Sadarwar sauti na ƙarƙashin ruwa

**Sadarwar sauti a karkashin ruwa** wata dabara ce ta aikawa da karɓar saƙonni a cikin ruwa. Akwai hanyoyi da yawa na yin amfani da irin wannan sadarwar amma mafi yawanci shine ta hanyar amfani da wayoyin hannu. Sadarwar karkashin ruwa yana da wuyar gaske saboda dalilai irin su yaduwar hanyoyi masu yawa, bambance-bambancen lokaci na tashar, ƙananan bandwidth samuwa da kuma karfin sigina mai karfi, musamman a kan dogon zangon. Idan aka kwatanta da sadarwar ƙasa, sadarwar ruwa tana da ƙarancin ƙimar bayanai saboda tana amfani da igiyoyin sauti maimakon igiyoyin lantarki.

A farkon karni na 20, wasu jiragen ruwa suna sadarwa ta hanyar kararrawa karkashin ruwa da kuma amfani da tsarin kewayawa. Sigina na karkashin ruwa sun kasance a lokacin gasa tare da na'urar rediyo na teku na farko. Daga baya Fessenden oscillator ya ba da damar sadarwa tare da jiragen ruwa.

## Nau'o'in gyare-gyare da aka yi amfani da su don sadarwa ta karkashin ruwa
Gabaɗaya hanyoyin gyare-gyaren da aka ƙera don sadarwar rediyo za a iya daidaita su don sadarwar muryar ruwa ta ƙarƙashin ruwa (UAC). Koyaya, wasu tsare-tsaren daidaitawa sun fi dacewa da keɓaɓɓen tashar sadarwar sauti ta ruwa fiye da sauran. Wasu daga cikin hanyoyin daidaitawa da ake amfani da su don UAC sune kamar haka:

* Maɓallin sauyawar mita (FSK) 
* Mataki-canji na maɓalli (PSK) 
* Yaduwar mita (FHSS) 
* Tsarin kai tsaye (DSSS) 
* Sauye-sauye da matsayi na bugun jini (FPPM da PPM) 
* Sauye-sauye da yawa (MFSK) 
* Multiplexing na rarraba mitar orthogonal (OFDM) 
* Ci gaba da Mataki na Ci gaba (CPM) 

Wadannan sune tattaunawa game da nau'ikan gyare-gyare daban-daban da amfanin su ga UAC.

### Maɓallin sauyawa na mita
FSK shine farkon nau'in daidaitawa da ake amfani dashi don modem masu sauti. FSK yawanci yana amfani da mitoci daban-daban don daidaita bayanai; misali, mitar F1 don nuna bit 0 da mita F2 don nuna bit 1. Don haka ana iya watsa zaren binary ta hanyar musanya waɗannan mitoci guda biyu dangane da ko 0 ne ko 1. Mai karɓa zai iya zama mai sauƙi kamar samun madaidaicin filtata na analog zuwa mitoci biyu da mai gano matakin don yanke shawarar ko an karɓi 1 ko 0. Wannan nau'i ne mai sauƙi na daidaitawa don haka ana amfani dashi a farkon modem masu sauti. Duk da haka za a iya amfani da ƙarin na'ura mai ƙima ta amfani da na'urori masu sarrafa siginar dijital (DSP) a yau.

Babban kalubalen da FSK ke fuskanta a cikin UAC shine tunani mai yawa. Tare da hanyoyi da yawa (musamman a cikin UAC) tunani mai ƙarfi da yawa na iya kasancewa a wurin karɓar hydrophone kuma masu gano bakin kofa sun rikice, don haka suna iyakance amfani da wannan nau'in UAC zuwa tashoshi na tsaye. An gwada hanyoyin daidaitawa tare da iyakataccen nasara. Daidaitaccen daidaitawa yana ƙoƙari ya ƙirƙira tashar UAC mai haskakawa sosai kuma ya rage tasirin siginar da aka karɓa. Nasarar ta kasance iyakance saboda yanayin sauye-sauye da sauri da wahalar daidaitawa cikin lokaci.

### Mataki-canji na maɓalli
Keying-shift keying (PSK) shine tsarin daidaitawa na dijital wanda ke isar da bayanai ta hanyar canza (daidaitawa) yanayin siginar tunani (mai ɗaukar nauyi). Ana sha'awar siginar a cikin filin maganadisu x,y ta hanyar sãɓã wa jũna na sine da cosine shigarwar a daidai lokacin. Ana amfani dashi sosai don sadarwar LANs mara waya, RFID da Bluetooth.

