To select a coordinate system that displays unwrapped phase along the Y-axis, send CALC:FORM UPH.
The displayed phase is referenced to the lowest measured frequency. There is no phase wrapping.
To select a coordinate system that displays a Nyquist diagram (imaginary numbers along the Y-axis and
real numbers along the X-axis), send CALC:FORM NYQ. It is not valid for RPM Profiles (CALC:FEED
‘XRPM:PROF’) and orbit diagrams (CALC:FEED ‘XVOL:VOLT’).
To select a coordinate system that displays a polar diagram (magnitude and phase displayed as a rotating
vector), send CALC:FORM POL. It is not valid for RPM profiles (CALC:FEED ‘XRPM:PROF’).
To select a coordinate system that displays time on the Y-axis and frequency on the X-axis, send
CALC:FORM GDEL. Group delay is defined as the negative of the derivative of the phase response. It
shows phase delays in time rather than degrees of phase shift.
tg = –dφ/dω
Where
φ = phase response in radians
w = frequency in radians/second
The analyzer uses a smoothing aperture to define the resolution of the group delay display. To specify the
smoothing aperture send the CALC:GDAPerture:APERture command. Group delay is not valid for time
data (CALC:FEED ‘XTIM:VOLT’). It is normally used in frequency response measurements.
The trace specifier, CALCulate [1|2|3|4], determines which trace you are selecting. Omit the specifier or
send 1 for trace A, 2 for trace B, 3 for trace C, or 4 for trace D. Use the query, CALC:FORMat?, to
determine the current coordinate system for the selected trace.
To query display data—that is, the analyzer has applied a coordinate system to the measurement
data—use the CALC:DATA command. To access “raw” measurement data—only math operations have
been performed on the data—use the TRAC:DATA command.
CALCulate
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