User manual

Mathematics
R&S
®
RTO
192User Manual 1316.0827.02 ─ 06
Table 6-10: Filter and power ("More" keys)
Icon Description Usage/Comment, FormulaEditor expression
Electric power Electric power is calculated from voltage, based on
measurement impedance (see "Measurement impe-
dance" on page 40)
elecpower(x) = U
2
/R
FIR Finite impulse response filter FIR(highpass,x,y) or FIR(lowpass,x,y)
with: x = source, y = cut-off frequency
Example: FIR(lowpass,Ch1Wfm1,2.5e+007)
See also: "FIR: Type, Cut-Off" on page 186.
parameter for FIR filter highpass / lowpass
6.3 FFT Analysis
6.3.1 Fundamentals of FFT Analysis
During FFT analysis, a signal in the time domain is converted to a spectrum of frequen-
cies. As a result, either the magnitude or the phase of the determined frequencies can
be displayed. FFT analysis can be restricted to an extract of the original time base, and
the results display can be restricted to a specified frequency range.
t[s]
FFT
f[Hz]
Frames
In order to convert the time domain signal to a frequency spectrum, an FFT (Fast Fourier
Transformation) unit is used which converts a vector of input values into a discrete spec-
trum of frequencies.
FFT Analysis