AsYncHRDNOUs DE TECTOR.
hw emodulate
4hlt)
NLD
fm
deice) (ct-oft)
tos 2nfet + V Ka mlt cos2nfet
MEsV
6 ’+ve constant)
V2 aV+bye fa
hamtt) cs 2nfct +
- a cer2nft t a
bVco2nft by Kå m?lt)co*2nfct t
co2fet
&b v ka mlt)
24ft taVo Kamlb Co4 2nfot t
-aVu
(Ifteaf
by2
2.{m
bv² kamlt) + bveomE)
de value.
+ban
not duired.
NOTE an anbiier.
Ay demodul ato is -follouwel by blockel
de COmponent is
Jn ampufer,thethis b Aç2 is biockked.
by capaito· So receiver, rotio of
nininum distoction at
For
to undesired sjghal
desived stgnal
Ratto bY Kamlt) Kamlt
be2 Ka m2{t)
2
mut be high
ve CoY mim distoli Cn Kamit)
o, \o becomw
It) + bVe Kamt).
9 Vo= bVe?Kam
mt)
2fm
mt has freq om
fm,
has auo 1gnihicant fros sepm
means m2l) Cawes imtuence
mt) Thu t
modlated sinal
So i
by
o caer am u prey ynt
euH in 2AD ton onich rell i
easy demduotion.
ii) EnNelcpe deaoL Verar
the envelee coutou
To datct msg we
hare to detoc the erele
SL) - ract cally
R
Vin V
Casacite chages to the peak value ot
input signal
Vin: -sbM
Vin
iode is
is încreasing
2 Vin it
Ve=0
idea! we can iapla.e
sinco t is
fG. = c'stats chcuging
wrth shot
ckt. Rc which u
eDntant ' t
chasging time ans Cgets changed
vey lo thot means
quiculy acrBs Capacit
voHge
hich meahs capadts
A = t , Ven
AL
nst &uddeny
udd enly doop to dereasing
de iode is RA )
VcVin =)
\votoge
Nicdo voplaced uoith
Capacte
TAisehage be vey lagt
Capncter disehage lowly.
At t=t, NË1 vËsVe = ode .6-t
t2 t3 t
Tie ipple ave veuy lso. sine signai
is very lous.
lalocled
Neired
Cn case of undermodulation.
Eme lope
Acltw
t
Crihcal noduloticn.
Sn cae of
slem
t
Jn case of hyeomodlatiun.
-’ m st
(En'b/p
ConclucLons
Co Bemodulatçn posside ony feusa
(E)
Signitcance af Ka
we det mit) = 2cestmt
veomnbdulateA.
be c o s
Keeps this in checle amd eeps Tts
7+ ate
uch that | ei (Lnder moculatitn]
ischarqng tinune CoAtant should oti sfy
we cannot sack the
RC e l
L
becaue 'c' dischauge
arviey
ênvelepe of
quicy
cips
taok, Ro itt
0nhot
’ED Counot
DIACAONAL
Khtwn as
which is.
00ne part
CUPPING.
aNoid diogonal clipping
2o t
Hence This is only a nece y
fm Condh but not sutrcient)
RC ce Jirue
Ju2 (time congtont of ED
depemds
and dulatrin ìnder)
mt)
vleo'enfot
c2nfot mlt)V.?os2nfctt
ve
(na 4 oRn
, Ka hNe we
(mustipier
ofp
e'mt)
mutplies mlt)
datectesynchnus we we uta
used hot EDslg»odulao ovesy -for
DETECTDR.SNCHROUOUS (")
20us Rc=
1fn
50Oe. us
).2
of
is EO cowstant time bf
valueSitae A
(LPF olp
arnoitley aich rejets
LPF folowed by an
dc tem
ampitude chanpe
mt) [Anplitude change can
LP = AcAc bbe easily manape d).
f (loop = Ac ces (2n! ct t 6).
tthen (AM)x LLO) op
Ac
+6)
Ces Lnfet c6s(2fct
Ae cos ( y tt ) +Ac
4Amt cos
Acmlt
ohen =o 2
This is called QUADRATURE NUL
EfPECT.
AM] of
Case n |eF
pwer
SB Pewe
D CorrieY
o'se Yotio-to ignol P5bW )
Pse
eliminataAr resed upp AM
Cawe &inseidal.
the f wos Over
na nessope nohen 33/ m= Yna AMr Jn ofDER
Advontgge
Modulation Carsier)
ressed sidebamd Double DsB-Sc
(
Comnnation ast BYod
ommicocion mutipoint toPoint
COSTAS
RX in
ud handuo
e additional Thu
ha,cdditono eqùres lhich YeceiveL
tansmitter lyeheen mentaid is
ti6 2
prolblem t
thy escomo Jb
enuated ctt cignal
is \e.
fAcmcos olp=
oea tohen
S
N
(same a priou)
(n case of DSB-Sc
FoL Same Sratio 4 2 otho conditto ns, pSB-SC
requires les pner
Standaudform of Dsß-Sc
st) = Ae Kamlt cos 2nfet neunaizatton)
Cohce pt of
Ka1 ho
Acmlt) cos2fettime domain e
DSBSc =
Sit) = m(t) ct)
PrequenCy doman qn'
st) = Ae tM Gf+fe)
MC-f) +M
MC)
-frn
w fc4fm-({c-fm) fm
NDTE
Bw of DSD-SC is So The ong
advantage wt AM iS
greater eficiency.
