Acquisition and Waveform Setup
R&S
®
RTM20xx
12
User Manual 1317.4726.02 ─ 01
Fig. 2-1: Input range and resolution of the ADC
2.1.1.3
Bandwidth
For analog applications the highest signal frequency determines the required oscillo-
scope bandwidth. As a rule of thumb, the oscilloscope bandwidth should be 3 times higher
than the maximum frequency included in the analog test signal to measure the amplitude
with high accuracy.
Most test signals are more complex than a simple sine wave and include several spectral
components. A digital signal, for example, is built up of several odd harmonics. As a rule
of thumb, for digital signals the oscilloscope bandwidth should be 5 times higher than the
clock frequency to be measured.
The oscilloscope is not a stand-alone system. You need a probe to measure the signal
of interest, and the probe has a limited bandwidth, too. The combination of oscilloscope
and probe creates a
system bandwidth
. To maintain the oscilloscope bandwidth, that is,
to reduce the effect of the probe on the system bandwidth, the probe bandwidth should
exceed the bandwidth of the oscilloscope, the recommended factor is 1.5 x oscilloscope
bandwidth.
See also:
chapter 2.1.4.1, "Voltage Probes"
2.1.2 Sampling and Acquisition
The vertical system of a digital oscilloscope conditions the test signal in a way that the
following A/D Converter (ADC) can transform the measured voltage into digital data.
Basics
