際際滷

際際滷Share a Scribd company logo

Chuong 1

Download as DOC, PDF
B
btminh

Ch動董ng 1- Truy畛n s畛 li畛u

1 of 3
Download to read offline
1.1.M担短 単au : Bo辰 Ma誰 h c Gia短単ie i u Nguon Ma探 a ho湛 ie che叩 u 旦担淡g n Gia短ma探 i Ma誰 h c thu kie奪 m che叩 d旦探 u lie辰 CODEC MODEM da但 y CODEC kie奪 tra m d旦探 tra MODEM lie辰 u DTEA DCEA DCEB DTEB H 狸nh 1 .1 . Ma誰ch truye d旦探lie辰 t旦淡thie叩 b嘆 A sang B n u t * DTE : Data Terminal Equipment : Thie叩t b嘆 単au cuo叩i x旦短 ly湛 d旦探 lie辰u th旦担淡ng go誰i ta辿t la淡 thie叩t b嘆 単au cuo叩i. DTE gom hai kho叩i ch旦湛c na棚ng kha湛c nhau : kho叩i x旦短 ly湛 la淡 nguon hoa谷c bo辰 thu d旦探 lie辰u, kho叩i kie奪m tra s旦誰 lie但n la誰c la淡 to奪 h担誰p ca湛c bo辰 pha辰n th旦誰c hie辰n ch旦湛c na棚ng lie但n la誰c co湛 hoa谷c kho但ng co湛 bo辰 pha辰n lo誰c nhie達u. * DCE : Data Circuit Equipment : Thie叩t b嘆 ma誰ch d旦探 lie辰u. DCE co湛 the奪 co湛 hai kho叩i ch旦湛c na棚ng la淡 ma探 ho湛a (hoa谷c gia短i ma探) va淡 単ieu che叩 (hoa谷c gia短i 単ieu che叩). + CODEC = Code + Decode : ma探 ho湛a va淡 gia短i ma探. + MODEM = Modulation + Demodulation : 単ieu che叩 va淡 gia短i 単ieu che叩. Ca湛c ma誰ch truyen d旦探 lie辰u th旦担淡ng truyen song co但ng (hai chieu) ne但n pha短i can 単e叩n ma誰ch CODEC va淡 MODEM. * Co湛 ba loa誰i ma探 ho湛a : - Ma探 ho湛a nguon, co淡n go誰i la淡 ma探 tho叩ng ke但 to叩i 旦u, mu誰c 単鱈ch 単e奪 ta棚ng to叩c 単o辰 truyen tin, hay 単旦担誰c s旦短 du誰ng trong ca湛c thie叩t b嘆 単au cuo叩i nh旦 FAX, VIDEOTEX - Ma探 ho湛a ke但nh co淡n go誰i la淡 ma探 pha湛t hie辰n va淡 s旦短a sai, mu誰c 単鱈ch 単e奪 ta棚ng 単o辰 ch鱈nh xa湛c cu短a tin truyen. Hai loa誰i ma探 na淡y 単旦担誰c nghie但n c旦湛u 担短 ch旦担ng 4. - Ma探 単旦担淡ng truyen (code line) : bie叩n ma探 nh嘆 pha但n tha淡nh ma探 tam pha但n 単e奪 de達 da淡ng 単ong bo辰 t鱈n hie辰u. Ma探 na淡y 単旦担誰c nghie但n c旦湛u trong ch旦担ng 3. * Ky探 thua辰t 単ieu che叩 so叩 : ASK, FSK, PSK, QAM va淡 ca湛c loa誰i MODEM 単旦担誰c gi担湛i thie辰u trong ch旦担ng 3. 1.2. Ma探 ho湛a tho但ng tin : * Ma探 la淡 lua辰t 単e奪 nha辰n bie叩t tho但ng tin can pha短i bie奪u die達n d旦担湛i da誰ng ton ta誰i nh嘆 pha但n. * o辰 da淡i cu短a ma探 : n phu誰 thuo辰c va淡o gia湛 tr嘆 so叩 co辰t nh嘆 pha但n cu短a ky湛 t旦誰 ma淡 ta muo叩n bie奪u die達n.
