Satellite ya Meteor M1
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Kugwira ntchito kwaukadaulo wa mlengalenga sikutheka popanda kulumikizana ndi wailesi, ndipo m'nkhaniyi ndiyesera kufotokoza malingaliro akulu omwe adapanga maziko amiyezo yopangidwa ndi International Advisory Committee for Space Data Systems (CCSDS. Chidule ichi chidzagwiritsidwa ntchito pansipa) .
Cholembachi chidzayang'ana kwambiri pamtundu wa data, koma mfundo zazikuluzikulu za zigawo zina zidzayambitsidwanso. Nkhaniyi sikutanthauza kulongosola bwino komanso kokwanira pamiyezo. Mutha kuziwona pa Zithunzi za CCSDS. Komabe, ndizovuta kwambiri kuzimvetsa, ndipo tinakhala nthawi yambiri ndikuyesera kuzimvetsa, kotero apa ndikufuna kupereka chidziwitso chofunikira, chomwe chidzakhala chosavuta kumvetsetsa china chirichonse. Kotero, tiyeni tiyambe.
Noble Mission ya CCSDS
Mwina wina ali ndi funso: chifukwa chiyani aliyense ayenera kumamatira ku mfundo ngati mungathe kupanga eni ake wailesi protocol stack (kapena muyezo wanu, ndi blackjack ndi zatsopano), potero kuwonjezera chitetezo cha dongosolo?
Monga momwe zimasonyezera, ndizopindulitsa kwambiri kutsatira mfundo za CCSDS pazifukwa zotsatirazi:
- Komiti yomwe ili ndi udindo wofalitsa miyezoyi ikuphatikizapo oimira bungwe lililonse lalikulu lazamlengalenga padziko lonse lapansi, zomwe zimabweretsa chidziwitso chamtengo wapatali chomwe chapeza pazaka zambiri za mapangidwe ndi kayendetsedwe ka ntchito zosiyanasiyana. Zingakhale zopanda nzeru kunyalanyaza zomwe zachitikazi ndi kupondanso.
- Miyezo iyi imathandizidwa ndi zida zapansi zomwe zili pamsika.
- Mukathetsa mavuto aliwonse, mutha kufunafuna thandizo kuchokera kwa anzanu kuchokera ku mabungwe ena kuti athe kuchita zokambirana ndi chipangizocho kuchokera pamalo awo oyambira. Monga mukuonera, miyezo ndi chinthu chothandiza kwambiri, kotero tiyeni tiwone mfundo zawo zazikulu.
zomangamanga
Miyezo ndi seti ya zolemba zomwe zikuwonetsa mtundu wodziwika bwino wa OSI (Open System Interconnection), kupatula kuti pamlingo wa ulalo wa data wamba amangokhala kugawanika kukhala telemetry (downlink - space - Earth) ndi telecommands (uplink).
Tiyeni tiwone ena mwamagawo mwatsatanetsatane, kuyambira ndi thupi ndikukwera mmwamba. Kuti timveke bwino, tidzalingalira kamangidwe ka mbali yolandirayo. Chotumiza ndi chithunzi chake chagalasi.
Thupi wosanjikiza
Pamulingo uwu, chizindikiro cha wailesi chosinthidwa chimasinthidwa kukhala mtsinje pang'ono. Miyezo apa ndi yaupangiri wachilengedwe, chifukwa pamlingo uwu ndizovuta kufotokozera pakukhazikitsa kwa hardware. Apa, ntchito yayikulu ya CCSDS ndikutanthauzira kusinthika kovomerezeka (BPSK, QPSK, 8-QAM, etc.) ndikupereka malingaliro ena pakukhazikitsa njira zolumikizira zizindikiro, kubweza kwa Doppler, ndi zina zambiri.
