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RADAR THCP

1.1.Cng dng:

S dng nguyn tc hi p (tch cc) pht hin, nhn bit cc my bay ctrang b my tr li ph hp trong khng phn do i qun l, phc v vickim sot khng lu v dn ng cho my bay.Radar th cp c th hotng c lp hoc hot ng kt hp vi radar scp (PSR).

1.2. Cc yu cu i vi Radar gim st thcp:

a/ Vng nhn bit:L vng phi bao qut c ton bvng khng gianquanh i vi cao,tm xa v trn cao phc vng thng bo bay mi m nhim.

Xc sut khng c nhtheo qui nh ( Pnhnbit t0,9-1).

Dng vng nhn bit ca Radar thcp trong mt phng thng ng c dnghnh Cosec hn hp.c trng cc tham shn hp sau:

- C ly Rmax- cao Hmax- Gc t max- Gc t nhnht min- Phm vi nhn bit phng v.b/Khnng phn bit:

Khnng phn bit cly v ta gc m bo yu cu phn bit ring bittng my bay

- Khnng phn bit cly phthuc vo rng xung v chm tn hiu trli.

- Khnng phn bit vta gc phthuc vo rng bp sng thu caanten my hi.

c/ chnh xc o ta :

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Phi tha mn yu cu ca ICAO.

d/ Khnng chng nhiu:

Phi c khnng chng nhiu cao cc tn hiu trli c m ha.

Radar thcp phi c cc mch chp nhiu tiu cc,nhiu xung trli ngb,nhiu trli theo bp sng ph.

e/Tnh thng nht v tinh cy:

Radar thcp phi c cc tham skthut ( Cc tn sthu pht,sng mang,ccMode hi,cc code hi v trli ) tun theo qui nh thng nht ca ICAO

Cc thit bhot ng phi c tinh cy v dphng nng,thng trang b02

my : mt my lm vic,mt my dphng sn sng thay th.

Phi c hthng kim tra theo di trng thi v duy tr hot ng vi tiu chunchnh xc v tin cy cao.

HNH 1 :He thong anten cua radar s cap va radar th

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HNH 2 : He thong anten radar s cap va th

Anten quay gi tnhieu hoi eu

Tan so tn hieu trali 1090 Mhz

BIEU O RADAR:

C ly va phng v May hoiHNH 4-3

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1.3 S o khoi tong quat cua ai radar th cap:

Trn my bay

Tn hiu ng b

Giai ma Ma hoa

May thu Chuyen machanten

May

May kiemtra tuyen thu

May phat Chuyen mach May thu

Ma hoa ieu khien

anten

Giai ma

Khoi ng b

Thiet b

hien th

Phoi hp

Tn hieu phan xa t radar

Tn hieu ong bo goc t radar

Khi ket hp vi radar s

Hnh 4-4: S o khoi tong quat cua ai radar th cap

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1.4 PHNG TRNH C LY CUA RADAR TH CAP:

Neu xet he thong radar th cap hoat ong trong khong gian t do,

va trong may tra li ca he thong thu va phat eu dung chungmot anten, ta a tm ra cong thc ( 4-1 ):

2tlp

mttl r4

AGPP

( 4-1 )

Trong o : r_ Khoang cach gia ai radar va may tra li

Pp_ Cong suat phat xa cua ai radar

G_ He so nh hng ( o li ) cua anten ai radar

Atl_ Dien tch hieu dung cua anten may tra li Atl =

Neu thay dien tch hieu dung cua anten may tra li Atlbang he sonh hng cua anten may tra li Gtlvao cong thc (4-1) , ta c:

2

tl2

p

mttl)r(4

GGP

P

(4-2)

Tng t nh vay , cong suat thu c cua tn hieu tra li tai antenthu cua may hoi (cua ai radar th cap) se la:

2

tl2

ptlmtradar

)r(4

GGPP

(4-3)

Vi : Pptl_ Cong suat phat xa cua may tra li tren may bayC ly hoat ong cua radar th cap (radar co tra li) c coi nhc ly lien lac theo ng radarmay tra li va c ly lien lac theong may tra liai radar. Neu o nhay may thu cua may trali la Pmttlmin th c ly lien lac theo ng theo ng ai radarmay tra li la :