### Multiplexing na rarraba mitar orthogonal
Maɓallin-rarrabuwar mitar orthogonal (OFDM) shine tsarin daidaitawa mai ɗaukar hoto na dijital. OFDM tana isar da bayanai akan tashoshi masu kamanceceniya da yawa ta hanyar haɗa siginonin masu ɗaukar hoto kusa da nesa.

OFDM tsari ne mai kyau na sadarwa a cikin sadarwa ta karkashin ruwa godiya ga juriya game da tashoshin zaɓaɓɓen mitar da ke yaduwar jinkiri mai tsawo.

### Ci gaba da sauyawa
Ci gaba da daidaita yanayin lokaci (CPM) dabara ce ta daidaitawa, wanda shine ci gaba da jujjuya lokaci, inda yanayin siginar mai ɗauka ya bambanta akan lokaci kuma yana guje wa canje-canje kwatsam tsakanin alamomi masu zuwa. Wannan yanayin yanayi mai santsi yana rage ɓangarorin gefe.

Rage lobes na gefen bakan yana ƙara ingancin bakan CPM kuma yana ba shi damar watsa bayanai a cikin ƙanƙanin bandwidth. Shahararrun bambance-bambance na CPM sun haɗa da mafi ƙarancin maɓallin sauyawa (MSK) da mafi ƙanƙanta maɓallin canji na Gaussian (GMSK), wanda ke amfani da matattarar Gaussian don daidaita sauye-sauyen lokaci.

Tun da yanayin da ke ƙarƙashin ruwa ya tarwatse sosai, yana iya haifar da yaɗuwar hanyoyi da lalata sigina. Siffar ci gaba ta CPM tana rage waɗannan tasirin kuma tana kiyaye amincin sigina. Bayan ingantaccen aikin sa na gani yana taimakawa yin mafi kyawun amfani da iyakanceccen bandwidth karkashin ruwa.

## Amfani da na'urori masu auna sigina
Tun da yanayin da ke halartar ruwa ya tarwartsatse sosai, yana iya kawo da yaɗuwar hoton da lalata sigina. Siffar ci gaba ta CPM tana rage damuwa kuma tana kiyaye wasu sigina. Bayan aikin aikin sa na gani yana canza yin mafi kyawun amfani da haɗin bandwidth karkashin ruwa.

An yi bincike sosai a kan na'urori masu auna sigina a cikin 'yan shekarun da suka gabata. An tsara algorithms masu sarrafa siginar siginar vector da yawa.

Aikace-aikacen firikwensin ruwa na karkashin ruwa an mayar da hankali kan sonar da gano manufa. An kuma ba da shawarar a yi amfani da su azaman masu karɓar sadarwa da yawa a ƙarƙashin ruwa da masu daidaitawa. Sauran masu bincike sun yi amfani da jerin na'urori masu auna sigina a matsayin masu daidaitawa da masu karɓa.

## Aikace-aikacen

### Wayar da ke karkashin ruwa
Wayar karkashin ruwa, wanda aka fi sani da UQC, AN / WQC-2, ko Gertrude, Sojojin Ruwa na Amurka ne suka yi amfani da ita a 1945  bayan a Kiel, Jamus, a 1935 an nuna abubuwan da suka faru daban-daban a teku.  Kalmomin UQC da AN / WQC-2 sun bi tsarin tsarin tsarin haɗin gwiwar lantarki. Nau'in "UQC" yana tsaye ne don Janar Utility (amfani da yawa), Sonar da Underwater Sound da Sadarwa (Karɓar / watsawa, hanyoyi biyu). "W" a cikin WQC yana tsaye ne don Ruwa da Ruwa. Ana amfani da tarho na karkashin ruwa a kan dukkan jiragen ruwa da jiragen ruwa da yawa da ke aiki. Murya ko sautin sauti (code morse) da aka sadarwa ta hanyar UQC suna heterodyned zuwa babban farar don watsa sauti ta hanyar ruwa.
 
