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

Real–Time Phase Noise Impairments (Option 432)DAC Over–Range Conditions and ScalingDAC Over–Range Conditions and ScalingWhen using phase noise impairment, it is possible to create a DAC over–range condition, whichcauses the Agilent MXG to generate an error. To minimize this condition with the phase noiseimpairment feature, the Agilent MXG incorporates an automatic DAC over–range protection featurethat scales down the I/Q data. Because it can scale the data by more than what is actually need, ittypically decreases the dynamic range of the waveform. This is especially noticeable when using aconstant amplitude signal such as GSM.For the Dual ARB Player, the automatic over–range protection can be turned off (on is the factorydefault). The control for the Dual ARB DAC over–range protection feature is located in the key pathas shown in Figure 10- 3.Figure 10-3 Dual ARB DAC Over–Range Protection Softkey LocationWhen the DAC over–range protection is off,eliminate over–range conditions bydecreasing the scaling value (see “SettingWaveform Runtime Scaling” on page 191).Default setting is On.For details on each key, use key helpas described on page 42.Turn off to manually control scaling whileusing the phase noise impairment option.Manually adjust the scaling using theWaveform Runtime Scaling softkeyshown above.In the Dual ARB Player, to avoid excessive scaling or to just perform scaling manually, turn theover–range protection off and use the Waveform Runtime Scaling softkey to eliminate DAC over–rangeconditions.When the automatic feature is disabled, the other options to eliminate a DAC over–range conditionare to reduce the f2 value, or the Lmid value, or both until the condition corrects itself.262 Agilent N5161A/62A/81A/82A/83A MXG Signal Generators User’s Guide