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2

mttlmin

tl2

p

1max)4(P

GGPr (4-4)

C ly lien lac theo ng may tra liai radar la :

2mtradarmin

tl2

pt l2max )4(P

GGPr (4-5)

Vi : Pmtradarmin_ o nhay may thu cua ai radar

Nh vay vi c ly r t gia ai radar mat at va may tra litren may bay neu :

r > r1maxth cac tn hieu phat xhi t ai radar se khong khi ongc may phat tra li .

r > r2max th tn hieu tra li se khong c phat hien tren nen tapcua ai radar

Do o, trong he thong radar th cap, ieu kien toi thieu e co thephat hien c muc tieu la hai ng c ly ai radarmay tra liva ng may tra liai radar phai bang nhau, tc la :

r1max= r2max= rmax (4-6)

Va luc o he thong cung se at gia tr tot nhat ve quan iemnanglng.

Can bang ve phai cua hai phng trnh (4-4) va (4-5) ta c ieukien e am bao ang thc (4-6):

PpPmtradarmin= PptlPmttlrmin (4-7)

Phng trnh (4-7) cho phep chon cong suat may phat va o nhaymay thu tra li .

Trong trng hp khong thc hien ung ang thc (4-6), c ly hoatong cua radar th cap c xac nh bi tr so nho trong hai trso c ly trong hai ng lien lac r1maxva r2max.

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Rmax = min{r1max,r2max}.

Tt nhin khi gii sng siu cao tn,cly hot ng Rmax ca Radar thcpkhng vt qu tm nhn thng.

Rmax r nhn thng.

Trong thc te c ly theo ng may tra liai radar thng ln hnmot t so vi c ly theo ng radarmay tra li, v may thu cuaai radar lam viec trong ieu kien tnh tai nen co cac tham sotot hn so vi may tra li tren cac muc tieu di ong.

Khi tnh en anh hng cua khuc xa kh quyen lam ng truyensong b be cong th ngi ta a tm ra c cong thc tnh c ly

cua radar th cap nh sau: cong thc (4-8)

mHmh4,12kmr mtAmt (4-8)

y: hA cao tm pha ng ten radar thcp.

Hmt- cao ca my bay.

V d: hA radar = 25 m,Hmaybay = 10.000 m th r mt = 433Km

1.5. CAC PHNG PHAP O CUA RADAR TH CAP

a. Phng phap o c ly:

Ta a biet trong radar th cap thi gian tre trcua tn hieu tra li thuc so vi tn hieu phat hoi la :

0

2

c

rtr

(4-9)

Trong o: c_ Toc o truyen song, thng c tnh bang toc oanh sang

0_ Thi gian gi cham trong may tra li, thng c layla mot lng co nh cho cac may tra li.

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Do o: )(t2

cr 0r (4-10)

Nh vay viec o c ly c quy ve o thi gian tre tr

* Sai so trong phep o c ly: Ngi ta tm c:

rt2

cc

c

rr (4-11)

b. Phng phap o phng v:

Thong thng phng v cua may bay c xac nh theo hngcc ai cua gian o hng anten may hoi (trung vi hng trucquang cua anten), khi o may tra li c kch hoat tin cay nhat.Phng v trong radar th cap c o theo phng phap dung ama gan quay ong bo vi truc cua anten radar. e tang o chnhxac o phng v, cac radar th cap hien ai eu dung phng

phap n xung bien o pha (se c xet trong phan radarRSM970). a ma co so bt (BIT) n=12 hoac n=14. Nh vay motvong quay 3600cua anten tng ng vi 2ngia tr.

V du: Neu n-12 th co 4096 gia tr, moi ban nhay tng ng vi

5,27'4096360

0

Neu n=14 th co 16384 gia tr, moi bac nhay tng ng 1,32

Sai so o phng v khong qua mot bac nhay nen phep o rat chnhxac.

