Sadarwar Kamara ta Optical ta Tushen Taron: Demodulation mai Ƙarfi don Muhallin Waje na Nisa

1. Gabatarwa & Bayyani

Wannan aikin ya gabatar da ci gaba mai mahimmanci a cikin Sadarwar Kamara ta Optical (OCC) ta hanyar amfani da Na'urori masu Gani na Tushen Taro (EVS) don ingantaccen watsa bayanai mai nisa a waje. Babban ƙirƙira yana cikin tsarin demodulation wanda ya haɗu da Maɓalli na Kunna-Kashe (OOK) tare da demodulation mai jujjuyawa da Madauki Mai Kulle na Lokaci na Lamba (DPLL), wanda aka tsara musamman don shawo kan iyakokin tsofaffin kamarori na tushen firam. Tsarin ya cimma rikodin ƙimar Kuskuren Bit (BER) na ƙasa da $10^{-3}$ a nisan mita 200 (60 kbps) da mita 400 (30 kbps), yana kafa sabon ma'auni don aikin OCC na waje kamar yadda aka kwatanta a cikin kwatancen ma'auni (Fig. 1b).

2. Tsarin Tsarin & Hanyoyin Aiki

Tsarin tsarin da aka tsara ya rabu da tsohuwar OCC ta hanyar maye gurbin kamarar tushen firam da mai karɓar EVS na asynchronous kuma yana amfani da ƙaramin microcontroller mai arha (misali, Arduino, M5Stack) a matsayin direban watsa LED.

3. Cikakkun Bayanai na Fasaha & Tsarin Lissafi

Babban sarrafa siginar ya ƙunshi ƙirar amsawar EVS da aikin DPLL. Ana iya ƙirar fitarwar pixel na EVS azaman aikin abin da aka samo asali na lokaci na shigarwar log-intensity $L(t)$:

$E(t) = \begin{cases} +1 & \text{idan } \frac{d}{dt}(\log(L(t))) > C_{+} \\ -1 & \text{idan } \frac{d}{dt}(\log(L(t))) < -C_{-} \\ 0 & \text{in ba haka ba} \end{cases}$

inda $C_{+}$ da $C_{-}$ suke bakin kofa na bambanci. DPLL yana aiki ta hanyar kwatanta lokaci na Oscillator Mai Sarrafa Ƙarfin Lantarki (VCO) na gida tare da lokacin abubuwan da ke shigowa. Ana ciyar da kuskuren lokaci $\phi_e$ cikin tacewa na madauki (misali, mai sarrafa ma'auni) don daidaita mitar VCO:

$\omega_{out}(n) = \omega_0 + K_p \phi_e(n) + K_i \sum_{i=0}^{n} \phi_e(i)$

inda $\omega_0$ shine mitar tsakiya, kuma $K_p$, $K_i$ su ne ƙayyadaddun riba.

4. Sakamakon Gwaji & Aiki

Gwaje-gwajen waje sun nuna ƙarfin tsarin. Jadawalin ma'auni (Fig. 1b a cikin PDF) a sarari ya sanya wannan aikin a gaban binciken da ya gabata kamar Wang 2022 da Shen 2018 a cikin ma'auni na haɗin nisa da ƙimar bit don yanayin waje. Amfani da DPLL yana da mahimmanci wajen kiyaye BER a ƙasa da bakin kofa na $10^{-3}$ duk da jitter daga mai watsa mai arha, yana tabbatar da ingancin dabarun ramawa na tushen software.

5. Tsarin Bincike & Nazarin Lamari

Tsarin don Kimanta Tsarin OCC: Don tantance irin wannan shawarwari da gaske, muna amfani da tsarin multi-axis: Ƙarfin Tashar (waje/ciki, amo), Farashin Kayan Aiki & Rikitarwa (mai watsa/mai karɓa), Ƙimar Bayanai & Kewayon, da Jinkirin Tsarin & Ƙarfi.

