7451A/7461A/7461P Digital Multimeter Operation Manual
4.2.1 Measurement Functions
4-16
9. Frequency measurement (FREQ)
Press .
The frequency in the ACV measurement function is displayed.
The DC component of the input signal is cut by using the AC coupling and the frequency is measured
at the zero-cross point.
Measurement method:
Reciprocal
Input voltage range:
100 mVrms to 700 Vrms and 5% or more of the range (Sinusoidal
wave)
The range does not mean the frequency range but the input voltage
range.
In the 100 mV range, the input voltage from 120 mV to about 1.2 V can
be measured without the “over” display.
Gate time
Figure 4-12 Frequency Measurement (FREQ)
Use a suitable measurement range for the input voltage.
If the input voltage exceeds the measurement range, the measurement is performed but the accuracy
of the measured value may fail of the specifications.
Sampling rate
Gate time
Measurement
frequency range
Maximum
measurement
period
Maximum display
7461A/61P
7451A
SLOW
1000 ms
1 Hz to 300 kHz
2.2 s
9999999
999999
MED
100 ms
10 Hz to 300 kHz
220 ms
999999
99999
FAST
10 ms 100 Hz to 300 kHz
22 ms
99999
9999
If the input signal cannot be detected because the period of the input signal is longer than the gate
time, 0 Hz is displayed.
Table 4-13 Maximum Allowable Applied Voltage (FREQ)
Between V and COM terminals
1000 Vpeak, 700 Vrms, 2.2
10
7
VHz
Between COM terminal and chassis
500 V
FREQ
1000Vpeak
AC700Vrms or less
2.2
10
7
VHz
500V or less