1.6. Nguyn l hi p ca SSR

a.Nguyn l hi:

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Cac ac trng tn hieu hoi:

- Tan so song mang: 1030 MHZ0,2MHz

- Tnh chat phan cc song mang: Phan cc ng

- Dang ieu che: ieu che xung

b. c trng ca tn hiu trli:

1. Tn ssng mang : 1090 MHz 3MHz.2. Phn cc ng3. Dng iu ch: iu chxung.4. Cc m trli: Thp m theo sxung ca tn hiu trli.

Ma tra li do may tra li phat e tra li tn hieu hoi mode3/A la tn hieu bao gom hai xung khung va cac xung thong tin cat gia chung . Xung hay xung khung bat au va ket thuc luonco mat trong bat ky s sap xep nhom ma nao va khoang cachgia chung la 20,3s trong moi ma

3

5

8

17

21

25

MODE Ap

1 Quan s

2 Quan s

3/A Pho bien (ATC)

B Dan s (ATC)

C Dn s(ATC)

D

HNH 4

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Mi i Radar thcp c c ng k 1 tn slp li nht nh PRF.

Mi thp m bao gm 02 xung khung F1 v F2 l 20,3 s.Cc xung mangthng tin nm gia chng,trong khong gin cch c 13 vtr nm cchu nhau 1,45 s ( trvtr gia khng mang thng tin).Cn li 12 vtr cthc hoc khng c xung phthuc thng tin chung ca thp m trli.

Thp m trli khi gii m c xp xp 4 thp con

{A},{B},{ C},{D}.Mi thp con c xp xp l thp 3 bt nhphn:

{A1A2A4},{B1B2B4},{C1C2C4},{D1D2D4}.Nhvy mi thp nhphnthuc khong {000,111}khi chuyn sang hthp phn stng ng mt snguyn nm trong khong ( 0,7).

Nh vy t12 vtr sto c 2 = 4096 thp m.

Mt sthp m c bit:

7700Emergency7600- Communication fails

7500-My bay bkhng tc.

V d: Mode A:

HNH 5

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{A 1 A 2A4} = {1,0,0} ta c :2 +2 + 2 = 4

{B1B2B4}= {0,1,1} ta c 2 +2 + 2 =3

{C1C2C4}={1,1,0} 2 +2 + 2 =6

{D1D2D4}= {1,1,1}. 2 +2 + 2 = 7.

Do vy Mode A c s` hiu :A 4367.

1.7 Mt sgii php kthut in hnh trong hthng Radar thcp.

1.7.1 Khc phc hin tng a tro nhm cly.

Tn hiu trli tmy bay chu khi no th cn vmy thu ca radar th

cp ngay trong chu k (mc tiu 1 trn hnh v).Cn nu Tl

nhhnthi gian trca tn hiu trli ca my bay nm cly r>0,5CTl ( mctiu 2 (trn hnh v) ssinh ra hin tng a tro cly: gi trcly thcca my bay tng ng vi tr2 nhng radar xung so ra gi trtr2(gi)= tr2-Tl + K1 dB cc tn hiu tbp sng chnh c xl.

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Nu < + K1 dB cc tn hiu tbp sng phkhng c xl.K1 c iu chnh li ( t0 dB n 10 dB)

b.Nguyn l chp bp sng cnh khi pht:ISLS ( Interrogattion SideLobe Suppresion).Tiu chun : My thu ca my bay so snh bin cc xung v chtrlikhi : P1(=P3) > (P2+k dB), vi K ( t0- 9 dB).Thc txung P1 v xung P3 ( pht ti knh tng ) c bin tn hiu lnhn 9 dB.My bay nm trong bp sng chnh .My Transponder ca my bay thu ccxung P1 v P3 c mc thu ln hn P2 .Sc trli.Trng hp my bay nm trong bp sng ph: My transponder thu xung P2ln hn xung P1 v P3 v skhng trli.

1.7.3 Cc trli bt ng b:False Replies Unsynchronised in Time(FRUIT).

Trng hp ngay ti thi im bp sng chnh ca 02 trm Radar thcpnh hng trc tip vo cng mt mc tiu.Trm A hi my bay v chai trm nhn c tn hiu trli.Trm Bcng nhn c tn hiu trli gi l FRUIT.Bin php xl:Thc hin xl De-Fruit,bng cch xl kt kp cc tn hiu trlivi cc tn hiu hi.Thc hin so snh ly mu 2/3 chu kcng chtrli.Nhng tn hiu trli khng ng bsbloi.