Aikace-aikacen Nazarin Lamari: Umarni da Sarrafa Jirgin Maras Matuki a Wuraren da RF ba ta da ƙarfi. Ka yi tunanin yanayin da jirgin mara matuki dole ne ya yi aiki a yankin da ke da ƙuntatawa mai ƙarfi na RF (misali, kusa da kayan aiki masu mahimmanci). Tsarin LED na tushen ƙasa yana watsa sabuntun kewayawa ko sigogin aiki ta amfani da ƙa'idar OOK/EVS/DPLL da aka tsara.

• Mataki 1 (Watsawa): Ƙaramin microcontroller yana daidaita tsarin LED tare da bayanan.
• Mataki 2 (Karɓa): Kamarar EVS da ke kan jirgin mara matuki, wanda aka daidaita zuwa mitar bugun jini, tana ɗaukar abubuwan da ba su da lokaci daga fitilar LED.
• Mataki 3 (Sarrafawa): Algorithm na DPLL akan na'urar sarrafa jirgin mara matuki yana kulle kan lokacin siginar, yana tace jitter daga mai watsa mai sauƙi kuma yana dawo da rafin bit duk da yuwuwar faɗuwar taron da motsin jirgin mara matuki ko canje-canjen hasken muhalli ya haifar.
• Mataki 4 (Sakamako): Jirgin mara matuki yana karɓar umarni masu aminci a 30 kbps daga nisan mita 400, yana ba da damar aiki ba tare da tsangwama na RF ba.

Wannan lamari ya nuna ƙimar tsarin: ingantacciyar sadarwa mai nisa, wacce ba ta RF, ta amfani da ƙima mai arha, mai gani na asynchronous.

6. Bincike Mai Mahimmanci & Fassarar Kwararru

Babban Fahimta: Wannan takarda ba kawai game da haɓaka ƙari ba ce; juyawa ce mai dabara. Ta yi watsi da neman gudu mai ƙarfi ta hanyar hadaddun saitin tashoshi da yawa (wanda sau da yawa yana sadaukar da BER, kamar yadda aka lura tare da binciken da aka cire na 100+kbps) kuma a maimakon haka yana mai da hankali kan ƙirƙirar ƙaƙƙarfan ƙa'ida, mai aiki, da mai tsada mai tsada don OCC na waje na gaske. Zaɓin EVS akan mai karɓar CMOS mai rufewa (gama gari a cikin sauran ayyukan OCC) shine mai canza wasa, yana cinikin manyan bayanan firam marasa amfani don abubuwan da suka dace marasa yawa.

Kwararar Hankali: Marubutan sun gano daidai matsalolin OCC na tushen firam (ƙimar iyaka ta fps, babban nauyin bayanai). Maganin su yana da kyau: 1) Yi amfani da EVS don ingantaccen gano siginar. 2) Haɓaka sigogin EVS don zama mai tacewa da ya dace da bugun jini na OOK. 3) Amini gaskiyar kayan aiki marasa kyau, masu arha (jitter) kuma warware shi a cikin yankin lamba tare da DPLL. 4) Tabbatar da tsarin haɗin gwiwa tare da ma'auni masu ƙarfi na waje. Wannan shine ingantaccen injiniyan tsarin.

Ƙarfi & Kurakurai: Babban ƙarfi shine aikin aiki da aka nuna. Cimma BER < $10^{-3}$ a 400m waje wani mataki ne wanda ke motsa OCC daga sha'awar dakin gwaje-gwaje zuwa fasahar da za a iya turawa filin. Amfani da microcontrollers masu arha ya yi daidai da ka'idar IoT. Duk da haka, babban aibi shine rashin cikakken ƙirar tashar. Takardar za ta fi ƙarfi tare da nazarin ƙididdiga na tasirin tashar waje (misali, tashin hankali na yanayi, hasken rana SNR) kama da ƙirar da aka yi amfani da su a cikin adabin FSO (Free-Space Optics) na gargajiya. Bugu da ƙari, yayin da DPLL ke sarrafa jitter na lokaci, juriyar tsarin ga tsangwama mai tsanani ko rufewa na ɓangare—gama gari a cikin yanayin motsi na waje—har yanzu ba a tabbatar da shi ba.