Mu dongosolo la EPON, OLT imalumikizidwa ku ma ONU angapo (mayunitsi opangira ma network) kudzera pa POS (passive optical splitter).Monga maziko a EPON, OLT optical modules adzakhudza mwachindunji ntchito ya dongosolo lonse la 10G EPON.
1.Chiyambi cha 10G EPON symmetrical OLT Optical module
The 10G EPON symmetrical OLT optical module imagwiritsa ntchito njira zolandirira zophulika za uplink ndi downlink mosalekeza, zomwe zimagwiritsidwa ntchito makamaka pakusintha kwamagetsi / magetsi mu machitidwe a 10G EPON.
Gawo lolandirira lili ndi TIA (transimpedance amplifier), APD (Avalanche Photodiode) pa 1270 / 1310nm, ndi awiri LA (ochepetsa amplifiers) pamitengo ya 1.25 ndi 10.3125 Gbit / s.
Mapeto otumizira amapangidwa ndi 10G EML (electro-absorption modulation laser) ndi 1.25 Gbit / s DFB (yogawa ndemanga laser), ndipo mafunde ake otulutsa ndi 1577 ndi 1490nm, motsatana.
Dera loyendetsa galimoto limaphatikizapo dera la digito la APC (Automatic Optical Power Control) ndi dera la TEC (Temperature Compensation) kuti likhale lokhazikika la 10G laser emission wavelength.Kuwunika kwa magawo otumizira ndi kulandira kumayendetsedwa ndi chip microcomputer imodzi molingana ndi protocol ya SFF-8077iv4.5.
Chifukwa mapeto olandila a OLT optical module amagwiritsa ntchito kulandirira kophulika, nthawi yokonzekera phwando ndiyofunika kwambiri.Ngati nthawi yokhazikika yolandirira maphwando ndi yayitali, imakhudza kwambiri chidwi, ndipo imatha kupangitsa kuti kulandilidwa kophulika kusagwire ntchito bwino.Malingana ndi zofunikira za protocol ya IEEE 802.3av, nthawi yokhazikitsidwa kwa 1.25Gbit / s yophulika iyenera kukhala <400 ns, ndipo kukhudzidwa kwa kuphulika kuyenera kukhala <-29.78 dBm ndi zolakwika pang'ono za 10-12;ndi 10.3125 Gbit / s Nthawi yokhazikika yolandirira yophulika iyenera kukhala <800ns, ndipo chidwi cholandirira chophulika chiyenera kukhala <-28.0 dBm ndi kulakwitsa pang'ono kwa 10-3.
2.10G EPON symmetrical OLT Optical module design
2.1 Kupanga dongosolo
The 10G EPON symmetrical OLT Optical module imapangidwa ndi triplexer (single-fiber three-way module), kutumiza, kulandira, ndi kuyang'anira.Trilexer imaphatikizapo ma lasers awiri ndi chowunikira.Kuwala komwe kumaperekedwa ndi kuwala komwe kunalandira kumaphatikizidwa mu chipangizo cha optical kudzera pa WDM (Wavelength Division Multiplexer) kuti akwaniritse kutumiza kwa bidirectional single-fiber.Kapangidwe kake kakuwonetsedwa mu Chithunzi 1.
Gawo lopatsirana limapangidwa ndi ma lasers awiri, omwe ntchito yawo yayikulu ndikusinthira 1G ndi 10G mazizindikiro amagetsi kukhala ma sign optical, motsatana, ndikusunga mphamvu yamagetsi yamagetsi mumayendedwe otsekedwa kudzera pagawo la digito la APC.Panthawi imodzimodziyo, microcomputer ya single-chip imayendetsa kukula kwa kusintha kwamakono kuti ipeze chiŵerengero cha kutha kofunikira ndi dongosolo.Dera la TEC likuwonjezedwa ku 10G yotumizira dera, yomwe imakhazikika kwambiri kutalika kwa kutalika kwa laser 10G.Gawo lolandira limagwiritsa ntchito APD kusintha chizindikiro chowoneka chophulika kukhala chizindikiro chamagetsi, ndikuchitulutsa pambuyo pakukulitsa ndi kupanga.Pofuna kuwonetsetsa kuti chidziwitsochi chikhoza kufika pamtunda woyenera, m'pofunika kupereka kupanikizika kwakukulu kwa APD pa kutentha kosiyana.Kompyuta ya chip imodzi imakwaniritsa cholinga ichi poyang'anira dera la APD high-voltage.
