PURPOSE: To send the data of plural stations to one station simultaneously by demultiplexing a multiplexed data into a data from a 1st point and a data from a 2nd point and decoding the demultiplexed data coded from the 1st point and the 2nd point.
CONSTITUTION: The data from a 1st point is generated by a 1st coding data transmission circuit 5 and sent to a 3rd point and the data coded from a 2nd point is generated by a 2nd coding data transmission circuit 6 and sent to the 3rd point. The data coded by the 1st and 2nd points 1, 2 is multiplexed and sent to a 4th point 4. Then the multiplexed data at the 4th point 4 is demultiplexed from the data coded from the 1st point 1 and the data coded from the 2nd point 2 at a demultiplex and decoding circuit 8 and the data are decoded. Thus, the data of plural stations are sent to one station and displayed thereon.