ly thuyet radar

7/23/2019 Ly Thuyet Radar

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Marine RadarLecture Do Minh Cuong 1

L THUYT RADAR

CHNG ICHNG ICHNG ICHNG INGUYEN LY RADAR HANG HAINGUYEN LY RADAR HANG HAINGUYEN LY RADAR HANG HAINGUYEN LY RADAR HANG HAI

1.1.1.1.1111 KHAI NIEM CHUNGKHAI NIEM CHUNGKHAI NIEM CHUNGKHAI NIEM CHUNG

Radar la phng tien vo tuyen ien dung e phat hien va xac nh v tr cua muc tieuso vi tram radar . V vay radar c s dung rong rai trong ca lnh vc quan s va giaothong . ac biet la nganh ng bien va ng khong .

Thuat ng RADAR la viet tac cua Radio Detection And Ranging , tc la dung songvo tuyen e xac nh phng v va khoang cach ti muc tieu .

Du cac nguyen ly c ban cua radar c cac nhakhoa hoc Anh va My phat hien autien trong chien tranh the gii th hai , viec dung tn hieu doi nh la mot thiet b hang haikhong phai la mot phat minh mi .

Trc khi co radar , khi hanh hai trong sng mu gan b bien go ghe , tau thuyenco the thoi mot hoi coi , ban mot phat sung , hoac go chuong . Khoang thi gian t khi phattn hieu am thanh en khi nhan c tn hieu phan hoi se ch ra khoang cach t tau ti bbien hoac vach a, ong thi hng nghe c tn hieu doi ve cung cho biet goc phng vtng oi (goc man ) cua b bien so vi tau .

T khi ra i en nay , radar khong ngng c cai tien , ngay cang c hoan thien. Cung s phat trien cua cac nganh khoa hoc , c ng dung thanh tu ve t ong hoa , kythuat ien , cung vi s phat trien ve vo tuyen ien t ; tnh nang ky thuat , khai thac vahoat ong cua radar c nang cao khong ngng . en nay vi tnh u viet cua no , tat cacac loai tau hang hai tren bien eu trang b radar . Radar a cang ngay cang ngay i sauphuc vu i song .

Vi can bo hang hai , e dan tau an toan can phai biet chnh xac v tr tau cua mnhva s chuyen ong tng quan vi cac muc tieu tren bien . Radar san sang cung cap nhngthong tin tren mot cach chnh xac va nhanh chongtrong khoang thi gian rat ngan e tranhva , xac nh v tr tau T nhng van e quan trong o , radar a tr thanh phng tiendan ng chu yeu va am bao an toan cho tau khi hanh hai. ac biet la khi hanh hai nico mat o tau thuyen ln , hanh hai ven b , trong sng mu , trong bang , trong em toi , khitam nhn xa b han che

ac biet loai radar phat xung c s dung hau het tren cac tau bien .


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2.2.2.2.2222 NGUYEN LY HOAT ONGNGUYEN LY HOAT ONGNGUYEN LY HOAT ONGNGUYEN LY HOAT ONG

I-NGUYEN LY CHUNG :e o khoang cach, radar xung s dung nguyen ly nh sau: dung song ien t sieu

cao tan (song radio) phat vao khong gian di dang xung radio va thu lai song phan xa tmuc tieu tr ve.Cong thc tnh:

2

* tCD=

trong o: - D: khoang cach t radar en muc tieu- C: toc o truyen song (3*108m/s)- t: thi gian truyen song (i va phan xa tr ve)

Tnh chat cua song radio:- Lan truyen trong khong gian theo ng thang.

- Toc o lan truyen khong oi: C = 3*10

8

m/s- Mang nang lng ln, gap muc tieu se phan xa tr ve.

Mo ta nguyen ly chung cua radar theo s o khoi:

Dien giai: may phat tao ra 1 xung ien t sieu cao tan, qua chuyen mach, ti anten, bc xavao khong gian. Xung radio gap muc tieu phan xa tr ve, qua mach vao may thu,qua bo khuech ai va sa oi tn hieu cho ta tn hieu quan sat c tren manhnh.

II- NGUYEN LY RADAR XUNG :Radar c trang b cho nganh hang hai, hang khong la loai dung nguyen ly radar xung.

Radar co nhiem vu phat hien va xac nh toa o muc tieu so vi tram radar. trong hang hai,toa o xac nh bang he toa o cc thong qua khoang cach va goc.

1111---- Xung ieXung ieXung ieXung ien:n:n:n:La ai lng bien thien nhanh theo 1 qui luat nhat nh (chu ky nhat nh), no c ac

trng bi tan so f va bc song .

Khoiong bo

Khoich bao

May phat

May thu

Khoichuyen mach

Anten


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Cong thc:

Cf =

Hien nay xung ien dung trong radar co cac loai sau:- xung nhon- xung rang ca- xung vuong- xung sieu cao tan (xung radio)

Cac ac trng cua xung radio bc xa vaokhong gian i tham sat muc tieu:

- chieu dai xung: x

- chu ky lap xung: TxThong thng hien nay:

-

x= 0.01 3 s- Tx= 1000 4000 s

Ta nhan thay rang x


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anh cua muc tieu. Khi tia quet i qua, nh co lp lu quang nen iem sang van con lu lai.Mot muc tieu khac xa tam hn nen tn hieu ve sau (thi iem t2) nen anh xa tam hn.

Anten va tia quet quay ong bo, ong pha. Muc tieu 1 nho, bup phat lt qua nhanh nentn hieu phan xa tr ve nho anh tren man hnh nho. Gia s co muc tieu la 1 dai b, tnhieu phan xa tr ve la 1 dai sang lien tuc. Vay cac muc tieu nho thi gian song phan xa tnen anh the hien nho & ngc lai.

e tia quet quay ong bo, ong pha vi anten, ngi ta tao ra co CRT 1 t trng xoaybang cach a vao cuon lai tia e t trng nay ieu khien tia quet quay ong bo, ong phavi anten.

e tia quet chuyen ong t tam ra bien, ngi ta tao ra xung rang ca a vao cuon laitia e xung nay ieu khien cac tia ien t chuyen ong t tam ra bien.

4444---- Nguyen ly o khoang cach:Nguyen ly o khoang cach:Nguyen ly o khoang cach:Nguyen ly o khoang cach:Radar phat xung radio bat au t anten lan truyen vao khong gian tham sat muc tieu

ong thi iem sang (tren tia quet) cung chay t tam ra bien man anh. Khi xung gap muctieu phan xa tr ve th iem sang cung chay c 1 khoang tren ban knh cua man anh tngng t le vi khoang cach ngoai thc te. Tai iem o, iem sang se sang hn len do co tnhieu cua muc tieu a vao cathode cua ong phong tia ien t. Nh vay song phan xa t muctieu ve se gay 1 vung sang tren man hnh co hnh dang, kch thc phu thuoc hnh dang, kchthc cua muc tieu.

Do o ch can nhn v tr vung sang tren man anh la co the xac nh c khoangcach thc te cua muc tieu ngoai thc a. Muc tieu xa th om sang gan bien man anh,ngc lai muc tieu gan th om sang gan tam nan anh (v tr tau ta). o sang cua anhphu thuoc mc o phan xa cua muc tieu.

Neu goi t la khoang thi gian t khi phat xung va cho en khi thu c song phan xa

t muc tieu tr ve radar, th khoang cach t anten ti muc tieu se la:2

* tCD=

trong o: - D: khoang cach t radar en muc tieu.- t: thi gian truyen song- C: van toc truyen song trong moi trng

Mav

dt= dk

v

dCD *

2

*==

trong o: d:khoang cach t tam en v tr iem sang tren man hnhv: toc o dch chuyen cua iem sang tren man hnh.

Nh vay muon o khoang cach t tau ta ti muc tieu th ch can o khoang cach ttam man hnh ti anh muc tieu qua c cau bien oi t le.

Hn na:vr

CD2

t maxmax == maxD2

Crv=

Ngha la thang tam xa khac nhau th toc o tia quet cung khac nhau.


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Minh hoa ieu tren nh sau: gia s co 2 muc tieu 1 & 2 cung nam tren 1 ng phngv so vi tau ta. Khi o cac muc tieu 1 & 2 se co anh tng ng la I & II tren cungng phng v tren man hnh. Cac khoang cachd1& d2cua I & II so vi tam manhnh t le vi khoang cach D1& D2cua cac muc tieu 1 & 2 so vi radar trongthc te.

5-

Nguyen ly o gocNguyen ly o gocNguyen ly o gocNguyen ly o goc:e o c goc man cua muc tieu, khi anten quay va phat song vao khong gian tham satmuc tieu, th tren man anh tia quet cung quay. Ngi ta thiet ke sao cho chung quay ongpha va ong bo vi nhau, ngha la anten va tia quet co cung toc o quay, va khi bup phattrung mat phang truc doc tau th tia quet ch ung hng 00tren mat ch bao.

Radar phai cung luc bao quat c ca khu vc quanh tau, va am bao phan biet ctng muc tieu cac hng khac nhau khi chung khong nam dnh vao nhau. e thc hienieu nay, ngi ta thiet ke sao cho anten quay tron 3600va co tnh nh hng song phat:anten radar bc xa song ien t vao khong gian co gian o phat hnh bup (goi la bup phatradar).

ac trng cua bup phat la goc m ngang nva goc m ng , ngha la cac goc theomat cat ngang va ng. Bup phat radar co n


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Gia s co 2 muc tieu 1 & 2 co goc man tng ng 1,2ngoai thc a nh hnh ve.Khi anten quay goc chup vao muc tieu 1 th tia quet tren man anh cung quay cgoc 1. Do o anh cua muc tieu 1 cung nam tren ng thang hp vi mui tau gocbang goc man that 1cua muc tieu. Tng t, vi muc tieu 2 ta cung xac nh c

goc tren man anh bang goc man ngoai thc te 2 cua muc tieu.Nh vay theo nguyen ly tren ta o c goc man cua muc tieu.

o sang cua anh tren man hnh phu thuoc:- s tang, giam o sang (do ngi dung thay oi)- song phan xa, khoang cach ti muc tieu, thi tiet

1

2

2

1

0

I

II1

2

2

1


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CHNG 2CHNG 2CHNG 2CHNG 2

THONG SOTHONG SOTHONG SOTHONG SO KHAI THAC & KY THUAT KHAI THAC & KY THUAT KHAI THAC & KY THUAT KHAI THAC & KY THUATCUA RADARCUA RADARCUA RADARCUA RADAR

2222....1111THONG SO KHAI THACTHONG SO KHAI THACTHONG SO KHAI THACTHONG SO KHAI THAC

1111---- Tam xa cc ai cua radar: (tam xa tac dung) DTam xa cc ai cua radar: (tam xa tac dung) DTam xa cc ai cua radar: (tam xa tac dung) DTam xa cc ai cua radar: (tam xa tac dung) D maxmaxmaxmaxTam xa tac dung cua radar la khoang cach ln nhat ma trong gii han o radar co the

phat hien c muc tieu, tc anh cua muc tieu con xuat hien u e quan sat tren man hnh.Muc tieu cang xa, tn hieu phan xa tr ve cang yeu. Muc tieu xa nhat la muc tieu co

song phan xa ve anten yeu nhat ma bo thu cua radar con co kha nang khuech ai len u lnthanh tn hieu muc tieu.

Tam xa cc ai tnh theo cong thc:8

2min.th

4210

2ax

max P)h.h.(S.G.P.4

D

=

trong o: Px cong suat phat xung cua radar.Ga he so phat nh hng cua radar (=4/n. )S0 be mat hieu dung cua muc tieuh1, h2 chieu cao cua anten va muc tieuPth.min o nhay may thu- bc song

Ta thay rang tam xa cc ai cua radar khong ch phu thuoc vao khoang cach nh santren man anh ma con phu thuoc vao:- o nhay may thu- cong suat may phat- ieu kien moi trng- o cao anten va muc tieu- kch thc, hnh dang, cau tao cua muc tieuHai hien tng chnh anh hng en Dmax:(a)

ng chan tri radar:Do be mat trai at la hnh cau nen vi radar cung xuat hien hien tng ng

chan tri nh oi vi th giac (tuy nhien trong ieu kien bnh thng, chan tri radarxa hn chan tri th giac khoang 6%). Neu muc tieu khong cao hn ng chan tri,song ien t phat i t radar khong the phan xa t muc tieu tr ve.

