YOKOGAWA ScopeCorder DL850E - FFT Function - User-Defined

App-7
IM DL850E-01EN
Pulse Width Computation
The signal is converted to binary values according to the preset threshold levels, and the time of the pulse width
is plotted as the Y-axis value for that interval.
You can select one of the following interval.
PWHH
From a rising edge to the next rising edge.
PWHL From a rising edge to the next falling edge.
PWLH From a falling edge to the next rising edge.
PWLL From a falling edge to the next falling edge.
PWXX From a rising or falling edge to the next rising or falling edge.
FV
Inverse of PWHH
Example for PWHH
Waveform to
be computed
t1
t1
t2
t2
t3
t3
Computed
result
Upper
threshold
level
Lower
threshold
level
FFT Function - user-defined
Each frequency component G of a linear spectrum is represented by G = R + jI, where R is the real part and I is
the imaginary part.
Linear Spectrum
The linear spectrum can be directly determined with the FFT. Through this spectrum, the magnitude and phase
of each frequency component included in the measured waveform can be found. The power spectrum and cross
spectrum can also be determined from the linear spectrums of one or two signals.
Because the FFT is a complex function, the linear spectrum produces the real part and imaginary part of the
frequency components. The magnitude and phase of the linear spectrum can also be determined from this
result.
The DL850E/DL850EV can determine the following spectrums.
Item Expression Computation
Real part LS-REAL R
Imaginary part LS-IMAG I
Magnitude LS-MAG
(R
2
+I
2
)
Log magnitude
LS-LOGMAG 20 × log
(R
2
+I
2
)
Phase LS-PHASE tan
−1
(I/R)
Log magnitude reference (0 dB): 1 Vpeak
Appendix