CABLE NETWORK SYSTEM, ITS TRANSMISSION LINE SWITCHING DEVICE, SUBSCRIBER DEVICE, ADAPTER DEVICE, AND MIXED NOISE MONITOR AND ANALYSIS DEVICE

摘要

PROBLEM TO BE SOLVED: To realize two-way transmission in good transmission environments by effectively suppressing an upward mixed noise with an inexpensive and practical means. ;SOLUTION: Not only a gate switch unit(GSU) is set in each of almost all subscribers' houses but also a set top box corresponding to the gate switch (G-STB) 31 and a modem corresponding to the gate switch (G-MDM) are set in a subscriber which wants to receive two-way services or a non-corresponding modem adapter (NGA) is added to an already prepared set top box corresponding to the gate switch (N-STB) or an N-MDM. The G-STB 31, the G-MDM 32, or the NGA monitors whether there is an upward transmission signal from home apparatus or not, and a transmission indication signal is given to a GSU 30 in the period when the upward transmission signal is detected, and the GSU makes the gate switch conductive to send the upward transmission signal to a drop cable 9 only in the period when the transmission indication signal is outputted; and meanwhile, it keeps the gate switch cut off in the period when the transmission indication signal is not outputted.;COPYRIGHT: (C)1998,JPO