Scans by ArtekMedia © 2007
Before plotting a measurement,
a
recording area should be prepared that is
appropriate for the application. Preparing a recording area accomplishes
several tasks - it defines the axes, boundaries, and scaling of the coordi
nate system; matches the sensitivity and range of the HP
7090
to the input
signal voltage(s); and establishes the recording time.
The procedures involved in preparing a recording area can be grouped into
the following four steps:
1.
Defining the axes.
The X- and Y-axes are defined using the
CHANNEL
SELECT
push buttons. For the preceding illustration,
CHAN 1
was selected
for the Y-axis;
TOTAL TIME
was selected for the X-axis.
2.
Establishing the recording area boundaries.
The coordinate sys
tem quadrants required for plotting are determined and the location and
size (boundaries) of the recording area are specified on the plotter paper
by positioning the zero and full·scale points.
Because the Channel l input signal used for the illustration consisted of
positive voltages, only Quadrant
I
(positive Y·axis values and positive
X-axis values) was required. The actual area intended for the quadrant
was then established on the plotter paper.
3.
Scaling the recording area boundaries.
The scaling (limits) of the
X- and Y-axes is defined by specifying appropriate setup condition
values.
In the example,
RANGE 1
was set at
6.0
volts to scale the Y-axis (Channel
1
input) to
0.0-6.0
volts.
TOTAL TIME
was set to
50.0
milliseconds
to
scale
the X·axis (time) to
0.0-50.0
milliseconds.
4.
Scaling and drawing the recording area grid.
The scaling for the
•
grid divisions is selected using the
GRID DIVISION
setup conditions, and
'
the grid is drawn. For the example, each Y-axis grid division represents
0.5
volt; each X·axis grid division represents 2.0 milliseconds.
The following four sections detail how to perform the four steps outlined
above. Although the steps can be performed in other sequences, the order
given here permits a logical presentation ofthe material. With the informa
tion in these sections, you will be able to design a suitable recording area
for nearly any measurement application.
Defining the Axes/Channel Selection
(Preparing the Recording Area: Step 1)
Measurements made using the HP
7090
may be classified as
versus·time
or
versus·chan3, depending upon the assignment of the X·axis variable. For
versus-time measurements, time is assigned to the X·axis; the Y-axis is
reserved for the channel input signal(s). For versus-chan3 measurements,
the Channel 3 input signal is assigned to the X·axis, and Channel l and/or
2
is assigned to the Y·axis. The following figure shows the axes defined for
both measurement types.
;3-2
Measurement Setup Operations
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