Sencore PS163 - PHASE SHIFT and TIME DELAY MEASUREMENTS; TIME DELAY BETWEEN SIGNALS; PHASE SHIFT BETWEEN SIGNALS

3. Adjust the control in the network until.a circle or
a near circle is obtained on the scope screen.
4. Apply the unknown frequency to the rear “Z”
Axis jack on the PS163, and slide the “Z” AXIS
switch to the ON position. Adjust the generator until
the pattern stands still. Count the number of line
segments, and multiply the known frequency by the
number of segments to find the unknown frequency.
The 11 segments shown in Fig. 9 indicate that the
unknown is higher than the known frequency. Note
that the shape of the overall circle is dependent upon
the phase shift network and not the frequencies in-
volved.
Tt P
= 3 +
S) t Ji
++ GR; ua +
١
i ١
|
1 A
سے󰾯
å󰾰 کد
+
| |11 Segments, |
Fig. 9. Modulated ring showing unknown frequency
11 times the known frequency.
PHASE SHIFT and TIME
DELAY MEASUREMENTS
There are two methods of measuring the phase shift
or time delay between two signals. The first method is
to measure the time delay between the two signals, and
compare this to the total time of one cycle to find
the phase shift. The second method is to use a Lissa-
jous figure to measure the phase directly. The first
method is most useful where the timing between
pulses, such as in color TV, is critical. The second
method is most useful in amplifiers where a phase
shift can cause a distorted output.
TIME DELAY BETWEEN SIGNALS
1. Use DUAL ALTERNATE VERTICAL INPUT,
AUTO TRIGGERED HORIZONTAL SWEEP, and
INT. A HORIZONTAL SYNC.
1
a
+
1
:
2. Connect CHANNEL A to the input or nonadjust-
able signal. Connect CHANNEL B to the other, and
adjust the 251683 controls for two cycles of informa-
tion as shown in Fig. 10. The actual time delay be-
tween the two signals can be measured as follows:
18
Fig. 10. Determining time delay between signals.
Count the number of horizontal divisions between
the same points on the two waveforms. (A to B).
Multiply this distance by the setting of the TIME
BASE - FREQUENCY switch. In this example the
distance is % division, the switch setting is .lmSec/
DIV, and the actual time delay is .05 milliseconds.
The total time for one 360 degree cycle in Fig.
10 is .6mSec. The phase difference can be found
with the following formula.
Time Delay
Angle = = © 6
Period of one cycle
Angle = E x 360
Angle = 30°
PHASE SHIFT BETWEEN SIGNALS
The closely matched horizontal and vertical channels
of the PS163 VECTOR mode allow this type of mea-
surement to 5MHz.
1. Press the VECTOR VERTICAL INPUT button and
AC couple CHANNEL A to one of the signals. Adjust
the CHANNEL A PPV PER DIV and trace position
for a vertical line four divisions high centered on the
scope screen.
2. Disconnect CHANNEL A and AC couple CHAN-
NEL B to the second signal. Adjust the CHANNEL B
PPV PER DIV and TRACE POSITION controls for
a horizontal line four division long
a horizontal line four division long centered on the
scope screen.
3. Reconnect CHANNEL A to the first signal and
use the following formula to find the phase angle.
For Fig. 11. 3