Agilent Technologies Signal Analyzer N9030a - Manual (Page 838)

6 RLC Swept SA Measurement Front-Panel & SCPI Reference
Meas Setup
PXA with option EP1: [single loop]
Models with option EP2: [medium loop bandwidth]
All other models: [same as Close-in]
State Saved Saved in instrument state.
Readback Fast Tuning.
If manually selected the “Man” will be underlined.
Initial S/W Revision Prior to A.02.00
Modified at S/W
Revision A.12.00
ADC Dither
Accesses the menu to control the ADC Dither function. The dither function enhances linearity for
low level signals at the expense of reduced clipping-to-noise ratio. The reduced clipping-to-noise
ratio results in higher noise, because we work to ensure that the clipping level of the ADC relative
to the front terminals remains unchanged with the introduction of dither, and this results in
reduced ADC dynamic range. So making measurements with ADC dither gives you better
amplitude linearity, but turning ADC dither off gives you a lower noise floor (better sensitivity).
With dither on, the third-order distortions are usually invisible for mixer levels below –35 dBm.
With dither off, these distortions can be visible, with typical power levels of –110 dBm referred to
the mixer. Detection nonlinearity can reach 1 dB for dither off at mixer levels around –70 dBm
and lower, while the specified nonlinearity is many times smaller with dither on.
When ADC Dither is on, the linearity of low-level signals is improved. The enhanced linearity is
mostly improved scale fidelity. The linearity improvements of dither are most significant for
RBWs of 3.9 kHz and less in swept mode, and FFT widths of 4 kHz and less in FFT mode.
The increased noise due to turning dither on is most significant in low band (0 to 3.6 GHz) with
IF Gain set to Low, where it can be about 0.2 dB.
Key Path Meas Setup
Remote Command [:SENSe]:ADC:DITHer[:STATe] OFF|ON|HIGH
[:SENSe]:ADC:DITHer[:STATe]?
Example ADC:DITH:HIGH Sets the ADC dither setting to High
ADC:DITH ON Sets the ADC dither setting to Medium
In older instruments the “Medium” key was labeled “On” and the SCPI for this setting is NOT
changing.
Dependencies In some models, the “High” parameter is not available. In some instruments, the HIGH
838 Remote Language Compatibility Measurement Application Reference