Waveform searching system

In a waveform searching system for a sampling oscilloscope, in which the instantaneous level of a high-speed sawtooth signal generated by a trigger signal synchronized with an input analog signal and the instantaneous level of a properly attenuated or amplified X-axis sweep wave are compared with each other to generate a pulse in a case of coincidence therebetween, thereby to generate sampling pulses sequentially delayed after the trigger signal by a constant time;

• the input analog signal is sampled by the sampling pulses to produce sampled pulses;
• and the sampled pulses are displayed by the X-axis sweep signal on a CRT, the improvement comprising detecting means for producing a coincidence signal if a predetermined condition is detected where a waveform formed by respective peak values of the sampled pulses cross in a predetermined direction at a predetermined search level by a predetermined number;
• and control means operatively connected to the detection means for sequentially changing a time base range of the CRT determined by the inclination of the high-speed saw-tooth signal and the amplitude of the X-axis sweep voltage wave until the detecting means produces the coincidence signal, whereby the sampled pulses having the predetermined condition are automatically displayed on the CRT.