3 VMA Mode
3.5 Channel Power Measurement
Option # Description
on page 890 phase noise performance
–
In instruments without EP0, this setting is accepted but no action
taken
Auto - Automatically selects LO (local oscillator) phase noise behavior to
optimize dynamic range and speed for various instrument operating
conditions
*Dependent on Option EP0 installation. See "Best Close-in" on page 889 below.
The actual behavior varies somewhat depending on model number and option; for
example, you always get Fast Tuning by choosing Option #3, but in some models,
"Fast Tuning" on page 890 is identical in effect to "Best Close-in" on page 889.
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 889 setting, parameter 1
selects "Balanced" on page 889 in EP0 instruments, in the interests of optimizing
code compatibility across the family. Parameter 4 selects "Best Close-in" on page
889, which is usually not as good a choice as "Balanced" on page 889.
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.
889 Vector Modulation Analyzer Mode User's &Programmer's Reference
To Next Page
Loading...
Need help?
General
