HP 83480A User Manual

Increasing Measurement Accuracy
and Time-Interval Measurement
Increasing Measurement Accuracy
Automatic measurements
Except in special cases, the simplest and most accurate way to measure the
width of a pulse is to use the instrument's automatic measurement.
For the instrument to measure the pulse width automatically, the
time/division control must be set so that the entire pulse, including the
leading and trailing edges, is on the screen. Thus, the resolution of the
measurement is limited by the time base resolution. In digitizing scopes,
the time base resolution is primarily limited by memory depth and by the
intrinsic hardware
resolution of
the
ne
interpolator
in
the
time
base
.
It is
important to
select the
optimum
time/division
scale
to
achieve
the
best
resolution and
accuracy.
Both
edges
of
the
pulse
must
be
on
the
screen,
and
at
the
same
time
,
there
must
be
sucient baseline
(or top
for
a
negative
pulse)
for
the
top
and
base
algorithm
to
reliably determine
the voltage
level
of
the
base
(or
top).
Refer
to
the
discussion
in
\Calculating top
and
base"
in
Chapter
7,
describing
the
algorithm
the
instrument
uses
to
determine
the top
and
base
levels
.
If
the
baseline
is
distorted
prior
to
the
initial
transition
of
the
pulse
,
enough
of
the
\true"
steady-state
baseline
must
be
present
on
the
screen
so
that
it
will
be
identied
clearly
in
a
voltage
histogram
as
the
most
prevalent
value
.
The
minimum
time/division
setting
that
achieves
this
will
give
the
most
accurate
measurement.
In
other
words
,
spread
the
pulse
out
to
occupy
as
much
of
the
screen
as possible
while allowing
the base
(or
top
for
a
negative
pulse)
to
occupy
at least
10 percent
of the
display
(1
division).
The instrument allows you to select time/division settings other than the
standard 1-2-5 sequence.For example, consider a pulse that is 5.8  swide.
At 1  s/division, the pulse will be 5.8 divisions wide, or 58 percent of the
screen width. However, at 500 ns/div, the leading and trailing edges will
not
be
on
the
screen
simultaneously.
Here
,
you
could
set
the
time
base
to
650
ns/division,
and
the
pulse
will occupy
90
percent
of
the
screen.
The instrument has automatic measurements for all
common pulse
parameters.Y
ou can congure the Delay automatic
measurement to measure
any
arbitrary time interval. Use the Dene Measure menu to specify which
interval the Delay
automatic measurement will measure
.Y
ou can store
several custom delay measurement
congurations using the Setup menu.
9-4

HP 83480A Specifications

General

Brand	HP
Model	83480A
Category	Measuring Instruments
Language	English