Residual Fm Test - Wavetek 3001 Instruction Manual

4.9 RE SIDU AL FM T
EST
ME THOD
E
QUIPMEN T
PR OC EDURE
3. Set the modulation meter to read %ΑΜ at 500 MH z. Set the RE inpu t
υΙπιηιιαΙιυιι
ιιι 10 ιΙβ .
ι
h
ι-
I
F hαιι(1 ωι dΙΙι Ιυ 1 400
k
Ι It, ΙΙω ιηιινι πνηι ιιτr
ιπ fart, Ι hε Ιιιη c ηυη ; .witch to Ι AM . t he meter range switch to 10, αηιΙ
if) ;
f
ill "ί ΜαηιΙωίd Ι tι
Ιιι
5Π Hi - 15 kH z .
4 .
Adj ust the
M
OD U LA f1O N FM/AM control for α mod ulation meter
read i ng of 10'tέ AM . ΝΟΤΕ ~ 10% AM is obtained at α full-scale r
eading of
100 wit h
t
h e modulatio n meter r
ange switch set to 10 .
5,
W
ith the distortion analyzer operating in level
m
ode, rall brate it for α
D dB meter read ing. Th e system is now calibrated at α reference level 20
d8 b elow t h e career, Since th e modulati ng signal
a
n d carr ier α mμΙίτιι de τ
a
r e equal at 100% AM .
i
t
follows that α1 10% AM the
m
odu lating signal
is 20 dB below the . carrier .
6 .
Set the Γι1Π(lI1 L A1 ΙπΝ
h 1 00 E τπ EXT.
7 .
W
it hou t distw hing the ;η s2rυmηπι and
m
od ulation m
eter controls
set th e d ίτιη rτίιι rι analyzer to read resi dual AM . Set t h e ra nge switch so
t h at Ι hι" ιπυω r rcarn Ιι r1 να ~c ιι Π αηο it) on
read the sesidlill Aft. ,
below ι he 0 dB ι-cference level in step 5 T hen ad d 20 dB to the αΙιπνι
reading to obtain ιΙιe rm ίdυα 1 AM
b
elow t h e carrier . ( F or example, α 48
t18 resi dual AM below the 0 d8 refe rence +20 d
8 = 68 d8 residual AM
below
t
he carrie ι . or -68 dBc.) The residual AM should be <-65 d
Βι
Record the re ιΡ d ιιαΙ AM in dB c on line 27 of the
P
TR ,
As many othet carrier frequencies may
b
e tested as desire d .
S
PECI F ICATIO N <200 Ητ in α 50 Hz to 15 kH z pnst r .l etect ί on
b
an dwi dth.
<100 Hz in α 300
Hz
".ο 3 kH z Post detection bandwi dth .
Α mo dulation πι eιοι which is set to read fre quency
d
eviation is used to
m
easure residual FM . The test is performed at maxim um freque ncy and
output level . T h e instrument is operated in an FM mo d e w
here
the residu al
F
M
is
greatest .
T
he resi du al FM is measured in an environment where t h e noise level <60
dB relative to 2 χ 1( Τ'
g
bar .
1 . Set the instrument controls as follows :
FR ED VERN I ER
CA L
F
requency
selector
520.000 MHz
MODULATION MODE
FMX110
MOD ULATIO N FRED
ΕΧΤ
M
OD UL ATIO N FM IA M
0 kH z
O UTPU T VERN IE R
Full cvv
OUT PU T Step Α r ιεηιια tοι
+10
d
Bm
2,
Connect th ε RE OUT connector to the 50 ohm RF input of the
m
odu lation meter .
3 .
Set the modu lation meter to
read
FM deviation at 520 MHz. Set the
4-1
1