You use
many
terms to
describe
the
types of
measurements
that you
take
with
your
oscilloscope.
This
section
describes
some of
the most
common
measurements
and
terms.
Frequency
and
Period
If a
signal
repeats,
it has a
frequency.
The
frequency
is
measured
in Hertz
(Hz) and
equals
the
number
of times
the
signal
repeats
itself
in one
second
(the
cycles
per
second).
A
repeating
signal
also has
a
period
- this
is the
amount
of time
it takes
the
signal
to
complete
one
cycle.
Period
and
frequency
are
reciprocals
of each
other,
so that
1/period
equals
the
frequency
and
1/frequency
equals
the
period.
So, for
example,
the sine
wave in
following
figure
has a
frequency
of 3 Hz
and a
period
of 1/3
second.
Voltage
is
the
amount
of
electric
potential
(a kind
of
signal
strength)
between
two
points
in a
circuit.
Usually
one of
these
points
is
ground
(zero
volts)
but not
always -
you may
want to
measure
the
voltage
from the
maximum
peak to
the
minimum
peak of
a
waveform,
referred
to at
the
peak-to-peak
voltage.
The word
amplitude
commonly
refers
to the
maximum
voltage
of a
signal
measured
from
ground
or zero
volts.
The
waveform
shown in
Figure 8
has an
amplitude
of one
volt and
a
peak-to-peak
voltage
of two
volts.
Phase
Phase
is best
explained
by
looking
at a
sine
wave.
Sine
waves
are
based on
circular
motion
and a
circle
has 360
degrees.
One
cycle of
a sine
wave has
360
degrees,
as shown
in
following
figure.
Using
degrees,
you can
refer to
the
phase
angle of
a sine
wave
when you
want to
describe
how much
of the
period
has
elapsed.
Sine
Wave
Degrees
Phase
shift
describes
the
difference
in
timing
between
two
otherwise
similar
signals.
In
following
figure,
the
waveform
labeled
"current"
is said
to be
905 out
of phase
with the
waveform
labeled
"voltage,"
since
the
waves
reach
similar
points
in their
cycles
exactly
1/4 of a
cycle
apart
(360
degrees/4
= 90
degrees).
Phase
shifts
are
common
in
electronics.
