DISPERSION 1 MHz/div.
d. Adjust the DISPERSION-CAL for 1 marker/division.
Use the Horizontal POSITION control or the IF CENTER FREQ
control to align the markers to the graticule lines. Dispersion
is calibrated over the center 8 divisions of the display. See
Fig. 2-10.
Video Filter Operation
The video filter restricts the video bandwidth so that noise
or beat signals are reduced. This application is very useful
when analyzing signals close to minimum resolution band-
width. Fig. 2-11 shows the apparent increased resolution
when the VIDEO FILTER is turned on. It does restrict the use-
able sweep rate, because of the filter time constant, to about
50 ms/div or slower.
The SQ LAW (power) position provides a display that is
Vertical Display Modes
approximately
proportional to the square of the input sig-
nal amplitude.
The display, therefore, approximates the input
The appearance of the displayed signal depends to a
signal power.
This is basically an expansion circuit to ac-
great extent on the setting of the VERTICAL DISPLAY switch.
centuate small
amplitude differences.
For example; to accentuate the side lobes of a signal, the
LOG (40 dB full screen) position should be used, as com-
pared to the SQ LAW (13 dB full screen) position. Fig, 2-12
Selecting the Sweep Rate
illustrates the effect of each display mode or each position
The sweep rate for wide dispersion coupled resolution set-
of the VERTICAL DISPLAY switch.
tings is usually set just above the visual flicker setting; how-
The LOG position increases the dynamic range of the dis-
ever, as the DISPERSION is decreased the sweep rate will
play by attenuating large amplitude signals more than small
begin to affect the resolution and sensitivity of the analyzer,
amplitude signals. This produces a display which approxi-
as described under Obtaining Optimum Resolution. There-
mates a logarithmic response curve. The circuit is basically
fore, as the DISPERSION settings are reduced the sweep
a compression circuit, and is most effective when there are
rate should also be reduced to maintain sensitivity and resolu-
large signal amplitude differences.
tion.
2-12
