5. Dual ARB

The following figure is a composite of all supported instruments, so some parameters may not apply to your instrument.

5. Dual ARB: Baseband Frequency Offset (EXT)

ARB Sample Clock

Range: 1 kHz to 125 MHz

Default: 100 MHz

The sample clock frequency of the signal generator is automatically calculated by the program (read-only). The range depends on the connected instrument.

VCO Clock

Choice: Internal | External

Default: Internal

Double-click or use the drop-down menu to select the signal generator’s VCO Clock.

Internal - the signal generator uses its internal VCO Clock.
External - the signal generator uses an external VCO Clock.

VCO Clock is enabled with E4438C-HEC and E8267D only.

Waveform Runtime Scaling

Range: 1%−100%

Default: 90%

Enter a scaling value for the signal generator to apply to the waveform while it is playing. Use scaling to get the best dynamic range without overflowing the I and Q digital-to-analog converters (DAC) and reduce the overshoot associated with the DAC interpolation filter.

I/Q Modulation Filter

Choice: Auto | 2.1 MHz | 40 MHz | Through

Default: Auto

Double-click or use the drop-down menu to select a filter for I/Q signals modulated onto the RF carrier. The bandwidth of the baseband signal should dictate the minimum reconstruction filter bandwidth you choose. Depending on the oversampling ratio and where the image frequencies appear, you may want to select a wider bandwidth.

Auto − automatically selects a digital modulation filter.
2.1 MHz − applies a 2.1 MHz baseband filter to the I/Q signals.
40 MHz − applies a 40 MHz baseband filter to the I/Q signals.
Through − bypasses filtering.

This parameter is not available with all instrument model numbers and may be grayed out.

I/Q Output Filter

Choice: Auto | 40 MHz | Through

Default: Auto

Double-click or use the drop-down menu to select a filter or through path for routing I and Q signals to the rear panel I/Q outputs.

Auto − automatically selects an I/Q output filter.
40 MHz − applies a 40 MHz baseband filter.
Through − bypasses filtering.

This parameter is not available with all instrument model numbers and may be grayed out.

Modulation Attenuation Mode

Choice: Auto | Manual

Default: Auto

Select the mode of the internal I/Q modulator.

Manual − manually set the attenuation level of the I/Q modulator using the Modulation Atten cell.
Auto − automatically sets the attenuation level to a value that provides the best performance, based on the digital modulation settings.

Modulation Attenuation

Range: 0.00−40.00 dB

Default: 6.00 dB

Set the attenuation of the I/Q signals being modulated through the signal generator RF path. Adjusting the attenuation may reduce signal distortion and improve the overall dynamic range.

Set Modulation Attenuation Mode to Manual to enable this parameter.

High Crest Mode

Choice: On | Off

Default: Off

Double-click or use the drop-down menu to enable or disable the signal generator’s high crest mode.

On − processes high-crest-factor arbitrary I/Q waveforms with less distortion. For crest factors higher than 4 dB, you should reduce I/Q Modulation Attenuation levels by 1 dB for each dB above that level. High Crest Mode reduces the maximum output level and degrades power level accuracy.
Off − disables the high crest mode.

This parameter is not available with all instrument model numbers and may be grayed out.

ARB Reference

Choice: Internal | External

Default: Internal

Double-click or use the drop-down menu to select the signal generator’s ARB Reference source .

Internal − the signal generator uses its internally generated 10 MHz signal as the reference source.
External − the signal generator uses an external signal as the reference frequency for the baseband I/Q signal. See the signal generator’s user’s guide for information on external references.

This parameter is not available with all instrument model numbers and may be grayed out.

Reference Frequency

Range: 0.2500000–100.0000000 MHz

Default: 10.0000000 MHz

Enter the frequency value of the external reference when using an externally supplied reference signal. See the signal generator’s user’s guide for information on external references.

Set ARB Reference to External to enable this parameter.

This parameter is not available with all instrument model numbers and may be grayed out.

Baseband Frequency Offset (EXT)

Range: -50.00 MHz to 50.00 MHz

Default: 0.000 Hz

Set ARB Reference to External to enable this parameter.

Enter a frequency value by which the baseband frequency is offset relative to the carrier. This parameter is only available when connected to the E6607 EXT.