Siginar da aka watsa akan hanyar sadarwar gidan talabijin ta kebul shine mai watsa shirye-shiryen watsa shirye-shirye, bakan rabe-raben mitar. Sigina na sigina, gami da mitoci da lambobin tashoshi a Rasha ana tsara su ta GOST 7845-92 da GOST R 52023-2003, amma mai aiki yana da 'yanci don zaɓar abun ciki na kowane tashoshi bisa ga ra'ayinsa.
Abubuwan da ke cikin jerin labaran
- Sashe na 2: Haɗin sigina da siffa
- Sashe na 3: Abubuwan Siginar Analog
- Sashe na 4: Bangaren Siginar Dijital
- Sashe na 5: Cibiyar Rarraba Coaxial
- Sashe na 6: Amplifiers Siginar RF
- Sashe na 7: Masu karɓar gani
- Sashe na 8: Cibiyar sadarwa ta Kashin baya na gani
- Kashi na 9: Gaba
- Sashe na 10: Matsalar hanyar sadarwa ta CATV
Bari in tunatar da ku cewa, ba littafin karatu nake rubuta ba, amma shiri ne na ilimantarwa don fadada tunani na da shiga duniyar talabijin ta USB. Sabili da haka, na yi ƙoƙari in rubuta cikin harshe mai sauƙi, barin kalmomi masu mahimmanci ga waɗanda ke da sha'awar kuma ba su zurfafa cikin bayanin fasahar da aka kwatanta daidai da daruruwan lokuta ba tare da ni ba.
Me muke aunawa?
Masu fasahar mu da farko suna amfani da Deviser DS2400T don samun bayanan sigina akan igiyoyin coaxial.
Mahimmanci wannan mai karɓar talabijin ne, amma maimakon hoto da sauti, muna ganin halaye masu ƙima da ƙima na duka bakan da tashoshi ɗaya. Misalai masu zuwa sune hotunan kariyar kwamfuta daga wannan na'urar.
Har ila yau, wannan Mai ƙira yana da ɗan ƙaramin aiki, amma akwai ma na'urori masu sanyaya: tare da allon da ke nuna hoton TV kai tsaye, yana karɓar siginar gani da kuma, abin da mai ƙira ya rasa, karɓar siginar tauraron dan adam DVB-S (amma wannan labari ne daban-daban) .
Bakan sigina
Yanayin nunin bakan yana ba ku damar tantance yanayin siginar da sauri "ta ido"
A cikin wannan yanayin, na'urar tana duba tashoshi daidai da ƙayyadadden tsarin mita. Don saukakawa, an cire mitoci da ba a yi amfani da su ba a cikin hanyar sadarwar mu daga cikakken bakan, don haka sakamakon da aka samu shine gunkin tashoshi.
Ana nuna tashoshi na dijital da shuɗi, tashoshin analog suna cikin rawaya. Bangaren koren tashar analog shine bangaren sautinsa.
Bambanci a cikin matakan tashoshi daban-daban yana bayyane a fili: rashin daidaituwa na mutum ya dogara da saitunan masu aikawa a cikin headend, kuma babban bambanci tsakanin babba da ƙananan ƙananan yana da wata ma'ana, wanda zan tattauna a kasa.
A cikin wannan yanayin, ƙetare mai ƙarfi daga al'ada za su kasance a bayyane a fili, kuma idan akwai matsaloli masu tsanani a cikin hanyar sadarwa, wannan zai bayyana nan da nan. Misali, a cikin hoton da ke sama zaku iya ganin tsalle-tsalle na tashoshi na dijital guda biyu a cikin babban yanki mai girma: suna nan ne kawai a cikin nau'ikan gajeriyar ratsi, da kyar suka kai matakin 10 dBµV (ana nuna matakin 80 dBµV. a saman - wannan shine babban iyaka na jadawali), wanda shine ainihin amo da kebul ɗin ke karɓa a kanta azaman eriya ko gudummawar kayan aiki masu aiki. Waɗannan tashoshi biyu tashoshin gwaji ne kuma an kashe su a lokacin rubutawa.
Rashin daidaituwar rarraba tashoshi na dijital da na analog na iya haifar da rudani. Wannan, ba shakka, ba daidai ba ne kuma ya faru saboda haɓakar juyin halitta na hanyar sadarwa: ƙarin tashoshi an ƙara su kawai zuwa tsarin mita a cikin ɓangaren kyauta na bakan. Lokacin ƙirƙirar tsarin mitar daga karce, zai zama daidai a sanya duk analog a ƙananan ƙarshen bakan. Bugu da ƙari, kayan aikin tashar da aka tsara don samar da sigina ga ƙasashen Turai suna da ƙuntatawa akan amfani da mitoci don watsa siginar dijital kuma, ko da yake babu irin wannan ƙuntatawa a cikin ƙasarmu, ta yin amfani da irin wannan kayan aiki ya zama dole don sanya tashoshi na dijital a cikin bakan. , sabanin hankali.
Waveform
Kamar yadda aka sani daga ilimin kimiyyar lissafi na asali, mafi girman yawan igiyoyin igiyar ruwa, yana da ƙarfi attenuation yayin da yake yaduwa. Lokacin watsa irin wannan siginar faɗaɗa kamar yadda ake samu a cikin hanyar sadarwa ta CATV, haɓakawa a cikin hanyar sadarwar rarraba na iya kaiwa dubun decibels kowace hannu, kuma a cikin ƙananan ɓangaren bakan zai zama ƙasa da yawa sau da yawa. Don haka, bayan aiko da sigina mai tsayuwa zuwa ga mai tashi daga bene, a bene na 25 za mu ga wani abu kamar haka:
Matsayin mitoci na sama yana gani ƙasa da na ƙasa. A cikin yanayi na ainihi, TV, ba tare da fahimtar shi ba, na iya ɗaukar tashoshi masu rauni kawai amo da tace su. Kuma idan an shigar da amplifier a cikin ɗakin, to, lokacin da kuka yi ƙoƙarin daidaita shi don karɓar tashoshi masu inganci daga babban ɓangaren kewayon, haɓakawa zai faru a cikin ƙananan ɓangaren. Ma'auni sun ƙayyade bambancin da bai wuce 15 dBµV ba a kan dukkan kewayon.
Don guje wa wannan, lokacin daidaita kayan aiki masu aiki, an saita matakin farko a cikin babban yankin mitar. Wannan shi ake kira “madaidaicin karkata”, ko kuma “karkatar da kai”. Kuma abin da aka nuna a cikin hoton shine "karkatar da baya", kuma irin wannan hoton ya riga ya zama haɗari. Ko, aƙalla, alamar cewa akwai matsala tare da kebul zuwa wurin aunawa.
Haka kuma yanayin akasin haka yana faruwa, lokacin da ƙananan mitoci ba su nan, kuma na sama da kyar suke shiga sama da matakin amo:
Wannan kuma yana gaya mana game da lalacewar kebul, wato tsakiya na tsakiya: mafi girman mita, kusa da gefen waveguide yana yadawa (tasirin fata a cikin kebul na coaxial). Saboda haka, muna ganin kawai tashoshin da aka rarraba a mafi girma, amma, a matsayin mai mulkin, TV ba zai iya samun su a wannan matakin ba.
source: www.habr.com