the data channels effectively and establishing the system at a low expense. CONSTITUTION: A video on demand(VOD) system comprises a video server, a video switch, a network management unit, an ADSL(asynchronous data subscriber line) terminal unit-central, an ADSL terminal unit-rack and a set top box(STB). In the ADSL terminal unit-central, a control command for selecting a data channel is inputted from the network management unit via a control signal transmission line(104). A micro-processor(200) generates a line connection signal in response to the control command. Signal modulation/demodulation units(207) are connected to corresponding subscriber lines through splitters(108). The first sub channels(206) are connected to the signal modulation/demodulation units. The second sub channels(103) receive data from the video switch. A line connection unit(208) coupled to the second sub channels connects a selected first sub channel to a selected second sub channel in response to the line connection signal.
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