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SECTION 3
ODeration
p-p, rms to dBV:
Press the dBV key when the Model
3933A displays the p-p or rms value.
p-p, dBV, to rms:
Press the Vrms or mVrms key when
the Model 3933A displays the p-p,
or dBV value.
rms, dBV, to p-p:
Press the V or mVrms key when the
Model 3933A displays the rms or
dBV value.
Note that amplitude conversion units do not correlate 1
to 1 with the original base unit. Therefore, following units
conversion, rounding of units occurs with slight shift in
display units caused by internal resolution limits. Thus,
the system will never return to precisely the same set-
tings following a conversion.
Phase
Pressing the PHASE key displays the present phase set-
tings and allows you to modify that parameter. The al-
lowed phase range is from -360.0" to 360.0", with 0.1"
resolution.
If the PHASE key is pressed during a sweep execution,
the display indicates actual phase angle being executed at
the instant the key is pressed. If the sweep is under
HOLD control, the display indicates the phase being exe-
cuted at the moment HOLD took effect. Under these con-
ditions, the setting cannot be changed.
Under other conditions, where the system allows phase
modification, the modifications can be made using either
the numeric keypad and/or the MODIFY knob. The nu-
meric position designated by the blinking cursor can be
modified as follows:
The indicated value can be increased or decreased by
direct entry from the numeric keypad.
The indicated value can be increased or decreased by
the MODIFY knob, with each detent producing a spe-
cific stepped change in value.
The step size change produced with the MODIFY
knob is controlled by the STEP SIZE key. The value of
the change is in four possible settings: 51, f5, x+2, and
x+10.
If the step size is +l, a clockwise step of one detent of
the MODIFY knob will produce a modification factor
of +l at the numeric position indicated by the blinking
cursor. If the modification factor is &5, the change will
increase by five. A counterclockwise click will cause a
corresponding decrease in value.
A step size of x+2 or x+10 will react differently than the
above modifications. In this case, a click clockwise will
multiply by two or ten. A counterclockwise click will
divide by two or ten. However, under these condi-
tions, the entire numeric entry, not just the indicated
numeric position, will be multiplied or divided. When
changes are made with these step sizes, the first modi-
fied value will be rounded upward by the internal sys-
tem and the results will not be a one-to-one correlation
to the original value. However, each successive
change will be mathematically correct.
Modification via the MODIFY knob will have no fur-
ther effect when the next increase or decrease opera-
tion will exceed the allowable limits. Thus, if the exist-
ing phase value is 240", and you try to double that
value via the MODIFY knob, while the step size is set
at x+2, the operation of the knob has no effect on the
numeric input.
The Model 3933A's phase value is directly related to
the signal output from the Model 3930A. The phase
value is the offset from the master unit signal. The
Model 3930A phase is considered phase one. The first
Model 3933A, in any multiphase chain, is phase two.
The second successive Model 3933A is designated as
phase three, to the allowable maximum of six phases
(one Model 3930A and five slaves). Phase, amplitude,
offset and waveform may be set independently for
each unit in the chain. See Figure 3.3 for details in set-
ting up a multiphase system.
The primary basis for all phases is the 0' point of the first
phase (master unit phase one). This is not sent directly to
other units. This first phase is dependent on the start/
stop settings of the master unit and that is directly de-
pendent on the sweep trigger source. When a Model
3930A (master unit) is used alone, the phase settings
work as start/stop parameters only when in burst and
gate modes. However, when the master unit is hooked
up to a Model 3933A slave unit, the master phase settings
work the same way as those in a Model 3933A slave unit.
The phase difference between the master phase one and
the Model 3933A phase is:
(Mode13933A phase) - (Model 3930A start/stop phase setting).
3-23
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