Time-Duration Measurements; Frequency Measurements - Tektronix 453 Instruction Manual

Operating Instructions-Type 453/R453
Point A
/
-i
~
/
--r
~---
---
---
~--
L"'
11 1 1 1 1 I I 11 I I
Vertical
distance
J __
'
Reference line
Fig. 2-16. Measuring instantaneous DC voltage with respect to a
reference.
2. Divide the amplitude of the reference signal (volts) by
the product of the deflection in divisions (established in
step 1) and the VOLTS/DIV switch setting. This is the Deflec-
tion Conversion Factor.
geflecti?n _ reference signal amplitude (volts)
o~;~;~~on
- deflection (divisions) X VOLTS/DIV setting
3. To establish an Adjusted Deflection Factor at any set-
ting of the VOLTS/DIV switch, multiply the VOLTS/DIV
switch setting by the Deflection Conversion Factor established
in step 2.
Adjusted VOLTS/DIV Deflecti.on
Deflection =
tt' X Conversion
Factor
se 1 ng
Factor
This Adjusted Deflection Factor applies only to the channel
used and is correct only if the VARIABLE VOLTS/DIV con-
trol is not moved from the position set in step 1.
4.
To determine the peak to peak amplitude of a signal
compared to a reference, disconnect the reference and apply
the signal to the INPUT connector.
5. Set the VOLTS/DIV switch to a setting that will provide
sufficient deflection to make the measurement. Do not re-
adjust the VARIABLE VOLTS/DIV control.
6. Measure the vertical deflection in divisions and deter-
mine the amplitude by the following formula:
Signal
Amplitude
Adjusted d fl t'
D fl
.
-v
e ec ion
- e ect1on /'- (d' . . )
Factor 1v1s1ons
Example.
Assume a reference signal amplitude of 30
volts, a VOLTS/DIV setting of 5 and a deflection of 4 divi-
sions. Substituting these values in the Deflection Conversion
Factor formula (step 2):
Deflection 30 V
Conversion
=
4
X
5
V
=
1 .5
Factor
Then, with a VOLTS/DIV switch setting of 10, the Adjusted
Deflection Factor (step 3) is:
2-22
Adjusted
Deflection
==
10 V X 1.5
==
15 volts/ division
Factor
To determine the peak-to-peak amplitude of an applied
signal which produces a vertical de.flection of 5 divisions,
use the Signal Amplitude formula (step 6):
Signal
1
A
l 'td ==15VX5==75vots
mp
1
u e
Ti me-Duration Measurements
To measure time between two points on a waveform, use
the following procedure.
1. Connect the signal to either INPUT connector.
2. Set the MODE switch to display the channel used.
3. Set the VOLTS/DIV switch to display about five divi-
sions of the waveform.
4. Set the A Triggering controls to obtain a stable display.
5. Set the TIME/DIV switch to the fastest sweep rate that
displays less than eight divisions between the time measure-
ment points (see Fig. 2-17). (See the topic e·ntitled Selecting
Sweep Rate in this section concerning non-linearity of first
and last divisions of display.)
6. Adjust the vertical POSITION control to move the points
between which the time measurement is made to the center
horizontal line.
7. Adjust the horizontal POSITION control to center the "'
display within the center eight divisions of the graticule.
8. Measure the horizontal distance betwe·en the time
measurement points. Be sure the A VARIABLE control is set
to CAL.
9. Multiply the distance measured in step 8 by the setting
of the TIME/DIV switch. If sweep magnification is used,
divide this answer by 10.
Example. Assume that the distance between the time
measurement points is 5 divisions (see Fig. 2-17) and the
TIME/DIV switch is set to .1 ms with the magnifier off.
Using the formula:
ho:izontal TIME/DIV
distance X .
(divisions) setting
Time Duration =
magnification
Substituting the given values:
T
. D . 5 X 0.1 ms
1me urat1on =
1
The time duration is 0.5 milliseconds.
Frequency Measurements
The time measurement technique can also be used to ,,-
measure the frequency of a signal. The frequency of a peri-
odically-recurrent signal is the reciprocal of the time dura-
tion of one cycle.
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