A new coherent sampling system with a triggered time interpolation

Equivalent-time sampling is a well-known technique to capture repetitive si gnals at finer time intervals than a sampling clock cycle time and it is wi dely used to implement waveform measurement with high time resolution. Ther e are three techniques for implementing its time base (i.e., sequential sam pling, random sampling and coherent sampling), and they have their respecti ve advantages and disadvantages. In this paper we propose a new coherent sa mpling system which incorporates a pretrigger and time jitter reduction fun ction for a fluctuating input signal which a random sampling system has, wh ile maintaining the waveform recording efficiency of a conventional coheren t sampling system. We also report on a technique for measuring a reference trigger time period accurately which is necessary to implement the proposed sampling system, and show its effectiveness through numerical calculations of its data recording time.