稼1 n * e奪 bie奪u die達n cho ma探 co湛 N ky湛 hie辰u ta can co湛 n bit sao cho : 2 <N<2 , tho但ng th旦担淡ng n = 5 歎 8. * Ca湛c ky湛 t旦誰 can ma探 ho湛a bao gom : ch旦探 ca湛i cu短a ba短n ch旦探 (ch旦探 in va淡 ch旦探 th旦担淡ng), ch旦探 so叩 cu短a he辰 単e叩m 10, mo辰t so叩 ky湛 hie辰u ch脱 ca湛c thao ta湛c can th旦誰c hie辰n ( +, * , ?, $ ) va淡 ta辰p h担誰p ca湛c ky湛 t旦誰 単ieu khie奪n. 1 2 n * S旦誰 bie奪u die達n nh嘆 pha但n ca湛c ky湛 t旦誰 : { d i , d i , d i } { 0, 1 } cu短a ky湛 t旦誰 c i go誰i la淡 mo辰t t旦淡 ma探. Ta辰p ca湛c t旦淡 ma探 go誰i la淡 ba短ng ma探. * Nga淡y nay to奪 ch旦湛c tie但u chua奪n quo叩c te叩 la叩y ma探 ASCII, go誰i la淡 ma探 n 0 5 cu短a CCITT cho phe湛p s旦短 du誰ng ro辰ng ra探i. Ma探 ASCII s旦短 du誰ng 7 co辰t (7 bit ) co湛 the奪 bie奪u die達n 128 ky湛 t旦誰 va淡 the但m mo辰t co辰t 単e奪 kie奪m tra cha端n le短. Ng旦担淡i ta du淡ng hai co辰t 単au tie但n 単e奪 ma探 ho湛a nh旦探ng ky湛 t旦誰 単ieu khie奪n. V鱈 du誰 v担湛i qui 旦担湛c kie奪m tra cha端n : b8 = 0 v担湛i ky湛 t旦誰 A 1000001 v狸 so叩 bit 1 trong ky湛 t旦誰 la淡 2 cha端n T旦淡 ma探 : 01000001 b8 = 1 v担湛i ky湛 t旦誰 1 0110001 v狸 so叩 bit 1 trong ky湛 t旦誰 la淡 3 le短 T旦淡 ma探 : 10110001. * Cho du淡 trong khi truyen ta du淡ng loa誰i ma探 na淡o, truyen 単ong bo辰 hay kho但ng 単ong bo辰, tho但ng tin truyen tre但n 単旦担淡ng da但y pha短i tua但n theo nh旦探ng qui lua辰t sau : - Ca湛c bit cu短a ky湛 t旦誰 単旦担誰c truyen lie但n tie叩p theo th旦湛 t旦誰 ta棚ng dan (b1, b2 b7). - Bit kie奪m tra la淡 bit th旦湛 8 cu短a ky湛 t旦誰 単旦担誰c truyen sau cu淡ng. - Nh旦探ng ky湛 t旦誰 単旦担誰c truyen theo kie奪u kho但ng 単ong bo辰 can pha短i the但m t鱈n hie辰u start (1 bit 0) va淡 1, 1,5 hoa谷c 2 bit stops (bit 1). - Kie奪u truyen kho但ng 単ong bo辰 th旦担淡ng du淡ng kie奪m tra cha端n, co淡n kie奪u truyen kho但ng 単ong bo辰 th旦担淡ng du淡ng kie奪m tra le短. 1.3. Ca湛ch truyen : * Khi truyen 単ong bo辰 単e奪 nha辰n bie叩t gia湛 tr嘆 ca湛c th担淡i 単ie奪m la淡 0 hay 1 can pha短i co湛 t鱈n hie辰u xung clock go誰i la淡 t鱈n hie辰u 単ong bo辰. T鱈n hie辰u 単ong bo辰 co湛 1 chu ky淡 la淡 T, ngh坦a la淡 mo達i gia但y nguon se探 cung ca叩p bits. Da探y nh旦 va辰y go誰i T la淡 da探y 単ong bo辰.