Kulunzanitsa ndi encoding level
Mwamwayi, ndi sublayer ya data link wosanjikiza, koma nthawi zambiri amapatulidwa kukhala osiyana wosanjikiza chifukwa cha kufunikira kwake mkati mwa CCSDS miyezo. Chosanjikiza ichi chimasintha mtsinjewo kukhala mafelemu otchedwa (telemetry kapena telecommands), zomwe tidzakambirana pambuyo pake. Mosiyana ndi kalunzanitsidwe chizindikiro pa wosanjikiza thupi, amene amalola kupeza olondola bit mtsinje, chimango kalunzanitsidwe ikuchitika apa. Ganizirani njira yomwe deta imatenga pamlingo uwu (kuyambira pansi mpaka pamwamba):
Komabe, izi zisanachitike, ndikofunikira kunena mawu ochepa okhudza kukopera. Njirayi ndiyofunikira kuti mupeze ndi/kapena kukonza zolakwika pang'ono zomwe zimachitika mukatumiza deta pawayilesi. Apa sitidzalingalira njira zosinthira, koma tingopeza chidziwitso chofunikira kuti timvetsetse malingaliro opitilira mulingowo.
Ma code akhoza kukhala block kapena mosalekeza. Miyezoyo siyikakamiza kugwiritsa ntchito mtundu wina wa encoding, koma iyenera kupezeka motere. Zizindikiro zosalekeza zimaphatikizapo ma code convolutional. Amagwiritsidwa ntchito kusindikiza mtsinje wopitilira pang'ono. Izi ndizosiyana ndi ma code block, pomwe deta imagawidwa kukhala ma codeblocks ndipo imatha kusinthidwa mkati mwa midadada yonse. Chotchinga kachidindo chimayimira zomwe zimatumizidwa ndi chidziwitso chowonjezera chofunikira kuti zitsimikizire kulondola kwazomwe zalandilidwa ndikuwongolera zolakwika zomwe zingatheke. Ma code block amaphatikizanso ma code odziwika a Reed-Solomon.
Ngati convolutional encoding ikugwiritsidwa ntchito, bitstream imalowa mu decoder kuyambira pachiyambi. Zotsatira za ntchito yake (zonsezi, ndithudi, zimachitika mosalekeza) ndi CADU (channel access data unit) midadada ya data. Kapangidwe kameneka ndi kofunikira pa kulumikizana kwa chimango. Pamapeto pa CADU iliyonse pali cholumikizira cholumikizira (ASM). Awa ndi ma byte 4 omwe amadziwika pasadakhale, omwe synchronizer amapeza chiyambi ndi mapeto a CADU. Umu ndi momwe kulunzanitsa chimango kumatheka.
Gawo lotsatira losasankha la kalunzanitsidwe ndi kabisidwe wosanjikiza limalumikizidwa ndi mawonekedwe akuthupi. Izi ndi derandomization. Chowonadi ndi chakuti kuti mukwaniritse kulumikizana kwa chizindikiro, kusintha pafupipafupi pakati pa zizindikiro ndikofunikira. Chifukwa chake, ngati titumiza, titi, kilobyte ya data yokhala ndi imodzi, kulunzanitsa kudzatayika. Chifukwa chake, pakupatsirana, zolowetsazo zimasakanizidwa ndi kutsatizana kwanthawi pseudo-mwachisawawa kuti kachulukidwe ka ziro ndi ena akhale ofanana.
Chotsatira, ma code block amasinthidwa, ndipo chomwe chatsalira ndicho chomaliza cha kalunzanitsidwe ndi encoding level - chimango.
Data Link Layer
Kumbali imodzi, purosesa yosanjikiza ulalo imalandira mafelemu, ndipo mbali inayo imatulutsa mapaketi. Popeza kukula kwa mapaketi sikuli kocheperako, chifukwa cha kufalikira kwawo kodalirika ndikofunikira kuwagawa m'magulu ang'onoang'ono - mafelemu. Apa tiwona zigawo ziwiri: padera za telemetry (TM) ndi telecommands (TC).
Telemetry
Mwachidule, iyi ndi data yomwe siteshoni yapansi imalandira kuchokera ku mlengalenga. Zonse zofalitsidwa zimagawidwa m'zidutswa ting'onoting'ono zautali wokhazikika - mafelemu omwe ali ndi deta yotumizidwa ndi magawo a ntchito. Tiyeni tiwone mwatsatanetsatane mawonekedwe a chimango:
Ndipo tiyeni tiyambe kulingalira kwathu ndi mutu waukulu wa chimango cha telemetry. Kupitilira apo, ndidzilola kuti ndingomasulira milingo m'malo ena, ndikuwunikiranso panjira.
