User manual

Acquisition and Setup
R&S
®
RTO
20User Manual 1316.0827.02 ─ 06
Two parameters set the position of the horizontal acquisition window in relation to the
trigger point: reference point (time reference) and trigger offset. With these parameters
you choose the part of the waveform you want to see: around the trigger, before, or after
the trigger.
2.1.4 Probes
A probe connects the signal source (DUT) to the oscilloscope, and delivers the signal to
be measured. It is the essential first link in the measurement chain.
An ideal probe fulfills the following requirements:
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Safe and reliable contacts
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Infinite bandwidth
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The probe should not load the signal source and thus impact the circuit operation.
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The connection should not introduce or suppress signal components (hum, noise,
filter) and thus degrade or distort the transferred signal.
In reality, the probe can never be an ideal one, it always affects the signal transmission
and the signal source, and thus the measured signal. It depends on the frequency to be
measured and on the signal source to determine the acceptable loading, and to determine
which kind of probe delivers good results.
The solution depends on the quantity to be measured with respect to:
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Signal type: voltage, current, power, pressure, optical, etc.
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Signal amplitude: The oscilloscope itself can only display voltages in a limited range.
Most probes can adjust the dynamic range to amplitudes from a few mV to 10 V.
Smaller or much larger signals require specialized equipment.
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Signal frequency: High frequencies require advanced equipment in order to get cor-
rect results.
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Source characteristic: The source impedance is the decisive factor when choosing
the suitable connection.
Basics