O)/ECTIVES* To vary t&e message signal's amplit$de and observe &o( it a))ects t&e mod$lated carrier To observe t&e e))ects o) mod$lating t&e carrier too m$c& To be able to meas$re t&e AM signal's dept& o) mod$lation $sing a scope
+I EL,I- pl$s connecting leads +I Data Ac%$isition $nit s$c& as t&e -/0231 4or a 25M67 d$al c&annel oscilloscope8 Emona DATEx experimental add0in mod$le t(o /+" to 2mm banana0pl$g leads Assorted 2mm banana0pl$g patc& leads
III.
(#T# #N( RESULTS*
9riginal Wave)orm
Wave)orm 2: Message -ignal and AM -ignal
Wave)orm 2: 6al) and ;$lly cloc(ise o) #
<$estions: 1. In (&at (ay is t&e Adder mod$le's o$tp$t no( di))erent to t&e signal o$t o) t&e Master -ignals mod$le's 267 -I+E o$tp$t= Ans(er: T&e Adder mod$le's o$tp$t signal di))ers )rom t&e signal o$t o) t&e Master -ignals mod$le's 267 -I+E o$tp$t d$e to t&e added re%$ired carrier )or t&e AM signal.
2. W&at )eat$re o) t&e M$ltiplier mod$le's o$tp$t s$ggests t&at it's an AM signal= Ans(er: T&e M$ltiplier mod$le's o$tp$t's )eat$re t&at s$ggests it is an AM signal is t&e variation o) t&e mod$lated carrier's amplit$de above and belo( t&e $nmod$lated amplit$de.
>. T&e AM signal is a complex (ave)orm consisting o) more t&an one signal. Is one o) t&e signals a 267 sine (ave= Explain yo$r ans(er. Ans(er: ?es@ beca$se t&e message signal &as t&e )re%$ency o) t&e carrier (&ic& is t&e 267 sine (ave signal.
. ;or t&e given inp$ts to t&e M$ltiplier mod$le@ &o( many sine (aves does t&e AM signal consist o)@ and (&at are t&eir )re%$encies= Ans(er: T&e AM &as t&ree sine (aves. ;irst@ t&e sine (ave (it& t&e carrier's )re%$ency. -econd@ t&e sine (ave (it& t&e )re%$ency (&ic& is t&e s$m o) t&e carrier and t&e message )re%$encies. Lastly@ t&e sine (ave (it& t&e )re%$ency (&ic& is t&e di))erence o) t&e carrier and t&e message )re%$encies.
3. W&y is t&ere still a signal o$t o) t&e M$ltiplier mod$le even (&en yo$'re not &$mming 4or taling@ etc8= Ans(er: T&ere is still a signal o$t o) t&e M$ltiplier mod$le beca$se t&ere is noise inter)erence.
B. W&at is t&e problem (it& t&e AM signal (&en it is over0mod$lated= Ans(er: T&ere (ill be an increase in mod$lation index above 1 i) t&ere is overmod$lation in t&e AM signal. T&e carrier &as 1C5 degrees p&ase reversal (&ere t&e carrier level (o$ld try to go belo( 7ero point.
C. W&at do yo$ t&in is a carrier's maxim$m mod$lation index (it&o$t over0 mod$lation= □ □ □ □
IV.
A min$s n$mber 5 1 #reater t&an 1
CONCLUSION*
I t&ere)ore concl$de t&at@ in t&is experiment@ by comparing t&e amplit$de signal )rom t&e original message@ (e can observe t&e )ormation o) envelopes (&ic& is a pair o) sine (ave above and belo( t&e carrier signal t&at gives t&e s&ape )or it. And@ (&en message signal's amplit$de is varied@ it also a))ects t&e amplit$de o) t&e carrier signal. T&ey vary directly proportional to eac& ot&er. T&e mod$lation index can be vie(ed )rom t&e oscilloscope display or can be meas$red t&ro$g& t&e minim$m and maxim$m val$es )or t&e mod$lated signal.
