Stanford Research Systems SR785, Руководство по эксплуатации и программированию

Страница: 238 / 546

4-42 Display Setup Menu
SR785 Dynamic Signal Analyzer
PSD Units
Power Spectral Density (PSD) is the energy in each frequency bin normalized to the
noise bandwidth of the bin. The noise bandwidth is calculated from the FFT Linewidth
and the Window function. This allows comparison of results taken at different spans and
with different Windows. If <PSD Units> are on, the units of the display will be V/
√
Hz,
or V
2
/Hz.
Command: PSDU (?) d {, i}
Phase Units
Selects radians or degrees as units for the phase and unwrapped phase views.
Command: UNPH (?) d {, i}
dBm Reference Impedance
Set the dBm Reference Impedance for both displays.
The dBm Reference Impedance is used to calculate dBm units. dBm is simply
10•log(power/1mW) where power = Vrms
2
/Reference Impedance.
Command: DBMR (?) {f}
Y Max
Set the Y Maximum (top reference) of the active display. The top reference is the Y
value of the top of the graph. The top reference has the same units as the display.
When Y Max is changed, the value of Y-Min is kept fixed and Y-mid and Y/Div are
adjusted.
The two displays can have different top reference values. This entry field can be linked
to both displays using the [Link] key.
Command: YMAX (?) d {, x}
Y Mid
Set the Y Midpoint (center reference) of the active display. The center reference is the Y
value of the center of the graph. The center reference has the same units as the display.
The two displays can have different center reference values. This entry field can be
linked to both displays using the [Link] key.
When Y Mid is changed, the value of Y/Div is kept fixed and Y-Max and Y-Min are
adjusted.