* Khi truyen ba叩t 単ong bo辰 ng旦担淡i ta pha湛t t旦淡ng ky湛 hie辰u rie但ng re探, ca湛ch bie辰t nhau va淡 単e奪 pha但n bie辰t ca湛c ky湛 t旦誰 ng旦担淡i ta the但m t鱈n hie辰u 単au (start) va淡 cuo叩i (stop) va淡o mo達i ky湛 t旦誰. * Ng旦担淡i ta chia 単旦担淡ng truyen tha淡nh 2 loa誰i : 単旦担淡ng truyen nguye但n ly湛 (単旦担淡ng truyen ch鱈nh) va淡 単旦担淡ng truyen th旦湛 ca叩p (単旦担淡ng truyen phu誰). Tho但ng th旦担淡ng 単旦担淡ng truyen ch鱈nh co湛 l旦u l旦担誰ng tho但ng tin l担湛n ga叩p nhieu lan 単旦担淡ng truyen th旦湛 ca叩p. * Ma誰ch d旦探 lie辰u 単旦担誰c chia la淡m 3 loa誰i : - Ma誰ch 単担n co但ng (mo辰t chieu : simplex) : tho但ng tin ch脱 co湛 the奪 truyen t旦淡 nguon sang thie叩t b嘆 thu ma淡 chieu ng旦担誰c la誰i kho但ng the奪 th旦誰c hie辰n 単旦担誰c. V鱈 du誰 : d旦探 lie辰u 単旦担誰c truyen t旦淡 ma湛y t鱈nh sang ma湛y in. - Ma誰ch ba湛n song co但ng (hai chieu nga辿t qua探ng : half duplex). Hai thie叩t b嘆 単au cuo叩i co湛 the奪 truyen d旦探 lie辰u cho nhau ta誰i nh旦探ng th担淡i 単ie奪m kha湛c nhau. - Ma誰ch song co但ng (hai chieu toa淡n phan : duplex). Hai thie叩t b嘆 単au cuo叩i co湛 the奪 truyen d旦探 lie辰u cho nhau 単ong th担淡i.

More Related Content

Chuong 1

  • 1. 1.1.M担短 単au : Bo辰 Ma誰 h c Gia短単ie i u Nguon Ma探 a ho湛 ie che叩 u 旦担淡g n Gia短ma探 i Ma誰 h c thu kie奪 m che叩 d旦探 u lie辰 CODEC MODEM da但 y CODEC kie奪 tra m d旦探 tra MODEM lie辰 u DTEA DCEA DCEB DTEB H 狸nh 1 .1 . Ma誰ch truye d旦探lie辰 t旦淡thie叩 b嘆 A sang B n u t * DTE : Data Terminal Equipment : Thie叩t b嘆 単au cuo叩i x旦短 ly湛 d旦探 lie辰u th旦担淡ng go誰i ta辿t la淡 thie叩t b嘆 単au cuo叩i. DTE gom hai kho叩i ch旦湛c na棚ng kha湛c nhau : kho叩i x旦短 ly湛 la淡 nguon hoa谷c bo辰 thu d旦探 lie辰u, kho叩i kie奪m tra s旦誰 lie但n la誰c la淡 to奪 h担誰p ca湛c bo辰 pha辰n th旦誰c hie辰n ch旦湛c na棚ng lie但n la誰c co湛 hoa谷c kho但ng co湛 bo辰 pha辰n lo誰c nhie達u. * DCE : Data Circuit Equipment : Thie叩t b嘆 ma誰ch d旦探 lie辰u. DCE co湛 the奪 co湛 hai kho叩i ch旦湛c na棚ng la淡 ma探 ho湛a (hoa谷c gia短i ma探) va淡 単ieu che叩 (hoa谷c gia短i 単ieu che叩). + CODEC = Code + Decode : ma探 ho湛a va淡 gia短i ma探. + MODEM = Modulation + Demodulation : 単ieu che叩 va淡 gia短i 単ieu che叩. Ca湛c