up to 2000 transferred measurements/s, each
individually triggered. If you save the results
to the internal memory of the instrument for
later transfer, you can even attain an impres
-
sive speed of 250,000 measurements/s.
Time Measurements
So far we have only been using the frequency
function. Now we will use some others.
To measure the period of the signal, simply
press the key MEAS FUNC followed by PE
-
RIOD. Select SINGLE or AVERAGE de
-
pending on the desired resolution and measur
-
ing speed. Finish by selecting the input chan
-
nel.
To measure pulse width, use the keys MEAS
FUNC and PULSE followed by POS or
NEG depending on whether you want to mea-
sure the positive or the negative pulse width.
Finish by selecting the input channel.
Jitter Measurements
(Statistics)
You can make statistical measurements, such
as pulse width jitter, directly via the front
panel of the counter.
Make sure the counter is measuring positive
pulse width on input A. To turn on statistics,
press the STAT/PLOT key. Change the dis
-
play mode by toggling the same key. Return
to the numerical mode and watch the results.
The display gives you a survey of several sta
-
tistical measures. See also page 3-4. The rms
jitter is equivalent to the standard deviation of
100 measurements, where 100 is the default
value for the sample size.
If you want to change the default values for
sample size, bin size or pacing time, then you
can press the SETTINGS menu key and after
that the STAT soft key.
Other
Single-Channel
Measurements
The counter/timer can help you characterize
signals even further. Recall the default settings
and press AUTOSET twice.
Duty Cycle
Use the MEAS FUNC key to select Duty and
then Positive A (for positive-pulse duty cy-
cle measurement on channel A). Change the
frequency of the generator to 10 kHz. Then
vary the symmetry (duty cycle) of the square
wave on your generator. The counter’s display
will directly show the duty cycle as a number
between 0 and 1. There is no need to manually
calculate duty cycle by dividing pulse width
by period.
The duty cycle (D) is defined as:
D=W/T
D = 0.5 for a square wave.
Exercises
4-4 Time Measurements
W
1
W
2
T
LOW
DUTY CYCLE
HIGH
DUTY CYCLE
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