Hai Habr!
A halin yanzu, babu ka'idojin sadarwa da yawa waɗanda, a gefe guda, suna da ban sha'awa da ban sha'awa, a gefe guda, bayanin su bai ɗauki shafuka 500 a cikin tsarin PDF ba. Ɗayan irin wannan sigina mai sauƙin yankewa ita ce siginar VHF Omni-directional Radio Beacon (VOR) da ake amfani da ita wajen kewayawa iska.
VOR Beacon (c) wikimedia.org
Na farko, tambaya ga masu karatu: yadda za a samar da sigina ta yadda za a iya ƙayyade hanyar ta amfani da eriya mai karɓa na ko'ina? Amsar tana ƙarƙashin yanke.
Janar bayanai
tsarin (VOR) an yi amfani da shi don kewayawar iska tun cikin 50s na ƙarnin da ya gabata, kuma ya ƙunshi ingantattun tashoshin rediyo masu ɗan gajeren zango (kilomita 100-200), waɗanda ke aiki a cikin kewayon mitar VHF 108-117 MHz. Yanzu, a cikin zamanin gigahertz, sunan yana da girma sosai dangane da irin waɗannan mitoci suna da ban dariya kuma a cikin kansa yana magana. shekaru wannan ma'auni, amma ta hanyar, tashoshi har yanzu suna aiki , Yana aiki a cikin matsakaicin matsakaicin kalaman 400-900 kHz.
Sanya eriyar jagora akan jirgin sama ba shi da daɗi a tsarin, don haka matsalar ta taso ta yadda ake ɓoye bayanai game da alkiblar fitilar da ke cikin siginar kanta. Ka'idar aiki "a kan yatsunsu" za a iya bayyana kamar haka. Bari mu yi tunanin cewa muna da fitila na yau da kullun wanda ke aika ƙunƙun haske na haske kore, wanda fitilarsa ke juyawa sau 1 a cikin minti daya. Babu shakka, sau ɗaya a minti ɗaya za mu ga walƙiyar haske, amma ɗaya irin wannan walƙiya ba ya ɗaukar bayanai da yawa. Bari mu ƙara na biyu zuwa fitilar mara shugabanci wata jar fitila da ke haskawa a lokacin da fitilun fitilun suka “wuce” hanyar zuwa arewa. Domin An san lokacin walƙiya da daidaitawar tashoshi, ta hanyar ƙididdige jinkiri tsakanin filasha ja da kore, zaku iya gano azimuth zuwa arewa. Yana da sauki. Ya rage don yin abu ɗaya, amma amfani da rediyo. An warware wannan ta hanyar canza matakai. Ana amfani da sigina guda biyu don watsawa: lokaci na farko ya kasance akai-akai (bayani), lokaci na biyu (mai canzawa) yana canzawa ta hanya mai rikitarwa dangane da jagorancin radiation - kowane kusurwa yana da nasa motsin lokaci. Don haka, kowane mai karɓa zai karɓi sigina tare da canjin lokaci na “na kansa”, daidai da azimuth zuwa fitilar. Ana aiwatar da fasahar “modulation na sararin samaniya” ta amfani da eriya ta musamman (Alford Loop, duba KDPV) da na musamman, mai ma'ana. Wanda a zahiri shine batun wannan labarin.
Bari mu yi tunanin cewa muna da taswirar gado na yau da kullun, wanda ke aiki tun daga 50s, da watsa sigina a cikin tsarin AM na yau da kullun a cikin lambar Morse. Wataƙila, sau ɗaya a wani lokaci, mai kewayawa ya saurari waɗannan sigina a cikin belun kunne kuma ya yi alamar kwatance tare da mai mulki da kamfas akan taswira. Muna so mu ƙara sababbin ayyuka zuwa siginar, amma ta hanyar da ba za a "karya" dacewa da tsofaffi ba. Maudu'in ya saba, ba sabon abu ba ... An yi shi kamar haka - an ƙara ƙararrakin sautin 30 Hz zuwa siginar AM, yana yin aikin siginar lokaci-lokaci, da kuma babban ɓangaren mita, wanda aka sanya ta mita. daidaitawa a mitar 9.96 kHz, yana watsa siginar lokaci mai canzawa. Ta hanyar zaɓar sigina biyu da kwatanta matakan, muna samun kusurwar da ake so daga digiri 0 zuwa 360, wanda shine azimuth da ake so. A lokaci guda, duk wannan ba zai tsoma baki tare da sauraren fitilar "a cikin hanyar da aka saba" ba kuma ya kasance mai dacewa da tsofaffin masu karɓar AM.