2.2 Kukhazikitsa kulandila kwapawiri kophulika
Gawo lolandira la 10G EPON symmetric OLT Optical module limagwiritsa ntchito njira yolandirira yophulika.Iyenera kulandira zizindikiro zophulika zamitundu iwiri yosiyana ya 1.25 ndi 10.3125 Gbit / s, zomwe zimafuna kuti gawo lolandira lizitha kusiyanitsa zizindikiro za kuwala kwa mitundu iwiriyi bwino kuti mupeze zizindikiro zokhazikika zamagetsi.Njira ziwiri zogwiritsira ntchito ma module a OLT Optical aperekedwa apa.
Chifukwa cholumikizira cholumikizira chimagwiritsa ntchito ukadaulo wa TDMA (Time Division Multiple Access), kuphulika kumodzi kokha kungakhalepo nthawi imodzi.Chizindikiro cholowera chikhoza kupatulidwa mu chigawo cha optical kupyolera mu 1: 2 optical splitter, monga Kuwonetsedwa mu Chithunzi 2. Kapena gwiritsani ntchito chojambulira chothamanga kwambiri kuti mutembenuzire zizindikiro za 1G ndi 10G kukhala zizindikiro zofooka zamagetsi, ndiyeno mulekanitse magetsi awiri amagetsi. ma siginecha okhala ndi mitengo yosiyana kudzera pa bandwidth yayikulu TIA, monga zikuwonekera pa Chithunzi 3.
Chiwembu choyamba chomwe chikuwonetsedwa mu Chithunzi 2 chidzabweretsa kutayika koyikapo pamene kuwala kumadutsa mu 1: 2 optical splitter, yomwe iyenera kukulitsa chizindikiro cha kuwala, kotero kuti amplifier optical imayikidwa kutsogolo kwa optical splitter.Ma siginecha opatulidwa owoneka amasinthidwa ndi optical / magetsi ndi zowunikira pamitengo yosiyana, ndipo pamapeto pake mitundu iwiri yamagetsi yokhazikika imatulutsidwa.Choyipa chachikulu cha yankho ili ndikuti amplifier optical ndi 1: 2 optical splitter amagwiritsidwa ntchito, ndipo ma detectors awiri amafunikira kuti atembenuzire chizindikiro cha kuwala, chomwe chimawonjezera zovuta za kukhazikitsa ndikuwonjezera mtengo.
Muchiwembu chachiwiri chowonetsedwa mu FIG.3, chizindikiro chowunikira chimangofunika kudutsa chowunikira ndi TIA kuti chikwaniritse kulekanitsidwa mudera lamagetsi.Mfundo yaikulu ya yankho ili pakusankhidwa kwa TIA, yomwe imafuna kuti TIA ikhale ndi bandwidth ya 1 ~ 10Gbit / s, ndipo nthawi yomweyo TIA imayankha mofulumira mkati mwa bandwidth iyi.Pokhapokha kudzera pazigawo zamakono za TIA zomwe zitha kuyankha mwachangu, kukhudzika kolandila kumatha kutsimikiziridwa bwino.Njira yothetsera vutoli imachepetsa kwambiri zovuta za kukhazikitsa ndikusunga ndalama.M'mapangidwe enieni, nthawi zambiri timasankha chiwembu chachiwiri kuti tikwaniritse kulandilidwa kwapawiri.
2.3 Mapangidwe a dera la hardware pamapeto olandira
Chithunzi 4 ndi gawo la hardware la gawo lolandirira lophulika.Pakakhala kuphulika kwa magetsi, APD imasintha chizindikiro cha kuwala kukhala chizindikiro chofooka chamagetsi ndikuchitumiza ku TIA.Chizindikirocho chimakulitsidwa ndi TIA kukhala chizindikiro chamagetsi cha 10G kapena 1G.Chizindikiro chamagetsi cha 10G chimalowetsedwa ku 10G LA kupyolera mu kugwirizana kwabwino kwa TIA, ndipo chizindikiro cha magetsi cha 1G chimalowetsedwa ku 1G LA kupyolera mu kugwirizana kolakwika kwa TIA.Ma capacitors C2 ndi C3 ndi ma capacitor ophatikizana omwe amagwiritsidwa ntchito kuti akwaniritse 10G ndi 1G AC-coupled output.Njira yophatikizika ya AC idasankhidwa chifukwa ndiyosavuta kuposa njira yophatikizira ya DC.
Komabe, kugwirizana kwa AC kuli ndi malipiro ndi kutulutsa kwa capacitor, ndipo liwiro la kuyankha kwa chizindikiro limakhudzidwa ndi malipiro ndi nthawi yotulutsa nthawi zonse, ndiko kuti, chizindikiro sichingayankhidwe panthawi yake.Izi zikuyenera kutaya nthawi yokhazikika yolandirira, kotero ndikofunikira kusankha kukula kwa AC coupling capacitor.Ngati capacitor yaying'ono yasankhidwa, nthawi yokhazikika ikhoza kufupikitsidwa, ndipo chizindikiro choperekedwa ndi ONU nthawi iliyonse chikhoza kulandiridwa kwathunthu popanda kukhudza zotsatira zolandirira chifukwa nthawi yokhazikika yolandirira ndi yaitali kwambiri komanso kufika kwa nthawi yotsatira. kagawo.