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1.7.4 Tn hiu trli bchng ln nhau (GABLING)Hin tng ny xy ra khi 2 my bay trong cng mt thi im c:

+ C cng cly hoc gn trm Radar.+ C cng v gn phng v.

+ C cao khc nhau.Bin php De-interleaving c thc hin bng cch sdng gi tr

OBA- Off Bore Side i vi tng xung trli ring l.V xung F1 ca my bay gn nht khng chng ln vi tt ccc xung cgi trOBA thch hp ca F1 tp hp li thnh tn hiu trli thnht.V gi trxung F2cng khng chng ln tt ccc xung trli c OBA gpli to nn trli thhai.

1.7.5 Phn xa ng (Multipath)Tn hiu trli phn xa vt ( phn xkhng trc tip)Xl phn xny l skt hp mt hay nhiu bin php kthut sau:IISLS ( Improved Interogation Side Lobe Supression):Trong trng hptn hiu hi tbp sng chnh ca my hi bphn xta vt ri miti my bay.Nu my bay thu c xung P1 ln hn mc P2 th my bayspht tn hiu trli mc d khng c hi trc x.khc phc hintng hi nhm ny,my pht ca my hi cn pht thm xung P1chptheo knh anten chp trng thi im vi xung P1 ca knh chnh v cmc nhiu chnh suy gim thch hp) thp hn xung P2 chnh caknh chp.

P1 P3

Knh chnh

P1chp P2

knh ph

knh chp tia trc x

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Hi theo tia phn x

+ RSLS,nu phn xtrn cng cao my bay.+TVBC (STC)- Time Variable Based Clipping+ Kt hp m,c ngha l 02 trli khng thc cng mt Identification.+ Thit kAnten.

1.7.6 NGUYN L XC NH PHNG V THEO PHNG PHP N XUNG

BIN - PHA

Phng php ny da trn c sng dng stng quan bin cng nhpha ca in p thu t 02 anten c gin hng ging nhau v tm pha cachng t cch nhau mt khong d.Phng php ny cn gi l phng php nxung tnghiu (hnh v)

Tn hiu thu t2 anten hng lch mt gc so vi trc quang.

=

=

dsin ; trong l bc sng thu.

dl khong cch gia hai tm thu.

r l sai lch di ng truyn sng.

Khi thu tn hiu trli thu t02 anten:

a v t

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- Vo mch tng : i qua cng mt on ng truyn nh nhau ( di /4)ca mch vng nn cng pha.

- Vo mch hiu : i qua hai on lch nhau /2 nn ngc pha nhau

U = U 1 U 2

Thit lp ts:

= tg

= tg [

]

Khi nhth :

Hoc

(4.12)

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d

U

/4 /4 U1 U

3/4 /4 U2U Circulator U

jU

jU/2 U+jU

U/2 U

-jU/2 U-jU

Nh vy khi v d cnh th tlvi ts

Nu biu din trong mt phng phc ,vi U nm trn trc thc,U nm trntrc o th gia U 1 v U 2 v U ,Uc mi quan hsau:

Chuyn mchanten

Trn tn Dao ng ti ch Trn tn

Khuych iTrung tn

Khuych iTrung tn

Tnh

hthgc lch

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U 1=

( U+jU )

U 2=

(U-jU)

Thc tkhng thu c ring U 1 v U 2 ,m chthu c U ( theo knhhiu),v U( theo knh tng ) Chcn mt xung tn hiu trli v2 antenthu th lp tc xc nh c gc sai lch ca phng vmy bay khihng trc quang ca hanten.Chnh v vy ngi ta gi phng phptng hiu ny l phng php n xung.

