Attenuator Hold

The attenuator hold feature allows you to adjust the output level in fine decrements without switching the internal attenuators on the NI RF signal generator. To achieve this, NI-RFSG sets the NI 5610 to the attenuation corresponding to the highest desired power level in a sweep (refer to the Power Sweep example) and then adjusts output signal amplitude by scaling the IF digital waveform such that it does not use the full scale of the DAC onboard the AWG module. Scaling the digital waveform potentially decreases the dynamic range and thus the signal-to-noise ratio.

Use attenuator hold when you need to keep the power monotonically changing while preserving the same power error at the specific frequency setting.

Complete the following steps to configure attenuator hold:

1. Open a session to the instrument.
2. Configure the Attenuator Hold Max Power (dBm) property or the NIRFSG_ATTR_ATTENUATOR_HOLD_MAX_POWER attribute. This setting specifies the highest power level on your sweep.
3. Specify the power level of the output signal (P).
4. Enable attenuator hold mode using the Attenuator Hold Enabled property or the NIRFSG_ATTR_ATTENUATOR_HOLD_ENABLED attribute. The attenuators are set at commit time.
5. Initiate signal generation.

Note  Generation starts at the specified power level P, but the attenuators are set in such a way that the requested maximum power can be achieved by incrementing the digital waveform.