Patent ID: 7508844

Claim:
A frame signal waveform observation apparatus comprising: a trigger signal generating apparatus comprising: a frame synchronous circuit which receives a frame signal having a predetermined bit rate and outputs a synchronous signal in synchronism with an input timing of leading data of the frame signal, a position information output circuit which receives the synchronous signal output by the frame synchronous circuit and outputs position information indicating an input bit position of the frame signal, a position designator which designates an arbitrary bit position of the frame signal, and a trigger signal generating circuit which outputs a trigger signal at a timing when the position information output by the position information output circuit is coincident with the arbitrary bit position designated by the position designator; and a sampling oscilloscope which receives the trigger signal output from the trigger signal generating circuit of the trigger signal generating apparatus, samples the frame signal with a trigger signal input timing as a reference timing, and acquires and displays waveform information in a neighborhood of the arbitrary bit position designated by the position designator, wherein the sampling oscilloscope has a function of acquiring the waveform information in the neighborhood of designated arbitrary bit position for a plurality of times and averaging them to thereby display averaged waveform information in the neighborhood of the designated arbitrary bit position in such a manner that a phase variation dependent on a bit pattern of the frame signal can be measured while suppressing the phase variation of random noise type of the frame signal.