| 摘要 |
PROBLEM TO BE SOLVED: To provide a satisfactory communication line, without extending a special device by inserting a specified data pattern into a prescribed position in data at the time of transmitting data from a center station to a subscriber terminal, calculating a data error rate and informing the center station of it in the subscriber terminal and selecting the frequency of a down line with less noise in the center station. SOLUTION: A data error rate control header 5 has a bit for deciding whether a data error rate is to be executed or not, a field designating a subscriber terminal measuring the data error rate and a field showing an area or individual ID. A user data part 9 is formed of the data error rate 1 control header 5, data error rate measuring data 6 and application data 7. For a frame structure 10, the data error rate control header 5 and data error rate measuring data 6 are inserted into prescribed positions, and a specified data pattern which has been previously decided is constituted. |
