Fluke PM6690 Operator's Manual page 78

Measurement Control
nal calibration ON) plus set measurement
time. For example, with a measurement time
of 0.1 ms, the time between each sample is ap-
proximately 104-108 ms.
n
Repetitive Sampling Profiling
The measurement setup just described will not
work when the profiling demands less than
4 ms intervals between samples.
How to do a VCO step response profil-
ing with 100 samples during a time of
10 ms.
This measurement scenario requires a repeti-
tive input step signal, and you have to repeat
your measurement 100 times, taking one new
sample per cycle. And every new sample
should be delayed 100 ms with respect to the
previous one.
The easiest way to do this is by means of a
controller, e.g. a PC, although it is possible
but tedious to manually set and perform all
100 measurements.
The following are required to setup a mea-
surement:
–
A repetitive input signal (e.g., frequency
output of VCO).
–
An external SYNC signal (e.g., step volt-
age input to VCO).
–
Use of arming delayed by a preset time
(e.g., 100, 200, 300 ms).
See Fig. 5-16 and Fig. 5-17.
5-14 Arming Examples
When all 100 measurements have been made,
the results can be used to plot frequency ver-
sus time. Note that the absolute accuracy of
the time scale is dependent on the input signal
itself. Although the measurements are armed
at 100 ms ± 100 ns intervals, the actual start of
measurement is always synchronized to the
first input signal trigger event after arming.
The TimeView™ software package will do
this measurement quickly and easily.
Voltage step
generator
Input E, Ext Arm
Fig. 5-16 Setup for transient profiling of a
VCO.
Fig. 5-17 Results from a transient profiling
measurement.
VCO
Input A