Trong khi ta co the thay cac muc tieu thap gan th radar lai co the bat c cacmuc tieu xa hn ma cao tren mat nc. Hn na, radar c lap at cang cao th


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cang tang kha nang phat hien muc tieu xa. Tuy nhien lap at anten qua cao se lamtang nhieu bien.Cong thc tnh Dmaxtrong thc te:

21max (2.2 hhD += )trong o: Dmax co n v tnh la dam

h1, h2 co n v tnh la met(b)

Tnh chat cua muc tieu:Nguyen tac chung la muc tieu cang ln cang de phat hien khoang cach ln. Tuy

nhien neu muc tieu ln ma tnh phan xa lai yeu co the kho nhan biet hn muc tieunho lai co tnh phan xa tot.

Cau tao cua vo tau muc tieu co anh hng en tam xa phat hien. Mot con tau covo bang kim loai se cho tn hieu phan xa tot, ngc lai vo tau bang go hay si thuytinh se cho tn hieu phan xa yeu hn.

Cac muc tieu thang ng nh vach nui, la cac muc tieu tot. Cac be mat nam

ngang, phang nh bai bun, b cat la cac muc tieu xau v chung lam khuc xa songhn la phan xa song.Nhng tn hieu phan xa t cac cong trnh xay dng, cau cang la nhng tn hieu

manh bi t phu thuoc vao s thay oi hnh dang. Chung co 3 mat rong, phang vavuong goc vi nhau; va ngi ta li dung cach sap xep nay oi vi cac phao radar etang khoang cach nhan biet cua chung.

2222---- Tam xa cc tieu cua radar (vung chet cua radar): DTam xa cc tieu cua radar (vung chet cua radar): DTam xa cc tieu cua radar (vung chet cua radar): DTam xa cc tieu cua radar (vung chet cua radar): D minminminminTam xa cc tieu cua radar la khoang cach gan nhat t radar ti muc tieu ma radar con

co kha nang nhan biet c muc tieu. oi vi nhng muc tieu nam khoang cach gan hn,

radar khong co kha nang phat hien.Tam xa cc tieu cua radar phu thuoc chieu dai xung phat, chieu cao anten va .(a)Theo chieu dai xung phat x:

Theo nguyen ly phat xung cua radar, th radar phat xung vi chieu dai xxong, ch song phan xa tr ve mi phat xung th 2. Neu co 1 muc tieu rat ganradar, khi may phat va phat xung xong th tnhieu phan xa cua muc tieu a tr ve ti anten.Nh vay thi gian t khi phat en luc thu xungla x. Vi muc tieu qua gan anten, khi xung thnhat ti muc tieu va phan xa ve anten ma phan

t cuoi cung cua xung phat cha ri khoianten, tc la cha phat xong th may thu se khong thu c v bo chuyen mach angngat may thu. Mat khac do bo chuyen mach, may thu, chuyen ong cua ien t echuyen t trang thai nay sang trang thai khac can khoang thi gian goi la thi gian i. Nh vay muc tieu gan nhat ma radar co the phat hien c co khoang cach:

Dmin= C.(x+ I)

Song phan xa

t1= 0

t1= x/2

t1= x


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Thong thng: x = 0.3si= 0.2s

Do o Dmin= 75 m

(b)

Theo chieu cao anten va Bup phat co goc m ng gii

han, do o co 1 vung gan antensong ien t khong ti c nenkhong phat hien c muc tieu.

Dmin= h * cotg

Cach xac nh Dmintrong thc te:

a radar vao hoat ong, e thang c li nho nhat, sau o dung 1 xuong (cothe la xuong cu sinh) buoc day roi tha ra xa cho en khi bat c anh tren manhnh. Sau o dung day keo t t xuong lai gan tau, quan sat tren man anh radarti khi nao anh cua xuong mat i. Khi o chieu dai day cong chieu dai xuong laDmin.

3333---- o phan giai theo khoang cach:o phan giai theo khoang cach:o phan giai theo khoang cach:o phan giai theo khoang cach:o phan giai theo khoang cach la kha

nang phan biet gia anh cac muc tieung gan nhau hien trng tren cungphng v, tc la cac muc tieu tach rinhau th anh cua chung khong b chap trenman anh cua radar.

ieu kien phan giai theo khoang cach:Gia s muc tieu A va B gan nhau, khi phan t au tien t B phan xa ve en Ama phan t cuoi cung phan xa t A cha ri khoi A th song phan xa cua 2 muc tieuse noi tiep nhau ve anten gay nen 1 vet sang cua ca 2 muc tieu tren man ch bao, vvay khong phan biet c anh cua 2 muc tieu nay.

e anh cua 2 muc tieu khong trung nhau tren man hnh th khoang cach d giachung phai la:

2*C

d x

>

Ngoai ra do iem sang tren mat may co kch thc nen o phan giai theo

khoang cach phai am bao:

max5.0

*

2

*

D

DdCD ax +

trong o: da: ng knh iem sang tren mat ch baoD: thang tam xaDmax: ng knh man anh

h

Dmin

/2

A B C

ca b


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4444---- o phan giai theo goc:o phan giai theo goc:o phan giai theo goc:o phan giai theo goc:o phan giai theo goc la kha nang phan biet gia anh cac muc tieu ng gan tren

man hnh khi chung co cung khoang cach ti tam (tc la cac muc tieu ng gan nhau, cocung khoang cach ti radar ngoai thc te).

Trng hp 2 muc tieu co cung khoang cach ti radar va nam gan nhau, anh cuachung tren man hnh b chap lam mot.

ieu kien phan giai theo goc:

Neu 2 muc tieu co cung khoang cach ti radar, goc kep gia chung vi radar ngth anh cua chung la 1 vet sang noi lien nhau do tn hieu phan xa ve ke tiep nhau,khong phan biet c. e anh cua 2 muc tieu nay khong trung nhau th goc kep giachung:

0> ngNgoai ra o phan giai theo goc con phu thuoc vao ng knh iem sang va

khoang cach t tam man hnh ti anh muc tieu.0 > ng+ 57.3da/D

a b a

B

A A

b

B

[ng > ng


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2 .2 .2 .2 . 2222 THONG SO KY THUATTHONG SO KY THUATTHONG SO KY THUATTHONG SO KY THUAT

1111---- Chieu dai bc songChieu dai bc songChieu dai bc songChieu dai bc song ::::Ngi ta chon bc song (tng ng tan so f = C/) sao cho thoa man cac yeu cau:

song truyen thang, tap trung nang lng vao 1 bup phat hep, co kha nang nh hng cao valoai bo c anh hng cua cac yeu to kh tng thuy van. ong thi e cho song co themang u nang lng i xa th trong chieu dai xung phat xphai co t 300 500 dao ongtoan phan.

Tuy nhien e tang o phan giai theo khoang cach th phai giam x tc giam (tang f).Radar ngay nay dung song co bc song cm, truyen thang toan bo oi vi muc tieu ln.Thng co 3 loai bc song:

= 10 cm = 3.2 cm = 0.8 cmBc song dai th tam tac dung ln song o phan giai kem, trai lai bc song ngan co

tam tac dung nho nhng lai phan giai tot hn. V vay tuy tng loai radar ma che tao theo

bc song phu hp. Hien nay radar dung chu yeu bc song 3.2 cm tc co tan so 9400 Mhz.2222---- ChieuChieuChieuChieu dai xung phatdai xung phatdai xung phatdai xung phat xxxx::::

Vi cac loai radar khac nhau, se co xkhac nhau. xcang ln th nang lng cua xung timuc tieu cang ln, tang tam xa tac dung nhng giam o phan giai, tang ban knh vung chet.Ngc lai, xnho, tam xa tac dung nho, giam ban knh vung chet nhng o phan giai tot hn.

Ngay nay radar c san xuat vi 2 che o xung dai va ngan, tuy thang tam xa va yeucau thc te hang hai ma chuyen che o xung phat cho phu hp. Ngi ta tao ra cong tacchuyen oi che o PULSE SWITCH vi 2 che o LONG va SHORT (vi mot so may cuaNhat th 2 che o nay la NORMAL va NARROW)Thong thng x= 0.01 3 s

3333---- Chu ky lap xung TChu ky lap xung TChu ky lap xung TChu ky lap xung Txxxx. Tan so lap xung F. Tan so lap xung F. Tan so lap xung F. Tan so lap xung Fxxxx= 1/T= 1/T= 1/T= 1/Txxxx::::Chu ky lap xung la khoang thi gian gia 2 lan phat xung ke tiep, tan so lap xung la

lng xung xuat hien trong mot n v thi gian, phu thuoc vao toc o quay cua anten.e thu c song phan xa t muc tieu xa nhat ( thang c li ang s dung) th trong thi

gian thu xung:Tx 2Dmax/C

(do x


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6Nmin* n / ngFxC / 2Dmaxtrong o: n: toc o quay cua anten (vong / phut)

N: so xung ap vao muc tieu trong mot vong quay cua antenTan so lap xung cua cac radar hien nay: Fx= 4003200 xung / giay

4444---- Cong suat phat xung:Cong suat phat xung:Cong suat phat xung:Cong suat phat xung:

Cong suat phat xung Px la cong suat may phat phat itrong thi gian x.

x

x

x

Pdt

P

= 0

Cong suat trung bnh Ptbcua may phat trong ca chu ky Tx.Ptb* Tx= Px* x

Do o:

x

xx

tb

T

PP

*=

5555---- o nhay may thu Po nhay may thu Po nhay may thu Po nhay may thu Pth.minth.minth.minth.min::::o nhay may thu la cong suat nho nhat phan xa t muc tieu tr ve ma may thu con co

kha nang khuech ai len a sang may ch bao the hien thanh anh tren man hnh. o nhaymay thu tnh theo cong thc:

Pth.min= N * q * K * f * TTrong o: N: he so tap am

q: he so phan giaiK: hang so Bozman (= 1.38 * 10 -3J/o)

f: o rong dai lot (dai thong)T: nhiet o tuyet oi ni thu (0K)Trong may thu, Pth.mincang nho, o nhay cang tot, radar cang co kha nang khuech ai

tn hieu muc tieu xa. Mot so cach e tang o nhay may thu:- Giam he so tap am N: thay linh kien ien t bang linh kien ban dan- Giam o rong dai lot f- Giam he so phan giai q.

6666---- o ro ro ro rong dai lot (dai thong)ong dai lot (dai thong)ong dai lot (dai thong)ong dai lot (dai thong) ffffDai thong la khoang tan so ma trong o may thu thu c tn hieu:

f = (0.8

1.2) / x1 / x

7777---- He so nh hng cua anten GHe so nh hng cua anten GHe so nh hng cua anten GHe so nh hng cua anten Gaaaa::::ai lng nay ac trng cho kha nang tap trung nang lng bc xa ve 1 pha (trong 1

bup phat) cua anten radar.He so nay phu thuoc vao goc m cua bup phat (ngva ).

P

t

Px

Ptb

Txx


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Ga= 4/ (ng * )oi vi anten khe co chieu dai l, o rong d th ng va tnh theo:

ng= 70/ l = 70/ d

8888---- Toc o voToc o voToc o voToc o vong quay cua anten: n (vong / phut)ng quay cua anten: n (vong / phut)ng quay cua anten: n (vong / phut)ng quay cua anten: n (vong / phut)Toc o thng c thiet ke trong cac loai anten hien nay la 18 30 vong / phut.

Thong thng hay dung n = 2224 vong / phut.


