Stanford Research Systems SR785, Руководство по эксплуатации и программированию

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4-8 FFT Frequency Menu
SR785 Dynamic Signal Analyzer
Command: FSPN (?) d {, f}
Linewidth
Select the Linewidth of the active display. The Linewidth is defined as the Span divided
by the FFT Resolution (100, 200, 400 or 800 lines). A numerically entered value is
rounded to the nearest allowable Linewidth.
Changing the Linewidth will change the Span (Linewidth x FFT Resolution) and
Acquisition Time (1/Linewidth). The Linewidth and Acquisition Time are other ways to
change the Span. If the new frequency Span would extend below 0 Hz or above the FFT
Base Frequency, then the Start and End frequencies will be adjusted.
The two displays can have different Linewidths if the Analyzer Configuration is set to
Independent Channels. In this configuration, no two channel measurements are allowed
(frequency response, cross-spectrum, etc.). but the entry field can be linked or unlinked
using the [Link] key. If Analyzer Configuration is set to Dual Channel the field is
automatically linked to both displays.
Command: FSPN (?) d {, f}
Acquisition Time
Select the Acquisition Time of the active display. The Acquisition Time is the time
record length for the FFT (FFT Resolution/Span). A numerically entered value is
rounded to the nearest allowable Acquisition Time.
Changing the Acquisition Time will change the Span (FFT Resolution/Acquisition Time)
and Linewidth (1/Acquisition Time). The Linewidth and Acquisition time are other ways
to change the Span. If the new frequency Span would extend below 0 Hz or above the
FFT Base Frequency, then the Start and End frequencies will be adjusted.
The two displays can have different Acquisition Times if the Analyzer Configuration is
set to Independent Channels. In this configuration, no two channel measurements are
allowed (frequency response, cross-spectrum, etc.), but the entry field can be linked or
unlinked using the [Link] key. If Analyzer Configuration is set to Dual Channel the field
is automatically linked to both displays.
Command: FSPN (?) d {, f}
Full Span
Set the FFT Span of both displays to the FFT Base Frequency 102.4 (100.0) kHz. The
Linewidth, Acquisition Time, Start frequency and Center frequency are set to
256 (250) Hz, 3.906 (4.00) ms, 0.0 Hz, and 51.2 (50.0) kHz respectively.