Pulse Amplitude Modulation I.
PU51 AMP5ITUD1 MODU5ATION Mu!ammad Mui00uddin 3in 6ainol A$idin (7'+'+'7+8') Mo!d Noor -ai0 3in A$dul Ra!im (7'+'+'7+77)
INTRODUCTION Pulse-amplitude modulation (PAM), is a form of signal modulation !ere t!e message information is en"oded in t!e amplitude of a series of signal pulses. It is an analog pulse modulation s"!eme in !i"! t!e amplitudes of a train of "arrier pulses are #aried a""ording to t!e sample #alue of t!e message signal. Demodulation is performed $% dete"ting t!e amplitude le#el of t!e "arrier at e#er% s%m$ol period &'
T!e "on#ersion of analog signals into digital signals is di#ided into se"tions important t!at is* &+ '. ampling Is t!e pro"ess of sampling of t!e signal information to $e pro"ess. -reuen"% signal a""ording to t!e rules of N%uist sampling is + fm, fm is t!e information signal to $e sampled. &+
$% means generates a signal pulse of t!e pulse generator to ad2ust t!e pulse idt! (To) is dis"rete. 3ut t!en it s!ould $e understood t!at in fa"t form a PAM signal is generated is* ignal PAM is s!aped dis"rete on time and "ontinuous le#el region •
ignal PAM s!ape is not purel% analog signals and digital signals are not pure form &+ •
II. 1/UIPM1NT 4 Analog "ommuni"ation module 4 Poer suppl% 4 -un"tion generator (it! seep option) 4 Os"illos"ope
+. /uanti0ing Is t!e aard of a signal t!at !as $een sampled $% $ringing t!e signal on t!e aard of $inar% $its reuired. &+ . 1n"oding Is a pro"ess of "!anging t!e $inar% "ode into o$2e"t "ode in a""ordan"e it! t!e appli"ation of t!e "orresponding digital signals. &+ At a sampling pro"ess "an $e done $% using to t%pes of signals, namel% a pulse or impulse. PAM modulation signal is a signal to t!e digiti0ation pro"ess in t!e form of a pulse signal input. PAM signal formation in t!e digitali0ation pro"ess using pulse represents a first step
Page | 1
Pulse Amplitude Modulation III. PROD1CUR1
7.
'.
+.
:.
. PU51 AMP5ITUD1 MODU5ATION
9.
In t!e imulin; MAT5A3, Pulse Amplitude Modulation need to $e "onstru"t $ased on t!e -igure '. Original signal (inus
Page | 2
Pulse Amplitude Modulation -igure 9 t!is ill $e ampling ignal. Pulse =enerator !ad to $e set in t!e parameter period (se"s) as s!on -igure +. et t!e period for pulse generator to >.+7 se"s 3ot! of t!e signals (Original signal and ampling signal) ill $e multiple $% using Produ"t $lo"; and "onne"t to "ope. T!e result of t!e multipli"ation ill produ"e Pulse Amplitude Modulation (PAM) as s!on in t!e -igure 7. Repeat t!e steps and "!ange t!e period for pulse generator to >.'+7 se"s and '.+7 se"s and o$ser#ed t!e "ope, "ope' and "ope+ to "ompare t!em.
Figure 3: Original Signal
I?. R1U5T
Figure 4: Sampling Signal
Figure 2: Pulse Generator Parameters (0.25 secs)
Figure 5: PAM Signal
Page | 3
Pulse Amplitude Modulation
Figure #: Sampling Signal
Figure 6: Pulse Generator Parameter (0.25 secs!
Figure $: PAM Signal
Figure ": Original Signal
Page | 4
Pulse Amplitude Modulation
Figure 2: Sampling Signal
Figure 0: Pulse Generator Parameter (.25 secs!
Figure 3: PAM Signal
?. ANA5@I
Figure : Original Signal
-rom t!e data "olle"ted, t!e stud% found t!at if fm is ;0 and fs B ;0, t!e "ut off freuen"% of t!e lo pass filter t!at demodulates s PAM signal s!ould $e slig!tl% a$o#e fm. and ' and $% sele"ting t!e rig!t time instants for sampling t!e
Page | 5
Pulse Amplitude Modulation PAM signal. 3ut if t!e $and limitation is strong enoug! to "reate inters%m$ol interferen"e (II), t!en an in#erse filter ma% !a#e to $e used to euali0e t!e "!annel $efore t!e tet message "an $e re"o#ered.
?I. CONC5UION In s!ort, PAM is a general signaling te"!niue !ere$% pulse amplitude is used to "on#e% t!e message. PAM pulses "ould $e t!e sampled amplitude #alues of an analogue signal. To main t%pe of PAM in"ludes natural PAM and flat top PAM. In order to "on#ert analog to digital signal using PAM, t!e signal !as to undergo
pro"esses su"! as sampling, uanti0ation and $inar% en"oding.
?II. R1-1R1NC1 &' !ttps*en.i;ipedia.orgi;iPulseE amplitudeFmodulation &+!ttp*ama0ing"rue.$logspot."om+>'+ >9dasarEteoriEpulseEamplitudoE modulation.!tml & 5e"turer Notes
Page | 6