(ess power e
SINGLETONE moDULATION oP DSB
Ket mit) z An Cos 2fmt
S\t)= AeAm cos2nft cog 2nfct
Slt) = Ac Am CoS 2n (fo+Prn)t t Ce9 2r Cef)t
USB LsB
s(t)= Ac Am s(f -(ietfm)) t s(f+ (Aetfs))+
4
AcAn
4
-(fctfn) -(fr) etfm
Puwey aleuloion
Pr=(amy(amAm
4 R
Ka=4
= A
Ghemeralsed -formula for DsB-power
sgnal
ci') mtt) Trianplae
P= Am
P AcA
cici) mlt) is ectogua
Pr= ezAm
2R
is modulated by a mS
mit) 5 Cos 27(6t is wsed to genen
gketch spectum
DSB Sinal.
Spse lt) clt)
Cos 2n (o-ot
27 (io4oJtt
= 520 fcos
PoweySavedi
bpooe saved
fe
Saved
lo Psaned =
2+u2
Psoned: (-nan)xi00
Note
Psared 2t
(00 2200 Y, =6667
Repeot te questicn
-
mlt)=
2co547bt
G¾NERATIDN of Dsß -SC
Any modulatee that femeral
CUe PRoDUct muoULATDR
mlt) Brocuct mlt)ett)
Modulata
c (tJ
product modulate?
Tuto
\cÛo ty pes of
) Baloncod modulato modulatu Co) Dousle
modulats. (o Lathce
Balane Moduloto
BALANCD oDULATOR
Suiteling
moollato
t
olp
LO (6LOCK þIAGRAM)
A S,tt)
mod (2
R C
(rciRCUT DAqRAy)
Analysis
S,IH= Ac(ttKamlt)) Coswet
S t) = Pel-kamlt))Coswat
DSB-sc S,t)-stt)
- Aclitkamlt) Jcos wtAcit-kamt
C
:A, tesuwt Acanit) cotot -
Ac Kamtt) cs wt
Actwct t
JA Kalt coswt
StlDsB-SC tNA Kamtt) oSwat
mit)ct)
off Dy 2Ds
2 D iode D
hay ouring
(E)ve
clu ofeycle
clt) On
ody four
di Gf
au, Opesoton
nt
ct
RAM DIAG CUROIT
sttDsg-sc
used re diodes four
fe>fm - AcAm
messa
cosomt Am mt=) Sgnal
Omt. ctt) of F-s
signal
of analog quivalent
fe
Ct)
qraqueny
fc. with wave
qu0 eipna!
is Caier modulatse, ing Ln
modulate Ring (2)
hay crcte of clt).
-uinq (-ve) - ) of
- on
Cquêvaleut siusoidal cqn af cl)
cl4)-_4 Iy cos 2n fetl2n-n)
n n
wil be
Lquiralemnt nodulatsd DeB-SC
slt)= mlt}.ct)
coS2nfet (2n-1))
.mt)
AAVERRM AALSIS -
e).
t
SLt).
Dg?yon
9:- ln a DSB- l caier AM Syte,
uu doubled, then Bre votiw of sdoband
t fao
nesases by a
Pawer o carver pnser
of
PË= Pet
ytine
1! u doubled, eio s
Considey &noid
ida!ovee modulaton in an AM
: modulat, the
System Ascuning2 min volucs of. envelope
when max
respeotieey ane
Vnin = Afe-)
uE Vimar-Vmin
Vmox
sfusoidal aies s atnpihde
A L MHz symmetical Sq uae twove
modulated by a
which ot the fsequencie
Of peiod be presett in moculad e9 2
wl
(a) kHe
qq0kHe (b) (o1o KHz
(030 k He
6-6
Snee modulattng slg is synntical
Sq. uove it contain ony odd hauoie
10kH, 36WHZ; 50H2 ere
Tuus nmodulald Sna has
ctfn = (o|D
fc-fm q90
Jct3P (o00 t30=l030
ore) nof avoulable
Con sider
denoulating it using Ep, the min
value of Ac should be
)
- Conade aa systen
ot
etemine fve fus
which ofp sls
3 (e 3L hoving