Komabe, capacitance yaying'ono ingakhudze zotsatira zolumikizana ndikuchepetsa kwambiri kukhazikika kwa kulandila.Capacitance yayikulu imatha kuchepetsa jitter ya dongosolo ndikuwongolera kukhudzika kwa gawo lolandira.Chifukwa chake, kuti muganizire za nthawi yokhazikika yolandirira ndikulandila, ma capacitor olumikizana oyenera C2 ndi C3 ayenera kusankhidwa.Kuphatikiza apo, pofuna kutsimikizira kukhazikika kwa chizindikiro chamagetsi cholowera, cholumikizira cholumikizira ndi chopinga chofananira chokhala ndi kukana kwa 50Ω zimalumikizidwa ku terminal yoyipa ya LA.
Dera la LVPECL (Low Voltage Positive Emitter Coupling Logic) lopangidwa ndi resistors R4 ndi R5 (R6 ndi R7) ndi gwero la voltage la 2.0 V DC kudzera pamagetsi osiyanitsa ndi 10G (1G) LA.chizindikiro chamagetsi.
2.4 Gawo Launch
Gawo lotumizira la 10G EPON symmetric OLT Optical module limagawidwa m'magawo awiri a 1.25 ndi 10G kutumiza, zomwe zimatumiza zizindikiro ndi kutalika kwa 1490 ndi 1577 nm ku downlink.Kutenga gawo lopatsirana la 10G mwachitsanzo, chizindikiro chosiyana cha 10G chimalowa mu CDR (Clock Shaping) chip, ndi AC-yophatikizidwa ndi 10G driver chip, ndipo pamapeto pake imalowetsa mosiyanasiyana mu laser 10G.Chifukwa kusintha kwa kutentha kudzakhala ndi chikoka chachikulu pa mawonekedwe a laser emission wavelength, kuti akhazikitse kutalika kwa mafunde mpaka pamlingo wofunikira ndi protocol (protocol imafuna 1575 ~ 1580nm), momwe ntchito yadera la TEC iyenera kusinthidwa, kotero kuti kutalika kwa kutalika kwake kumatha kuyendetsedwa bwino.
3. Zotsatira zoyesa ndi kusanthula
Zizindikiro zazikulu zoyesera za 10G EPON symmetric OLT optical module zimaphatikizapo nthawi yokonzekera wolandila, kukhudzidwa kwa wolandila, ndi kufalitsa chithunzi cha diso.Mayeso enieni ndi awa:
(1) Landirani nthawi yokhazikitsa
Pansi pa malo ogwirira ntchito a uplink burst optical mphamvu ya -24.0 dBm, chizindikiro cha kuwala chomwe chimatulutsidwa ndi gwero la kuwala chimagwiritsidwa ntchito ngati poyambira, ndipo gawoli limalandira ndikukhazikitsa chizindikiro chamagetsi chathunthu monga mapeto a kuyeza, kunyalanyaza kuchedwa kwa nthawi ya kuwala muzitsulo zoyesera.Kuyeza kwa 1G kuphulika kwa nthawi yokonzekera ndi 76.7 ns, yomwe ikugwirizana ndi mayiko a <400 ns;nthawi ya 10G yoyambira kulandirira ndi 241.8 ns, yomwe imakumananso ndi mayiko a <800 ns.
3. Zotsatira zoyesa ndi kusanthula
Zizindikiro zazikulu zoyesera za 10G EPON symmetric OLT optical module zimaphatikizapo nthawi yokonzekera wolandila, kukhudzidwa kwa wolandila, ndi kufalitsa chithunzi cha diso.Mayeso enieni ndi awa:
(1) Landirani nthawi yokhazikitsa
Pansi pa malo ogwirira ntchito a uplink burst optical mphamvu ya -24.0 dBm, chizindikiro cha kuwala chomwe chimatulutsidwa ndi gwero la kuwala chimagwiritsidwa ntchito ngati poyambira, ndipo gawoli limalandira ndikukhazikitsa chizindikiro chamagetsi chathunthu monga mapeto a kuyeza, kunyalanyaza kuchedwa kwa nthawi ya kuwala mu fiber yoyesera.Kuyeza kwa 1G kuphulika kwa nthawi yokonzekera ndi 76.7 ns, yomwe imagwirizana ndi mayiko onse a <400 ns;nthawi ya 10G yoyambira kulandirira ndi 241.8 ns, yomwe imakumananso ndi mayiko a <800 ns.
