3 VMA Mode
3.1 Digital Demod Measurement
IQ Ref Spectrum
Available for all modulation formats except any FSK type.
IQ Ref Spectrum is the frequency spectrum of the IQ Ref Time trace data. The
demodulator produces the spectrum by windowing and FFT the IQ reference data. If
the reference filter is selected, the spectrum represents the signal after filtering.
Example
:DISP:DDEM:WIND:DATA RSP
Sets the first window data to IQ Ref Spectrum
FSK Meas Time
Available only when the demodulation format is any FSK type.
FSK Meas Time is the measured time data results for the input signal. There are 6
available formats for this trace data: I-Q, Constellation, Real, Imaginary, I-Eye and
Q-Eye. Normally this trace data is displayed with I-Q format.
Format name Description
I-Q Real part of data is shown on horizontal axis, imaginary part is shown on vertical axis, Independent
variable (X axis) is normal to display
Constellation Same as I-Q, but for data with symbols defined, only the symbol points are shown as dots with no
connecting lines
Real (I) Real part of data is shown on a linear Y axis
Imaginary (Q) Imaginary part of data is shown on linear Y axis
I-Eye Real part of data is shown with X axis segmented (generally into 2 symbol segments) and each segment
is overlaid to show signal crossings at symbol boundaries
Q-Eye Same as I-eye but imaginary part of data is shown
Example
:DISP:DDEM:WIND:DATA MTIM
Sets the first window data to FSK Meas Time
:DISP:DDEM:WIND:FORM CONS
Selects Constellation as the first window data format
FSK Ref Time
Available only when the demodulation format is any FSK type.
FSK Ref Time is the reconstructed ideal time waveform to compare FSK Meas Time
against. There are 6 available formats for this trace data: I-Q, Constellation, Real,
Imaginary, I-Eye and Q-Eye. Normally this trace data is displayed with I-Q format.
217 Vector Modulation Analyzer Mode User's &Programmer's Reference
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