1077
Meas Setup
Best Wide-offset Noise
The LO phase noise is optimized for wider offsets from the carrier. Optimization is especially improved
for offsets from 70 kHz to 300 kHz. Closer offsets are compromised and the throughput of measurements
(especially remote measurements where the center frequency is changing rapidly), is reduced.
Fast Tuning
In this mode, the LO behavior compromises phase noise at many offsets from the carrier in order to
allow rapid measurement throughput when changing the center frequency or span. The term “fast
tuning” refers to the time it takes to move the local oscillator to the start frequency and begin a sweep;
this setting does not impact the actual sweep time in any way.
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.
Initial S/W Revision Prior to A.02.00
Key Path Meas Setup, PhNoise Opt
Example FREQ:SYNT 2
Couplings offset >30 kHz
Readback Wide-offset.
If manually selected the “Man” is underlined. The actual frequency offset
beyond which noise is optimized is shown with in square brackets, as this can
vary depending on the hardware set in use. For example, in some test sets this
annotation appears as [offset >30 kHz]
Initial S/W Revision Prior to A.02.00
Key Path Meas Setup, PhNoise Opt
Example FREQ:SYNT 3
State Saved Saved in instrument state.
Readback Fast Tuning. Also, the “Man” must be underlined.
Initial S/W Revision Prior to A.02.00