292 Keysight InfiniiVision 3000T X-Series Oscilloscopes User's Guide
17 Digital Voltmeter and Counter
 
2 Press Features; then, select Counter.
3 Press Features again to enable the counter.
4 Press the Source softkey and turn the Entry knob to select the analog channel or 
Trigger Qualified Event signal to make counter measurements on.
With the Trigger Qualified Event source (available when the trigger mode is not 
Edge), you can see how often trigger events are detected. This can be more 
often than when triggers actually occur, due to the oscilloscope's acquisition 
time or update rate capabilities. The TRIG OUT signal shows when triggers 
actually occur. Remember that the oscilloscope's trigger circuitry does not 
re-arm until the holdoff time occurs and that the minimum holdoff time is 40 ns; 
therefore, the maximum trigger qualified event frequency that can be counted 
is 25 MHz.
The selected channel does not have to be on (displaying a waveform) in order 
for counter measurements to be made.
5 Press Auto Setup Threshold softkey to have the oscilloscope automatically 
determine and set the threshold voltage (trigger) level for the selected analog 
channel source.
6 Press the Measure softkey and turn the Entry knob to select what the counter 
measures:
• Frequency — the cycles per second (Hz, kHz, or MHz) of the signal.
• Period — the time periods of the signal's cycles.
• Totalize — the count of edge events on the signal.
Frequency and
Period Counter
For frequency and period measurements, press the # of Digits softkey to specify the 
resolution of the counter. You can choose from 3 to 8 digit resolutions.
Higher resolutions require longer gate times, which cause the measurement times 
to be longer as well.
Totalize Counter For (edge event) totalize measurements, press the Clear Count softkey to zero the 
edge event counter.
Press the Totalize softkey to open the Counter Totalize Menu where you can: