DSBSC report

Lab Project Report on

Lab Project Report on

DOUBLE SIDE BAND SUPPRESSED CARRIER 

DOUBLE SIDE BAND SUPPRESSED CARRIER 

Carried out and Submitted in

Carried out and Submitted in partial fulfillment of the requirement of 

partial fulfillment of the requirement of 

 Analog Communications Lab

 Analog Communications Lab

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)ac"lt# In*char+e, L.-.R Cha%tan#a Praa/

R Cha%tan#a Praa/

Assistant

Assistant Professor,

Professor, ECE

ECE Dept

Dept

Department of 

Department of 

Electronics and Communication Engineering

Electronics and Communication Engineering

SREENID0I INSIUE O) SCIENCE AND EC0NOLOG

SREENID0I INSIUE O) SCIENCE AND EC0NOLOG

An A"tono'o" Int%t"t%on "n/er 4NU05

An A"tono'o" Int%t"t%on "n/er 4NU05

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)ac"lt# S%+nat"re

Content

ABSRAC

Chapter 1 Intro/"ct%on

1.1 Objective

1. Components used and !ec"nical specifications

Chapter 2 0ar/6are Decr%pt%on

.1 Circuit Diagram

. Components Description .# $or%ing Principle

Chapter 3 Project I'ple'entat%on an/ Re"lt

#.1 &mplementation Procedure #. 'esults

Concl"%on Re(erence

ABSRAC,

Do"ble*%/eban/ "ppree/*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 doublesideband 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 02 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 12 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 0dB at 189 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 

INRODUCION,

OB4ECI-E,

!o design and study t"e *or%ing of DO;B<E -&DE BA=D -;PP'E--ED CA''&E'.

CO$PONENS AND SPECI)ICAIONS,

• 1567 &C

• 'esistors1%,1.%,>,#.#%,1 • Capacitors1u,1n,1n.

• :unction generator 

• Cat"ode 'ay Oscilloscope(C'O) • Po*er supply

• C'O probes and Connecting *ires

0ARD7ARE DESCRIPION,

CIRCUI DIAGRA$,

DESCRIPION O) CO$PONENS,

)UNCION GENERAOR,

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 singles"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"aseloc%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

• Adjustable ain and -ignal 8andling • Balanced &nputs and Outputs

• 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 

or s*itc"ing operations.

:or e3ample, if a modulating signal is input to a circuit using nonlinear 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 12 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.

• Connect t"e circuit as per circuit diagram.

• Apply m(t) of fre+uency 089 and amplitude greater t"an .1v • Apply c(t) of amplitude 0mv and fre+uency 0F89.

• 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, 12 modulation and over

modulation by varying t"e 1% potentiometer.

CONCLUSION,

!"e design of DO;B<E -&DE BA=D -;PP'E--ED CA''&E' is done and output is obtained.

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.}