14/49





MUC TIEU RADAR , CAMUC TIEU RADAR , CAMUC TIEU RADAR , CAMUC TIEU RADAR , CAC LOAI ANH AOC LOAI ANH AOC LOAI ANH AOC LOAI ANH AOTREN MAN ANH RADAR , ANH HNGTREN MAN ANH RADAR , ANH HNGTREN MAN ANH RADAR , ANH HNGTREN MAN ANH RADAR , ANH HNG

CUA MOI TRNG TI TAM TACCUA MOI TRNG TI TAM TACCUA MOI TRNG TI TAM TACCUA MOI TRNG TI TAM TACDUNG CUA RADARDUNG CUA RADARDUNG CUA RADARDUNG CUA RADAR

3333....1111 MUC TIEU RADARMUC TIEU RADARMUC TIEU RADARMUC TIEU RADAR

1111---- Muc tieu rieng biet:Muc tieu rieng biet:Muc tieu rieng biet:Muc tieu rieng biet:La nhng muc tieu nam rieng biet vi nhau, anh cua chung la nhng iem sang rieng

biet tren man hnh.ieu kien e co muc tieu rieng biet:

- o phan giai theo khoang cach:ma

x

D

DdCD

5.0

*

2

*+

- o phan giai theo goc:D

dng 3.570 +

2222---- Muc tieu nhom:Muc tieu nhom:Muc tieu nhom:Muc tieu nhom:La cum muc tieu khong phan biet c ve goc va khoang cach. Nhng muc tieu nay tren

man anh se chap lai vi nhau khong phan biet c. Trong trng hp nay, e kh ta hathang tam xa va chuyen sang che o phat xung ngan.

3333---- Muc tieu khoi:Muc tieu khoi:Muc tieu khoi:Muc tieu khoi:Hien tng nay do cac am may huyen phu, may tch ien gay ra. Anh cac muc tieu nay

tren man anh tng oi ln, bien m va bien oi theo thi gian. e phan biet, da vao tnhchat quan trong nhat la hnh anh co o ln thay oi theo thi gian va ha thang tam xa xuong.

3.23.23.23.2. PHAN XA SONG RADIO VA KHUC XA D THNG. PHAN XA SONG RADIO VA KHUC XA D THNG. PHAN XA SONG RADIO VA KHUC XA D THNG. PHAN XA SONG RADIO VA KHUC XA D THNG

Tat ca moi vat co tnh chat khac vi tnh chat cua moi trng truyen song va namtren ng lan truyen cua song ien t, khi co tac dung cua ien t trng se xay ra hientng xuat hien dong ien cao tan. Nguon nang lng th cap nay se bc xa nang lngngc tr lai ve pha nguon phat. S phan xa nay phu thuoc vao kch thc vat the so vibc song .

1111---- Phan xa gng:Phan xa gng:Phan xa gng:Phan xa gng:

Phan xa gng


15/49




Xay ra theo nh luat quang hnh (goc ti = goc phan xa). Muon vay be mat phan xa(be mat vat the) phai nhan va vat the phai co kch thc ln hn nhieu so vi . oi vinhng vat the nh vay, nang lng tr ve radar ln nen anh cua muc tieu ro net hn.

2222---- Phan xa phan ky:Phan xa phan ky:Phan xa phan ky:Phan xa phan ky:Hien tng nay xay ra oi vi cac vat the co kch

thc ln hn rat nhieu so vi nhng co be mat go ghe.Trng hp nay nang lng phan xa tr ve nho va anhmuc tieu tren man hnh m nhat.

3333---- Phan xa cong hng:Phan xa cong hng:Phan xa cong hng:Phan xa cong hng:Hien tng nay xay ra oi vi cac vat the co kch thc bang hoac xap x . Trng

hp nay vat the b kch thch, song phan xa tr lai rat manh, anh muc tieu ro net trenman hnh nhng khong ben do t khi gap nhng vat the co kch thc nho nh vay.

4444---- Khuc xa vong:Khuc xa vong:Khuc xa vong:Khuc xa vong:oi vi nhng vat the co kch thc nho hn , song radio se i qua vat the ma

khong tr lai.

5555---- Hien tng khuc xa thap: subHien tng khuc xa thap: subHien tng khuc xa thap: subHien tng khuc xa thap: sub----refractionrefractionrefractionrefractionTrong nhng ieu kien kh quyen ac biet, ch so khuc xa co the thay oi lam cho s

bc xa song se khuc xa len tren hoac xuong di hn bnh thng.Hien tng khuc xa thap thng xay ra v o cao khi 1 khoi kh lanh thoi ti 1 be

mat nong. Khi o nhiet o giam nhanh theo o cao so vi ieu kien bnh thng, con oam co the tang theo o cao. Do o mc suy giam ch so khuc xa (theo o cao) thap hnbnh thng, lam chum tia radar cong len. Mc o suy giam cang chenh lech so vi ieukien bnh thng th chum tia cang b be cong nhieu hn, v vay tam xa tac dung cuaradar b giam.

6666---- Hien tHien tHien tHien tng khuc xa cao: superng khuc xa cao: superng khuc xa cao: superng khuc xa cao: super----refractionrefractionrefractionrefractionHien tng nay la chum tia radar b be cong xuong di nhieu hn so vi ieu kienkh quyen bnh thng. No xay ra sau khi khong kh thoi qua 1 vung at nong lai thoi ti1 vung bien lanh hn. Chenh lech nhiet o gia khong kh va bien cang ln th hientng nay cang de xay ra. Hien tng nay thng xay ra vung lan can at lien vung

Phan xa phan ky

ng bien thien he sokhuc xa trung bnh

nhanh

cham

khuc xa thaptrung bnh

cao


16/49




nhiet i. No cung co the xay ra trong vung bien co gio mau dch. Anh hng cua hientng nay la tam xa tac dung cua radar se ln hn mc bnh thng.

Trng hp song b khuc xa nhieu hn na, no ap vao mat bien roi phan xa lentren, sau o lai uon cong xuong mat bien. C nh vay chum tia radar se men theo becong cua trai at lam tam xa tac dung tang len rat nhieu. Trng hp khuc xa cao hiemhoi nay coi nh chum tia radar c dan trong ong dan va gii han trong ong dan o, goila hien tng ong dan.

3.3.3.3.3333 CAC LOAI ANH AO TREN MAN ANH RADARCAC LOAI ANH AO TREN MAN ANH RADARCAC LOAI ANH AO TREN MAN ANH RADARCAC LOAI ANH AO TREN MAN ANH RADAR

Thong thng anh ao hien tren man hnh nhng ni khong co muc tieu. trong motso trng hp co the lam giam hay mat anh tren hng o.

1111---- Anh ao do phan xa nhieu laAnh ao do phan xa nhieu laAnh ao do phan xa nhieu laAnh ao do phan xa nhieu lan.n.n.n.Khi tau ta i gan cac muc tieu ln phan xa

song tot, th song phan xa qua lai gia tau va muctieu nhieu lan dan ti ngoai anh that ra con co 1hoac nhieu anh ao nam pha sau anh that. aciem cac anh ao nay la cach xa tam va nho dan,anh that nam gan tam va ln nhat. Cac anh naynam tren cung 1 hng va cach eu nhau. Tnhieu phan xa nhieu lan co the giam hay loai bo bang cach giam o khuech ai hay chnhung A/C SEA.

2222---- Anh ao do bup phat phu:Anh ao do bup phat phu:Anh ao do bup phat phu:Anh ao do bup phat phu:Moi khi bo phan quet quay, mot vai nang

lng bc xa se vt ra khoi gii han cua bup phatc goi la cac bup phat phu. Neu co 1 muc tieuxuat hien ni ma bup phat chnh cung nh bupphat phu phat hien c no, cac tn hieu do bupphat phu gay nen se xuat hien 2 ben anh that cung 1 khoang cach ti tau. Cac bup phat phuthng ch anh hng khoang cach ngan va t cac muc tieu cho song phan xa manh. Ta cothe giam hay loai bo bang cach giam o khuech ai hay chnh ung A/C SEA.

3333---- Anh do phan xa th cap:Anh do phan xa th cap:Anh do phan xa th cap:Anh do phan xa th cap:

Neu gap nhng muc tieu phan xa tot nh echan song, cau th song t radar ap vao cacmuc tieu o roi phan xa ti cac muc tieu khac. Tigap muc tieu sau nay no lai phan xa ve muc tieu 1,sau o mi phan xa tr ve anten. Nh vay tnhieu phan xa sau khi phan hoi t muc tieu se ve

Anh that

Muc tieu

Bup phat phu

Anh that

Anh ao

Tau ta

Vat phan xath cap

Man anh chuyen ong that

Anh that


17/49




anten bang con ng gian tiep.Khi o tren man hnh se xuat hien anh ao cua muc tieu th 2, co cung hng vi be mat

phan xa va co khoang cach ti tau khac so vi tn hieu phan xa trc tiep, cach be mat phanxa vi khoang cach t muc tieu that ti be mat nay. Anh ao nay khong xac nh, khi v trtng oi gia tau ta va muc tieu thay oi th anh nay mat.

4444---- Anh ao do nhieu giao thoa:Anh ao do nhieu giao thoa:Anh ao do nhieu giao thoa:Anh ao do nhieu giao thoa:Neu tau ta i gan tau khac ma tren tau o co radar ang

hoat ong co cung tan so vi radar tau ta th nhieu do radartau o gay nen oi vi tau ta la nhng ng cong t netchay t tam ra bien man anh. e kh nhieu nay, tren radarco nut IR (Interference rejection).

5555---- Anh cua mAnh cua mAnh cua mAnh cua may:ay:ay:ay:Khi tau chay trong vung co thi tiet xau, tri co nhieu may thap, khi bat radar th tren

man hnh cung bat c anh cua chung do chum bup phat cung chup vao cac am may va

cac am may nay cung phan xa tn hieu song radar ve anten. Anh cua chung la nhng amsang troi bong benh khong co nh. e giam anh do may ta giam thang tam xa.

3333....4444 ANH NHAN TAOANH NHAN TAOANH NHAN TAOANH NHAN TAO

1111---- Anh cua RAMARK:Anh cua RAMARK:Anh cua RAMARK:Anh cua RAMARK:RAMARK la 1 muc tieu nhan tao, thc chat la

1 tram phat song lien tuc co bc song tng ngbc song lam viec cua radar. Khi tau i ngang khuvc co lap at Ramark th radar se nhan c song

cua tram nay. Tren radar xuat hien nhng ngxuyen tam keo dai t tam ra bien man anh. Cacng nay co the la chuoi cac net t, chuoi cac cham hay chuoi hon hp. Nhng ng nayi qua v tr Ramark, co o rong 1030. Do o radar ch xac nh c phng v ti tramRamark ma thoi. Cac tram nay thng lap at nhng khu vc nhieu tau qua lai hay gannhng vung hanh hai nguy hiem nh bai ngam, bai can hay nhng muc tieu xung quanh maradar kho phat hien.

2222---- Anh cua RACON:Anh cua RACON: Anh cua RACON:Anh cua RACON:Racon la 1 tram thu phat song, phat ra 1 dau hieu

de phan biet khi c khi ong bi xung en t radar.Khi song radar truyen ti anten cua Racon th tram naythu tn hieu o ong thi phat ngay tn hieu cua mnhtren cung tan so vi radar. Tn hieu Racon hien trenman hnh la 1 ng xuyen tam co goc la 1 iem namngay ben ngoai phao tieu radar, hoac la tn hieu ma Morse c the hien xuyen tam ngay t

10430

Tau ta RACON


18/49




pha ngoai phao tieu. Tram Racon cho biet khoang cach va phng v t tau ta en tram. Khim cac mach FTC hay IR nhng dau hieu cua tram Racon co the mat.

2222---- Anh cua SART:Anh cua SART:Anh cua SART:Anh cua SART:SART la phng tien chnh trong

GMDSS dung xac nh v tr tau thuyen

ang gap nan. No hoat ong dai tan so 9Ghz, phat ra tn hieu khi c khi ongbi song ti t bat ky radar nao ang hoatong tren tau hay tren may bay dai tanso nay. Tren man hnh, anh cua no lanhng cham, bat au t v tr cua tram SART, keo dai theo ng phng v, khoang cachgia cac cham la 0.6 nm. e de phan biet, nen s dung thang tam xa 6 12 nm. Khi taucu ho en gan SART khoang cach 1 nm th cac cham chuyen thanh cac cung tron, vatham ch khi qua gan SART chung se bien thanh cac ng tron e bao cho tau cu ho bietva x ly.