Gawo la ID la Master Channel liyenera kukhala ndi nambala yachithunzicho ndi chizindikiritso cha chipangizocho.
Chombo chilichonse, malinga ndi miyezo ya CCSDS, chiyenera kukhala ndi chizindikiritso chake chapadera, chomwe, pokhala ndi chimango, munthu angathe kudziwa chomwe chiri chipangizo chake. Mwamwayi, ndikofunikira kutumiza pulogalamu yolembetsa chipangizocho, ndipo dzina lake, pamodzi ndi chizindikiritso chake, zidzasindikizidwa m'malo otseguka. Komabe, opanga ku Russia nthawi zambiri amanyalanyaza njirayi, popereka chizindikiritso chosagwirizana ndi chipangizocho. Nambala ya mtundu wa chimango imathandiza kudziwa mtundu wa miyezo yomwe imagwiritsidwa ntchito kuti muwerenge bwino chimango. Apa tingowona mulingo wokhazikika kwambiri wokhala ndi mtundu "0".
Munda wa ID wa Virtual Channel uyenera kukhala ndi VCID ya njira yomwe paketiyo idachokera. Palibe zoletsa pakusankha kwa VCID; makamaka, mayendedwe enieni samawerengedwa motsatizana.
Nthawi zambiri pamafunika kuchuluka kwa data yopatsirana. Chifukwa chaichi, pali limagwirira pafupifupi njira. Mwachitsanzo, satellite ya Meteor-M2 imatumiza chithunzi chamtundu mumtundu wowoneka, ndikuchigawa mumitundu itatu yakuda ndi yoyera - mtundu uliwonse umafalitsidwa munjira yakeyake mu paketi yosiyana, ngakhale pali kupatuka kwina pamiyezo. kapangidwe ka mafelemu ake.
Gawo la mbendera ya Operational Control lidzakhala chizindikiro cha kukhalapo kapena kusapezeka kwa gawo la Operational Control mu chimango cha telemetry. 4 ma byte awa kumapeto kwa chimango amathandiza kupereka ndemanga poyang'anira kutumiza kwa mafelemu a telecommand. Tikambirana za iwo posachedwa.
Zowerengera zazikulu komanso zenizeni zamakina ndi minda yomwe imakulitsidwa ndi imodzi nthawi iliyonse chimango chitumizidwa. Kutumikira monga chizindikiro kuti palibe chimango chimodzi anatayika.
Maonekedwe a data ya telemetry ndi ma byte ena awiri a mbendera ndi data, zomwe tiwona zochepa chabe.
Gawo la mbendera ya Sekondale ya Header liyenera kukhala chizindikiro cha kukhalapo kapena kusapezeka kwa Sekondale Header mu telemetry frame.
Ngati mukufuna, mutha kuwonjezera mutu wowonjezera pa chimango chilichonse ndikuyika chilichonse pamenepo mwakufuna kwanu.
Gawo Loyamba Lolozera Pamutu, pomwe mbendera yolumikizira yakhazikitsidwa kukhala "1", idzakhala ndi chiwonetsero chaposachedwa cha malo a octet woyamba wa Paketi yoyamba mu Data Field ya chimango cha telemetry. Malowa amawerengedwa kuchokera ku 0 mu dongosolo lokwera kuyambira pachiyambi cha deta. Ngati palibe chiyambi cha paketi m'munda wa data wa chimango cha telemetry, ndiye kuti cholozera pamutu woyamba chiyenera kukhala ndi mtengo woyimira bayinare "11111111111" (izi zikhoza kuchitika ngati paketi imodzi yaitali yafalikira pamwamba pa chimango chimodzi. ).
Ngati gawo la deta lili ndi paketi yopanda kanthu (Idle Data), ndiye cholozera pamutu woyamba chiyenera kukhala ndi mtengo woyimira binary "11111111110". Pogwiritsa ntchito gawoli, wolandila ayenera kulunzanitsa mtsinjewo. Gawoli limatsimikizira kuti kulunzanitsa kwabwezeretsedwa ngakhale mafelemu atayidwa.
