0 ratings0% found this document useful (0 votes) 15 views12 pages2.modulation and Demodulation
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content,
claim it here.
Available Formats
Download as PDF or read online on Scribd
\
o [et Pen coe ta cic ono ay
Speen late ieee eerreeeeeroreeeee
a
ab
~_~3t ties op- Modulation 2
. ‘|
@ scanned with OKEN Scanner \
a a
[
———Tn_pera_the_cinalog_ingoomation signal sampled —
ta descrete tine fnlerual, gach sample is
hen converted 40 0 sepial n- bit _binapy code.
——“this_binaey code consisting of strings Of O¢ 1. _
— tp ic
ogtc Y__fepresents _as ‘pulse’.
ogic 0 represents OS ' Na pulse’.
0 Pr essentially has +hpee steps +
| Sampling
2) Quontisation
| =4 ign m i amples
Lapa SC wis We)
thus, at the end of the step continuous
analog signal_is_conuepted into _clescrete time
7
q)
—J
—A., sampling.
—
4
@ scanned with OKEN Scanner ‘finite number of values.
tan i imi UMbey
combinahons.
“The _quatized _sample ape assign o_binapy —
qr ti \ \ 4
ro |
i; ati coded in b
%
~ Se Pom system
5 pcm modulator consists op 2
* ii iS iHer
x __$) sampler
| 3] converter
> | 4] tow pass piitop
‘ | 5) abc 2 pac
, i
2 a
> tl
IS ed 1
i rile '
@ scanned with OKEN Scanner ~\\\
Way)
ampler
at samples the infopmotian signa) ato
Nyquist pate.
4
3
2
Apc
—rhe_voriable_cimplitude descrete signal is canuerte
6 encaded cligifal foem using Abc.
—4]|_parniiel - seria} conueeter _____— ¥
| the digitally converted deta jg in paralied
tion uses serial —
e
—foem._All_ong distance communice:
Inde, se _parauiel_cafa needs tobe converted —
~—linto sepia
using_Pparallel-_seriol=
| =this is dane by
—_conuerter -
__this_daja is then jrongmitted quer channel -
@ scanned with OKEN Scanner q [Page No] 24")
| [Bate
es L
) LS
AL ; ite "
coded dada back info_analag-—Ingrramnatian, ~
i j)_Sepia) -parallel ee ibinceitnds pace
a tonuertessental_binarsy coe etek
eh enieels The pamllel pom Cle to —
: lanaiog to peproduced the opiginal_anaiog
isignal » ! !
a i
ae Noplications af_PCM
—_8 | i do: n aS
| commercial conpies ke the bei) systems cappien
OSe PCM system
of : h s smit voice signal quer
| fou
fo
+1 | Uinitofions op Per
* o dre n, 2
si A loeqe amount oF fopu -
deansmitted £pifopy information has 49
@ scanned with OKEN Scanner y TT
Controls ay
oscillator FSk Ojp «
{weoy_, ae
“Pechnel
@ scanned with OKEN Scanner wo
i ilo} Anko
7. Esk_medulation dechriquc—is ue ee
a —pansmissions._hene_inpaemetion signal 9 ee
-\___ i.e, sining_of_ones 4_20n0s_(1's 4-08) a
5 'signol_is Analog._medulated_signal_also_ahalog,
: a sce
__ stn fsR_connesponding_4o binary o¢ he 8ign
waves of 2 difpemen! frequencies are 4ponsmi
ie. for_pinopy__a= fo frequeney} for. binary
> Jas Fi_frequency i a ;
ch | A i ed_mark frequency
iW fre. Lis ca :
7 | freq. fo is call ed__space —Prequency
7\___sthis_change_fn_freq._is obtain by changing
cannier freq.
r
~N
| fck Modulator _¢ Demodulator:
~—__fsk_modulafon _is__simply_an_oscitlafon whose
; uu Nc s
s above Sig. shows an fsk _modutaton using voltage _
5 co later (VCo). ca generates ojp
s ‘Sgnal_whose freq. is dependent an_ip voltage _
S————shen_binopy__4 jp is Opplied co op
i Oscillafes with $4 freq
NE Lh Nogic a yp ShINS +he yco orp tothe
< [po gre : : /
4 | ane ;
7 Jpetpives back
digital data;
“Follows + it Wonks as_
I
I
ae ees
|
@ scanned with OKEN Scanner ; yi ;
tind amplitude —
detector _ojp i ‘ fip's .
The Comparator compares tho two 1p Signal ¢
#S_o\P__is_either positive gotupation ap -ve
1 rc
=that_means it generates oithen binaey 4 on
binary. Q signals.
|
# phase shift eying 1Psk) +
4 : i, ' a !
Pal A nt
depending upon where the data fs ero op
‘phase _dippepence of “Ir.
@ scanned with OKEN Scanner ae
|
Ll
fi
= SS
Guadea{ure phase. apy_Reying —$
n_apsk modulation _4- phases _are_~
| eanamfssion_. phase difference *
Ue bet each a ae the major advantage op ~
+ psk $6 the bal f ¢
t half_of +the ppsk ws Mey
1 =Truth table far nd . =
ue igs
P py ual qpsk api put
A Ons up ya phase «
0 + 0. as°
: olliiaisliciil abt8S°D uv |
| +.
m }
_ y 6 aise T
hs |
rs | 1 225°
BK | ial sclesetsesssiaease
® |
i a) phase diagram
> ot t 26
ye pgs? ‘
i + WI 1 as®
N { i
, | ? ote
| 2057 ae
X uv 10
ct is =
@ scanned with OKEN Scanner \ae\
————
| constellation — Ofagpam
208 No
= 19 i] 22
a |
/
Ty
4 OI
aT —> 10
—T
—T
- 4
[ i
ls voit i
QPSK Modulafon
I \ Balanced ,
tt ‘ oh Modulator LC
} Binary tf L : :
F [aaa | [Reference
| =e l | comnien
{ I ae phase | oscillafor| i | =
| eft ej Tf shift spl
[ —| | linear _|—
lt ep! A i
[ rr Summer} of
@ scanned with OKEN Scanner | Nove_gig. shows _@PSR_mModulator cfrcutt. .
© | \_D-bil_is_inpute ul}
Senet anion Ca
— pion 1s_data_inta_parallel
VVV\\
t
can Se ee the
+o -+the g- channel,
6 athe t-bit modulates +he carrier _j-e. Inphase
wwith the pePerence ascflator.
VAVVAVAA
© “he g-bil_modulales the cappier i.e. 90° outoge
e =the go° culofr phase signals of + £@ modulators
“2p fermhinesl_—in_ inert Summers. Lig
a L @psk Domodulatop
DT TTT]
@ scanned with OKEN Scanner LPF
te
| roduct LPE
=channet >) Cetecton_ |
i @
@ scanned with OKEN Scanner
