2024 Tus sau: Elizabeth Oswald | [email protected]. Kawg hloov kho: 2024-01-13 00:07
OFDM: Orthogonal Frequency Division Multiplexing, yog a daim ntawv ntawm cov teeb liab modulation teeb liab modulation Qhov ntsuas ntsuas (lossis qhov tob ntawm qhov ntsuas) ntawm cov qauv kev hloov pauv piav qhia los ntawm ntau npaum li cas qhov hloov pauv hloov pauv ntawm cov teeb liab sib txawv nyob ib puag ncig nws qib unmodulated. Nws yog txhais txawv nyob rau hauv txhua lub tswv yim modulation. https://en.wikipedia.org › wiki › Modulation_index
Modulation index - Wikipedia
uas faib cov ntaub ntawv siab tus nqi hloov pauv cov kwj tso lawv mus rau ntau qhov maj mam hloov kho cov nqaim nqaim nyob ze-spaced subcarriers, thiab hauv txoj kev no tsis tshua nkag siab rau zaus xaiv fading.
Dab tsi yog orthogonal zaus siv rau?
OFDM daim ntawv thov. Orthogonal zaus-division multiplexing yog siv ntau yam thev naus laus zis, suav nrog cov hauv qab no: xov tooj cua digital, Digital Radio Mondiale, thiab digital audio broadcasting thiab satellite radio. Cov qauv hauv xov tooj cua, Digital Video Broadcasting-Terrestrial/Handheld (DVB-T/H), DVB-Cable 2 (DVB-C2).
Yuav ua li cas orthogonality tau tiav hauv OFDM?
Hauv qhov yooj yim OFDM system no muaj N sinusoidal input signals. Txhua subcarrier xa ib me ntsis ntawm cov ntaub ntawv (N ntsis tag nrho) raws li qhia los ntawm nws muaj los yog tsis muaj nyob rau hauv cov zis spectrum. … Txhawm rau kom muaj kev sib haum xeeb, T yuav tsum yog qhov sib txuas ntawm qhov sib txuas ntawm subcarrier.
Txoj cai ua haujlwm ntawm OFDM yog dab tsi?
Lub tswv yim OFDM yog raws onnthuav tawm cov ntaub ntawv ceev ceev kom kis tau ntau tus neeg nqa khoom qis. Cov cab kuj yog orthogonal rau ib leeg thiab zaus sib nrug ntawm lawv yog tsim los ntawm kev siv ceev Fourier transform (FFT).
Lub luag haujlwm ntawm orthogonal zaus division multiplexing hauv kev sib txuas lus wireless yog dab tsi?
In telecommunications, orthogonal zaus-division multiplexing (OFDM) yog ib hom kev xa tawm digital thiab ib txoj hauv kev encoding cov ntaub ntawv digital ntawm ntau lub xov tooj zaus. … Qhov no tuav tag nrho cov ntaub ntawv tus nqi zoo ib yam li cov qauv kev hloov pauv ib leeg ib leeg hauv tib lub bandwidth.
Pom zoo:
Yuav ua li cas thiaj nrhiav tau pom zaus?
Cov suav ua vim cov ntaub ntawv ntawm kev sim tau hais tias yog Observed Frequency. Nws tuav cov lus teb tiag tiag ntawm ntau zaus. Nws tuaj yeem xam tau yooj yim los ntawm faib qhov tseeb zaus nrog tus qauv loj. Qhov kev soj ntsuam zaus yog dab tsi?
Yuav ua li cas thiaj nrhiav tau qhov zaus ntawm sine yoj?
Qhov sib npaug ntawm qhov kev ua haujlwm sine yog f(x)=sinx. Hauv qhov no b, zaus, sib npaug rau 1 uas txhais tau tias ib lub voj voog tshwm sim hauv 2π. Dab tsi yog qhov zaus ntawm sine yoj? Qhov zaus ntawm sine yoj yog tus naj npawb ntawm cov voj voog tiav uas tshwm sim txhua ob.
Puas eigenvectors yuav tsum yog orthogonal?
Feem ntau, rau ib qho matrix, the eigenvectors tsis yog ib txwm orthogonal. Tab sis rau ib hom tshwj xeeb ntawm matrix, symmetric matrix, eigenvalues yeej ib txwm muaj tseeb thiab cov eigenvectors sib raug zoo ib txwm orthogonal. Puas yog eigenvectors ntawm eigenvalues ib txwm orthogonal?
Tus encoder ntau zaus ua haujlwm li cas?
Qhov yooj yim tshaj plaws ntawm ntau qhov kev hloov pauv tsis muaj kev cuam tshuam muaj ob lub discs: ib qho rau kev saib xyuas ± 360 ° thiab cov lej thib ob rau kev saib xyuas tag nrho cov kev sib hloov ntawm thawj cov lej disc. Qhov ob yog kev cob cog rua los ntawm ib tug complex gearing system uas indexes lub thib ob disc rau txhua txhua rotation ntawm thawj disc.
Lub chaw haujlwm neeg ua haujlwm ua haujlwm li cas?
Cov neeg nrhiav haujlwm tuaj yeem thov rau cov haujlwm tshwj xeeb los ntawm lub chaw haujlwm ua haujlwm, lossis tuaj yeem hu rau lub koomhaum pabcuam nrhiav haujlwm. Lub chaw haujlwm xam phaj cov neeg nrhiav haujlwm thiab muab lawv tso rau hauv txoj haujlwm tsim nyog.
