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a slope of 2 volts per volt per segment).
This increase
in slope will increase the noise level proportionately, but
this effect will not be objectionable with reasonable gains.
Even the sample curve shown in Figure 20c, which requires a
pot-setting of 0.050 (slope of 20 volts per volt) should pre-
sent no noise problems.
When setting breakpoints, the standard
lOOK feedback should be used (no pot).
Otherwise the 0.10
volt criterion for setting the breakpoint will not apply.
To find out whether amplification is necessary, the slopes be-
tween adjacent breakpoints may be tabulated.
The slope between
the i-th and the (i
+
l)st breakpoints is:
f(X
i
+
1) - f(X
i
)
x.
+
1 - X.
l
l
This is easily calculated.
It is important to realize that
except for the center slope (the slope at x = 0), the actual
slope of the curve is not as important as the increment in
slope.
For instance, if a function had a center slope of 0.85
volt per volt, and successive slopes of 1.50, 2.10 and 3 volts
per volt, no amplification would be necessary, since the center
slope and the slope increments are all less than one volt per
volt.
(The slope at any point, is the
~
of the slopes due to
all diodes that are conducting at the point, plus the center slope.
Hence, except for the center slope, any slope may exceed 1 volt
per volt as long as the change in slope between successive seg-
ments does not.)
(3)
Sample Function Setup Procedure.
The steps listed in Sub-paragraphs
(4) and (5) are used for the setup of the sample function.
The same steps, in
the same order, are also used for the setup of any arbitrary function.
Some
modif~cations
of the basic procedure may be required for the setup of a specific
funct~on;
for example, if thesegrnent-to-segment change of slope for a given func-
tion ooes not exceed I volt per volt, the feedback pot (pot 17 of Figure 22a) is
not required.
Experience gained while setting up the sample function permits the
opera~or
to determine when to deviate from the steps provided.
(4)
Breakpoint Setup Patching.
If sufficient coefficient-setting atten-
uators are available, patch the configuration shown in Figure 19a.
If the re-
quire~
number of attenuators is not available, the circuit of Figure 19b may be
used.
The method described in Figure 19a is much faster, and therefore preferred.
The attenuators are required for setup only, and are released for other functions
when the setup is complete.
The first part of the setup procedure consists of
settling the breakpoints.
The steps outlined in this procedure should be followed
care~~ly
to assure maximum accuracy of the diode generated function.
39
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