Reference; Problems With Single-Ended Measurements; Differential Measurements - Tektronix P6246 Mode D'emploi

Reference

This section contains important reference information about
differential measurements and how to increase the accuracy of your
measurements.

Problems with Single-Ended Measurements

While suitable in many applications, single-ended measurements can
present problems in the following situations:
H when the signal is not referenced to earth ground
H when connecting or disconnecting the probe ground distorts the
signal
H when connecting the signal reference to ground damages or
upsets the circuit

Differential Measurements

Devices designed to make differential measurements avoid the
problems posed by single-ended systems. These devices include a
variety of differential probes, differential amplifiers, and isolators.
The differential amplifier (Figure 6) is at the heart of any device or
system designed to make differential measurements. Ideally, the
differential amplifier rejects any voltage that is common to the
inputs and amplifies any difference between the inputs. Voltage that
is common to both inputs is often referred to as the Common-Mode
Voltage (V
Voltage (V
20
) and voltage that is different as the Differential-Mode
CM
).
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P6246 & P6247 Instructions