TRANSMISSION QUALITY MONITORING SYSTEM IN DIGITAL COMMUNICATION NETWORK

PURPOSE: To further improve monitoring services of transmission quality, with respect to a transmission quality monitoring system in digital communication networks. CONSTITUTION: In a digital communication network provided with a first terminal station 11 incorporated with a first multiplex part 21 and a second terminal station 12 incorporated with a second multiplex part 22 for performing transmission and reception with the first terminal station 11, a monitoring means 30 is provided inside the first terminal station 11, signal accuracy is monitored for reception signals received from the first terminal station 11 in the second terminal station 12, sub-signal information is extracted by the monitoring means 30 from input signals Sin incorporated with the information of the signal accuracy as the sub-signal information and inputted from the second terminal station 12 to the first terminal station 11 and thus, the signal accuracy of the input signals Sin is monitored in the first terminal station 11 as well.