Nyob rau hauv tsab xov xwm peb yuav sim qhia koj paub meej txog qhov kev sib txuas lus duplex yog dab tsi. Qhov no yog lub hauv paus ntsiab lus ntawm kev sib txuas cov receiver thiab transmitter, uas txhais tau hais tias kev sib kis ntawm cov ntaub ntawv ib txhij nyob rau hauv ob qho tib si cov lus qhia. Thawj zaug, lub tswv yim ntawm kev sib txuas zoo li no tau ua tiav ib puas xyoo thiab ib nrab xyoo dhau los hauv transatlantic telegraph thiab me ntsis tom qab hauv teleprinters. Ib lub tswv yim zoo li no tau txais kev cawmdim ntawm kev sib txuas lus ntawm lub cev. Xav txog yuav ua li cas ib tug cable yuav raug nqi nteg thoob plaws hauv dej hiav txwv. Koj tuaj yeem pom ntawm koj tus kheej - kev txuag nyiaj yog qhov tseem ceeb. Nyob rau hauv cov ntaub ntawv ntawm ib tug teletype, txhua yam yog ntau yooj yim. Lub tswv yim twb tau paub rau txhua tus, tab sis lawv tuaj nrog ib qho txawv me ntsis ntawm kev nthuav tawm cov ntaub ntawv (siv cov khoom siv luam ntawv).
Simplex systems
Kev sib txuas lus yooj yim thiab duplex yog, ib tus yuav hais, cov lus sib piv. Tab sis muaj qhov sib txawv ntawm lub hauv paus ntsiab lus ntawm kev xa thiab txais cov ntaub ntawv. Nyob rau hauv cov ntaub ntawv ntawm kev sib txuas lus duplex, ntau yam khoom siv tuaj yeem sib pauv cov ntaub ntawv (tau txais thiab xa tawm). Tab sis thaum npaj kev sib txuas lus yooj yim, thawj ib lub cuab yeej tshaj tawm, tom qab ntawd qhov thib ob, thib peb, thiab lwm yam.e. Hauv lwm lo lus, muaj qee qhov kev txiav txim.
Ntawm no yog cov piv txwv ntawm cov txheej txheem yooj yim:
- Broadcasting.
- Microphones rau suab kaw.
- Baby saib.
- Wireless thiab wired headphones.
- Ntau lub koob yees duab kev ruaj ntseg.
- Wireless tswj tshuab rau txhua yam khoom siv.
Kev sib txuas lus yooj yim tsis tas yuav hloov cov ntaub ntawv hauv ob qho lus qhia.
Lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm cov khoom siv duplex
Raws li cov khoom siv sib txuas lus duplex, lawv muaj qhov sib txawv me ntsis. Lawv txuas ob lub ntsiab lus. Ib qho piv txwv yog niaj hnub computer ports xws li Ethernet. Nws yog nyob rau hauv lawv tias xws li kev sib pauv ntaub ntawv feem ntau tshwm sim. Ib txoj hauv kev zoo sib xws tau muab tso rau hauv kev sib txuas lus hauv xov tooj - tom qab tag nrho, koj paub zoo tias ob tus neeg tuaj yeem tham thiab hnov tib lub sijhawm.
Hauv cov thev naus laus zis thev naus laus zis, tsuas yog qhov tshwm sim ntawm cov txiaj ntsig ntawm kev sib txuas lus xov tooj cua duplex (thiab xaim ib yam nkaus). Yog tias qhov kev txais thiab xa tawm tau ua haujlwm ib txhij, cov khoom siv yuav hlawv tawm hauv ib lub vib nas this. Muaj qee lub sij hawm faib, nrog rau nws cov kev pab, tsim thiab hloov cov pob khoom siv qhov chaw. Thiab cov neeg siv cov cuab yeej sib txuas lus tsis tuaj yeem pom qhov "trick". Muaj ib tug thiaj li hu ua tsis tiav duplex, uas yog nquag siv nyob rau hauv walkie-talkies. Hauv qhov no, cov channel tau tawg los ntawm kev qhia qee cov lus code uas haissubscribers.
Yuav ua li cas cov channel faib raws sijhawm
Raws li qhov piv txwv tom ntej, peb yuav xav txog Lub Ntiaj Teb Wide Web - Internet. Nws nyob ntawm no tias kev sib cais ntawm cov channel thiab faib cov sijhawm sib txawv rau ntau tus neeg siv khoom yog qhov tseem ceeb. Cov no yog cov kab nrog asymmetric speeds (muaj ob qho tib si upload thiab rub tawm cov ntaub ntawv tib lub sijhawm). Qhov tsis sib xws ntawm cov channel rau cov xov xwm sib txawv ua rau nws muaj peev xwm paub txog kev nkag mus rau satellites. Nrog xws li kev nkag mus, qhov kev thov tau ua rau lub network ze tshaj plaws ntawm tus neeg teb xov tooj ntawm tes, thiab cov lus teb yog twb los ntawm satellite los ntawm qhov tob ntawm qhov chaw.
