Stanford Research Systems SR620, Руководство пользователя

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6 Front Panel Operation
SR620 Universal Time Interval Counter
resolution. The maximum period measurable in
this mode is 1 s.
In both period and frequency modes the statistical
data is displayed with the number of significant
digits allowed by the SR620's resolution. Using
longer gate times increases the resolution.
GRAPHICS OUTPUTS
In addition to the 16 digit LED display the SR620's
scope and chart outputs may be used to give the
user alternative methods of viewing the data.
SCOPE OUTPUTS
The SR620 may be attached to an oscilloscope
operating in x-y mode to provide a graphical
presentation of the output data. The oscilloscope
should be set in x-y mode with sensitivities set to
1V/div and the SR620's x and y rear panel
outputs attached.
GRAPH TYPES
The SR620 can then display either a histogram of
number of samples vs. measured parameter for
the samples within a measurement, a stripchart of
mean values for successive measurements, or a
stripchart of jitter values for successive
measurements. In histogram mode a new graph
will be displayed after each measurement of N
samples is complete, showing the distribution of
samples in that measurement. In the stripchart
modes a new point will be added to the graph after
each measurement indicating the mean and jitter
values for that measurement. The display desired
is chosen by pressing the select button below the
indicator LEDs. The data for all three graphs are
saved so that all of the graphs may be viewed by
cycling through the three choices. The data, the
scale values, and the cursor position are all
displayed on the scope screen. In the stripchart
modes up to 250 points will be displayed. When
the display fills up new data will start to overwrite
the old starting from the left. The graph may be
cleared by pressing the CLR button below the
PRINT button.
SCALING GRAPHS
In histogram mode the vertical scale, horizontal
scale, and number of bins may be adjusted. In the
stripchart modes the vertical scales may be
adjusted. The easiest way to scale the graphs is
to press the "AUTO" button to autoscale the graph.
Autoscale will automatically adjust the scales so
that the data fits on the screen. In histogram
mode the actual scaling of the graph does not
occur until the next measurement is complete.
The scale may also be adjusted manually.
Pressing the up and down arrow keys with the
normal display on the 16 digit LEDs will adjust the
vertical scale on the displayed graph. In the
histogram mode , incrementing the vertical scale
past the largest value (200,000 / div) will change
the vertical scale to a log scale. To view the
scales on the LED display press the "DISP"
button. First, the cursor position (discussed
below) will be displayed. Pressing the button
again will display the vertical graph scales in the
appropriate units. In the histogram mode pressing
the button again will display the horizontal scale
and then the number of bins. The scales may be
adjusted using the up and down arrow keys.
When the REL is set the graphs are centered
about the REL and, thus, very fine detail may be
observed on a large number.
GRAPHICS CURSOR
The displayed graphs have a moveable cursor that
allows one to read the values of individual points
on the screen. The cursor is represented on
screen by a dotted line. The cursor is moved by
pressing the "DISP" button to display the cursor
position and using the up and down arrow keys to
move it about. The cursor x position is displayed
on the LED display ( in the correct units of s, Hz,
etc.) for the histogram display and measurement
number for the stripcharts. Both the x and y
positions are displayed on the scope screen.
GRAPHICS ZOOM
The SR620 has a feature which allows one to
zoom in on any feature in a displayed histogram,
this feature also allows the REL to be set to any
value desired. First, press the DISP button to
display the cursor position. Then, move the cursor
until it is at the desired position ( or the cursor
value is the desired REL value if setting the REL).
Push the "SET" button. This will set the REL to
the cursor position. Now, adjust the graph
horizontal scale to get the magnification desired.
If setting the REL value, note that the amount that
the cursor value changes for each press of the
arrow keys is determined by the horizontal
histogram scale and that the scale may have to be
adjusted to get the REL value desired.