Phng vca my bay chnh l phng vca trc quang ca hanten trhoc cng vi lng sai lch gc khi hng ny

my bay = trc quang .Tcng thc ( 14.12) suy ra kthut n xung o gc lch ca hng my bay

khi hng trc quang ca hngten c ththc hin theo hai phng php:

1. Phng php n xung bin : o U v U ri tnh ra tsU/ U ,xcnh theo cng thc.

2. Phng php pha : o U v U ri xc nh gc pha gia U+jU vU-jU ri tnh theo cng thc.

So snh hai phng php o ta thy phng php bin km chnh xc khi gn ti khng,tn hiu U qu b,kt qudo chu nh hng ca tpnhiu nn sai sln.Phng php n xung pha trnh c nhc im ca phng php bin.

Tm li:Radar thcp n xung cn c 03 knh :Knh tng () ,knh chp ( ),knh hiu()

Knh t

ng () l knh chnh ,thu pht nh hng:pht tn hi

u h

i vthu tn hiu trli .

Knh chp () l knh thu pht ton hng chp nh hngca bp sng phca anten my hi .

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Knh hiu () l knh chthu tn hiu trli ,kt hp vi tn hiu thutknh tng xc nh phng vca my bay theo nguyn l nxung pha.

1.8 MODE S : ( Select)

a. Cng dng:Hthng hi p Mode S cung cp thng tin chnh xc v tin cy,cn thitcho cc hthng dch vkhng lu (ATS Automatic TelecommunicationServices).to ra ng truyn dliu khng a 2 chiu gia My bay v

Thit bgim st mt t.Gia cc my bay trong mt vng tri .(24 BITS =16.777.214 a chmy bay)

u im:

Nng cao kh nng qun l khng lu: A/C :4096;Mode S :dung

lng bn tin ln, chn thc cao,son tho cp nht thng tin trn mybay.Tranh c cac sai sot trong cac thong tin ve nhan biet phienhieu (callsign) may bay, o cao bay, trang thai may bay va cactham so ng bay.

Thong thng khi khong co mode S th ngi ta dung mode Ae nhan biet phien hieu may bay, mode C e hoi va nhan tra

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li ve o cao bay. So to hp ma tra li toi a trong 2 mode nayla 4096 va thong tin tra li phai cai at trc nen co nhieuhan che.

-

Trgip cho lin lc thoiViec lien lac thoai qua kenh ien thoai votuyen thng kem chnh xac do ngon ng va giong ieu cua

nhan vien tren may bay khi am thoai co kho khan. oi viviec trao oi thong tin bang d lieu cua radar mode S (nhan viench soan thao tren may tnh ch khong noi ra bang li thoai) chophep khac phuc c nhng nhc iem tren, tang o tin caytruyen tn (do co them kenh truyen d phong ngay ca cho trnghp kenh lien lac ien thoai vo tuyen b hong).

- Tang toc o va dung lng thong tin: Thong tin c truyen theokenh truyen d lieu mode S co toc o va dung lng ln, nho:

+ Giam thi gian mat lien lac nh lien lac theo ng ienthoaivo tuyen.

+ Giam thi gian hoiap

+ Giam tai cho ieu phai vien mat at va to lai may bay.

- + Truyen tai kp thi c nhieu thong tin ve: Ke hoach bay, thitiet, trang thai va cac thong so may bay, cac ch dan cua matat e dan ng cho may.

b.CU TRC TN HIU MODE S:

Mode S c thc hin theo 02 thtc:

1.Thtc hi tt c( All- Call Procedure)

p dng khi ai radar th cap bat au lam viec theo mode S, luc otat ca cac may bay trong pham vi hoat ong cua ai eu choi e radar th cap co the nhan biet chung, ngha la tat cacac may bay khi nhan c tn hieu hoi mode S eu phat tn hieutra li e thong bao ve tng a ch rieng biet cua mnh.

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2. Thtc hi vng ( Roll- Call Procedure)

c ap dung khi radar th cap mode S a biet a ch cua tngmay bay, va bat au tien hanh hoi co s chon loc oi vi cac

may bay co a ch ghi trong ien van (Message) hoi.

Cu trc tn hiu hi Mode S chunghi tt c ( All-CallProcedure)

- Tn hiu hi knh chnh:

P1 P3 P4

0.8s 0.8s 0.8s hoc 1.6s

Mode A:8.0s/Mode C:21s 2.0s

- Tn hiu pht knh chp:P1 P2

Tn hieu hoi kenh chnh, ngoai cap xung P1, P3 ra con co them xung

P4 cham 2s sau xung P3.