3333....5555 TAM XA TAC DUNG CUA RADARTAM XA TAC DUNG CUA RADARTAM XA TAC DUNG CUA RADARTAM XA TAC DUNG CUA RADAR

1111---- Tam xa tac dung cua radar khi khong co tac ong cua moi trng:Tam xa tac dung cua radar khi khong co tac ong cua moi trng:Tam xa tac dung cua radar khi khong co tac ong cua moi trng:Tam xa tac dung cua radar khi khong co tac ong cua moi trng: ay ta bo qua anh hng cua cac yeu to khong kh, mat nc va song i thang t radar

ti gap muc tieu phan xa tr ve.Gia s radar phat vi cong suat Px, khoang cach t radar ti muc tieu la D. Neu radar

phat khong nh hng th mat o cong suat tai v tr co khoang cach D la:

2.4 D

PM x

=

trong o 4D2la dien tch mat cau tam la tau ta, ban knh DDo anten phat co nh hng vi he so nh hng Ganen cong suat tai muc tieu la:

214

**

D

GPGMP axa

==

Goi S0la be mat hieu dung cua muc tieu. Cong suat phat t muc tieu phan xa tr laianten la:

2

0

0124

***

D

SGPSPP ax

==

Tai v tr anten thu c cong suat:

22

0

22316

**41*

DSGP

DPP ax

==

Goi A0la be mat hieu dung cua anten, trong o:

4

*2

0

aGA =

Khi o cong suat au vao may thu:

khoang 1 Nm

SART

SART xa tau rat gan


19/49




433

2

0

2

03**4

****

D

SGPAPP axth

==

433

2

0

2

**4

***

th

ax

P

SGPD

=

Muc tieu cang xa (D tang) th Pthcang nho, ti 1 luc nao o tng ng Pth.min(ng

vi Dmax), cuoi cung ta co tam xa tac dung cua radar khi khong co tac dung cua moi trngla:

4

min.

3

2

0

2

max*64

***

th

ax

P

SGPD

=

vi Pth.min= N.q.f.k.T

2222---- Tam xa tac dung cua radar khi co tac dung cua moi trng:Tam xa tac dung cua radar khi co tac dung cua moi trng:Tam xa tac dung cua radar khi co tac dung cua moi trng:Tam xa tac dung cua radar khi co tac dung cua moi trng: ay xet khi song truyen t anten ti mat nc, sau o phan xa ti muc tieu cung vi

song truyen trc tiep t anten ti muc tieu.Goi E0la cng o ien trng thu c tai v tr cua muc tieu do song truyen trc tiep,

Epla cng o ien trng thu c tai v tr muc tieu do phan xa.Ngi ta chng minh c: Ep= .E0Trong o la he so phan xa.Khi o ien trng tong cong tai v tr muc tieu:

ET= E0+ Ep= (1 + ).E0at 1 + = &

ET= &.E0Vi &: la he so giao thoa gia song truyen trc tiep va song phan xa.

Tai v tr cua muc tieu, neu ien trng tong ET cang ln th tam xa tac dung cua

radar cang ln.Neu ch co ien trng E0th tam xa tac dung la Dmax. Trong trng hp xet ti anhhng cua moi trng, ien trng thu c tai v tr muc tieu la ET. Khi o, ta co tam xa tacdung la Dmax: Dmax= &.DmaxXac nh &theo cong thc:

'

max

21

*

**4

D

hh

=

Do o:

82

min.th

421

2a0x'

max .P)h.h.(G.S.P.4

D

=

3333....6666 ANH HNG CUA VUNG CHETANH HNG CUA VUNG CHETANH HNG CUA VUNG CHETANH HNG CUA VUNG CHET VUNG MUVUNG MUVUNG MUVUNG MU VUNG RAMVUNG RAMVUNG RAMVUNG RAM GOC CHETGOC CHETGOC CHETGOC CHET


20/49




1111---- Vung mu (re quat mu) :Vung mu (re quat mu) :Vung mu (re quat mu) :Vung mu (re quat mu) :La vung b cac cau truc cua tau nh ong

khoi, can cau che khong cho song cua radarvt qua dan ti toan bo khu vc pha sau caccau truc o khong nhan c song radar. Do oradar khong phat hien c cac muc tieu namtrong khu vc o.

2222---- Vung ram:Vung ram:Vung ram:Vung ram:La vung cung do anh hng cua cac cau truc tren tau nen song radar bc xa rat yeu, dan

ti viec la radar luc phat hien c luc khong phat hien c cac muc tieu nam trong khuvc o.

3333---- Goc chet: Goc chet: Goc chet:Goc chet:Do tau ta i gan nhng vat the hay muc tieu co kch thc ln ngan khong cho song radar

vt qua dan ti radar khong phat hien c cac muc tieu nam sau vat the o. Goc b ngan

bi muc tieu ma radar khong phat hien c goi la goc chet.3- Vung chet:Vung chet:Vung chet:Vung chet:

La 1 vung nam xung quanh tau ma bup phat antenkhong chup xuong c, nen radar khong phat hienc cac muc tieu nam trong vung o.

oi vi moi con tau, ta can xac nh c vungchet, vung ram, vung mu e t o khi dungradar can phai chu y ti nhng vung nay.Viec xac nh vung mu va ram thng da vao song bien. Vung nao khong co tn

hieu nhieu la vung mu, vung nao tn hieu nhieu yeu la vung ram. Con vung chet thxac nh bang phng phap theo doi anh cua xuong. Khi xac nh cac yeu to tren nenxac nh tren thang tam xa nho nhat.

Cot che

Muc tieu

Vung mu

Vung ram

Goc chet


21/49





MAY PHAT RADMAY PHAT RADMAY PHAT RADMAY PHAT RADARARARARay phat radar co nhiem vu tao ra dao ong sieu cao tan co cong suat u ln, o dai x

va chu ky Tx nhat nh tng ng vi cac thang tam xa khac nhau e bc xa vaokhong gian.Hien nay, ngi ta thng thiet ke radar co x= 0.01 3 s, tan so lap xung = 400

3200 , ng vi cong suat xung nh la 10 kw oi vi thang tam gan , 25 kw oi vi thangtam xa.

S o khoi may phat:

- Xung t bo khi ong en khi ong bo ieu che- Bo ieu che (co kem theo bo tien ieu che) se tao ra 1 xung vuong co be rong e

a vao cathode cua en magnetron. o rong xung nay tuy thuoc vao thang tamxa va v tr cua cong tac chieu dai xung.

-

en magnetron la bo phan chu yeu trong may phat, tao ra cac xung radio sieucao tan. en hoat ong trong khoang thi gian tac ong cua x tao dao ong cotan so f = 9400 Mhz trong thi gian x(co khoang 300 500 dao ong hnh sin).Xung nay c a vao ong dan song, qua chuyen mach anten, ti anten va bcxa ra khong gian.

1.Bo ieu che xung:1.Bo ieu che xung:1.Bo ieu che xung:1.Bo ieu che xung:

M

Bo ieu che

xung vuong mach

ChuyenBo taodao ong

sieu cao tan

Tx


22/49




Bo ieu che xung co nhiem vu tao ra 1 xung cao ap khi co xung khi ong a ti. Xungcao ap nay co o dai xva co chu ky Txnhat nh e a sang bo tao song sieu cao tan. bo nay co cong tac PULSE SWITCH e chuyen oi chieu dai xung phat.

S o khoi: S o khoi bo ieu che xung-

Bo chnh lu cao ap: cung cap ien 1 chieu (t 10 20 Kv) cho mach ieu che.- Bo han che: han che bt bien o dong ien cao ap, gi cho ien ap bo tch nang

on nh.- Bo ao mach:

Khi cha co xung khi ong (trigger) ti se khong hoat ong. Dong 1 chieu

cao ap se qua bo han che, tch nang va phan dong e nap nang lng cho botch nang.

Khi co xung khi ong ti, bo ao mach se hoat ong. Nang lng t bo tch

nang qua ao mach ti en magnetron. en hoat ong sinh ra song sieu caotan. Luc nay bo phan dong khong cho dong ien chay qua do xung ien quanhanh.

- Bo phan dong: phan dong cho nhanh, gom cuon cam va tu ien.-

Bo tch nang: tch tr nang lng cung cap cho tai.Can c vao bo tch nang ngi ta phan loai bo ieu che:

+ Dung tu tch nang.+ Dung t tch nang.+ Dung ng day tch nang.

Lu y:-

Xung khi ong a en bo ao mach ong thi cung a en bo ch bao ekhi ong tia quet chay t tam ra bien.

- Cong tac chuyen oi xung phat PULSE SWITCH: ng vi cac thang tam xakhac nhau se phat xung co chieu dai phu hp. Muon xung dai th lam sao chobo tch nang phong ien cham va ngc lai.

Chnh lu

Han che

Trigger ao mach

Tch nang

Phan dong

Magnetron


23/49




1111---- Bo tao dao ong sieu cao tan:Bo tao dao ong sieu cao tan:Bo tao dao ong sieu cao tan:Bo tao dao ong sieu cao tan:Bo nay nhan xung vuong co chieu dai x, tan so lap xung Fx t bo ieu che: tao xungsieu cao tan cong suat ln co o dai xung x, tan so lap xung Fxa vao ong dan song.Dung cu tao dao ong sieu cao tan chu yeu la en magnetron co nguyen ly giong enien t 2 cc, song mac gia anode va cathode 1 mach dao ong ac biet goi la hoc conghng. Ngi ta at t trng co ng sc song song vi mach anode va cathode, vuonggoc vi ien trng anode va cathode. Hoc cong hng tng ng vi mach cong hngco tan so cong hng vi tan so dao ong sieu cao tan, thanh thang tng ng vi tu,phan quay tng ng vi cuon day.

Cau tao va nguyen ly hoat ong cua en magneCau tao va nguyen ly hoat ong cua en magneCau tao va nguyen ly hoat ong cua en magneCau tao va nguyen ly hoat ong cua en magnetron:tron:tron:tron:

Cau tao en MagnetronAnode c lam bang ong hnh tru, tren o co khoet 1 so chan cac hoc cong hng.

Cac hoc cong hng nay c thong vi khoang ben trong cua anode bi cac khe hepvuong goc.

Cathode, ben trong, cung co hnh tru va la loai c ot gian tiep. e tang cngs bc xa ien t cathode, tren be mat cua cathode ngi ta phu 1 lp oxit.

Khoang gia anode va cathode c hut chan khong. Tat ca c boc kn va cat trong t trng cua nam cham vnh cu NS. Nam cham vnh cu nay c che taoac biet e tao ra cng o t trng ln.

Cathode ban ra cac ien t khi b nung nong. Neu bo nam cham vnh cu NS th hethong giong en ien t 2 cc, cac ien t sau khi thoat khoi cathode se ban thang veanode di tac dung cua ien trng E. Nhng do co t trng cua nam cham, quy ao

cua cac ien t b thay oi. Chung chuyen ong theo ng xoan oc ve pha anode. Schuyen ong nay phu thuoc vao o ln cua t trng H:- Khi H = 0 (khong co nam cham): cac ien t ban thang ve anode- Khi H < Hti han: cac ien t chuyen ong ap vao anode khong tr ve.- Khi H = Hti han: cac ien t chuyen ong tiep xuc vi anode roi tr ve.- Khi H > Hti han: cac ien t chuyen ong khong ti anode a quay ngc tr ve.

Anode

AK

U

S

Ea- +

Canh am may ien t

Cathode


24/49




Cac ien t chuyen ong theo ng cong ti sat anode roi bat ngc tr lai cathodetao thanh nhng am may ien t (rotor ien t) hnh canh sao (so lng canh sao = solng hoc cong hng). Cac rotor ien t kch thch cac ien t tren be mat anode. Cacien t nay se chuyen ong gay ra cac dao ong sieu cao tan vi rat nhieu tan so, trongo co tan so f ma ta mong muon. Neu anode c noi vi khung dao ong LC th ta layra c cac dao ong o. Nhng thc te cac dao ong o la cac dao ong sieu cao tannen ngi ta phai thay khung dao ong LC bang cac hoc cong hng, cong hng vi tanso f mong muon. Muon a c cac dao ong sieu cao tan nay ra ong dan song ngi talay bat c 1 hoc nao bang moc ghep.

