User`s guide

314 Agilent X-Series Signal Generators User’s Guide

Real–Time Phase Noise Impairments (Option 432)

DAC Over–Range Conditions and Scaling

When using phase noise impairment, it is possible to create a DAC over–range condition, which

causes the signal generator to generate an error. To minimize this condition with the phase noise

impairment feature, the Agilent X- Series signal generator incorporates an automatic DAC over–range

protection feature that scales down the I/Q data. Because it can scale the data by more than what is

actually need, it typically decreases the dynamic range of the waveform. This is especially noticeable

when using a constant amplitude signal such as GSM.

For the Dual ARB Player, the automatic over–range protection can be turned off (on is the factory

default). The control for the Dual ARB DAC over–range protection feature is located in the key path

as shown in Figure 12- 3.

Figure 12-3 Dual ARB DAC Over–Range Protection Softkey Location

In the Dual ARB Player, to avoid excessive scaling or to just perform scaling manually, turn the

over–range protection off and use the Waveform Runtime Scaling softkey to eliminate DAC over–range

conditions.

When the automatic feature is disabled, the other options to eliminate a DAC over–range condition

are to reduce the f2 value, or the Lmid value, or both until the condition corrects itself.

For details on each key, use key help

as described on page 44.

When the DAC over–range protection is off,

eliminate over–range conditions by

decreasing the scaling value (see “Setting

Waveform Runtime Scaling” on page 197).

Default setting is On.

Turn off to manually control scaling while

using the phase noise impairment option.

Manually adjust the scaling using the

Waveform Runtime Scaling softkey

shown above.