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Tn hieu phat kenh che ap gom xung P2 (khi thc hien che apcanh song phu khi hoi ISLS) va xung P1che ap (khi thc hien cheap canh song phu khi thu RSLS). Xung P1che ap phat cung thi

iem vi xung P1 cua kenh chnh, xung P2 phat cham 2s so vi

xung P1 cua kenh chnh

Trong phng thc hoi nay can chu y vai tro cua xung P4 phat kenh chnh:

- Neu o rong cua xung P4 bang 1,6s th se kch hoat c cacmay tra li co trang b mode S va tat ca cac may tra li thongthng mode A va mode C.

- Neu o rong cua xung P4 bang 0,8s th ch co cac may tra lithong thng mode A va mode C c kch hoat. Chnh v ch canthay oi o rong xung P4 ma co the xen ke hoat ong cua mode Sva cac mode A va C.

Cu trc tn hiu hi Mode S chn lc ( Roll-Call Procedure).

Mode S - short (56 bits - 16.25 s).

Xung P5 l tn hiu ch p ng vai tr nh xung P2 ca Mode A/C

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Mode S - long (112 bits - 30.25 s).

Tn hieu kenh hoi chnh gom co xung P1, P2, P6. Gian cach thi giangia cac xung nay khac han gian cach cua cac cap xung trongcac mode hoi thong thng, do vay no khong kch hoat c cacmay tra li co mode S khc a ch.

Xung P6 cha khi d liu bao gm a ch v ni dung hi,di 56 bt hoc 112bit.Mi bit di 0.25s.Do vy rng xung P6 = 16.25s khi pht 56 bits.Khi P6 = 30.45 s khi pht 112 bits.Gi tr bit nh phn ( 0 hoc 1) s dng

phng php DPSK (Difference Phase- Shift Keying) xung v tuyn qui cgi tr ca bit bng 1 khi pha xung v tuyn thay i 180 so vi bit cachng ng trc n v bng 0 khi khng thay i pha.

Knh ch p xung P5 s dng kp ly thi im kch hot i pha cho php

my tr li gii m d liu hi.

Vic nh a chhi trong Mode S c 03 kiu:

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- (A unique aircraft address) :Mt a chduy nht cho mi my bay c trangbmy trli.

- ( The All-Call address): nh a chlin tip cho cc my bay c trliMode S.

- ( The Broadcast Address): Gi thng bo cho tt ccc my bay.Tng ng vi cch nh a chtrn,c 03 chlm vic Mode S:

1. Mode S only All-Call: Chlm vic ny hi v nhn trli chca mybay Mode S.Nu xung P4 =0.8s my trli ssdng Mode A/C,nu P4=1.6s my trli strli m code c bit v a chring bit ca mybay.

2. Mode S Broadcast: Pht phng thin thng bo cho tt cmy bay Mode Skhng yu cu trli.

3. Mode S Selective : Hi chn lc tc l chhi v nhn trli t01 my trli Mode S c a chnm trong khi dliu c gi tmy hi Mode S.

c.CU TRC TN HIU TRLI MODE S

Tn hiu trli Mode S bao gm 02 phn,phn khi u v khi dliu

- Phn khi u ( preamble) chim 8s ( mi xung c rng 0.5s)Khong cch xung th1 n xung th2 l 1sKhong cch xung th2 n xung th3 l 3.5sKhong cch xung th3 n xung th4 l 4.5 s.

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- Khi dliu (data block) trli gm 56 bt hoc 112 bits.Mi bit chia thnh1 na,mi na chim 0.5s.Bt nhn gi tr1v gi tr0 ( nh hnh v).di khi dliu c thl 56 s hoc 112 s.