Mu matsa daga ka'idar zuwa aiki. Bari mu ƙaddamar da mai karɓar SDR, zaɓi AM modulation da bandwidth 12 kHz. Za a iya samun mitocin tashoshi na VOR cikin sauƙi akan layi. A kan bakan, siginar yayi kama da haka:
A wannan yanayin, ana watsa siginar fitila a mitar 113.950 MHz. A cikin tsakiyar za ku iya ganin layin daidaitawa na amplitude mai sauƙin ganewa da siginar lambar Morse (.- - ... wanda ke nufin AMS, Amsterdam, Schiphol Airport). A kusa da nisa na 9.6 KHz daga mai ɗaukar hoto, ana iya ganin kololuwa biyu, suna watsa sigina na biyu.
Bari mu yi rikodin siginar a cikin WAV (ba MP3 ba - matsawa mai lalacewa zai "kashe" gaba ɗaya tsarin siginar) kuma mu buɗe shi a cikin GNU Radio.
Ƙaddamarwa
Mataki 1. Bari mu buɗe fayil ɗin tare da siginar da aka yi rikodi kuma mu yi amfani da matattara mai ƙarancin wucewa don samun siginar tunani na farko. Ana nuna hoton GNU Radio a cikin adadi.
Sakamakon: ƙananan sigina a 30 Hz.
Mataki 2: yanke siginar mai canzawa. Kamar yadda aka ambata a sama, yana da mitar 9.96 kHz, muna buƙatar matsar da shi zuwa mitar sifili kuma mu ciyar da shi zuwa na'urar demodulator na FM.
GNU Radio graph:
Shi ke nan, an warware matsalar. Muna ganin sigina biyu, bambancin lokaci wanda ke nuna kusurwar daga mai karɓa zuwa fitilar VOR:
Alamar tana da hayaniya sosai, kuma ana iya buƙatar ƙarin tacewa don ƙididdige bambancin lokaci, amma ina fata ƙa'idar ta fito fili. Ga wadanda suka manta yadda aka ƙayyade bambancin lokaci, hoto daga :
Abin farin ciki, ba lallai ne ku yi duk wannan da hannu ba: akwai riga a cikin Python, yana yanke siginar VOR daga fayilolin WAV. A haƙiƙa, bincikensa ya ƙarfafa ni in yi nazarin wannan batu.
Masu sha'awar za su iya gudanar da shirin a cikin na'ura wasan bidiyo kuma su sami ƙarshen kusurwa a cikin digiri daga fayil ɗin da aka riga aka yi rikodi:
Magoya bayan jirgin suna iya yin nasu mai karɓar mai ɗaukar hoto ta amfani da RTL-SDR da Rasberi Pi. Af, a kan jirgin "ainihin" wannan alamar yana kama da wani abu kamar haka:
Hoto ©
ƙarshe
Irin waɗannan sigina "daga ƙarni na ƙarshe" tabbas suna da ban sha'awa don bincike. Da fari dai, suna da sauƙi, DRM na zamani ko, musamman, GSM, ba zai yuwu a sake yin la'akari da "a kan yatsun ku". Suna buɗe don karɓu kuma ba su da maɓalli ko ɓoyewa. Na biyu, watakila nan gaba za su zama tarihi kuma za a maye gurbinsu da kewayawa tauraron dan adam da ƙarin tsarin dijital na zamani. Na uku, nazarin irin waɗannan ma'auni yana ba ku damar koyon fasaha mai ban sha'awa da cikakkun bayanai na tarihi na yadda aka warware matsalolin ta hanyar amfani da wasu hanyoyin kewayawa da tushe na ƙarni na ƙarshe. Don haka ana iya ba masu karɓa shawara su karɓi irin waɗannan sigina yayin da suke ci gaba da aiki.
Kamar yadda aka saba, gwaji na farin ciki kowa da kowa.
source: www.habr.com