I-Software Defined Radio yindlela yokutshintsha umsebenzi wentsimbi (okuyiyona nto ilungileyo kwimpilo yakho) ngentloko ebuhlungu yokucwangcisa. Ii-SDR ziqikelela ikamva elikhulu kwaye inzuzo ephambili ithathwa njengokususwa kwezithintelo ekuphunyezweni kweeprotocol zerediyo. Umzekelo yi-OFDM (i-Orthogonal frequency-division multiplexing) indlela yokumodareyitha, eyenziwa kuphela yindlela ye-SDR. Kodwa i-SDR ikwanalo elinye, ithuba lobunjineli kuphela- ukukwazi ukulawula kunye nokubona umqondiso kuyo nayiphi na indawo engafanelekanga ngomzamo omncinci.
Omnye wemigangatho yonxibelelwano enomdla ngumabonakude osemhlabeni we-DVB-T2.
Yantoni? Ewe kunjalo, unokuvula iTV ngaphandle kokuvuka, kodwa akukho nto inokuyibukela apho kwaye ayiselulo uluvo lwam, kodwa yinyaniso yezonyango.
Ngokunyanisekileyo, i-DVB-T2 iyilwe ngamandla abanzi kakhulu, kubandakanya:
- isicelo sangaphakathi
- Ukumodareyitha ukusuka kwi-QPSK ukuya kwi-256QAM
- bandwidth ukusuka 1,7MHz ukuya 8MHz
Ndinamava ekufumaneni umabonakude wedijithali usebenzisa umgaqo we-SDR. Umgangatho we-DVB-T ukwiprojekthi eyaziwayo ye-GNURadio. Kukho ibhloko ye-gr-dvbs2rx yomgangatho we-DVB-T2 (yonke i-GNURadio efanayo), kodwa ifuna ungqamaniso lwesignali yokuqala kwaye iyakhuthaza (umbulelo okhethekileyo kuRon Economos).
Into esinayo.
Kukho umgangatho we-ETSI EN 302 755 ochaza ukuhanjiswa, kodwa hayi ulwamkelo.
Isiginali isemoyeni kunye nesampulu yesampulu ye-9,14285714285714285714 MHz, imodareyithwe yi-COFDM kunye nabathwali be-32768, kwiqela le-8 MHZ.
Kucetyiswa ukuba ufumane imiqondiso enjalo ngokuphindwe kabini kwisampulu yesampulu (ukuze ungalahleki nantoni na) kwaye kwi-intermediate frequency ngaphezulu kwe-bandwidth (i-superheterodyne reception), ukulahla i-offset yangoku (DC) kunye "nokuvuza" kwe-oscillator yendawo. (LO) kwigalelo lomamkeli. Izixhobo ezanelisa ezi meko zibiza kakhulu kumdla nje.
I-SdrPlay ene-10Msps 10bit okanye i-AirSpy eneempawu ezifanayo zibiza kakhulu. Akukho mbuzo wokuphinda kabini iisampulu rhoqo apha kwaye ulwamkelo lunokwenziwa kuphela ngoguqulo oluthe ngqo (Zero IF). Ngoko ke (ngenxa yezizathu zemali) sitshintshela kwicala labalandeli be-SDR "ecocekileyo" kunye nobuncinci bokuguqulwa kwe-hardware.
Kwakuyimfuneko ukusombulula iingxaki ezimbini:
- Ungqamaniso. Fumana esona sigaba sichanekileyo sokutenxa kwiRF kunye nesampulu yokutenxa kwamaza.
- Phinda ubhale umgangatho weDVB-T2 ngasemva.
Umsebenzi wesibini ufuna ikhowudi eninzi kakhulu, kodwa unokusombulula ngokunyamezela kwaye unokuqinisekiswa ngokulula usebenzisa iimpawu zokuvavanya.
Iimpawu zovavanyo ziyafumaneka kwiseva ye-BBC ftp://ftp.kw.bbc.co.uk/t2refs/ enemiyalelo eneenkcukacha.
Isisombululo kwingxaki yokuqala sixhomekeke kakhulu kwiimpawu zesixhobo se-SDR kunye nobuchule bayo bokulawula. Ukusebenzisa imisebenzi ecetyiswayo yokulawula amaza, njengoko besitsho, akuphumelelanga, kodwa kunika amava amaninzi okufunda ezo. amaxwebhu, inkqubo, ukubukela uchungechunge lweTV, ukuxazulula imibuzo yefilosofi ..., ngokufutshane, kwakungenakwenzeka ukushiya iprojekthi.
Ukholo "kwi-SDR ecocekileyo" luye lwaqina ngakumbi.
Sithatha isignali njengoko injalo, siyifakela phantse kwi-analogue kwaye sikhuphe enye ecacileyo, kodwa efana neyokwenyani.