Cach mac en magnCach mac en magnCach mac en magnCach mac en magnetron vao mach:etron vao mach:etron vao mach:etron vao mach:en magnetron c at vao vi xung ieu che t 10 20 kv e tao ien trng xoaychieu sieu cao tan. Vay e am bao an toan, ngi ta khong a trc tiep xung dngvao anode ma cho anode noi at va a xung am vao cathode.Co 2 cach mac:

+ Mac trc tiep: a thang xung ieu che vao cathode.

+ Mac gian tiep: a xung ieu che vao cathode thong qua 1 bien ap.

Cach mac en magnetron vao mach. ien ap ot Ukhoang 6.3V. Do en hoat ong ien the rat cao va cong suat ln t 10 25 kw, v vay ngi taphai dung quat gio e lam mat cho en.. Tu C co nhiem vu dap tia la ien.

. Khoa K co nhiem vu ngat ra sau khi en hoat ong 1 thi gian.

Lu y oi vi may phat:Lu y oi vi may phat:Lu y oi vi may phat:Lu y oi vi may phat:- Do ien ap at vao cathode va anode cua en magnetron rat ln nen e am bao

an toan ngi ta noi anode tiep at va at ien ap am vao cathode. Xung t boieu che vao en magnetron la xung am.

Trc tiep Gian tiep

U U


25/49




- Do s ban pha cua cac ien t len anode nen 1 phan nang lng ien tr thanhnang lng nhiet, do vay anode b ot nong. V vay ngi ta lam mat enmagnetron bang cac la toa nhiet, bang quat gio Khi bat radar sang che o phat,nghe tieng rao rao trong may la do bo lam mat lam viec. Neu bo phan nay khonghoat ong th en nong, dong tang len, bo phan bao ve en se t ngat. Cong tacthng at trong mach nay (OVERLOAD) se nhay sang v tr OFF.

-

Tam tac dung cua radar ln hay nho phu thuoc vao s lam viec cua enmagnetron tot hay xau. V vay yeu cau en phai hoat ong on nh nen tren matmay co cong tac kiem tra va ch bao cua en magnetron. en phai hoat ongung quy trnh, phai co thi gian cho en chuan b trc khi phat.

- Khi a ieu chnh tat ca cac num nut v tr thch hp e co anh ro net ma anhvan m, ngha la en magnetron phat xa yeu.

- Tren phng dien s dung va bao quan, en magnetron hoat ong theo nguyen lyien va t, nen khong c lam mat hay anh hng en nguon t cua en.

- Cac radar hien nay eu s dung en magnetron e tao dao ong sieu cao tan. ola en tao dao ong theo nguyen tac co ien nen can co thi gian ot nongcathode. Khi tn hieu bao radar a san sang ta mi bat radar sang che o phatxung. mot so tau trong tai ln, ngi ta thng lap them radar co che o khancap EMERGENCY. Khi s dung che o nay radar co the hoat ong c ngayma khong can thi gian chuan b. Tuy nhien khong nen li dung chc nang nay vse gay hai cho radar.

- Neu tren man hnh, anh cua cac muc tieu thang ng, phang nh: e chan song,cau cang, b bien dang, th co ngha co s khong ong bo gia may ch bao vamay phat va can phai kiem tra lai.


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ANTENNA RADAR HANG HAIANTENNA RADAR HANG HAIANTENNA RADAR HANG HAIANTENNA RADAR HANG HAI1111---- Yeu cau:Yeu cau:Yeu cau:Yeu cau:

Antenna radar la thiet b phat song radio va thu song phan xa tr ve a vao ong dansong, la loai antenna nh hng, lap at tren tau thoa man cac yeu cau sau:- Phai quet tron 3600va chup nang lng xuong mat bien.- Tao ra bup phat co tnh nh hng cao, am bao kha nang phan giai theo goc va

theo khoang cach, loai c cac bup phat phu neu nang lng bup phat phu nhohn 1% bup phat chnh.

- Toc o quay cua antenna sao cho trong 1 vong quay cua antenna phai co t nhat

10 12 xung ap vao muc tieu (n = 22 24 vong / phut)- Be mat hieu dung cua antenna phai u ln e am bao tam xa tac dung cua

antenna.

-

Dai lot phai u ln e thu tat ca cac tn hieu phan xa tr ve.- Chieu cao antenna phai u ln e tang tam xa nhng khong qua ln se lam tangban knh vung chet. ong thi bo tr sao cho tranh c anh hng cua cac dungcu nghi kh hang hai, cot c, can cau e giam vung ram vung mu.

- Phai gon nhe, o ben c hoc cao, chu c song gio.e co tnh nang tren ngi ta che tao 2 loai antenna: antenna parabol va antenna khe.

Thc te hien nay tren tau ch dung antenna khe, antenna parabol ch dung cho radar b.

2222---- Cac thong so chnh cua antenna:Cac thong so chnh cua antenna:Cac thong so chnh cua antenna:Cac thong so chnh cua antenna:-

Thong so gian o phat: ac trng bi ngva bieu hien s phu thuoc cng oien trng hoac mat o cong suat vao cac hng khi phat.

- He so nh hng G: kha nang tap trung nang lng ve 1 hng. Neu bup phat

cang hep th kha nang phan biet cang tot, o chnh xac nh hng cao va con cotac dung tang tam xa tac dung, giam nhieu xa t cac hng vao antenna.

- He so hieu dung: la t so nang lng co ch / nang lng phat.- He so khuech ai: he so hieu dung * he so nh hng.- Toc o quay cua antenna : am bao 20 30 vong / phut.

3333---- Mot so chu y khi s dung :Mot so chu y khi s dung :Mot so chu y khi s dung :Mot so chu y khi s dung :- Nang lng bc xa t antenna la nang lng sieu cao tan co anh hng en sc

khoe, khi antenna quet khong nen nhn vao antenna.- Khong sn vao mat bt nc cua loa bc xa.-

Antenna phai kn nc- Trong khi lap at phai chu y ti khoang cach an toan vi la ban t va la ban ien

theo hng dan cua nha san xuat.

4444---- Mot so thiet b:Mot so thiet b:Mot so thiet b:Mot so thiet b:


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(1)Cap ong truc:Nang lng sieu cao tan co the truyen theo ng day dai, cap ong truc hay cac ong

dan song. Neu truyen tai bang cac ng day tran song song th se b ton hao nang lngrat ln do bc xa ra ngoai khong gian (v cong suat bc xa t le bnh phng tan so) vachu anh hng rat nhieu bi dao ong ien t ben ngoai. Do o ngi ta s dung capong truc.

(HNH VE)- Vector E : ng sc cua ien trng doc theo ban knh .- Vector H : ng sc t trng la nhng vong tron ong tamT trng nam gia li kim loai va loi , do o no tranh c ton hao do bc xa. Voboc ben ngoai giup tranh c anh hng ien t trng ben ngoai . Ta thay rangdong ien va ien tch tap trung be mat ngoai cua loi va li kim loai , nen be matloi ngi ta ma bac , con li kim loai c noi at . Nh vay li kim loai va loi nhhai cc cua nguon ien .Cap ong truc thng ch dung e truyen tai nang lng vi tan so < 3000 Mhz tng

ng bc song > 10 cm.Trong radar ngi ta dung cap ong truc e noi cac khoi va lay nang lng t chung.

Khi nang lng vi tan so > 3000 Mhz th dung ong dan song.

(2)Ong dan song:Dung truyen tai nang lng song sieu cao tan t may phat ti anten va song phan xa

tr ve anten ti may thu.Thanh ong dan song c lam bang vat lieu dan ien tot (thng la ong hay Ni), co

tiet dien tron hay ch nhat. e tranh hien tng bc xa nang lng vao khong gian dohieu ng dong ien gay ra, be mat trong ong dan song c phu 1 lp bac mong.Ong dan song tron c dung trong khp noi gia ong co nh va anten khi quay, viec

dan song chu yeu dung ong ch nhat vi thanh rong la a, thanh hep la b.Song radar hien nay = 3.2 cm th a*b = 22.9*10.2 mm

a*b = 28.6*12.7 mmOng dan song ch nhat c ac trng bi bc song ti han, la bc song dai nhat

cua song ien t ma ong co the truyen ma khong ton hao.th2a

Bc song lan truyen trong ong c tnh bi cong thc:

2)(1

th

b

=

Nguyen ly lan truyen song: song i ti phan xa t thanh no sang thanh kia, lan truyent au en cuoi ong.

ien trng, t trng trong ong phan bo nh hnh ve :( HNH VE )

@. Cach uon ong dan song : Co 2 cach :


28/49




. Uon theo ien trng 900 : sau khi uon ien trng doi chieu 900 con t trngvan gi nguyen hng.

. Uon theo t trng 900 : t trn doi hng 900, ien trng gi nguyen hng.( HNH VE )

@. Cac dang ong dan song ac biet :( HNH VE ). Ong dan song cong bien oi t tiet dien nam ngang sang thang ng.. Ong dan song thu nho phong to tiet dien.. Ong dan song chuyen oi tiet dien t trong sang vuong ( ch nhat ).

e tranh hien tng phan xa nang lng th chieu dai cua nhng oan ong naythng vao khoang vai lan bc song.

@. Phan nhanh nang lng :Trong radar nhieu khi phai phan nhanh nang lng t 1 ong dan chnh ra nhieu ong

dan phu, v vay can co nhng oan phan hanh nang lng.. Phan nhanh nang lng theo ien trng : sau khi phan nhanh, ien trng 2

nhanh phu se ngc chieu nhau.( HNH VE ). Phan nhanh nang lng theo t trng : sau khi phan nhanh t trng 2 nhanh

phu cung chieu.( HNH VE )

@. Ghep noi :e thuan tien cho viec ghep ong dan song, ngi ta che tao tng oan ong mot roi

ghep lai vi nhau theo ung nguyen ly h ngan mach e tr khang bang 0. e lam nhvay 2 au ong dan song ( noi vi nhau ) ngi ta che tao cac mat bch co kch thcnh hnh ve. e tranh nc vao cac moi ghep, ngi ta s dung em cao su.

(HNH VE )

@. Cach truyen tai nang lng vao ong dan song :

e truyen tai nang lngvao ong dan song ngi ta dung

1 cap ong truc co vo ngoai noivi thanh ong dan song bendi. au cua oan cap ongtruc o c a len ong dansong di ong nh hnh ve. Cachghep noi nay c s dung khi

a/2 b/2

b

/4

/4

/4


29/49




noi ghep ong dan song co nh vi ong dan song di ong anten.

(3)Anten khe:La loai anten trc tiep bc xa song

vao khong gian khong can loa bc xa vagng phan xa.

Khe hep c khoet tren thanh ongdan song thanh rong hay thanh hep, kheco chieu dai o/ 2, chieu rong


30/49




- o ton hao nang lng nho.

a.

Chuyen mach antenna ien t ( dung en phong ien ) :@. Cau tao cua en 2 cc :Bnh thuy tinh co 2 cc noi vi ien ap moi 800 1000 v. en nay khi co songsieu cao tan nang lng ln ti se co hien tng phong ien ngan mach.@. Chuyen mach :( HNH VE )Cau tao :Tren ong dan song phan nhanh ngi ta at cac en ien t ATR ( en phat )va en TR ( en baao ve may thu ) lan lt trc may phat va may thu nhhnh ve.Nguyen ly hoat ong :

. Khi phat : nang lng song rat ln lam cho cac en phong ien nganmach. oi vi en ATR : noi lien thanh ong dan song. oi vi en TR: en phong ien gay ra hien tng ngan mach /2 lam tr khang gia2 iem a va b bang 0, tach may thu ra ngoai. Khi o toan bo nanglng se t may phat a ti antenna.. Khi thu : nang lng song phan xa tr ve nho, 2 en ien t eukhong phong ien. en ATR cach c mot khoang /4 nen xay ra hientng ngan mach /4 lam cho tr khang gia 2 iem b va c bang 0,ngat may phat ra ngoai. Khi o toan bo nang lng song phan xa trve se en may thu.Trng hp nang lng phan xa ve qua manh, en TR se phong ien,khong cho song phan xa vao may thu lam hong may thu.

Hi nc va hydro ap suat thap trong en ien t co tac dung dap not nhngion con lai sau khi en khong phong ien ( giam i).u nhc iem :

. u : gon nhe, re tien, de thay the.