Cc dliu khi c chia nh sau:5 bits u du hiu nh dng , 27 bitst gim st v iu khin v 24 bits dnh cho m ring ID ca my bay,cui cng l mt thng tin chn l.

nh dng m haCc thnh phn chc nng ca ch Mode S l ng ln nh dng (UF) v nhdng ng xung (DF).+ Gim st c bnTransponder cp 1:UF l hi c th t SSR hoc my bay khc yu cu c th, thng tin a ch v

phin hiu my bay .DF l tr li ca phin hiu my bay lin quan n vic xt hi UF0, UF 4,UF5,UF 11 . gim st thng ip c bn l bao gm a ch phin hiu my bay,bitchn l v mt t 56-bit d liu c gi l hi v tr li"ngn".Mi chdownlink S nh dng c mt mc ch cth. Cc nh dng DF0,DF4, DF5, DF11,+ Gim st transponder cp 2:C tt ccc tnh nng mc 1 v c khnng thc hin DF20, DF16,DF21.Huht cc transponders ngy nay ci t l cp 2.+ Gim st transponder cp 3 c kh nng nhn c mt UELM (Uplink extendedlength messaging) t cc cuc hi bng cch s dng mt t comm C (UF24)

B

Phnk

BB BBit

B

Khoi dlieu

56 hoac

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nh dng, nhng khng cn phi tr li trc tip. Cc tr li UELM s bao gmmt bn tm tt cc cuc hi.+ Gim st Trasponder cp 4 l tin tin nht trong kh nng ca mnh.transponder ny thm chiu di ng xung m rng tin nhn (DELM) -Downlink extended length messagingcho transponder 3 cp . Cc DELM cs dng tng t nh cc UELM tr DELM l truyn thng tin khng a.

.- Cc nh dng cung cp thng tin DF0 cho ACAS(Airborne CollisionAvoidance System). Trli vi nh dng DF0 l png cho vic pht hica ACAS hoc TCAS(Traffic collision avoidance system )- Downlink l nh dng 16 ca truyn c sdng bi ACAS hoc TCASn vgiao tip gia my bay.

- Cc nh dng DF17 c sdng cho hthng ADS-B.Nhng png cho mt t hi c nh dng DF4. DF11 v DF17 l"squittered" ca chS bthu ti mt tldanh ngha ca 1 Hz.

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( Ni dung ) Content

DF0

Short Air to Air ACAS(Airborne Collision Avoidance System) (altitude Mode C and Mode S address).

DF0 s bao gm cc cao C , cc a ch Mode S.. Ngoi ra mha tr li DF0 bao gmtrng thi thng ng (VS) bit, thngtin tr li (RI) trng. Cc bit VS s cho bit mt 1 nu phinhiu my bay c trn mt t v mt s 0 nu l ngykhng kh. Cc trng RI l mt t bn-bit c kh nng tc tht s ca phin hiu my bay vcc loi phin hiu my baytr li hi

DF4

Surveillance (roll call) .DF4 bo co cao v a ch Mode S . Ngoi ra m ha trong cc

tr li DF4 l tnh trng chuyn bay (FS) trng, ng xungyu cu (DR) trng, tin ch tin nhn (UM) v m s cao(AC) trng. Cc trng FS l mt t ba-bit phn nh tm iukin khc nhau ca ch s v tr trong khng kh, cnh bo v c

bit (SPI) tnh trng ca phin hiu my bay. Cc trng DR lmt t nm-bit s cha cc yu cu thng tin ng xung phin

http://en.wikipedia.org/wiki/Traffic_collision_avoidance_systemhttp://en.wikipedia.org/wiki/Traffic_collision_avoidance_systemhttp://en.wikipedia.org/wiki/Traffic_collision_avoidance_systemhttp://en.wikipedia.org/wiki/Traffic_collision_avoidance_system

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hiu my bay nht nh. Cc trng UM l mt t su-bit ccha transponder thng tin trng thi giao tip. Cc trng AC lmt t 13-bit c cha cc cao ca phin hiu my bay vi mha c bit i vi feethoc cc n v mt v nu phn gii

cao l 25 feet hay 100 feet.

