Basic Applications-2230 Operators
Substituting the given values
in
the phase difference
formula:
Phase Difference = 6 div x 4.5°
/div
= 27°
CHANNEL 1 (REFERENCE)
1V
I - HORIZONTAL
r DIFFERENCE
MEASURE
TIME FROM
@ro@
4998-43
Figure 6-25. High-resolution phase difference.
TIME COMPARISON
In
a similar manner to "Amplitude Comparison,"
repeated time comparisons between unknown signals and
a reference signal (e.g.,
on
assembly-line test) may
be
easily and accurately measured with the instrument. To
accomplish this, a reference signal. of known time duration
is first set to
an
exact number of horizontal divisions by
adjusting the A SEC/DIV switch and the SEC/DIV Variable
control. Unknown signals can then
be
compared with the
reference signal without disturbing the setting of the
SEC/DIV Variable control. The procedure
is
as
follows:
1 . Set the time duration of the reference signal to
an
exact number
of
horizontal divisions by adjusting the A
SEC/DIV switch and the SEC/DIV Variable control.
2.
Establish a horizontal conversion factor, using the
following formula (reference-signal time duration must
be
known):
Horizontal reference signal
Conversion =
___
ti_m_e_d_u_r_a_tio_n__,_(s_e_c_o_n_d--'s
)
__
_
Factor horizontal distance A SEC/DIV
(divisions) X switch setting
6-24
3.
For the unknown signal, adjust the A SEC/DIV
switch to a setting that provides sufficient horizontal
deflection to make
an
accurate measurement. Do not
readjust the SEC/DIV Variable control.
4. Establish
an
arbitrary deflection factor, using the fol-
lowing formula:
Arbitrary horizontal
Deflection = conversion x
A SEC/DIV
switch
setting
Factor factor
5. Measure the horizontal distance
of
the unknown sig-
nal
in
divisions and calculate its time duration using the fol-
lowing formula:
arbitrary horizontal
Time Duration = deflection x distance
factor (divisions)
EXAMPLE:
The reference signal time duration
is
2.19
ms, the A SEC/DIV switch setting
is
0.2
ms,
and the
SEC/DIV Variable control
is
adjusted to provide a hor-
izontal distance
of
exactly 8 divisions.
Substituting the given values
in
the horizontal
conversion factor formula:
Horizontal
2.19
ms
Conversion =
-------
= 1.37
Factor 8 div x 0.2 ms/div
For the unknown signal the A SEC/DIV switch setting
is
50
µS,
and one complete cycle spans seven horizontal divi-
sions. The arbitrary deflection factor
is
then determined by
substituting values
in
the formula:
Arbitrary
Deflection = 1.37 x 50 µs/div = 68.5 µs/div
Factor
The time duration
of
the unknown signal can then
be
computed by substituting values
in
the formula:
Tim~ = 68.5 µS/div X 7 div = 480
µS
Duration
--
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