Lab Project Report on DOUBLE SIDE BAND SUPPRESSED CARRIER
Carried out and Submitted in partial fulfillment of the requirement of
Analog Communications Lab Class: III B. Tech ECE (A
A.!.: "#$%&"#$' i irst Semester
By G.S.Archana
Roll No. 12311A!1
D.Ar"na
Roll No.12311A!11
S.Bab# $o"n%&a
Roll No.12311A!12
Na'e o( the )ac"lt# In*char+e, L.-.R L.-.R Cha%tan#a Praa/
Assistant Professor, ECE Dept
Department of Electronics and Communication Engineering SREENID0I INSIUE O) SCIENCE AND EC0NOLOG An A"tono'o" Int%t"t%on "n/er 4NU05
)ac"lt# S%+nat"re
Content
ABSRAC
Chapter 1
Chapter 2
Chapter 3
Concl"%on Re(erence
Intro/"ct%on 1.1
Objective
1.
Components used and !ec"nical specifications
0ar/6are Decr%pt%on .1
Circuit Diagram
.
Components Description
.#
$or%ing Principle
Project I'ple'entat%on an/ Re"lt #.1
&mplementation Procedure
#.
'esults
ABSRAC, Do"ble*%/eban/ "ppree/*carr%er tran'%%on (DSB*SC) is transmission in *"ic" fre+uencies produced by amplitude modulation (A) are symmetrically spaced above and belo* t"e carrier fre+uency and t"e carrier level is reduced to t"e lo*est practical level, ideally being completely suppressed. &n t"e D-B-C modulation, unli%e in A, t"e *ave carrier is not transmitted/ t"us, muc" of t"e po*er is distributed bet*een t"e sidebands, *"ic" implies an increase of t"e cover in D-B-C, compared to A, for t"e same po*er used. D-B-C transmission is a special case of doublesideband reduced carrier transmission. &t is used for radio data systems.
D-B-C is basically an amplitude modulation *ave *it"out t"e carrier, t"erefore reducing po*er *aste, giving it a 02 efficiency. !"is is an increase compared to normal A transmission (D-B), *"ic" "as a ma3imum efficiency of ##.###2, since 4# of t"e po*er is in t"e carrier *"ic" carries no intelligence, and eac" sideband carries t"e same information. -ingle -ide Band (--B) -uppressed Carrier is 12 efficient. !"e C1567 is a monolit"ic transistor array arranged as a balanced modulator demodulator. !"e device ta%es advantage of t"e e3cellent matc"ing +ualities of monolit"ic devices to provide superior carrier and signal rejection. Carrier suppressions of 0dB at 189 are typical *it" no e3ternal balancing net*or%s re+uired.Applications include A and suppressed carrier modulators, A and : demodulators, and p"ase detector
INRODUCION, OB4ECI-E,
!o design and study t"e *or%ing of DO;B
CO$PONENS AND SPECI)ICAIONS,
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1567 &C 'esistors1%,1.%,>,#.#%,1
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Capacitors1u,1n,1n.
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?ector board
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:unction generator
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Cat"ode 'ay Oscilloscope(C'O)
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Po*er supply
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C'O probes and Connecting *ires
0ARD7ARE DESCRIPION, CIRCUI DIAGRA$,
DESCRIPION O) CO$PONENS, )UNCION GENERAOR,
A ("nct%on +enerator is usually a piece of electronic test e+uipment or soft*are used to generate different types of electrical *aveforms over a *ide range of fre+uencies. -ome of t"e most common *aveforms produced by t"e function generator are t"e sine, s+uare, triangular and sa* toot" s"apes. !"ese *aveforms can be eit"er repetitive or singles"ot (*"ic" re+uires an internal or e3ternal trigger source).@&ntegrated circuits used to generate *aveforms may also be described as function generator &Cs. Alt"oug" function generators cover bot" audio and ': fre+uencies, t"ey are usually not suitable for applications t"at need lo* distortion or stable fre+uency signals. $"en t"ose traits are re+uired, ot"er signal generators *ould be more appropriate. -ome function
generators can be p"aseloc%ed to an e3ternal signal source (*"ic" may be a fre+uency reference) or anot"er function generator.:unction generators are used in t"e development, test and repair of electronic e+uipment. :or e3ample, t"ey may be used as a signal source to test amplifiers or to introduce an error signal into a control loop.
1567 &C C1567B *as designed for use *"ere t"e output voltage is a product of an input voltage (signal) and a s*itc"ing function (carrier). !ypical applications include suppressed carrier and amplitude modulation, sync"ronous detection, : detection, p"ase detection, and c"opper applications. •
E3cellent Carrier -uppression 70 dB typ .0 89 0 dB typ 1 89
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Adjustable ain and -ignal 8andling
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Balanced &nputs and Outputs
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8ig" Common ode 'ejection >0 dB typical
7OR8ING, odulation $e e3plained t"e t"eory of amplitude modulation above, but *"at sort of circuit is actually used !"e symbol for amplitude modulation is a multiplier, but actual circuits use t"e nonlinearity of transistors or diodes,
or s*itc"ing operations. :or e3ample, if a modulating signal is input to a circuit using nonlinear amplification, several "ig"er "armonics are generated in t"e output due to t"e amplification c"aracteristics of t"e circuit. !"is "ig"er "armonic contains a sum (or difference) component of t"e information signal fre+uency and carrier fre+uency, and if a suitable filter is used to eliminate t"e un*anted components, t"e correct amplitude modulation *aveform can be obtained. Demodulation Demodulation (detection) met"ods for amplitude modulation on t"e receiving side include sync"ronous detection and async"ronous detection. -ync"ronous detection demodulates t"e received signal by multiplying it *it" a carrier fre+uency *"ic" "as t"e same fre+uency and p"ase as t"e transmission carrier *ave. Async"ronous detection includes envelope detection and rectification detection. $it" async"ronous detection, t"e information signal m(t) must be incorporated in t"e envelope of t"e receiving *aveform. $it" a modulation factor of 12 or more, demodulation is not possible *it" async"ronous detection, but *it" sync"ronous detection, correct demodulation is possible. 8o*ever, sync"ronous detection re+uires comple3, costly circuits.
I$PLE$ENAION PROCEDURE,
• • • • •
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Connect t"e circuit as per circuit diagram. Apply m(t) of fre+uency 089 and amplitude greater t"an .1v Apply c(t) of amplitude 0mv and fre+uency 0F89. Observe t"e output D-B-C *aveform at ?o. Plot t"e *aveforms (Amplitude, fre+uency) of m(t) and s(t) to t"e same time base scale. 'epeat t"e e3periment for under modulation, 12 modulation and over modulation by varying t"e 1% potentiometer.
RESUL,
CONCLUSION, !"e design of DO;B
RE)ERENCES, !"is article incorporates public domain material from t"e eneral -ervices Administration document G:ederal -tandard 1#HCG Electronic communications by eorge Fennedy. Analog communications 1st edition by B.P lat"i.
