Technical data

Digital Modulation Commands 10
Agilent N8211A/N8212A Performance Upconverter Synthetic Instrument Module, 250 kHz to 20 / 40 GHz 323
[:SOURce]:DM:IQADjustment:SKEW?
Changes the input skew which is a time delay difference between the I and Q signals. Equal
and opposite skew is applied to both I and Q and affects the RF Output and I/Q output paths
simultaneously. A positive value delays the I signal relative to the Q signal, and a negative
value delays the Q signal relative to the I signal.
If the internal I/Q correction path is set to RF or BB the I/Q signals are already optimized
and adjusting I/Q skew would add an impairment to the signals. If the internal I/Q
correction path is set to Off, then adjusting the I/Q skew could improve the I/Q signals. The
I/Q skew adjustment cannot be performed on the MSK, FSK, and C4FM constant envelope
modulations.
I/Q skew adjustments are preserved when the instrument state is saved. I/Q skew
adjustments are also preserved when instrument settings are changed. If the
N8211A/N8212A is calibrated, the skew adjustments are added to the calibration value
used for the given N8211A/N8212A state. If the N8211A/N8212A is uncalibrated, the skew
adjustments are re-applied directly.
Using I/Q skew while playing a user FIR file greater than 32 symbols will generate an error.
The variable <val> is expressed in seconds. Range limits are determined by the modulation
configuration but is limited to a maximum of ±2 seconds.
Example
:DM:IQAD:SKEW .5
The example sets the time delay difference between the I and Q signals to 500 mS.
*RST +0.00000000E+000
:IQADjustment:SKEW:Path
Supported N8212A
[:SOURce]:DM:IQADjustment:SKEW:PATH RF BB
[:SOURce]:DM:IQADjustment:SKEW?
Selects either the RF or BB (baseband) path as the path to which skew timing corrections
will be applied. If there are no factory I/Q timing skew corrections data, then adjusting the
I/Q timing skew for the selected path may improve the error vector magnitude (EVM) of the
signal. Refer to the “:IQADjustment:SKEW" on page 322 for more information.
If internal I/Q corrections are available for the RF or external I/Q output (BB) path then the
I/Q signals are already optimized and adjusting I/Q skew for either path would add an
impairment to the signal.