Chapter 2  Operating Your Universal Counter
Using CHANNEL 1 and CHANNEL 2 Input Conditioning Keys
2-46 Operating Guide
2
DEFINITION OF SENSITIVITY. Sensitivity is the lowest amplitude 
signal at a particular frequency that the Counter will count. The amplifier 
gain and the voltage difference between the input trigger hysteresis levels 
determine the Counter’s sensitivity. Sensitivity is specified with the 
trigger level set at a value equal to the midpoint of the input signal. 
The input waveform must cross both the upper and lower hysteresis levels 
to generate a count as shown in the following figure.
Signal crosses through both hysteresis levels to effect a count.
If the signal peaks do not exceed beyond both hysteresis limits, the input 
signal will not generate a count. For example, the peak-to-peak amplitude 
is insufficient, or trigger level is set above or below the midpoint of the 
input signal as shown in the following figures.
Signal will not generate a count because the peak-to-peak amplitude of 
the signal is insufficient.
Upper
Hysteresis
Level
Peak-to-Peak
Sensitivity
Trigger
Level
Lower
Hysteresis
Level
Input signal
to Counter
Trigger
Level
Upper
Hysteresis
Level
Peak-to-Peak
Sensitivity
Lower
Hysteresis
Level
Input signal
to Counter