Keysight Truevolt Series Operating And Service Manual page 57

Features and Functions
For the 34465A/70A , the Aperture NPLC softkey is selected by default. Use the up/down arrow keys
l
to specify integration time in power-line cycles (PLCs) to use for the measurement . 1, 10, and 100 PLC
provide normal mode (line frequency noise) rejection. Selecting 100 PLC provides the best noise rejec-
tion and resolution, but the slowest measurements:
To set integration time precisely, instead of using PLCs, press Aperture Time and use the left/right
up/down arrow keys to specify integration time in seconds. For Aperture Time , you can specify from
200 µs (20 µs with the DIG option) to 1 s integration time (2 µs resolution):
Step 4: Press Range to select a range for the measurement. You can also use the [+] , [-] , and [Range]
keys on the front panel to select the range. ( Auto (autorange) automatically selects the range for the meas-
urement based on the input. Autoranging is convenient, but it results in slower measurements than using
a manual range. Autoranging goes up a range at 120% of the present range, and down a range below 10%
of the present range.
Step 5: Auto Zero : Autozero provides the most accurate measurements, but requires additional time to
perform the zero measurement.With autozero enabled (On), the DMM internally measures the offset fol-
lowing each measurement. It then subtracts that measurement from the preceding reading. This prevents
offset voltages present on the DMM's input circuitry from affecting measurement accuracy. With autozero
disabled (Off), the DMM measures the offset once and subtracts the offset from all subsequent meas-
urements. The DMM takes a new offset measurement each time you change the function, range, or integ-
ration time. ( There is no autozero setting for 4-wire measurements.)
Step 6: Specify the input impedance to the test leads ( Input Z ). This specifies the measurement terminal
input impedance, which is either Auto or 10 MΩ. The Auto mode selects high impedance (HighZ) for the
100 mV, 1 V and 10 V ranges, and 10 MΩ for the 100 V and 1000 V ranges. In most situations, 10 MΩ is
high enough to not load most circuits, but low enough to make readings stable for high impedance cir-
cuits. It also leads to readings with less noise than the HighZ option, which is included for situations where
the 10 MΩ load is significant.
58 Keysight True volt Series Operating and Service Guide