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Sect.
tr
Page
I
s,\'itches pc)sitive, Notc the
coLrnt.
Switch l)oth
TIIIG-
GEii SLOPE
Srvitches
to
cgati\/c
and note thc' count.
U
these
two counts
are
not
equal, rdjust
the
STATiT
T;UCCE,l
LEI EL
VOLTS
coDtrol unLil equal
{rounts
aIe
obtained
with
both
TliIGGElt
SLOPE
s* itchcs
positive
ind
both
negativc.
Phase
shiJt
(clegrees)
=
360
x
F
x
Count
(miLlise((xds)
1000
Where
F is thl, i'oquency oI
the
\!'a!eforln
beilg
nr(,as
-
ured. This is
the lrur]1bel'of degrees t]re
STAiiT
rvave-
form
leads
fie
STOP
wavcfor-m.
II
an
efiernal
TIME
LrNn
-is
used
that
is
360
times the flequency of
the
me:rsurcd ivaYeforl1r,
the count
will
i)e
the nuntl]er
oI degrees
thc S'I'AttT
ivayefol.m leads the STOp \r,.tve-
Iornr
and rlo
ca]culations
will
be requir.ed.
Maximum accuracy
is
obtirined
when
the
instrunlent
is triggered at or near
the
zero axis crossing of
the
sine wave. The two counts
will
he equal lvhen
the
STAITT
ilnd STOP channels
itre triggered
rhe same
number oI
electrical
degrecs
lrom
the
zero
a-xis
crossing
ol
each
wa\.efo.rm.
This
measurernent is
explained as follows:
2d.o,'or-b,+b.+1+rr
T,.T.,or,o,,b.bt
+. r
.r.
t'igure
2-5.
Phase Measule ments
In
Lhc
illustratlon
T1 =
T2 since
we
ha,,
c specrlied
equal counts with both TiIIGGER SLOPE
srvitches
*
and
both
-.
Because
of the
synl[tetry
oI
thc
xil,,'e
-
fornrs
a1
= a2 and
b1
=
b2,
_
_:c!oo
1lq!cl]rrr.
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