. Nhc : tnh ln do phu thuoc vao thi gian phong ien cua enien t.

b. Chuyen mach fe-rit :( HNH VE )

Cau tao :. Ong dan song kep, co oan uon cong sao cho chieu dai ong di ln

hn ong tren la /4 e khi i qua song di se cham hn song tren la900( oan dch pha DF ).. Hai cau khe CK1va CK2co tac dung khi i qua cau khe se cham pha900.. Hai thanh fe-rit 1va 2at ong tren va ong di trong t trngvnh cu. Thanh fe-rit co tac dung :


31/49




+ Khi phat song, song i qua oan ong ben di se cham pha sovi song ben tren la 900.+ Khi thu song, song i ben tren se cham pha so vi song iben di la 900.

Kch thc thanh fe-rit khoang 100 * 8 * 6 mm.Nguyen ly hoat ong :

. Khi phat : song ti CK1chia lam 2 phan. Mot phan i qua CK1se bcham pha 900. Neu song nay ti may thu, nang lng ln, en TR sechap mach ngan khong cho vao may thu. Song di i qua thanh fe-ritse cham pha them 900, qua oan dch pha DF tiep tuc cham pha i 90 0na. Khi song ben di qua CK2 len ben tren lai tiep tuc cham phathem 900, tong cong cham pha 3600, cung pha vi song ben tren tiantenna, nang lng vao antenna cc ai.Tai CK2, mot phan song ben tren se i xuong di, b cham pha 90 0,ngc pha vi song 2700ben di. Hai song nay se triet tieu nhau vatieu huy di dang nhiet vat hap thu.. Khi thu : song t antenna phan xa tr ve, 1 phan qua CK2i xuongdi cham pha 900, qua oan DF cham i 900na. ong thi song betren i qua thanh fe-rit b cham i 900, qua CK1 cham them 900, haisong tren va di cung pha ti may thu.Thanh phan song ben di qua CK1 len tren se cham pha tiep 900( -2700) ngc pha vi song ben tren ( -900) se b triet tieu.

u nhc iem :. u iem : tnh nho. Nhc iem : che tao at tien, phc tap.


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MAY THU RADARMAY THU RADARMAY THU RADARMAY THU RADARay thu radar co nhiem vu nhan tn hieu sieu cao tan t muc tieu ve, qua antenna, bien

thanh tn hieu ien roi khuech ai len a sang may ch bao.Yeu cau oi vi may thu:- o nhay cao.- Tap am nho, thu c nhng tn hieu yeu.-

Dai lot u rong e am bao cac xung tn hieu khong b bien dang.-

Co kha nang chu va cham c hoc, o ben cao, kch thc gon nhe, kha nang lamviec on nh.

- Phai co bo ieu chnh tot e co anh ro net.

S o khoi :

I. Bo han che :Trng hp xung phan xa tr ve may thu qua manh co nguy c lam hong may thu th bo hanche co nhiem vu han che bt xung phan xa (han che bt bien o nhng van am bao ginguyen tan so).Bo han che thng dung diode can bien lap vao ong dan song trc khi vao bo tron, cung cothe dung en phong ien.

II. Bo tron oi xng:( HNH VE )Bo tron oi xng co nhiem vu nhan tn hieu phan xa t muc tieu tr ve (qua chuyen machantenna) va tn hieu t bo dao ong noi a sang e ket hp tao ra tn hieu trung tan.Bo tron c lap tang au may thu. Mot oan ong dan song cau tao nh hnh ve. Nhanhtren thanh rong a tn hieu phan xa t muc tieu tr ve vao ( ft). Nhanh hep a tn hieu t

M

Chuyenmach

Hanche

Botron

K/aitrungtan

Tachsong F.T.C

K/aixunganh

/chnhtan so

AFC

dao

noi

TUNE AFCFTC

CRT

CONTRASTGAIN S.T.C STC

ong


33/49




bo dao ong noi ti ( fk). Hai ben thanh ong chnh at 2 en tron D1va D2giong het nhau.Hai en nay c noi vi bien ap trung tan e a ti cac khoi sau.Do ac tnh phan nhanh ien trng cua ong dan song, tn hieu ftsau khi phan nhanh ngcpha nhau 1800khi qua 2 en, fkqua 2 en cung pha. Tn hieu ftva fkc tron tai en D1vaD2, lay ra tn hieu trung tan :

ftt= fk ftTan so trung tan nho hn rat nhieu nhng van am bao nguyen dang cua tn hieu phan xa.S d lam nh vay la e chon tan so thch hp cho may thu lam viec, nang cao tnh kinh teva chat lng may thu. Thng :

ftt= 60 Mhz fk= 9460 Mhz ft= 9400 MhzTheo s o tng ng, tn hieu phan xa qua phan nhanh T1, tn hieu t bo dao ong oi quaphan nhanh T2. Nh tac dung cua D1, D2 va khung LC ta lay ra c ftt. Tap am cua maythu chu yeu do bo dao ong noi gay ra. Vi s o tron can bang, phan tap am chu yeu cloai tr. Xet ve pha :

D1 dong co pha tt1= k tD2 dong co pha tt2= k (t ) = tt1+

Vay tn hieu trung tan qua cuon L se cung chieu va c lay ra qua bien ap T3.Tap am : dong tap am do fkgay ra qua 2 en cung pha va ngc chieu nen chung se cloai tr khi qua cuon L.

III. Bo dao ong noi:Bo dao ong noi co nhiem vu tao ra dao ong sieu cao tan vi cong suat nho a sang botron, vi tan so sao cho no tr i tan so tn hieu phan xa tr ve th bang tan so trung tanchuan. Cong suat do bo dao ong noi tao ra khoang 5 w.Bo dao ong noi co yeu cau :

. Co he so nhieu on nho.. Hoat ong tan so on nh.

. Khi can co the thay oi tan so bang phng phap c hay ien.Bo dao ong noi thng s dung en sieu cao tan co ien Klistron hoac diode Gunn.

en Klistron :( HNH VE)

. en bao gom ong hnh tru bang thuy tinh co o chan khong cao, lien ket vi mothop cong hng. Anode cua en co dang li. Ngoai ra en con co cc phan xa cgan vi nguo 1 chieu tao ien ap am so vi cathode. hop cong hng co vt ieu

chnh the tch cua buong cong hng va co moc ghep e lay dao ong sieu cao tana sang bo tron.

. Hoat ong : Cac ien t bat ra t cathode, di tac dung cua ien trng anode-cathode se chuyen ong ve anode. V anode co dang li nen mot so ien t se tianode tao thanh dong anode ia, con mot so ien t do gia toc se chuyen ong vtqua anode ve pha cc F. Khi qua hoc cong hng, cac ien t nay se kch thch hoc


34/49




cong hng. Tren hoc cong hng se xuat hien cac dao ong sieu cao tan, trong oco tan so f ma ta mong muon.Trong qua trnh dao ong, hoc cong hng se tao hai vach li cua hoc ien trngbien thien. Khi cac ien t i ti vach li vao thi iem tren di +, cac ien tnay se c tang toc o i ti cc phan xa. Do cc phan xa mang ien ap am so vicathode, cac ien t se b bat ngc tr lai vi van toc nho. Nhng ien t tiep theokhi ti vach li vao thi iem tren + di -, se b can va i qua vach li vi van tocnho, b cc phan xa ay tr lai vi van toc ln. Cac ien t ti vach li vao thiiem ien trng bang 0 se b bat ngc tr lai vi van toc trung bnh. Ngi ta chetao ( bang cach thay oi ien ap va the tch hoc cong hng ) sao cho 3 lp ien tnoi tren se tr ve hoc cong hng cung mot luc va cac ien t nay se bo sung nanglng e duy tr tan so fk. ay ngi ta dung moc ghep lay ra tan so fka sang bo tron. Ngi ta dung vtieu chnh the tch e hop cong hng vi tan so fk khi can thay oi ln. e ieuchnh tan so fk trong khoang thay oi nho, ngi ta se thay oi ien ap at vao ccphan xa va ay chnh la num ieu chnh TUNE tren mat may radar.

. u iem : viec che tao tng oi n gian, de ieu chnh tan so, lam vien on nh,kch thc nho, am bao cong suat u ln e bien oi tan so dai song cm.

. Nhc iem : o nhieu on ban than tng oi ln.

Diode Gunn :

( HNH VE )

. Cau tao : la loai diode khong tiep giap, thng dung cac loai hp chat GeAs, InSb,InAs at ben trong hop cong hng.

. Hoat ong : Da tren hien tng Gunn : Khi co mot ien trng u ln at vao 2au cua 1 thanh hp chat ban dan nh tren ( hoan toan tinh khiet ) th se nhan ctrong hp chat ban dan nay 1 dao ong sieu cao tan, ket hp vi hoc cong hngchung ta co the lay c dao ong sieu cao tan nay ra lam dao ong noi.e ieu chnh tan so cua bo dao ong noi, ta co the thay oi the tch cua hoc conghng hoac thay oi ien ap dat vao diode Gunn.Diode Gunn thng dung trong mach co cong suat nho.

. u iem :

+ Gon, nhe, de che tao, cong suat tieu thu nho.

+ ng at tnh tuyen tnh hn en Klistron.+ o nhieu on ban than nho.

+ Cong suat phat ra u ln, dai tan lam viec rong.

. Nhc iem : de h hong.

IV. Bo t ong ieu chnh tan so:


35/49




Hieu qua lam viec cua radar phu thuoc rat nhieu vao s on nh cua tan so trung tan ftt. Khifttthay oi th he so khuech ai may thu thay oi rat ln. V vay ngi ta lap mach t ongieu chnh tan so am bao may thu cong hng tot nhat.

( e ieu chnh tan so trung tan bang tan so trung tan chuan ngi ta ieu chnh tanso dao ong noi. Co 2 cach : bang tay hoac t ong. )

S o mach t ong ieu chnh tan so :( HNH VE ). Han che AFC : giam cong suat tn hieu roi a vao bo tron AFC.. Tron AFC : tron tn hieu t bo han che AFC a sang vi tan so dao ong noi.. Phan biet tan so : kiem tra xem tan so trung tan AFC ln hay nho hn so vi tan sotrung tan chuan.. Bo ieu khien : tao ien ap ieu khien Ukhat vao cc phan xa cua en Klistron.

Hoat ong :Khi may phat phat song mot phan tn hieu se qua han che AFC ti bo tron can bang AFCcua mach ieu chnh tan so giong het bo tron may thu va co cung thong so. Bo tron AFC se

tron tn hieu nay vi tn hieu t bo dao ong noi a sang thanh tn hieu trung tan AFC (fttAFC).Khi en magnetron phat song tang th fttAFCse giam va ngc lai, qua mach phan biet tan socho thay co s thay oi tan so so vi tan so trung tan chuan, thay oi thanh tn hieu ien ea sang mach ieu khien. Mach ieu khien se tac ong lam cho bo dao ong noi thay oisao cho tan so fkphat ra am bao khi a sang bo tron may thu tron vi tn hieu phan xa trve at ung bang tan so trung tan chuan.

V. Bo khuech ai trung tan :Tn hieu phan xa ve may thu co nang lng rat thap. e co u kha nang lam viec, ngi ta

khuech ai len e cho tn hieu gi nguyen hnh dang va o dai nhng bien o ln len ratnhieu, vi nang lng ln hn.Tuy tng loai radar ma bo khuech ai trung tan s dung en ien t hay ban dan, bo tr sotang khuech ai nhieu hay t, he so khuech ai ln hay nho. Thong thng ien ap ra khoitang khuech ai c 1 1.5 v. Khi s dung nhieu tang khuech ai th he so khuech ai bangtch cac he so khuech ai cua tng tang. Ta co the thay oi he so nay qua nut ieu chnhGAIN bo tr mat may va trong may thu.Thong thng khuech ai trung tan c thiet ke e khuech ai tan so 60 Mhz, tuy nhiencung co loai tan so 35 Mhz, 40 Mhz

So lng va he so khuech ai c thiet ke sao cho :. He so khuech ai ln, khong b meo va co the ieu chnh theo thi gian.. Thay oi c dai thong cho xung ngan va dai khac nhau.. Tranh c nhieu tap am, giam c o on, tang c o nhay may thu.

