Interpreting Meter Specifications; Number Of Digits And Overrange; Sensitivity - Agilent Technologies 34420A User Manual

Chapter 8

Interpreting Meter Specifications

Interpreting Meter Specifications
This section is provided to give you a better understanding of the
terminology used and will help you interpret the meter's specifications.

Number of Digits and Overrange

The number of digits specification is the most fundamental, and
sometimes, the most confusing characteristic of a meter. The number of
digits is equal to the maximum number of "9's" the meter can measure or
display. This indicates the number of full digits. Most meters have the
ability to overrange and add a partial or "1/2" digit.
For example, the 34420A can measure 9.999999 Vdc on
the 10 V range. This represents seven full digits of resolution. The
meter can also overrange on the 10 V range and measure up to a
maximum of 12.000000 V. This corresponds to a 7 1/2-digit measurement
with 20% overrange capability.

Sensitivity

Sensitivity is the minimum level that the meter can detect for a given
measurement. Sensitivity defines the ability of the meter to respond to
small changes in the input level. For example, suppose you are
monitoring a 1 mV signal and you want to adjust the level to
within ±1 V. To be able to respond to an adjustment this small, this
measurement would require a meter with a sensitivity of at least 1 V.
You could use a 6 1/2-digit meter if it has a 1 Vdc or smaller range. You
could also use a 4 1/2-digit meter with a 10 mV range.
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