User manual

Acquisition and Setup
R&S
®
RTO
34User Manual 1316.0827.02 ─ 06
Decimation
Decimation reduces the data stream of the ADC to a stream of waveform points with
lower sample rate and a less precise time resolution. The R&S RTO uses decimation, if
the waveform "Sample rate" is less than the "ADC sample rate". In this case, enhance-
ment settings are ignored. The decimation mode ist waveform-specific, you can select
another mode for each waveform.
There are different methods to define the recorded waveform point out of a number of n
sample points:
"Sample"
One of n samples in a sample interval of the ADC is recorded as wave-
form point, the other samples are discarded. The time between the two
adjacent waveform points is exactly the resolution. Very short glitches
might remain undiscovered by this method.
"Peak detect"
The minimum and the maximum of n samples in a sample interval are
recorded as waveform points, the other samples are discarded.
"High res"
The average of n sample points is recorded as one waveform sample.
Averaging reduces the noise, the result is a more precise waveform with
higher vertical resolution.
"RMS"
The waveform point is the root mean square of n sample values. Thus,
the RMS value reflects the instantaneous power.
SCPI command:
CHANnel<m>[:WAVeform<n>]:TYPE on page 434
Wfm Arithmetic
Waveform arithmetic builds the resulting waveform from several consecutive acquisitions
of the signal. This setting is waveform-specific. The arithmetic works with enhanced and
decimated waveforms.
The methods are:
"Off"
The data of only one acquisition is recorded according to the decimation
settings. In effect, no waveform arithmetic are processed.
"Envelope"
Detects the minimum and maximum values in an sample interval over
a number of acquisitions. Each acquisition is done in the "Peak
detect" decimation mode, and the most extreme values for all acquisi-
tions build the envelope. The resulting diagram shows two envelope
waveforms: the minimums (floor) and maximums (roof).
The envelope is built until the restart criterion is reached, see "Reset
mode" on page 35.
"Average"
The average is calculated from the data of the current acquisition and
a number of acquisitions before. The method reduces random noise
and other heterodyne signals. It requires a stable, triggered and peri-
odic signal for correct function.
The number of acquisitions for average calculation is defined with
"Average count", and the "Reset mode" defines the restart condition.
SCPI command:
CHANnel<m>[:WAVeform<n>]:ARIThmetics on page 434
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Reference for Acquisition and Setup