VI. Bo tach song :


36/49




Tn hieu phan xa, qua khuech ai trung tan co tan so cao, e a ti ong phong tia ien tphai tach xung th tan ra. Muon vay dung mach tach song tach xung th tan khoi xung caotan.Bo tach song co 2 loai : tach song ca chu ky va na chu ky. No co cau tao n gian gom tuien C1ong vai tro bo loc xung cao tan, tu ien C2lay xung th tan, diode ( hoac enien t ) tach song va ien tr e thoat thanh phan 1 chieu.( HNH VE )Dao ong nam trong ng bao khong gay sut ap khi qua tu C1( Uc= Ic* Xc


37/49




Mach khuech ai gom 1 hoac vai tang, khong oi hoi he so khuech ai cao song dai lot phaiu ln e tranh meo tn hieu. Tuy theo phng phap a xung anh vao ong phong tia ien tma ngi ta bo tr mach sao cho ra khoi mach khuech ai xung anh se la xung am haydng. Thong thng tn hieu c a en cathode nen thng la xung am.Mach nay tuy radar ma co the dung khuech ai ien t hay ban dan.


38/49





MAY CH BAO RADARMAY CH BAO RADARMAY CH BAO RADARMAY CH BAO RADARay ch bao at buong lai, la thiet b au cuoi cua radar the hien moi thong tin can

thiet va at toan bo cac num nut ieu khien. Ngi s dung trc tiep ieu khien tramradar lay cac thong so muc tieu can thiet. May ch bao cho 2 thong so chnh cua muctieu la khoang cach va goc. May ch bao co cac loai: ch bao chuyen ong tng oi, ch baochuyen ong that, radar + ARPA.

Cac yeu cau vi may ch bao:-

Gon nhe- Tieu hao nang lng t- o ben c hoc cao- Cac ch tieu ky thuat ap ng- Kha nang t ong ln

- Co cac num nut ieu khien vi chc nang m rong- o phan giai cao, cho anh ro.- Cac vong c li phai c ieu chnh chnh xac- o nhay thch hp.

S o khoi (phan chnh la ong phong tia ien t)

I. C cau o c li :

o c li ti muc tieu la o khoang cach t le man hnh t tam tia quet en anh muc tieu.Thng e o c li ngi ta thiet ke c cau o bang vong c li co nh va di ong.. o bang vong c ly di ong : a mot xung vuong dng co the di chuyen ctren ng quet, khi tia quet quay ta c mot vong tron. Vong tron nay co the thayoi c ban knh. Viec thay oi ban knh vong tron do mot nut ieu khien tren matmay, quay nut th ban knh vong tron thay oi ong thi lam lam thay oi gia tr cuaen ien t ch th khoang cach ten ong ho ch bao, tng ng vi khoang cach

M

MT

K/ai

hoi tu

quet

xung anh

K/ai

CONTRAST

tre dap quettao dau

VRM Brilliance

RRbien oi

VRM Control

co nhc li nghch

treco nhkhi ong

Tao xungxunggian tao quet

chnhtam

tangsang

dau muitao SHM

CENTER

machquet tron

FOCUS

Anten

cao ap

BRILLIANCEtao dau

di ongc li


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ngoai thc a. Muon o khoang cach ta ieu chnh cho vong tron nay tiep xuc vimuc tieu va oc gia tr tren ong ho.. o bang vong c ly co nh : co 2 cach

+ Cach 1 : ngi ta vach tren mot tam mica nhng vong tron ong tam hoacnhng ng thang song song e o khoang cach bang noi suy. Tam cua tammica c at trung vi tam tia quet cua man hnh.+ Cach 2 : a cac xung dng cach eu nhau len tia quet, khi tia quet quay setao thanh nhng vong tron ong tam cach eu nhau e co the noi suy ra c ly.

Ngoai ra cac radar mi ngay nay tren man hnh ngi ta con tao ra con tro co the s dunge o khoang cach en cac muc tieu.

II. C cau o hng :Ngi ta bo tr thc o o( con goi la vong khac o hoac vong phng v ) mep man anh.Thc o co nh ( vong khac o co nh hoac vong phng v co nh ) cho ta goc man (hay con goi la phng v tng oi ), thc di ong ( vong khac o di ong hoac vongphng v i ong ) dung o phng v. Tuy loai radar ma ngi ta bo tr 1 hoac ca 2 loai

tren. man hnh radar ngi ta bo tr thc ngam c kh ( thc song song ) hay ien t (ng phng v ien t EBL ), chung xoay c nh nut ieu khien. Khi muon o hngen muc tieu ta xoay thc ngam len muc tieu va oc gia tr thc o o hoac cac ongho ch th.Ngoai ra cung giong nh o khoang cach, cac radar mi nhi ta cung co the s dung contro e xac nh ga tr nay.

III. Ong phong tia ien t :Ong phong tia ien t co nhiem vu bien tn hieuien thanh tn hieu anh sang quan sat c trenman hnh.Cau tao :

Cathode K Cc ieu che M Anode A1co dang tru Anode A2 la man than dan ien, noi

vi nguon cao ap. Cuon day hoi tu e hoi tu tia ien t.

Cuon day gay lech XX, YY co 2 loai la co nh hay quay, nhiem vu quay tia

quet.

Man huynh quang phat sang khi ien t ap vao va gi lai 1 thi gian.

ien ap nung khoang 6 12 v ng knh CRT thng khoang 10 16

VI. Bo tao xung khi ong :

K M A1

X X

Y Y

Man

huynhquangNguoncao ap

Cuon gay lech

Cuon hoi tu


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Bo tao xung khi ong co nhiem vu ieu khien toan bo tram radar hoat ong ong bo vinhau, am bao cac khoi quan he thi gian chat che vi nhau.Thong thng la bo blocking t kch thch tao xung khi ong t nhng dao ong hnhvuong hoac trc tiep t nguon nuoi tram radar.Xet mach ien blocking :( HNH VE )Khi cung cap nguon ien Ea, en se hoat ong. Trong cuon 2 se co dong ia chay qua. Doc ghep t vi nhau, cuon 2 se cam ng sang cuon 1 & 3. Tren cuon 1 sinh ra 1 suat ienong. Ngi ta thiet ke sao cho au dng cua cuon nay at vao li cua en, au am atvao cathode. Khi o en hoat ong rat manh, dong ia tang ot ngot. Luc nay cuon 3 tacung lay ra c mot ien ap tang.ong thi khi en hoat ong th se co dong li igchay qua en : t au + cua cuon 1 qua tuC, qua en roi ve au -. Dong li se nap ien cho tu, au am cua tu at vao li cua en.Khi o co 2 ien ap at vao li cua en : + do cuon 1 tao ra va do tu C at vao. Ti lucnao o ien ap se ln hn ien ap + lam cho ien ap li giam en gia tr ti han va enkhoa. V the dong i

a mat, ien ap cam ng sang cuon 3 giam ot ngot. ong thi khi o

dong igmat, tu C phong ien qua cuon 1 & Rg. Ti 1 luc nao o ien ap + at vao li cuaen lai ln hn ien ap -, en lai hoat ong tiep tuc qua trnh tiep theo.

V. Bo gay tre :Bo gay tre ( bo tre xung ) co nhiem vu a xung khi ong ti cac mach co yeu cau xungkhi ong nhng khoang thi gian khac nhau.Co 2 phng phap tao tre :

1. Tao tre ien t :( HNH VE )Xung khi ong kch thch tao xung vuong nham tao ra xung vuong am, sau o a

qua mach vi phan va mach xen. Bang cach o ta co khoang thi gian chenh lech giaxung vao va ra la t. Gia tr nay co the thay oi c nh o dai cua xung vuong.2. Tao tre theo phng phap dung ng day gay tre:ng day gay tre gon cac mat xch LC lien ket vi nhau. Tn hieu qua bo nay secham i khoang thi gian can thiet thch hp cho tng khoi.Thi gian tre xac nh theo cong thc :

t = n CL* trong o : n : so mat xch LC

VI. Mach tao quet :

Mach tao quet co nhiem vu a 1 ien ap co dang xung rang ca bien thien tuyen tnh theothi gian vao cuon gay lech lam tia ien t chay t tam ra bien tng ng vi viec xung sieucao tan i tham sat muc tieu roi phan xa tr ve. Mach nay chnh la thc o thi gian. eradar co nhieu thang tam xa, ngi ta thiet ke bo tao quet co xung rang ca co o dai khacnhau tng ng tng thang tam xa. La mach o thi gian nen no phai quet t khi xung thamsat muc tieu ri antenna, viec nay do xung ieu khien lam ong bo phat va quet. e tao


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xung rang ca ngi ta da vao ng ac tnh nap ien cho tu, no la ng tuyen tnh nenam bao tia ien t chay eu.Mach tao quet co yeu cau la ng dac tnh cua ien ap phai thang va thi gian quet nghchcua tia quet phai nho. Khi tu ien tch ien th tia ien t cung bat au dch chuyen t tam.Nguyen ly hoat ong cua s o :( HNH VE)Khi cung cap nguon ien +Eacho mach ong thi cha co xung khi ong ti, do co ien apdng qua Rgat vao li cua en nen en hoat ong rat manh.Khhi co xung am ( rong bang ng quet ) a ti at ien ap am vao gia li va cathode,en b khoa. Khi o dong ien t Eaqua Ra, C1ve at nap ien cho tu. ien ap lay ra tren tuC se tang dan theo thi gian. Ngi ta thiet ke Rava C sao cho ien ap nay la tuyen tnh.ien ap nay se c a qua khuech ai e at vao cuon lai tia. Khi xung khi ong maten lai hoat ong rat manh, tu se phong ien. Thi gian phong nho tng ng luc radar phatxung.Khoa K ay thay oi ien dung tu ien ( C1, C2, C3) e thay oi thi gian thu xung. Vvay khoa K chnh la thang tam xa tren may.

VII. Mach khuech ai quet :Xung rang ca t bo tao quet co nang lng yeu khong ieu khien c tia ien t nen phaic a qua bo khuech ai quet. Sau khi qua bo nay xung rang ca co bien o ln hn ratnhieu, u nang lng e ieu khien tia ien t. No c a ti cuon gay lech. Mach naydung ban dan hay ien t.

VIII. Mach tao quet tron :Nhiem vu cua mach tao quet tron la lam cho tia quet tren man anh quay ong bo, ong phavi antenna, am bao khi antenna quay c goc so vi mui tau th tia quet cung quay gocso vi dau mui tau e muc tieu hien ung goc so vi thc te. e quay tia quet ngi tadung cac sensin lam quay cuon gay lech hay tao t trng quay e quay tia ien t. Quaycuon gay lech goi la phng phap c, tao t trng quay la phng phap ien.

Phng phap c ( cuon gay lech di ong ) :( HNH VE)Thi iem ban au, do c cau tao nh nhau va lam ong pha, hai motor quay hethong truyen banh rang lam antenna va cuon lai tia quay ong bo ong pha vi nhau.Khi o rotor cua 2 sensin quay ong pha vn nhau, cac sensin can bang nen khong codong trong rotor sensin thu.Neu v ly do ben ngoai tac ong, motor lai antenna quay nhanh len ( hoac cham i ),

2 sensin quay vi toc o khac nhau lam cho 2 sensin khong con can bang, sinh radong trong sensin thu. Dong nay qua khuech ai phu tr, en motor lai cuon lai tialam tang ( hoac giam ) toc o e at bang vi motor lai antenna. Mach sensin tr laican bang.Phng phap ien ( cuon gay lech co nh ) :( HNH VE )Cuon gay lech gon 3 cuon day at co nh lech nhau 1200.


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Tn hieu t bo tao quet c a ti khuech ai quet, sau o a ti bo phan giaiquet. ay la bo vi x ly. T bo phan giai quet nay tn hieu se c a en motorlai antenna, cung nh a ti 3 cuon day cua cuon gay lech e tao ra t trng xoay cuon nay.Viec ong bo ong pha gia antenna va t trng quay cuon gay lech do bo phangiai quet am nhiem.

