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  • 1 - Khi thu pht tn hiu

    1. S khi tng qut knh Thu - Pht tn hiu .

    S khi ca knh thu tn hiu

    z ngha cc mch v tn hiu trn s khi : - ANTEN SWITCH : Chuyn mch Anten, do c mt Anten hot ng chung cho c hai ch thu v pht bng sng GSM v DCS v vy cn c chuyn mch, trong mt thi im Chuyn mch s ng cho Anten tip xc vo 1 trong 4 ng trn .

    Hnh dng thc t ca chuyn mch Anten

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  • S nguyn l bn trong chuyn mch Anten - FILTER : L b lc, knh thu l b lc thu, nhim v ca b lc l cho tn hiu trong gii sng cn thu i qua, trit tiu cc tn hiu can nhiu .

    Hnh dng thc t ca cc b lc K hiu trn s - RXI v RXQ : Cc tn hiu iu ch vung gc thu c sau mch tch sng iu pha, y l cc tn hiu s . - RF IC : IC Cao trung tn, thc hin cc cng vic : Khuch i, trn tn v tch sng iu pha ch thu v iu ch cao tn ch pht .

    Hnh dng thc t ca IC Cao Trung tn, l IC chn gm . - AUDIO : IC M m tn, thc hin cc cng vic : Gii m v m ho tn hiu, i tn hiu t Analog sang Digital v ngc li .

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  • Hnh dng thc t ca IC Audio - VCO : ( Vol Control Ossilator ) : Mch dao ng iu khin bng in p , c nhim v to dao ng cao tn cung cp cho mch trn tn ch thu v mch iu ch cao tn ch pht

    Hnh dng ca b dao ng VCO - 13MHz : y l mch dao ng tao ra tn s 13MHz ( trong my Samsung ) hoc 26MHz ( Trong my Nokia ) mch ny to ra xung nhp ng b mi hot ng ca cc IC trn my nh IC Cao tn, IC m m tn v IC Vi x l, ngoi ra 13MHz l tn hiu Clock cung cp cho CPU hot ng .

    Hnh dng ca b dao ng 13MHz hoc 26MHz - Speaker

    Hnh nh thc t ca Loa trong in thoi di ng - IC PA ( Power Amply )

    Hnh dng IC cng sut pht

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  • - POWER : Khi ngun, iu khin cp ngun cho khi iu khin thng qua cc in p khi ng VK1, VK2, VK3 v cp ngun cho khi thu pht thng qua cc in p iu khin VK1, VK2, VK3 .( Xem li khi ngun ) - CPU v Memory : IC Vi x l v cc IC nh : iu khin mi s hot ng ca my ( Xem li khi iu khin ), trong c iu khin qu trnh thu pht , iu khin m ho v gii m tn hiu m thoi v cc tn hiu khc nh tin nhn, m bo vv..

    2. S v nguyn l hot ng ca knh Thu tn hiu

    Bn a tr chut vo s xem ch thch

    S knh thu tn hiu

    z Nguyn l hot ng ca knh thu : - knh thu v pht u tn ti 2 bng sng l bng GSM v DCS hot ng song song, tuy nhin Vit Nam ch s dng bng GSM nn ta ch cn quan tm n bng sng ny l chnh : - Bng GSM c di tn thu t 935MHz - 960MHz, mi in thoi khi lin lc ch s dng mt knh c gii thng l 200KHz nhn thng tin, vic s dng knh no trong gii tn trn l do i pht quy nh mt cch t ng, khi s thu bao lin lc vt qu s knh cho php th sinh hin tng nghn mch . - Tn hiu pht i t cc trm BTS ( Trm pht sng ) c thu vo MS ( My thu ) thng qua Anten .