A watan Afrilu na shekara ta 2017, Cibiyar Nazarin Ruwa da Gwaje-gwaje ta NATO ta ba da sanarwar  amincewar JANUS, daidaitaccen yarjejeniya don watsa bayanai na dijital a ƙarƙashin ruwa ta amfani da sauti (kamar modems da na'urorin Fax suna yin akan layin tarho).  An rubuta shi a cikin STANAG 4748, yana amfani da 900 Hz zuwa 60 kHz a nesa har zuwa kilomita 28 (17 . Ana samunsa don amfani tare da sojoji da farar hula, NATO da na'urorin da ba na NATO ba; an sanya masa suna ne bayan Allahn Romawa na ƙofofi, buɗewa, da dai sauransu.&nbsp;&nbsp;

Bayanan JANUS (ANEP-87) yana ba da tsarin jigilar kaya mai sauƙi. A baseline JANUS fakiti ya kunshi 64 bits zuwa abin da za a iya ƙara ƙarin bayanai na son rai (Cargo). Wannan yana ba da damar aikace-aikace daban-daban kamar wurin gaggawa, AIS na karkashin ruwa (Automatic Identification System), da Tattaunawa. Misali na Matsayi na Gaggawa da saƙon Matsayi za a iya rubuta shi azaman wakilcin JSON mai zuwa (ainihin fakitin yana cikin ingantaccen tsarin binary):  
```json
{
    "ClassUserID": 0,
    "ApplicationType": 3,
    "Nationality": "PT",
    "Latitude": "38.386547",  // internally in units of 90/8388607 degrees
    "Longitude": "-9.055858", // ditto
    "Depth": "16",    // internally an integer, meters
    "Speed": "1.4",   // internally in units of 0.1 knots
    "Heading": "0.0", // internally in units of 0.705 degrees
    "O2": "17.8",     // internally in units of 0.1% (17%-23.3%)
    "CO2": "5.0",     // internally in units of 0.1% (0-6.3%)
    "CO": "76",       // internally in units of 1 ppm
    "H2": "3.5",      // internally in units of 0.1% (0-6.3%)
    "Pressure": "45.0",    // internally in units of 0.1 bar (0.9-103.2 bar)
    "Temperature": "21.0", // internally in units of 1 celcius (0-63 deg C)
    "Survivors": "43",     // 0-255
    "MobilityFlag": "1",          // rows starting here are "baseline message" content, as are ClassUserID and ApplicationType. 1 = mobile
    "ForwardingCapability": "1",  // Used for routing
    "TxRxFlag": "0",              // 0 = transmit-only; 1 = bidirectional able
    "ScheduleFlag": "0"
}
```
Wannan Matsayin Gaggawa da Saƙon Matsayi (ID ɗin Class 0 Aikace-aikacen 3 Plug-in) yana nuna jirgin ruwa na Portuguese a 38.386547 latitude -9.055858 a zurfin mita 16. Yana tafiya arewa a 1.4 knots, kuma yana da 43 da suka tsira a cikin jirgin kuma yana nuna yanayin muhalli.

### Saƙon da ke ƙarƙashin ruwa
An tsara samfuran kayan aikin kasuwanci don ba da damar saƙon ruwa guda biyu tsakanin masu nutsewa. Wadannan tallafin aikawa daga jerin sakonnin da aka riga aka ayyana daga kwamfutar nutsewa ta amfani da sadarwa ta sauti.

Har ila yau, kokarin bincike sun binciki amfani da wayoyin salula na zamani a cikin lokuta masu hana ruwa don sadarwa a karkashin ruwa, ta amfani da kayan aikin modem na acoustic a matsayin haɗe-haɗe na waya  da kuma amfani da aikace-aikacen software ba tare da wani ƙarin kayan aiki ba.  Aikace-aikacen software na Android, AquaApp, daga Jami'ar Washington yana amfani da makirufo da masu magana a kan wayoyin salula na zamani da agogo masu wayo don ba da damar sadarwa ta karkashin ruwa. An gwada shi don aika saƙonnin dijital ta amfani da wayoyin salula na zamani tsakanin masu nutsewa a nesa har zuwa 100 m.

## Dubi kuma

* Sadarwar sauti a cikin dabbobi na ruwa
* Sadarwar sauti a cikin kifi
* Sadarwa
* Acoustic release - Hanyar dawo da na'urar Oceanographic
* Underwater acoustics - Nazarin yaduwar sauti a cikin ruwa

## Bayanan da aka ambata

## Haɗin waje

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