N5161A/62A/81A/82A/83A MXG Signal Generators User's Guide

Basic Digital Operation (Option 651/652/654)I/Q AdjustmentsI/Q AdjustmentsUse the I/Q Adjustments to compensate for or add impairments to the I/Q signal.I/Q > I/Q AdjustmentsAdjusts the I signal amplitude relative to the Qsignal amplitude. Use this as an internalimpairment, or to compensate for differences insignal path loss that occur due to path irregularitiesin the external I and Q output cabling.The DC offset values are calibrated relative tothe RMS waveform voltage being played out ofthe ARB. See page 152.This feature allows adjustment of the absolute phase of the internal I/Q channel byrotating both I and Q, thus adjusting the relative phase of the RF carrier. Foroption 012, this is the only way to adjust the RF phase for a unit with an externalLO.Available onlywith Option 1ELThe I/Q Attenuator softkey affects the I/Q signal tothe RF Output and the External I/Q Outputs.This softkey is active when the I/Q optimized path isset to Ext I/Q Output and a digital modulationpersonality is on. This attenuation is also adjustableusing the Mod Attenuator key located in the ArbSetup menus in each personality. This adjustment isnot affected by the I/Q Adjustments On/Off key.Offsets the phase of the Q signalrelative to the phase of the I signal.The baseband quadratureadjustment key is calibrated in unitsof degrees. The external inputquadrature adjustment is notcalibrated.The function provided by this key isnot the same as the functionprovided by the I/Q Skew key.Note: The I/Q signal will bescaled down by 0.7071 for allphase offsets except 0. Use-360 or +360, if it is desirableto maintain a constant powerlevel with the ALC off whileadjusting the I/Q phase.Skew is typically used either to createimpairments, or to reduce error vectors on largebandwidth signals.Provides a relative time delay correction betweenthe I and Q signals. The different signal pathstraveled by the I and Q signals result in time delaydifferences that show up as an EVM error in largebandwidth modulated signals.Adding an equal and opposite time delay (skew) inthe I/Q signals during baseband generationeliminates the time delay error, correcting for anydelays in signals that are generated in the internalbaseband generator.When Auto mode is selected, the signal generatorautomatically optimizes I/Q attenuation for thecurrent conditions. When the Manual mode isselected, I/Q Attenuation is the active function. Thevalue you enter sets the attenuation level of the I/Qsignal.Available only when awaveform is playing.SCPI Commands (Refer to the commands for eachpersonality):[:SOURce]:RADio::IQ:MODulation:ATTenOffsets are typically used to either reduce carrier leakage, or to create an impairment that simulates carrier leakage.Common Mode I/Q Offset RangeThis changes the adjustment range of the Common Mode I/Q Offset from Coarse (Default) to fine or vice versa. The Coarserange corresponds to the default value of ± 2.5V. The Fine range corresponds to a value of ± 100 mV.Common Mode I/Q OffsetThis adjusts the DC offset of both I and Q signals simultaneously.Diff Mode I OffsetThis adjusts the DC offset level of the I and I–bar output signal. I and I–bar cannot be adjusted independently.Diff Mode Q OffsetThis adjusts the DC offset level of the I and I–bar output signal. I and I–bar cannot be adjusted independently.Changes the absolute phase ofboth the I and Q signals withrespect to triggers and markers.Positive values add delay andnegative values advance thesignals. This value affects boththe baseband signal modulatedonto the RF and the externaloutput signals (I and Q). Thissetting cannot be used withconstant envelope modulationand it does not affect external Iand Q inputs.Agilent N5161A/62A/81A/82A/83A MXG Signal Generators User’s Guide 201