PURPOSE: To perform the reliable observation of data by obtaining a cursor signal superposed on a picture signal by a 1st mixing device, displaying it at an optional position on a display screen and externally synchronizing a waveform observation device with the cursor signal by a 2nd mixing device so that the picture signal waveform that a measurer desires to watch can be observed.

CONSTITUTION: The picture signal 3 is inputted in the 1st mixing device 10 and displayed on the display screen 20 as an image 21, then a vertical synchronizing signal 4a and a horizontal synchronizing signal 4b are inputted in monostable-multivibrator circuits 6 and 8 from an external equipment. The respective circuits 6 and 8 output an optional vertical and horizontal cursor position signals 12 and 13 on the display screen 21 respectively, and monostable-multivibrator circuits 7 and 9 which receive the respective signals 12 and 13 output vertical and horizontal cursor signals 14 and 15 in synchronism with the signals 12 and 13. The signals 14 and 15 are inputted in the 1st and the 2nd mixing devices 10 and 11 where the signals are inputted and the respective signals 14 and 15 are superposed on the picture signal by the mixing device 10 and outputted to a display device 1. The signals 14 and 15 are mixed by the mixing device 11 and outputted to a waveform observation device 2.