Pulse Building does not directly control the Baseband Filter and Modulator Attenuation properties for the source. The source firmware has been optimized to set the modulator attenuator value based on the waveform RMS voltage. You may override this feature by manually setting the modulator attenuator value in the source from the front panel or with SCPI commands.
There are 40 MHz low pass filters in the I/Q signal path before the I/Q modulator. The filters help reduce broadband noise and spurs for signals with an 80 MHz or less RF bandwidth. This parameter should be set to Through when using external I/Q inputs and signals that have RF bandwidths greater than 80 MHz. These filters have no affect on the PSG Options 015, 016, H16, or HBQ Wide Band signal path. The baseband filter value is used by Generate Correction. The baseband filter reset value is System configuration specific:
PSG/ESG Internal Arb - 40 MHz
PSG/ESG External I/Q - Through
PSG Option 015, 016, H16, HBQ - Disabled
Adjust the signal generator's modulator attenuation level to optimize signal performance at the RF output. When ALC Enable is on, the RF output amplitude will not change while the attenuator value is changed until the ALC range is exceeded. The modulator attenuator is used by Generate Correction.
The range of values is 0 to 40 dB. The attenuation can be set in 0.01 dB increments. Changes to the modulator attenuation levels can affect the corrections applied to the downloaded signal. If this parameter is changed for a pattern definition, clear the calibration data from the signal generator using the Download menu's Clear Calibration Data menu selection. If an I/Q calibration was done at one modulator attenuator level and the level is changed, the I/Q calibration will automatically be initiated.
The default value is system configuration specific:
ESG/PSG Internal Arb - 12 dB
ESG/PSG External Arb - 4 dB
PSG Option 015, 016, H16, HBQ - Disabled