Introduction; Averaging; Mathematics; Example - Fluke PM6690 Operator's Manual

Process

Introduction

Three different ways to process a measuring
result are available: Averaging, Mathematics
and Statistics. They can be used separately or
all together.
In addition to postprocessing you can also
monitor the measurement results in real time
by setting limits and deciding how to react
when they are crossed.

Averaging

Hardware averaging by means of counting
clock pulses during several full input signal
cycles is only used for the measurement func-
tions Frequency and Period Average. The
parameter to be set by the operator in this case
is Meas Time under SETTINGS, and the
range is 20 ns to 1000 s. Longer measuring
times mean higher resolution.
The other functions employ single cycle mea-
suring, and the method to get average results
is to utilize the statistics features described
later.

Mathematics

The counter can use four mathematical ex-
pressions to process the measurement result
before it is displayed:
1. K * X+L
2. K/X+L
3. K * X/M+L
4. (K/X+L)/M
Press MATH/LIM ® Math to enter the first
mathematics submenu. See page 2-12how to
enter the constants K, L and M and how to se-
lect the formula that best suits your need.
6-2 Introduction
The default values of K, L and M are chosen
so that the measurement result is not affected
directly after activating Math. Recalling the
default setting will restore these values as
well.

Example:

If you want to observe the deviation from a
certain initial frequency instead of the abso-
lute frequency itself, you can do like this:
–
Recall the default settings by pressing
USER OPT ® Save/Recall ® Recall
Setup ® Default.
–
Connect the signal to be measured to input
A.
–
Press AUTO SET to let the counter find
the optimum trigger conditions on its own.
Press MATH/LIM ® Math ® L
–
–
If the current display value is suitable for
your purpose, then press X
be transferred to the constant L. You can
repeat pressing X
0
The constant will be updated with the lat-
est measurement result.
–
Instead of using X
merical value from the front panel. Let's
assume that 10 MHz is your reference fre-
quency. The mantissa is marked by text in-
version for immediate editing. Press 1 ®
0 ® ± ® EE ® 6.
–
Confirm by pressing EXIT/OK. Now the
constant L is updated and displayed as
-10E6.
–
Press Math and choose the expression
K * X+L by pressing the softkey below it.
–
Now the display will show the deviation
from the value you have just entered.
By changing the constant K you can scale the
result instead.
. It will then
0
until you are satisfied.
you can enter any nu-
0