3 VMA Mode
3.4 IQ Waveform Measurement
Best Close-in
Without option EP0
:FREQ:SYNT 1
The LO phase noise is optimized for smaller offsets from the carrier, at the expense
of phase noise farther out.
The actual frequency offset within 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 instruments this annotation appears as [offset <20 kHz]
With option EP0
:FREQ:SYNT 4
In instruments with Option EP0, the LO is configured for the best possible close-in
phase noise (offsets up to 600 kHz from the carrier), regardless of spurious products
that occur with some center frequencies. Because this is generally less desirable for
close-in measurements than the "Balanced" on page 769 setting, parameter 1
selects "Balanced" on page 769 in EP0 instruments, in the interests of optimizing
code compatibility across the family. Parameter 4 selects "Best Close-in" on page
769, which is usually not as good a choice as "Balanced" on page 769.
Balanced
:FREQ:SYNT 1
In instruments with EP0, the LO is configured for the best possible phase noise at
offsets up to 600 kHz from the carrier whenever there are no significant spurs within
the span observed with an on-screen carrier. When there will be such a spur, the LO
is reconfigured in a way that allows the phase noise to increase by 7 dB mostly
within ±1 octave around 400 kHz offset. The spurs will always be below −70 dBc.
Best Spurs
:FREQ:SYNT 5
In instruments with EP0, the LO is configured for better phase noise than the "Best
Wide-offset" on page 769 case close to the carrier, but the configuration has 11 dB
worse phase noise than the "Best Close-in" on page 769 case mostly within ±1
octave around 300 kHz offset. Spurs are even lower than in the "Balanced" on page
769 case at better than −90 dBc, whether or not the carrier is on-screen.
This setting is never selected when Phase Noise Optimization is in Auto, you must
select it manually.
Best Wide-offset
:FREQ:SYNT 2
769 Vector Modulation Analyzer Mode User's &Programmer's Reference
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