7/30/2019 Phng php iu ch s

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Phng php iu ch ASK ( bin ):

Phng php iu ch ASK cho php ti to tn hiu ASK dng sin vi 2 bin .Bin ASK ph thuc vo gi tr bit d liu .+ DATA=1 iu khin kha K ng, ASK nhn c li ra chnh l sng mang

truyn qua, c bin bng bin sng mang.+ DATA = 0 iu khin kha K m, sng mang khng truyn qua c, ASK c tnhiu bng 0.Phng php gii iu ch:

iop sa dng--> b lc filter--> sa dng former--> data+ t/h c tch trc tip, sau qua b lc thng thp vs qua mach sa dngxung

Phng php iu ch FSK (tn s) :

Phng php iu ch FSK cho php ti to tn hiu FSK dng sin vi 2 tn s, gitr ca FSK ph thuc vo gi tr bit d liu.- Khi s dng biu a :+ DT=1 : kha k v tr ni sng mang tn s F1 vi li ra FSK+ DT=0 : kha k v tr ni sng mang tn s F2 vi li ra FSK- Khi s dng s b :+ DT=1 : s dng my pht iu khin bng in th VCO ung vi trng thi 0hoc 1 ca d liu, VCO s pht 2 tn s F1 vs F2 tng ng- Khi s dng s c : s dng cc b chia vi cc h s chia khc nhau, M vs N.

D liu bit s dng iu khin chn h s .+ khi DT =1: b chia c h s chia N. to xung ra c tn s F1= Fclock/N+ khi DT =0 : b chia c h s chia M, to xung ra c tn s F2Phng php iu ch PSK (pha) :

S ti tn hiu tn hiu PSK dng sin vi 2 gi tr pha, ty thuc gi tr bit d liu+ DT=1 : sng PSK cng pha vi sng mang+ DT=0 : sng PSK ngc pha vi sng mangS iu ch thng c thc hin trn b nhn sng mang vi d liu bitGii iu ch:

sng PSK->(x) bnh phng sng->PLL->delta phi->:2->x->filter->former->data

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S gm b ti lp sng vs b nhn

+ b ti lp sng mang: bnh phng sng chuyn cc tn hiu khc pha v

cng mt pha. Vng gi pha PLL pht li nhp vi f=2f sng mang. B dch pha

7/30/2019 Phng php iu ch s

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deltaphi dng hiu chnh pha. B chia 2 a tn s tn hiu ti lp v bng

tn s sng mang

+ B nhn tn hiu thc hin nhn sng iu ch 2-PSK vi sng ti lp.