Model DMM7510 7½ Digit Graphical Sampling Multimeter Reference Manual
Section 2: General operation
DMM7510-901-01 Rev. B / May 2015
2-115
Frequency measurements
This section describes how you can set up frequency measurements from the front panel. Frequency
measurements are only applicable to voltage signals.
Frequency and period support fixed and autorange threshold ranging, with a range of 100 mV to
700 V. Ranges are scaled to RMS sine wave voltages.
When autorange is selected, there are two measurement phases, measure AC voltage and measure
frequency or period. When the AC voltage is measured, the amplitude is measured and the
appropriate range is selected to ensure 11 % to 110 % signal scaling. In the second phase, the
frequency or period is measured.
Frequency and period are specified for square wave inputs. The input signal must be more than 10%
of the AC voltage range. If the input is less than 20 mV and measured on the 100 mV range, the
frequency must be more than 10 Hz. For sine wave inputs, the input frequency must be more than
100 Hz.
You can set a zero crossing threshold trigger level. The level can be set from -700 V to 700 V. The
input signal is AC coupled to the zero crossing threshold level detection.
Threshold levels are scaled to 100 % peak of the selected range. For example, if the 1 V range is
selected and the threshold level is set to 0.5 V, the frequency or period counter counts for portions of
the input at more than 0.5 V, or 0.353 V
rms
for a sine wave.
To use the threshold level, you must set the threshold range to a set value (it cannot be set to
autorange).
Do not apply more than 1000 V
peak
between INPUT HI and LO. Failure to observe this caution may
result in instrument damage.
Frequency measure connections
Figure 78: Front panel connections: Frequency measurement
