Time Duration Measurements - Tektronix 7B70 Time Base Instruction Manual

Operating Instructions-7B70 (SN B205000 and Up)
6. Measure the horizontal deflection in divisions and measurement points (see Fig. 2-8). (See the topic entitled
calculate the repetition rate of the unknown signal using
Horizontal Sweep Rate in this section concerning non-
the following formula:
linearity of first and last divisions of a display.)
TIM €ID I V
horizontal horizontal
6.
Adjust the vertical POSITION control to move the
Repetition
=
switch
x
conversion
x
deflection points between which the time measurement is made to the
Rate setting factor (divisions)
center horizontal reference line.
NO JE
7. Adjust the horizontal POSITION control to position
If the horizontal magnifier is used, be sure to use the the time-measurement points within the center eight divi-
magnified sweep rate in place of the TlME/DIV sions of the graticule.
switch setting.
8. Measure the horizontal distance between the time
Example. Assume a reference signal frequency of 455 measurement points. Be sure the A VARIABLE control
i s
hertz (repetition rate 2.19 milliseconds), a TIMEIDIV set to CAL.
switch setting of .2 ms, and the VARIABLE TIMEIDIV
control adjusted to provide a horizontal deflection of eight
divisions. Substituting these values in the horizontal conver-
9. Multiply the distance measured in step 8 by the
sion factor formula (step 4):
setting of the TIMEIDIV switch. I f sweep magnification is
used, divide this answer by 10.
Horizontal
2.19 milliseconds
Conversion
=
=
1.37
.2 X 8
Example. Assume that the distance between the time
Factor
measurement points is five divisions (see Fig. 2-1 O), and the
TIMEIDIV switch is set to .1 ms with the magnifier to X I .
Then, with a TIMEIDIV switch setting of 50 ps, .the
using
the formula:
repetition rate of an unknown signal which completes one
cycle in seven horizontal divisions can be determined by
horizontal
using .the repetition rate formula (step 6):
distance
x
TIME/DIV
Time Duration
=
setting
(divisions)
Repetition =
50 us X 1.37 X 7
=
480
us
magnification
Rate
This answer can be converted to frequency by taking the
reciprocal of the repetition rate (see application on Deter-
mining Frequency Measurements).
Time-Duration Measurements
To measure time between two points on a waveform, use
the following procedure:
1. Connect the signal to either Vertical plug-in.
2. Set the MODE switch to display the plug-in used.
3. Set the VOLTS/DIV switch to display about four
divisions of the waveform.
4. Set the 7B70 triggering controls to obtain a stable
display.
I I
1 - Center measurement area
-
1
I
I
5. Set the
switch to the fastest sweep rate
Fig. 2-10. Measuring the time duration between points on a
that displays less than eight divisions between the time
Scans by ArtekMedia O 2006