Agilent Technologies 34410A User Manual page 118

4 Measurement Tutorial
Make sure the multimeter and the ac source are connected to the same
electrical outlet whenever possible. You should also minimize the area of
any ground loops that cannot be avoided. A high–impedance source is
more susceptible to noise pickup than a low–impedance source. You can
reduce the high–frequency impedance of a source by placing a capacitor in
parallel with the multimeter's input terminals. You may have to
experiment to determine the correct capacitor value for your application.
Most extraneous noise is not correlated with the input signal. You can
determine the error as shown below.
Correlated noise, while rare, is especially detrimental. Correlated noise
will always add directly to the input signal. Measuring a low–level signal
with the same frequency as the local power line is a common situation
that is prone to this error.
118 34410A/11A User's Guide