Ndiye kuti, paketi imatha, tinene, kuyambira pakati pa chimango cha 4 ndikutha kumayambiriro kwa 20. Munda uwu umagwiritsidwa ntchito kupeza chiyambi chake. Mapaketi amakhalanso ndi mutu womwe umatchula kutalika kwake, kotero pamene cholozera kumutu woyamba chikupezeka, pulosesa yolumikizira ulalo iyenera kuiwerenga, potero kudziwa komwe paketiyo ithera.
Ngati gawo lowongolera zolakwika likupezeka, liyenera kukhala mumtundu uliwonse wa telemetry panjira inayake yakuthupi munthawi yonseyi.
Gawoli limawerengedwa pogwiritsa ntchito njira ya CRC. Njirayi iyenera kutenga n-16 bits ya chimango cha telemetry ndikuyika zotsatira za kuwerengera muzitsulo 16 zomaliza.
Magulu a TV
Choyimira cholamula cha TV chili ndi zosiyana zingapo. Mwa iwo:
- Kapangidwe ka mutu kosiyana
- Kutalika kwamphamvu. Izi zikutanthauza kuti kutalika kwa chimango sikukhazikitsidwa mokhazikika, monga momwe zimachitikira mu telemetry, koma zimatha kusiyanasiyana malinga ndi mapaketi opatsirana.
- Packet delivery guarantee mechanism. Ndiko kuti, chombocho chiyenera, pambuyo pochilandira, chitsimikizire kulondola kwa chiwongolero cha chimango, kapena kupempha kutumiza kuchokera ku chimango chomwe chikanalandiridwa ndi cholakwika chosayenera.
Minda yambiri tikudziwa kale kuchokera pamutu wamtundu wa telemetry. Iwo ali ndi cholinga chomwecho, kotero pano tingoganizira za minda yatsopano yokha.
Pang'ono pang'onopang'ono mbendera yodutsa iyenera kugwiritsidwa ntchito kuyang'anira mawonekedwe pa wolandila. Mtengo wa "0" pa mbendera iyi uwonetsa kuti chimango ndi chimango cha Mtundu A ndipo chiyenera kutsimikiziridwa molingana ndi FARM. Mtengo wa "1" pa mbendera iyi uyenera kusonyeza kwa wolandirayo kuti chimangochi ndi chamtundu wa B ndipo chiyenera kulambalala FARM.
Mbenderayi imadziwitsa wolandirayo ngati angagwiritse ntchito njira yovomerezera zotumizira zomwe zimatchedwa FARM - Frame Acceptance and Reporting Mechanism.
Lamulo lolamulira liyenera kugwiritsidwa ntchito kuti mumvetsetse ngati gawo la data limanyamula lamulo kapena deta. Ngati mbendera ndi "0", ndiye kuti gawo la deta liyenera kukhala ndi deta. Ngati mbendera ili "1", ndiye kuti gawo la data liyenera kukhala ndi chidziwitso chowongolera FARM.
FARM ndi makina okhazikika omwe magawo ake amatha kukhazikitsidwa.
RSVD. SPARE - zidutswa zosungidwa.
Zikuwoneka kuti CCSDS ili ndi mapulani kwa iwo mtsogolomo, komanso kuti agwirizane ndi ma protocol omwe adasunga kale mabizinesi amakono.
Gawo lautali wa chimango liyenera kukhala ndi nambala yoyimira pang'ono yomwe ili yofanana ndi kutalika kwa chimango mu octets kuchotsera imodzi.
Gawo la data la chimango liyenera kutsatira mutu wopanda mipata ndipo likhale ndi chiwerengero chokwanira cha ma octets, chomwe chingakhale kutalika kwa ma octets 1019. Gawoli liyenera kukhala ndi chipika cha data cha frame kapena zambiri zamalamulo. Tsamba la data block liyenera kukhala ndi:
- chiwerengero cha chiwerengero cha octets deta
- mutu wagawo wotsatiridwa ndi chiwerengero chokwanira cha octets a data
Ngati mutu ulipo, ndiye kuti chipika cha data chiyenera kukhala ndi Paketi, seti ya Paketi, kapena gawo la Paketi. Chotchinga cha data chopanda mutu sichingakhale ndi magawo a Paketi, koma imatha kukhala ndi midadada yamtundu wachinsinsi. Izi zimachokera ku izi kuti mutu umafunika pamene chipika chotumizira sichikulowa mu chimango chimodzi. Chida cha data chomwe chili ndi mutu chimatchedwa gawo
Gawo la mbendera ziwiri liyenera kukhala ndi:
- "01" - ngati gawo loyamba la deta lili mu block block
- "00" - ngati gawo lapakati la deta lili mu block block
- "10" - ngati gawo lomaliza la deta lili mu block block
- "11" - ngati palibe magawano ndipo paketi imodzi kapena zingapo zimagwirizana kwathunthu mu block block.