IX. Mach tao dau c li co nh :Nhiem vu cua mach tao dau c ly co nh la tao ra cac xung vuong cach eu nhau rai trentia quet e a vao cathode ong phong tia ien t. Khi tia quet quay se tao thanh cac vongsang co nh ong tam cach eu nhau tren man anh.S o khoi :( HNH VE )Bo tao dao ong hnh sine tao ra dao ong vi so chu ky tng ng vi so vong c ly co nhmong muon treen man anh. Khi qua bo han che se cat phan am, lay phan dng a sang bovi phan. Bo nay co nhiem vu bop hep gian o phat va lam cho khoang cach gia moi xung

tng ng vi thi gian xung i c trong mot khoang cach D. Bo dao ong nghetblocking, tng ng vi 1 xung ien ap a t bo vi phan sang, se tao ra 1 xung vuongdng. Tn hieu nay khi a qua khuech ai xung anh se c khuech ai cung nh aochieu xung e a ti cathode. e co c s ong bo, bo nay se hoat ong trong s kiemche cua xung khi ong.

X. Mach tao dau c li di ong :Nhiem vu cua mach tao dau c ly di ong la tao ra xung dng di chuyen c tren ngquet va ong bo vi ong ho ch th khoang cach. Khi tia quet quay ta co c vong tron banknh thay oi c. Thay oi ban knh vong tron ket hp vi ch th khoang cach ta co thexac nh khoang cach en muc tieu 1 cach chnh xac.

e tao c xung dng co the di chuyen tren ng quet can phai tao c daoong hnh sine co pha thay oi c theo thi gian. e lam c viec o ngi tathc hien nh sau :( HNH VE )Hai cuon day A va B ( goi la stator ) c at vuong goc vi nhau. Cuon C ( goila rotor ) at trong long 2 cuon A & B, hp vi truc cuon A mot goc la . Cuon A & Bmac noi tiep va mac noi tiep vi cuon th cap cua bien ap T. Cuon s cap cua bienap T c mac vi nguon dao ong tan so f.ieu chnh tu C cho cong hng vi tan so f. Khi o dong ien qua A & B lech pha

nhau 90

0

(do truc A & B vuong goc vi nhau ). Gia s goi dong ien chay trong cuonA la :iA= IA sint

Dong ien chay trong cuon B se la :iB= IB cost

Hai dong ien nay chay trong cuon A & B se cam ng sang cuon C cac suat ienong EAva EB. V cuon C at lech truc so vi cuon A mot goc , ta co :


43/49




EA= -sindiA/dt = -sin. IAcostEB= -cosdiB/dt = +cos. IBsint

Suat ien ong tong cong tren C se la :Ura= EA+ EB

= -sin. IA cost +cos. IBsintieu chnh ien dung tu C va R sao cho dong IA = IB = I, ta co :

Ura= I (sint cos- cost sin)= I sin(t - )

Vay au ra cuon C ta a tao c 1 dao ong co the thay oi c pha theo thigian, phu thuoc vao goc lech .Xung khi ong ay c a qua ien tr R 1e khong che mach hoat ong trongthi gian nhat nh.

.

XI. Mach tao dau mui tau :Tao vet sang anh dau hng mui tau e thuan tien quan sat theo doi muc tieu. Viec nayc thc hien bi xung ien ap dng hay am a vao cc ieu che hay cathode ong phong

tia ien t lam tia ien t manh len thanh 1 vet sang khi anten quay qua hng mui tau.Cng o sang dau mui tau co the ieu chnh bang nut ieu khien tren mat ch bao, thcchat la chnh xung ien ap.Mach tao dau mui tau :(HNH VE)

. Khi tiep iem K h ( bup phat antenna cha chup vao mat phang truc doc tau), dongien li igse tch ien cho tu C co dau nh hnh ve. Do co ien ap qua Rgat vaoli cua en nen dong ien chay qua en rat ln ien the anode se sut xuong =Uamin0.. Khi bup phat chup vao mat phang truc doc tau, do motor lai M quay ong bo ong

pha vi antenna cho nen luc nay tiep iem K c ong lai. Khi o au dng cua tuC c noi at ( hay cung chnh la cathode cua en ), con au am cua tu C c atvao li cua en lam cho en ngng hoat ong. ien the cua anode se tang t UaminEa.

Tom lai, tai thi iem bup phat trung mat phang truc doc tau, tren anode cua de9en ta layc mot xung ien ap dng a en bo khuech ai xung anh roi t o a vao cathodecua CRT. Luc o tren man hnh radar se co 1 vet sang t tam tia quet chay ra bien man hnhanh dau hng mui tau ( SHM ).Chu y :

. Khi muon kiem tra xem di SHM co muc tieu nho nao lan trong o khong, ta tat

tam thi dau mui tau (neu la num van : van sang het trai va gi, neu la nut an : an vagi ).. Ngi ta cung s dung diode quang e tao dau mui tau : khoi quet ngi ta atdiode quang ve pha mui tau. Ben tren co 1 bo phan xoay theo antenna co khoet 1ranh. Khi ranh nay quay qua diode quang ( antenna quay ve hng mui tau ), diodese phat tn hieu a vao CRT e the hien dau mui tau.


44/49




. Khi SHM lech khoi 00 cua vong khac o co nh, ta ieu chnh banh rang laiantenna tren khoi quet bang 1 vt luc lang dch theo chieu ngc lai sao cho vetsang dng lai vach 00o la c.


45/49





MANMANMANMAN ANH RADARANH RADARANH RADARANH RADAR1111---- Cac che o ch hng:Cac che o ch hng:Cac che o ch hng:Cac che o ch hng:

(a)Che o ch hng mui tau: HEAD UPTren man anh radar, dau mui tau SHM luon co nh tai vach 00cua vong khac o co

nh. Khi tau quay tr, SHM van ng yen, anh cac muc tieu co nh se quay ngchung quay tr cua tau.

u iem: s phan bo cua anh cac muc tieu tren man hnh giong thc te hien trngkhi nhn t buong lai tren tau ve pha mui nen thng s dung khi ieu ong tau, khi ravao luong hay hanh hai ni ong tau thuyen qua lai.

Khuyet iem:- Khi tau quay tr, anh cac muc tieu quay tr theo chieu ngc lai tao cac vet nhoe

tren man hnh, lam kho quan sat, khong xac nh c cac muc tieu gan nhau, othieu chnh xac.

- Khong cho biet hng that 1 cach trc quan.- Ch o c goc man ( phng v tng oi ) cua muc tieu. Muon xac nh c

phng v cua muc tieu phai lay gia tr goc man cong hng i, hoac mot soradar co the ket hp viec s dung vong phng v di ong.

(b)

Che o ch hng bac that: NORTH UP che o nay radar phai noi vi la ban. Vach dau mui tau tren man anh se lech i 1

goc so vi iem 00ung bang hng i thc te cua tau (dau mui tau cung toan bo mananh xoay i 1 goc ung bang hng chay tau). Khi o ta oc goc kep gia vach 00 va

ng ngam qua anh muc tieu se cho ta biet phng v cua no. Khi tau quay tr, SHMquay theo, luon am bao ch bao ung hng thc te cua tau, anh cac muc tieu co nh seco nh.

u iem:- Anh cac muc tieu co nh gi nguyen khi tau quay tr nen man anh khong b

nhoe, de quan sat, xac nh v tr chnh xac.- Quang canh tren man hnh radar giong tren hai o. Thng c dung khi hanh

hai xa b hay khi dung xac nh v tr tau lam ngi quan sat de nhan muc tieuhn.

Khuyet iem:- Man anh xoay i 1 goc ung bang hng chay tau nen de gay cam giac sai nhat

la khi chay hng Nam.- Quang canh thc te pha trc mui tau va man hnh khac nhau, khong dung e ra

vao luong.

(c)Che o ch hng lai tau: COURSE UP


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Che o la che o ma trong o man hnh c cai at 1 hng nao o, thng lahng chay tau. V the khi quan sat tren man hnh ta thay che o nay tng t che o chhng mui tau, ch khac la vach dau mui tau se dao ong khi tau b ao hng quanh.

u iem : tng t nh che o hng mui tau. Ngoai ra, khi tau quay tr, vdau mui tau quay con cac muc tieu ng yen nen man anh khong b nhoe.

Chu y : che o nay khi tau thay oi hng goc ln, ta phai cai at lai hng choman hnh.

2222---- Man anh ch bao chuyen ong that:Man anh ch bao chuyen ong that:Man anh ch bao chuyen ong that:Man anh ch bao chuyen ong that:Radar co man anh ch bao chuyen ong that la radar co man anh the hien anh cua muc

tieu ung vi thc te cua no ngoai hien trng ngha la cac muc tieu chuyen ong th anhcua chung cung chuyen ong vi hng va toc o tng ng, cac muc tieu co nh se ngyen. Tau ta (tam tia quet) cung chuyen ong tng ng hng va toc o ngoai thc te.

Ve mat cau tao, radar ch bao chuyen ong that ch khac vi radar chuyen ong tngoi c cau ch bao chuyen ong that. C cau nay co nhiem vu nhan tn hieu toc o t toco ke hay at bang tay va tn hieu hng i t la ban con quay (hay nhan 2 loai tn hieu nayt GPS). Sau o no se phan tch, bien oi cac tn hieu nay thanh cac tn hieu a vao caccuon day gay lech e tao ra t trng ieu khien tam quet. Do o anh cua cac muc tieu dichuyen tng ng ngoai thc te. Can c s di chuyen anh cac muc tieu tren man hnh ta cohng i va van toc thc te cua no.

Mot so chu y khi s dung che o nay:- Radar ch bao chuyen ong that oi hoi phai co 1 lp d huy tot hn radar thng

va nen hoat ong thang tam gan (< 24 nm).

- Radar ch bao chuyen ong that bao gi cung co che o ch bao tng oi. V the

khi hoat ong che o nao chuyen cong tac ve ni tng ng.

-

Trc khi a ve che o ch bao chuyen ong that, phai a tn hieu toc o vahng i vao radar. Tn hieu hng i phai noi trc tiep t la ban, tn hieu toc oco the nhap bang tay.

- Thng ta at v tr tau cach bien 1/3 ban knh va cho dau mui tau i qua tam

man anh e tang kha nang quan sat pha trc va thi gian at lai v tr tau selau hn. Khi ti ben kia cach 1/3 ban knh th phai at lai v tr tau, neu khong atlai, radar se t ong chuyen ve che o chuyen ong tng oi (v tr tau ta tamman hnh)

- Viec o khoang cach cung s dung cac vong c li bnh thng v tam cac vong cli o la tau ta. Do o chung co the ch la 1 cung tron. Viec o hng khong thedung thc c kh ma phai dung tia ien t, ta ch can xoay tia ien t qua muctieu, c cau ch bao cho ta biet hng muc tieu.

- loai rada nay co nut ZERO SPEED. Khi dung nut nay, ta dng man anh radar.S dung khi o ac ti muc tieu, hay can quan sat ky hien trang quang canh manhnh luc o.


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CAC AC TNH TIEU CHUANCAC AC TNH TIEU CHUANCAC AC TNH TIEU CHUANCAC AC TNH TIEU CHUANTHEO YEU CAU CUA IMO VE RADARTHEO YEU CAU CUA IMO VE RADARTHEO YEU CAU CUA IMO VE RADARTHEO YEU CAU CUA IMO VE RADAR

( Ap dung cho nhng radar lap at sau 01/01/1999)

Radar phai am bao yeu cau khai thac trong ieu kien bnh thng, cung cap anh v trcac phng tien noi, chng ngai nguy hiem, phao tieu, ng b cung nh cac dau hieuhang hai khac e nh v, dan tau va tranh va.

1111---- Tam hoat ong :Tam hoat ong :Tam hoat ong :Tam hoat ong :Trong ieu kien bnh thng, neu anten radar at o cao 15 m so vi mat bien th

phai bat c anh ro rang cac muc tieu sau:(a)Mep b :

- Hb: = 60 m t khoang cach 20 Nm-

Hb: = 6 m t khoang cach 7 Nm(b)

Cac muc tieu noi:-

Tau co trong tai 5000 GRT t khoang cach 7 Nm.- Tau co chieu dai 10 m t khoang cach 3 Nm.

- Muc tieu nho, nh la cac phao tieu hang hai co be mat hieu dung 10 m2t khoangcach 2 Nm.

2222---- Tam cc tieu:Tam cc tieu:Tam cc ti

ly thuyet radar

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