ma誰ch truyen d旦探 lie辰u th旦担淡ng truyen song co但ng (hai chieu) ne但n pha短i can 単e叩n ma誰ch CODEC va淡 MODEM. * Co湛 ba loa誰i ma探 ho湛a : - Ma探 ho湛a nguon, co淡n go誰i la淡 ma探 tho叩ng ke但 to叩i 旦u, mu誰c 単鱈ch 単e奪 ta棚ng to叩c 単o辰 truyen tin, hay 単旦担誰c s旦短 du誰ng trong ca湛c thie叩t b嘆 単au cuo叩i nh旦 FAX, VIDEOTEX - Ma探 ho湛a ke但nh co淡n go誰i la淡 ma探 pha湛t hie辰n va淡 s旦短a sai, mu誰c 単鱈ch 単e奪 ta棚ng 単o辰 ch鱈nh xa湛c cu短a tin truyen. Hai loa誰i ma探 na淡y 単旦担誰c nghie但n c旦湛u 担短 ch旦担ng 4. - Ma探 単旦担淡ng truyen (code line) : bie叩n ma探 nh嘆 pha但n tha淡nh ma探 tam pha但n 単e奪 de達 da淡ng 単ong bo辰 t鱈n hie辰u. Ma探 na淡y 単旦担誰c nghie但n c旦湛u trong ch旦担ng 3. * Ky探 thua辰t 単ieu che叩 so叩 : ASK, FSK, PSK, QAM va淡 ca湛c loa誰i MODEM 単旦担誰c gi担湛i thie辰u trong ch旦担ng 3. 1.2. Ma探 ho湛a tho但ng tin : * Ma探 la淡 lua辰t 単e奪 nha辰n bie叩t tho但ng tin can pha短i bie奪u die達n d旦担湛i da誰ng ton ta誰i nh嘆 pha但n. * o辰 da淡i cu短a ma探 : n phu誰 thuo辰c va淡o gia湛 tr嘆 so叩 co辰t nh嘆 pha但n cu短a ky湛 t旦誰 ma淡 ta muo叩n bie奪u die達n.
  • 2. 稼1 n * e奪 bie奪u die達n cho ma探 co湛 N ky湛 hie辰u ta can co湛 n bit sao cho : 2 <N<2 , tho但ng th旦担淡ng n = 5 歎 8. * Ca湛c ky湛 t旦誰 can ma探 ho湛a bao gom : ch旦探 ca湛i cu短a ba短n ch旦探 (ch旦探 in va淡 ch旦探 th旦担淡ng), ch旦探 so叩 cu短a he辰 単e叩m 10, mo辰t so叩 ky湛 hie辰u ch脱 ca湛c thao ta湛c can th旦誰c hie辰n ( +, * , ?, $ ) va淡 ta辰p h担誰p ca湛c ky湛 t旦誰 単ieu khie奪n. 1 2 n * S旦誰 bie奪u die達n nh嘆 pha但n ca湛c ky湛 t旦誰 : { d i , d i , d i } { 0, 1 } cu短a ky湛 t旦誰 c i go誰i la淡 mo辰t t旦淡 ma探. Ta辰p ca湛c t旦淡 ma探 go誰i la淡 ba短ng ma探. * Nga淡y nay to奪 ch旦湛c tie但u chua奪n quo叩c te叩 la叩y ma探 ASCII, go誰i la淡 ma探 n 0 5 cu短a CCITT cho phe湛p s旦短 du誰ng ro辰ng ra探i. Ma探 ASCII s旦短 du誰ng 7 co辰t (7 bit ) co湛 the奪 bie奪u die達n 128 ky湛 t旦誰 va淡 the但m mo辰t co辰t 単e奪 kie奪m tra cha端n le短. Ng旦担淡i ta du淡ng hai co辰t 単au tie但n 単e奪 ma探 ho湛a nh旦探ng ky湛 t旦誰 単ieu khie奪n. V鱈 du誰 v担湛i qui 旦担湛c kie奪m tra cha端n : b8 = 0 v担湛i ky湛 t旦誰 A 1000001 v狸 so叩 bit 1 trong ky湛 t旦誰 la淡 2 cha端n T旦淡 ma探 : 01000001 b8 = 1 v担湛i ky湛 t旦誰 1 0110001 