DF5

Surveillance (roll call) IDENT Reply.Cc tr li DF5 l phin hiu mybay v c so snh vi cc

ch A m 4096 cho hiu lc. Ngoi ra m ha trong cc trli DF5 l tnh trng chuyn bay (FS) trng, ng xungyu cu (DR) , tin ch tin nhn (UM) v xc nh (ID)trng. Cc trngFS l mt t ba-bit phn nh tm iukin khc nhau ca ch s v tr trong khng gian, cnh bo vc bit (SPI) tnh trng ca phin hiu my bay. Cc trng

DR l mt t nm-bit s cha cc yu cu thng tin ngxung phin hiu my bay nht nh. Cc trng UM l mtt su-bit c cha transponder thng tin trng thi giao tip.Cc trng ID l mt t 24-bit c cha cc ch A xc nh

phin hiu my bay.

DF11

Mode S Only All-Call Reply (Acq. Squitter if II=0)Cc DF11, hoc tr li tt c cc cuc gi, s tr li vi a ch

phin hiu my bay (squitter a ch) cng nh kh nng(CA), tnh chn l / hi nh danh (PI) thc a, cc hi nhdanh (II) v gim st nh danh (SI) . Trng CA l mt tba-bit c cha cc kh nng giao tip ca Transponder ny.Cc trng PI l mt t 24-bit s bo co cc m s nhndng vi mts bitschn l. Cc II l mt t bn-bit, 0-15,cha m nhn dng ca hi . Cc trng SI l mt t su-bit,0-63, c s dng xc nh cc kiu loi gim st.

DF16

Long Air to Air ACAS & TCAS(Traffic collision avoidancesystem

)

, DF16 l 112 bit di.Cc tr li DF16 s c trong cao C ch , cng nh a

ch modeS. Kim tra DF0, tr li cao so vi cao ch C, a ch s S ch xc minh. Ngoi ra m ha trong cctr li DF16 l trng thi thng ng (VS) bit, thng tin tr li

http://en.wikipedia.org/wiki/Traffic_collision_avoidance_systemhttp://en.wikipedia.org/wiki/Traffic_collision_avoidance_systemhttp://en.wikipedia.org/wiki/Traffic_collision_avoidance_systemhttp://en.wikipedia.org/wiki/Traffic_collision_avoidance_systemhttp://en.wikipedia.org/wiki/Traffic_collision_avoidance_system

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(RI) v m trng cao (AC) trng. Cc bit VS s cho bitmt 1 nu phin hiu my bay c trn mt t v mt s 0nu l trong khng kh. Cc lnh vc RI l mt t bn-bitc kh nng tc tht s ca phin hiu my bay v cc loi

phin hiu my bay tr li hi. AC lnh vc l ch S cao l so vi ch tr li C cho hiu lc.Cng trong DF16 lcomm tin V (MV) trng. Trng ny cha thng tin c sdng trong khng-i-khng kh giao lu (phi hp tr li tinnhn).

DF17

1090 Extended Squitter.DF17 l mt squitter v khng cn xthi. Do , cc DF17 s bo co thng tin ca mnh bt kca bt k trm mt t hoc phin hiu my bay yu cu.

DF17 squitter m rng c h tr bi FAA v s lm chomt phn quan trng ca gim st ph thuc t ng - phtsng (ADS-B). DF17 squitter m rng bao gmbo co v trtrn khng , v tr b mt , tnh trng ko di squitter , Identcng nh vn tc khng kh.V tr trn khng bao gm kinh v v ca my bay, cao kh p, GNSS (GPS btngun)chiu cao v gim st trng thi

DF19 Military Extended Squitter

DF20DF21

Comm. B Altitude, IDENT Reply. DF20 cn c gi l comm yu

cu cao. Cc tr li DF20 cng cha mt trng tin nhn 56-bit chuyn cc thng s my bay (DAPS).Cc tr li DF21 cn c gi l comm ,yu cu nhn dng. Cc tr

li DF21 cng cha mt trng tin nhn 56-bit chuyn ccthng s my bay (DAPS).

DF22 Military use only

DF24 Comm. D Extended Length Message (ELM)

Hnh di l khi dliu in vn ca ADS-B

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Preamble;5 bit DF, 3bit CA, 24 bit address, 56 bits ADS-B report , 24 bit Parity information.

ADS-B report bao gm:- Loi my bay ,ID aircraft.- cao.- V c m ha ( encoded latitude)- Kinh c m ha ( encoded longitude).- Vn tc my bay.(airbone velocity).

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