Nov yog cov piv txwv ntawm cov cuab yeej siv cov thev naus laus zis no:
- thib peb ntawm kev sib txuas lus ntawm tes (kev paub ntau dua 3G).
- Ntau ntau yam ntawm LTE.
- WiMAX (los yog 3G+).
- As as well as the lesser know wireless DECT telephony.
Ntau yam ntawm cov ntaub ntawv xa tawm
Ib me ntsis dhau 50 xyoo dhau los, cov cuab yeej txhawb nqa tau pib nthuav dav. Yog vim li cas rau nws cov lus qhia loj yog tias cov khoom siv hluav taws xob hauv xeev tau tshwm sim thiab tau ua pov thawj nws tus kheej zoo. Cov khoom siv hluav taws xob tsis sib xws tau siv ntau qhov chaw (piv rau cov khoom siv semiconductor siab dua).
Thaum xub thawj muaj ob hom uas cov channel tau compressed:
- Cyclic (synchronous) kis hom - cov neeg siv khoom txuas mus rau cov kab ib ntus. Ntxiv mus, kev sib txuas ua ntu zus yog nruj me ntsis teev. Ua ntejkoj yuav tsum tau tsim cov qauv thav duab, tom qab ntawd siv lub sijhawm teeb tsa. Raws li qhov xwm txheej ntawm qhov encoding, nws tsis muaj teeb meem.
- Asynchronous kis hom yog dav siv hauv cov tshuab digital. Hauv qhov no, cov ntaub ntawv raug xa mus rau hauv cov pob ntawv ua ntej, qhov loj ntawm ntau pua lossis ntau txhiab ntawm cov khoom. Txij li thaum muaj qhov chaw nyob, nws tuaj yeem tsim kev sib cuam tshuam asynchronous. Lub hauv paus ntsiab lus no tau siv niaj hnub no txawm tias hauv kev sib txuas lus ntawm tes. Koj yuav tsum tau xyuam xim rau qhov tseeb hais tias nyob rau hauv niaj hnub kev sib txuas lus raws tu qauv tus naj npawb ntawm bytes yog txawm. Vim li no, tsis muaj synchronization nkaus xwb.
Signal zaus thiab cov duab
Nws tseem yuav tsum tau muab sau tseg tias txhua pob ntawv ntawm cov ntaub ntawv tau ntxiv los ntawm lub taub hau. Qhov sib xyaw ua ke ntawm cov ntaub ntawv xa mus yog txiav txim siab los ntawm tus qauv txheej txheem uas muaj. Lub channel yog loaded nrog ib lub sij hawm thiab zaus. Soviet duplex kev sib txuas lus channel ua haujlwm ntawm qhov zaus ntawm 8 kHz (lub xov tooj teeb liab raug kuaj ntawm tus nqi ntawm 64 kbps).
Nco ntsoov ntau txoj hauv kev ntawm tus neeg nqa khoom zaus hloov pauv:
- PWM (pulse width).
- sijhawm-pulse.
- Pulse-amplitude.
Binary hom teeb liab yog encoded siv square wave pulses. Nyob rau hauv cov ntaub ntawv no, ib tug infinitely dav spectrum yog tau, thiab qhov tseeb teeb liab yuav raug txiav siv cov ntxaij lim dej. Qhov tshwm sim ntawm qhov no yog qhov smoothing ntawm fronts. Vim stretching, interpulse cuam tshuam tshwm sim. Kev cuam tshuam tshwm sim hauv cov channel uas nyob ib sab - qhov no yog vim qhov tseeb tias qhov spectrakev sib tshuam.
qhia sijhawm sib cais
Thiab tam sim no cia saib dab tsi theem ntawm cov teeb liab sib cais tuaj yeem pom hauv duplex intercoms. Peb tuaj yeem paub qhov txawv ntawm cov hauv qab no:
- Muaj 32 channel ntawm thawj theem, ob ntawm lawv tau tshwj tseg rau cov lus pabcuam. Tag nrho cov ceev ntawm cov channel no yog 2048 kbps.
- Cov theem ntxiv yog tsim los ntawm multiplexing plaub kwj (ntsis los ntawm me ntsis). Nws tsim nyog sau cia tias txhua ntu ntawm cov qauv tsim ua ntej.
Kev faib ntau zaus
Thiab thaum kawg, cia peb tham txog kev faib zaus. Nws yog thawj zaug muab tso rau hauv kev xyaum los ntawm tus signalman G. G. Ignatiev nyob rau hauv 1880. Lub teeb liab transmitter generates ib co ntawm cov analog hom pulses (feem ntau yog 12 ntawm lawv). Lub teeb liab dav yog tus qauv - nyob rau hauv thaj tsam ntawm 300-3500 Hz. Lub thaiv muaj tus naj npawb ntawm cov tshuab hluav taws xob uas yuav tsum tau ua hauv qhov no.
Kev faib zaus tuaj yeem hu ua qhov zoo tshaj plaws rau kev teeb tsa cov kab tsheb sib luag. Nws nquag siv hauv ADSL, IEEE 802.16, CDMA2000.