v狸 so叩 bit 1 trong ky湛 t旦誰 la淡 3 le短 T旦淡 ma探 : 10110001. * Cho du淡 trong khi truyen ta du淡ng loa誰i ma探 na淡o, truyen 単ong bo辰 hay kho但ng 単ong bo辰, tho但ng tin truyen tre但n 単旦担淡ng da但y pha短i tua但n theo nh旦探ng qui lua辰t sau : - Ca湛c bit cu短a ky湛 t旦誰 単旦担誰c truyen lie但n tie叩p theo th旦湛 t旦誰 ta棚ng dan (b1, b2 b7). - Bit kie奪m tra la淡 bit th旦湛 8 cu短a ky湛 t旦誰 単旦担誰c truyen sau cu淡ng. - Nh旦探ng ky湛 t旦誰 単旦担誰c truyen theo kie奪u kho但ng 単ong bo辰 can pha短i the但m t鱈n hie辰u start (1 bit 0) va淡 1, 1,5 hoa谷c 2 bit stops (bit 1). - Kie奪u truyen kho但ng 単ong bo辰 th旦担淡ng du淡ng kie奪m tra cha端n, co淡n kie奪u truyen kho但ng 単ong bo辰 th旦担淡ng du淡ng kie奪m tra le短. 1.3. Ca湛ch truyen : * Khi truyen 単ong bo辰 単e奪 nha辰n bie叩t gia湛 tr嘆 ca湛c th担淡i 単ie奪m la淡 0 hay 1 can pha短i co湛 t鱈n hie辰u xung clock go誰i la淡 t鱈n hie辰u 単ong bo辰. T鱈n hie辰u 単ong bo辰 co湛 1 chu ky淡 la淡 T, ngh坦a la淡 mo達i gia但y nguon se探 cung ca叩p bits. Da探y nh旦 va辰y go誰i T la淡 da探y 単ong bo辰.
  • 3. * Khi truyen ba叩t 単ong bo辰 ng旦担淡i ta pha湛t t旦淡ng ky湛 hie辰u rie但ng re探, ca湛ch bie辰t nhau va淡 単e奪 pha但n bie辰t ca湛c ky湛 t旦誰 ng旦担淡i ta the但m t鱈n hie辰u 単au (start) va淡 cuo叩i (stop) va淡o mo達i ky湛 t旦誰. * Ng旦担淡i ta chia 単旦担淡ng truyen tha淡nh 2 loa誰i : 単旦担淡ng truyen nguye但n ly湛 (単旦担淡ng truyen ch鱈nh) va淡 単旦担淡ng truyen th旦湛 ca叩p (単旦担淡ng truyen phu誰). Tho但ng th旦担淡ng 単旦担淡ng truyen ch鱈nh co湛 l旦u l旦担誰ng tho但ng tin l担湛n ga叩p nhieu lan 単旦担淡ng truyen th旦湛 ca叩p. * Ma誰ch d旦探 lie辰u 単旦担誰c chia la淡m 3 loa誰i : - Ma誰ch 単担n co但ng (mo辰t chieu : simplex) : tho但ng tin ch脱 co湛 the奪 truyen t旦淡 nguon sang thie叩t b嘆 thu ma淡 chieu ng旦担誰c la誰i kho但ng the奪 th旦誰c hie辰n 単旦担誰c. V鱈 du誰 : d旦探 lie辰u 単旦担誰c truyen t旦淡 ma湛y t鱈nh sang ma湛y in. - Ma誰ch ba湛n song co但ng (hai chieu nga辿t qua探ng : half duplex). Hai thie叩t b嘆 単au cuo叩i co湛 the奪 truyen d旦探 lie辰u cho nhau ta誰i nh旦探ng th担淡i 単ie奪m kha湛c nhau. - Ma誰ch song co但ng (hai chieu toa淡n phan : duplex). Hai thie叩t b嘆 単au cuo叩i co湛 the奪 truyen d旦探 lie辰u cho nhau 単ong th担淡i.