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  • => Tn hiu thu qua Anten => i qua Chuyn mch ( ANTEN SWITCH ) => Qua b lc thu ( FILTER ) loi b can nhiu => Sau tn hiu c khuch i ( AMPLY ) tng bin => i qua b ghp h cm ( COUPLE ) chia tn hiu thnh hai tn hiu cn bng => i vo IC RF => tn hiu c khuch i ri a vo mch trn tn ( MIXER ) => Tn hiu dao ng ni VCO c chia tn qua mch ( DIV ) sau cng c a vo mch trn tn ( MIXER ) - u ra mch trng tn ta thu c tn hiu trung tn, tn hiu c a sang mch tch sng iu pha ( DETECT ) ly ra cc tn hiu s RXI v RXQ => a sang IC m m tn Audio . - IC m m tn cho gii m GMSK ( DEMOD ) sau tn hiu c a qua CPU g m chng nghe nn v tch ra cc tn hiu iu khin, tn hiu thoi cho quay tr li IC m m tn => a qua mch i DAC ( Digital Analog Converter ) i tn hiu s sang tn hiu Analog ly ra tn hiu m tn, cho khuch i ri a ra tai nghe. - Cc tn hiu iu khin c CPU s dng so snh vi d liu SIM Card, chy phn mm iu khin Dung chung Led v hin th thng tin trn mn hnh .

    Bn a tr chut vo s xem ch thch

    V my NOKIA 8210

    3. S v nguyn l hot ng ca knh Pht tn hiu

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  • Bn a tr chut vo s xem ch thch .

    S nguyn l knh pht tn hiu

    z Nguyn l hot ng ca knh pht . - Tn hiu thu vo qua Micro c a vo IC Audio ( IC m m tn cn gi l IC COBBA ) => Tn hiu qua mch i ADC ( Analog Digital Converter ) i thnh tn hiu s sau a sang IC Vi x l ci m chng nghe nn v chn thm cc tn hiu iu khin => tip theo tn hiu quay tr li IC m m tn v a vo mch iu ch GMSK ( MODULATION ) to ra 4 tn hiu TX-IP, TX-IN, TX-QP, TX-QN , bn tn hiu ny c a sang IC Cao trung tn ( IC RF ) , y cc tn hiu c tng hp li qua mch ASSEMBLE ri cho iu ch ln sng cao tn thng qua mch MIXER , tn s dao ng ni t mch VCO c chia 2 qua mch DIV sau a vo mch iu ch cao tn MIXER , to thnh tn hiu pht TX-GSM c tn s nm trong phm vi 890MHz - 915MHz => Tn hiu TX-GSM ra khi IC Cao tn theo 2 ng v c tp hp li thnh 1 ng thng qua cun h cm T1 ( Couple ) => sau i qua b lc pht FILLTER => khuch i qua tng tin khuch i PRE AMPLY => i vi IC khuch i cng sut PA ( Power Amply ) => tn hiu ra khi IC khuch i cng sut => i qua b cm ng pht T2 ri a ln chuyn mch Anten ( ANTEN SW ) => a ra Anten pht ra ngoi khng gian .

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  • - T IC RF a ra in p iu khin thay i cng sut pht VAPC ( Vol Amply Power Control ), khi my thu xa i pht, IC cng sut c iu khin pht mnh hn, khi my thu gn i pht, IC cng sut pht cng sut yu hn . - Tn hiu ly ra t b cm ng pht T2 cho hi tip v IC Cao tn RF ( TX-DET ) c tc dng gi n nh cng sut pht sng .

    z Cc linh kin trn ng pht sng . - Micro

    - IC - AUDIO

    - IC - RF

    - Dao ng VCO

    - B lc pht FILTER

    - IC PA ( Power Amply )

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  • 2 - Khi thu pht May NOKIA

    - Chuyn mch Anten - ANTEN SW

    z IC Cng sut pht hot ng khi no ? - IC cng sut pht c cp ngun V.BAT tc l ngun cp lin tc k c khi ta tt my, nhng IC khng hot ng v khng n dng khi cha c lnh VAPC . - Khi ch ch , khong 15 pht IC cng sut pht mi hot ng 1 ln ( trong vi giy ) pht tn hiu lin lc v tng i . - Khi bn di chuyn ( i trn ng ) my s pht sng v tng i mi khi bn tin gn ti mt trm BTS mi . - Khi ta m thoi IC cng sut pht hot ng lin tc v tiu th dng kh ln khong 150mA - 200mA, v vy d b hng nu thi gian m thoi ko di .

