User`s guide

142 Agilent X-Series Signal Generators User’s Guide
Basic Digital Operation—No BBG Option Installed
I/Q Modulation
I/Q Modulation
The following factors contribute to the error vector magnitude:
• Differences in amplitude, phase, and delay between the I and Q channels
•DC offsets
The I/Q menu provides adjustments and calibration to compensate for some of the differences in the
I and Q signals or to add impairments. See I/Q Modulation on page 204 for additional information.
See also “Modulating the Carrier Signal” on page 59.
Figure 7-1 I/Q Display and Softkeys
This panel displays the external
I/Q signal routing.
This panel displays the current status and settings
of the I/Q adjustments. Grey text indicates I/Q
adjustments are off.
For details on each key, use key help
as described on page 44.
Offsets the phase of the Q signal
relative to the phase of the I signal.
The quadrature adjustment key is in
units of degrees. This adjustment is
not calibrated.
Sets the dc
offset
Toggles between DC, User, and Full IQ calibration types.
DC: Calibrates I/Q offset, gain and quadrature error for a single
frequency at the current signal generator settings.
This calibration requires that the I/Q be on, the optimized path be set to
RF Out, and the source be set to the internal baseband generator.
Changing any instrument setting except for I/Q adjustments after
performing a DC calibration voids the DC calibration and causes the
signal generator to revert to the factory supplied calibration data.
User: Calibrates I/Q offset, gain, and quadrature error for all signal
generator settings over a range of frequencies that you define.
Full: Calibrates I/Q offset, gain, and quadrature error for all settings
over the full frequency range of the signal generator.
Starts the I/Q calibration
routine for the selected
frequency range. (Use the
Calibration Type softkey to
select the frequency range.)
You can abort the
calibration by pressing the
Abort Cal softkey or the
Local Cancel/(Esc) hardkey.
If you abort the calibration,
the previous calibration data
is restored.
This calibration should be
run when the ambient
temperature has varied by
at least +/-5 degrees
Celsius from the ambient
temperature at which the
previous calibration was
run.