Umzobo webhloko yongqamaniso:
Yonke into apha ngokwencwadi yesifundo. Okulandelayo kunzima ngakumbi. Izitenxo kufuneka zibalwe. Kukho uncwadi oluninzi kunye namanqaku ophando athelekisa iingenelo kunye nokungalunganga kweendlela ezahlukeneyo. Ukusuka kwiiklasikhi- lo "nguMichael Speth, uStefan Fechtel, uGunnar Fock, uHeinrich Meyr, uYilo oluNgcono loMamkeli woThutho olusekwe kwi-OFDM-Icandelo loku-I kunye nele-II." Kodwa andizange ndidibane nenjineli enye ekwaziyo kwaye efuna ukubala, ngoko ke kwasetyenziswa indlela yobunjineli. Ukusebenzisa indlela yongqamaniso efanayo, ukuchithwa kwangeniswa kwisignali yovavanyo. Ngokuthelekisa iimethrikhi ezahlukeneyo kunye nokuphambuka okwaziwayo (wazazisa ngokwakhe), ezona zibalaseleyo zakhethwa ukusebenza kunye nokulula ukuphunyezwa. Ukutenxa kwamaza okwamkela kubalwa ngokuthelekisa ixesha lokulinda kunye nenxalenye yalo ephinda-phindayo. Isigaba sokufunyanwa rhoqo kunye nesampulu yesampulu kuqikelelwa ukusuka kwisigaba sokutenxa kwimiqondiso yokulinga kwaye oku kukwasetyenziswa ngendlela elula, elinganayo yokulinganisa umqondiso we-OFDM.
Uphawu lomlinganisi:
Kwaye konke oku kusebenza kakuhle ukuba uyazi xa isakhelo DVB-T2 iqala. Ukwenza oku, uphawu lwentshayelelo lwe-P1 lugqithiselwa kwisiginali. Indlela yokufumanisa kunye nokudibanisa uphawu lwe-P1 luchazwe kwi-Technical Specification ETSI TS 102 831 (kwakhona kukho iingcebiso ezininzi eziluncedo zokwamkelwa).
Ulungelelwaniso oluzenzekelayo lwesignali ye-P1 (eyona ndawo iphakamileyo ekuqaleni kwesakhelo):
Umfanekiso wokuqala (ziinyanga ezintandathu kuphela ezishiyekileyo de kube ngumfanekiso oshukumayo...):
Kwaye kulapho sifunda khona ukuba yintoni ukungalingani kwe-IQ, i-DC offset kunye nokuvuza kwe-LO. Njengomthetho, imbuyekezo yezi ziphazamiso ezichanekileyo zokuguqulwa ngokuthe ngqo ziphunyezwe kumqhubi wesixhobo se-SDR. Ke ngoko, kwathatha ixesha elide ukuqonda: ukunkqonkqoza iinkwenkwezi kwiqela le-QAM64 elinobubele ngumsebenzi wemisebenzi yembuyekezo. Kwafuneka ndicime yonke into ndibhale ibhayisekile yam.
Kwaye emva koko umfanekiso washukuma:
Ukumodareyitha kwe-QAM64 kunye nokujikeleza okuthe ngqo kweenkwenkwezi kumgangatho we-DVB-T2:
Ngamafutshane, esi sisiphumo sokudlulisa inyama egayiweyo emva kwe-grinder yenyama. Umgangatho ubonelela ngeentlobo ezine zokuxuba:
- ukushiya kancinci
- iseli interleaving (ukuxuba iiseli kwibhloko yekhowudi)
- ixesha lokushiyana (likwakwiqela leekhowudi zokungena)
- ukushiyana ngokuphindaphindiweyo (ukuxubana rhoqo kwisimboli ye-OFDM)
Ngenxa yoko, sinophawu olulandelayo kwigalelo:
Konke oku kumzabalazo wokunganyangeki kwengxolo yesiginali ekhowudiweyo.
Isiphumo
Ngoku asikwazi ukubona kuphela isignali ngokwayo kunye nokuma kwayo, kodwa kunye nolwazi lwenkonzo.
Kukho ii-multiplexes ezimbini emoyeni. Ngamnye uneendlela ezimbini zomzimba (PLP).
Enye into engaqhelekanga yaqatshelwa kwi-multiplex yokuqala - i-PLP yokuqala ibhalwe "multiple", enengqiqo, kuba kukho ngaphezu kwesinye kwi-multiplex, kwaye i-PLP yesibini ibhalwe "enye" ββkwaye lo ngumbuzo.
Okunomdla ngakumbi kukungaqhelekanga kwesibini kwi-multiplex yesibini - zonke iinkqubo zikwi-PLP yokuqala, kodwa kwi-PLP yesibini kukho umqondiso wendalo engaziwayo kwisantya esiphantsi. Ubuncinci umdlali weVLC, oqondayo malunga neefomati zevidiyo ezingamashumi amahlanu kunye nomthamo ofanayo weaudio, akawuqondi.
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Le projekthi yadalwa ngenjongo yokumisela eyona nto inokwenzeka yokuguqula i-DVB-T2 usebenzisa i-SdrPlay (kwaye ngoku i-AirSpy.), ngoko ke oku ayisiyiyo nenguqulelo yealpha.
PS Ngelixa ndibhala inqaku ngobunzima, ndakwazi ukudibanisa iPlutoSDR kwiprojekthi.
Omnye umntu uya kuthi ngokukhawuleza ukuba kukho i-6Msps kuphela yesignali ye-IQ kwimveliso ye-USB2.0, kodwa ufuna ubuncinane i-9,2Msps, kodwa esi sisihloko esahlukileyo.
umthombo: www.habr.com