    1. Phn tch khi thu pht my NOKIA 8250

    A - Knh Thu

    S mch : Bn a tr chut vo s xem ch thch

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  • S nguyn l knh thu my NOKIA 8250 Bng GSM

    Nguyn l hot ng ca knh thu :

    z Tn hiu t cc trm BTS c thu vo my qua Anten, tn hiu i vo chuyn mch Anten Z670, i qua t C614 qua b lc thu Z620 lc ly cc tn hiu cn thu trong gii tn 935MHz n 960MHz v loi b can nhiu, sau tn hiu c khuch i qua n V904 v i qua b lc thu th hai Z600 => qua b ghp h cm T600 v tch lm hai ng i vo IC cao tn RF .

    z Trong IC cao tn tn hiu tip tc c khuch i sau a vo mch i tn + Dao ng ni VCO cng c a vo mch i tn + Mch i tn s trn tn hiu RF vi VCO ly ra tn hiu trung tn IF + Tn hiu IF c khuch i sau a vo mch tch sng iu pha ly ra hai tn hiu iu ch vung gc RXI v RXQ + IC RF c cung cp cc in p VRX, VCP, VREF v VSYN

    z Hai tn hiu RXI v RXQ c a sang IC m m tn gii m GMSK sau chia lm hai, tn hiu thoi c i D-A ( Digital sang Analog ) ly ra tn hiu m tn => khuch i ri a ra loa . => Cc tn hiu iu khin c a xung CPU x l ly ra tn hiu m bo hoc tin nhn v v .

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  • Bn a tr chut vo nh xem ch thch

    V my NOKIA 8250

    B. Knh pht

    S mch Bn a tr chut vo s xem ch thch

    S nguyn l knh pht my NOKIA 8250 bng GSM

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  • Nguyn l hot ng ca knh pht

    z Tn hiu t Micro i vo IC m m tn Audio => Ti IC Audio tn hiu m tn c i thnh tn hiu s thng qua mch ADC (Analog-Digital Converter ) ri chn thm cc tn hiu iu khin sau tn hiu c m ho GMSK to ra 4 tn hiu TX-IP, TX-IN, TX-QP, TX-QN a sang IC RF .

    z IC RF tng hp cc tn hiu trn li sau iu ch vo sng cao tn ri a ra hai chn A1 v B1 .

    z Mch dao ng VCO ch pht cung cp dao ng cho mch iu ch pht, tn s pht trong khong 890MHz n 915MHz

    z Tn hiu pht i ra t hai chn A1 v B1 c tp hp thnh tn hiu duy nht thng qua cun ghp h cm T700 => i qua b lc pht Z700 => i qua cun h cm T750 => khuch i qua tng V801 ri a vo IC khuch i cng sut N702 ( Power Amply )

    z IC P-A (N702) c cp trc tip t ngun V.BAT, lnh VAPC t IC RF iu khin thay i cng sut pht m bo duy tr lin lc v tit kim pin - khi my thu gn trm BTS th cng sut pht s gim, khi my thu xa trm BTS cng sut pht s tng - IC cng sut pht hot ng lin tc khi ta m thoi v n dng khong 150 n 200mA v vy n d b hng nu thi gian m thoi ko di .

    z L553 l cun cm ng pht ly mt phn tn hiu ra hi tip v IC RF n nh cng sut pht sng .

    z Chuyn mch Anten ch pht c ng v ng TX-GSM a tn hiu pht ra anten ri bc x ra ngoi .

    a tr chut vo nh xem ch thch

    V my NOKIA 8250

    2. Phn tch khi thu pht my NOKIA6610

    A. Knh thu

    S mch Bn a tr chut vo s xem ch thch

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  • S mch knh thu my NOKIA 6610

    Mt s c im ca NOKIA 6610 ( i din cho cc my i cao )

    z Mch n gin hn cc my i thp z Cc IC c xu hng tch hp z IC RF kim lun chc nng khuch i v lc tn hiu cao tn . z IC Audio c tch hp trong IC ngun z IC np, IC Dung chung cng tch hp lun trong IC ngun .

    Nguyn l hot