TIME Measurement

1.2.2

TIME Measurement

Time measurements, as the name implies, utilize the internal clock oscillator of the instrument to

provide precise predetermined pulses of such a frequency that, when fed to the totalizer and display

section, indicate actual elapsed time (i.e. seconds, milliseconds, microseconds, etc.). Precise starting

and stopping of the counting process enables accurate measurements of the time for an event or for

the period of repetitive events. The method used for start-stop control depends on the application and

may be accomplished in a number of ways as discussed below.

When measuring periods of repetitive waveforms or time intervals between low level signals, the

amplified input (Input A) should be used. This input has selectable gain and provides for operation

over a wide range of input signal levels.

When using Input A, the counter will start and stop the count cycle on consecutive waveforms or after

a selected number of waveforms. The figure below pictorializes what is taking place.

Input Signal

Time Increments

Eight pulses transpired during one cycle of Input A or the time required for one cycle was eighty

microseconds. When the input waveform is sinusoidal in nature, the measurement mode is usually

referred to as a Period Measurement.

The accuracy of time readings may be improved by averaging a number of readings. For this reason,

most counters have multiple period selection (i.e. 1, 10 and 100 periods) or where preset

thumbswitches are included, any number of periods may be selected depending upon the setting on

the thumbswitches. When multiple periods are used, it must be remembered to divide the resultant

readings by the number of periods selected to arrive at the actual time for one period (period average).

1-17