Gawo la MAP ID liyenera kukhala ndi ziro ngati mayendedwe a MAP sagwiritsidwa ntchito.
Nthawi zina ma 6 bits omwe amaperekedwa kumayendedwe enieni sakhala okwanira. Ndipo ngati kuli kofunikira kuti muchulukitse deta pamayendedwe okulirapo, ma bits ena 6 kuchokera pamutu wagawo amagwiritsidwa ntchito.
Farm
Tiyeni tione mwatsatanetsatane njira yoyendetsera kayendetsedwe ka kayendetsedwe ka anthu. Dongosololi limangopereka zogwirira ntchito ndi mafelemu a ma telecommand chifukwa cha kufunikira kwawo (telemetry ikhoza kufunsidwanso nthawi zonse, ndipo chombocho chiyenera kumva malo apansi momveka bwino ndikumvera malamulo ake nthawi zonse). Chifukwa chake, tiyerekeze kuti tasankha kuwunikiranso satellite yathu, ndikutumiza fayilo ya binary ya 10 kilobytes kukula kwake. Pa mulingo wolumikizira, fayiloyo imagawidwa m'mafelemu 10 (0, 1, ..., 9), omwe amatumizidwa m'mwamba imodzi ndi imodzi. Kutumiza kukamalizidwa, satellite iyenera kutsimikizira kulondola kwa paketi yolandirira, kapena lipoti pamutu womwe cholakwikacho chidachitika. Chidziwitsochi chimatumizidwa kugawo loyang'anira ntchito mumtundu wapafupi wa telemetry (Kapena chombocho chikhoza kuyambitsa kufalitsa kwa chimango chopanda ntchito ngati chilibe chonena). Kutengera ndi telemetry yomwe talandira, timaonetsetsa kuti zonse zili bwino, kapena timatumiza uthengawo. Tiyerekeze kuti satellite sinamve chimango #7. Izi zikutanthauza kuti timamutumizira mafelemu 7, 8, 9. Ngati palibe yankho, paketi yonseyo imatumizidwanso (ndi zina zotero kangapo mpaka titazindikira kuti zoyesayesazo ndizopanda pake).
Pansipa pali dongosolo la gawo lowongolera magwiridwe antchito ndi kufotokozera kwa magawo ena. Zomwe zili m'gawoli zimatchedwa CLCW - Communication Link Control Word.
Popeza mutha kulingalira mosavuta pachithunzichi cholinga cha minda yayikulu, ndipo enawo ndi otopetsa kuyang'ana, ndikubisa kufotokozera mwatsatanetsatane pansi pa wowononga.
Kufotokozera za minda ya CLCWSinthani Mtundu wa Mawu:
Kwa mtundu uwu, mawu owongolera ayenera kukhala ndi 0
Control Word Version (CLCW Version Number):
Kwa mtundu uwu, mawu owongolera ayenera kukhala ofanana ndi "00" pakuyimira pang'ono.
Status Field:
Kugwiritsa ntchito gawoli kumatsimikiziridwa pa ntchito iliyonse padera. Itha kugwiritsidwa ntchito pakusintha kwanuko ndi mabungwe osiyanasiyana am'mlengalenga.
Chizindikiritso cha Virtual Channel:
Iyenera kukhala ndi chizindikiritso cha tchanelo chomwe mawu owongolerawa amalumikizidwa.
mbendera yofikira panjira:
Mbendera iyenera kupereka zambiri za kukonzekera kwa gawo la thupi la wolandirayo. Ngati gawo lakuthupi la wolandila silinakonzekere kulandira mafelemu, ndiye kuti gawolo liyenera kukhala ndi "1", apo ayi "0".
