BIDIRECTIONAL CATV SYSTEM

摘要

PURPOSE:To shorten the waiting time to the data generated urgently by providing a function to a terminal device to detect the head code contained in the down-data signal sent to the terminal device from a center device and to transmit the own address in the form of an up-data signal. CONSTITUTION:A terminal device B generates urgently the data which is transmitted to a center device 101, and the head code 302 of the down-data 301 sent from the device 101 is received normally within the device B. Then the own address number is transmitted immediately from the device B in the form of the up- data 310. The data 310 is received by the device 101 and demodulated as an address code 305. Then it is recognized that the data to be urgently transmitted is generated. The address number corresponding to the device B is inserted to an address code 319 within the down-data 317 and transmitted in the next polling in place of the next address and out of the normal polling sequence after receiving the up-data 311 given from a terminal device A.