User manual

Mathematics
R&S
®
RTO
186User Manual 1316.0827.02 ─ 06
Source 1 / 2
Defines the signal source to be evaluated by the math function. Waveform 1 of each
channel waveform can be selected.
Note: If you require other signal sources not listed here, use the formula editor provided
in the "Advanced" tab. In Advanced mode, any waveform of any input channel can be
used as a source. See: chapter 6.2.2, "Advanced Expressions", on page 187.
Operator
Defines the type of operation to be performed on the selected signal sources. The fol-
lowing functions are available:
Note: If you require other operators not listed here, use the formula editor provided in the
"Advanced" tab. See: chapter 6.2.2, "Advanced Expressions", on page 187.
"+"
Adds up the sources
"-"
Subtracts source 2 from source 1.
"x"
Multiplies source 1 by source 2.
"|x|"
Determines the absolute value of the source.
"dx/dt"
Differentiates the source value with respect to the time value.
"log(x)"
Calculates the logarithm of the source value based on 10.
"ln(x)"
Calculates the natural logarithm of the source value (based on e).
"ld(x)"
Calculates the binary logarithm of the source value (logarithmus dualis,
based on 2).
"Rescale"
Rescales the source values by a factor a and an offset b: ax+b. See
also: "a / b" on page 186.
"FIR filter"
Finite impulse response filter - highpass or lowpass filter for a specified
cut-off frequency. See also: "FIR: Type, Cut-Off" on page 186.
"Mag(FFT(x))"
Determines the magnitude of the FFT for the source values.
Noise reject
In order to suppress noise effects during differentiation it can be useful not to consider
two directly neighboring points to calculate dx (x
n
-x
n-1
), but rather to skip a number of
samples inbetween and use a point a few samples further (e.g. x
n
-x
n-3
).
The number of samples shown here defines the number of neighboring samples that are
skipped for differentiation.
Only available for the "dx/dt" operator.
a / b
Defines the values for the "Rescale" function (ax+b).
"a"
is the factor the signal source is multiplied with
"b"
is the offset of the signal source on the y-axis
FIR: Type, Cut-Off
The Finite Impulse Response filter ("Operator" = FIR) is a Gauss filter that requires two
additional settings:
●
"Type": defines whether the FIR filter is a highpass or lowpass filter.
Mathematical Functions and Formulas