Mbendera yolephera kulunzanitsa:
Mbendera ikhoza kuwonetsa kuti mawonekedwewo akugwira ntchito molakwika komanso kuti mafelemu okanidwa ndi okwera kwambiri. Kugwiritsa ntchito gawoli ndikusankha; ngati litagwiritsidwa ntchito, liyenera kukhala ndi "0" ngati kulunzanitsa kulipo, ndi "1" ngati palibe.
Kuletsa mbendera:
Gawoli lizikhala ndi loko ya FARM panjira iliyonse. Mtengo wa "1" pagawoli uyenera kuwonetsa kuti FARM ndiyozimitsidwa ndipo mafelemu adzatayidwa pagawo lililonse, apo ayi "0".
Dikirani mbendera:
Bino ili lidzagwiritsidwa ntchito kusonyeza kuti wolandira sangathe kukonza deta pa njira yomwe yatchulidwa. Mtengo wa "1" ukuwonetsa kuti mafelemu onse adzatayidwa panjira iyi, apo ayi "0".
Mbendera Patsogolo:
Mbendera iyi ikhale ndi "1" ngati mafelemu amtundu umodzi kapena angapo atayidwa kapena mipata yapezeka, kotero kutumizanso ndikofunikira. Mbendera ya "0" ikuwonetsa kuti panalibe mafelemu ogwetsedwa kapena kulumpha.
Mayankho:
Nambala ya chimango yomwe sinalandiridwe. Zimatsimikiziridwa ndi kauntala mu mutu wa chimango cha telecommand
network wosanjikiza
Tiyeni tikhudze pa mlingo uwu pang'ono. Pali njira ziwiri apa: gwiritsani ntchito paketi ya danga, kapena phatikizani protocol ina iliyonse mu paketi ya CCSDS.
Chidule cha protocol paketi ya danga ndi mutu wankhani ina. Zapangidwa kuti zilole zomwe zimatchedwa mapulogalamu kuti azisinthana mosasintha. Pulogalamu iliyonse ili ndi adilesi yake komanso magwiridwe antchito osinthana ndi mapulogalamu ena. Palinso mautumiki omwe amayendetsa magalimoto pamsewu, kuwongolera kutumiza, ndi zina.
Ndi encapsulation zonse zimakhala zosavuta komanso zomveka bwino. Miyezo imapangitsa kuti zitheke kuyika ma protocol aliwonse mu mapaketi a CCSDS powonjezera mutu wina.
Kumene mutu uli ndi matanthauzo osiyanasiyana kutengera kutalika kwa protocol yomwe ikuphatikizidwa:
Pano gawo lalikulu ndi kutalika kwa kutalika. Itha kusintha kuchokera ku 0 mpaka 4 mabayiti. Komanso pamutuwu muyenera kuwonetsa mtundu wa protocol yolumikizidwa pogwiritsa ntchito tebulo .
IP encapsulation imagwiritsa ntchito chowonjezera china kuti mudziwe mtundu wa paketi.
Muyenera kuwonjezera mutu wina, octet imodzi kutalika:
Kumene PID ndi chizindikiritso china cha protocol chatengedwa
Pomaliza
Poyamba, zitha kuwoneka kuti mitu ya CCSDS ndiyosowa kwambiri ndipo magawo ena akhoza kutayidwa. Zowonadi, mphamvu ya njira yotuluka (mpaka pa intaneti) ndi pafupifupi 40%. Komabe, pakangofunika kufunikira kukhazikitsa mfundozi, zimawonekeratu kuti gawo lililonse, mutu uliwonse uli ndi ntchito yake yofunika kwambiri, kunyalanyaza zomwe zimapangitsa kuti pakhale zovuta zambiri.
Ngati habrasociety ikuwonetsa chidwi pamutuwu, ndidzakhala wokondwa kufalitsa mndandanda wonse wa zolemba zomwe zimaperekedwa ku chiphunzitso ndi machitidwe a kulumikizana kwa mlengalenga. Zikomo chifukwa chakumvetsera!
Zotsatira
PS
Osagunda kwambiri ngati mutapeza zolakwika. Afotokozereni ndipo adzakonzedwa :)
Source: www.habr.com