HP E42 manual Model 5328A Theory of Operation Ratio, Time Interval

Model 5328A

Theory of Operation

4-18.Ratio

4-19. By replacing the time base with a second input of frequency, f2; the same configuration as in Figure 4-2 can be used to measure the ratio f2/f. For higher resolution the signal at fre- quency f can be divided in decade steps in a manner identical to multiple period averaging.

4-20.Time Interval

4-21. Figure 4-3shows the configuration for the measurement of time between two events or time interval. The main gate is now opened by the START input and closed by the STOP. The decade divider output is again counted and the display shows the elapsed time between START and STOP signals. The measurement of time interval is considered in more detail in para- graph 4-22.

4-22. TIME INTERVAL, RESOLUTION, AND AVERAGING TECHNIQUES

4-23. Time interval, the measurement of the time between two events, is shown in the block diagram shown in Figure 4-3.The main gate is now controlled by two independent inputs, the START input opening the gate and the STOP input closing it. Clock pulses are accumulated for START and STOP. This is shown in Figure 4-4.

Figure 4-3.Basic Elements of a Time Interval Counter

Figure 4-4.Clock Pulses

NOTE

In a time interval measurement, clock pulses are accumulated for the duration the main gate is open, The gate is opened by one event, START and closed by the other, STOP.

4-3