Measurement Fundamentals
This section explains how the 34970A makes measurements and
discusses the most common sources of error related to these measurements.

The Internal DMM

The internal DMM provides a universal input front-end for measuring
a variety of transducer types without the need for additional external
signal conditioning. The internal DMM includes signal conditioning,
amplification (or attenuation), and a high resolution (up to 22 bits)
analog-to-digital converter. A simplified diagram of the internal DMM is
shown below. For complete details on the operation of the internal DMM,
refer to “Measurement Input” on page 60.
The internal DMM can directly make the following types of measurements.
Each of these measurements is described in the following sections of
this chapter.
•Temperature (thermocouple, RTD, and thermistor)
•Voltage (dc and ac up to 300V)
•Resistance (2-wire and 4-wire up to 100 MΩ)
•Current (dc and ac up to 1A)
•Frequency and Period (up to 300 kHz)
= Optical Isolators
Analog
Input
Signal
Signal
Conditioning Amp Main
Processor
To / From
Earth
Referenced
Section
Analog to
Digital
Converter
8
Chapter 8 Tutorial
Measurement Fundamentals
343