Ngliien ciiu - Trao doi
^Danh gia l(ha nang
do tim phat hien cong,trinh ngam cua may radar xuyen dat Ramac X3IVI
O PGS.TS. T R A N VI^'T TUAN Trffdng Dai hpc Md - Dja chit
ThS. PHAM TRAN KI^N
Trffdng Dai hpc Til nguyen vi Mdi trffdng Hi Noi
B
ai bio niy sS trinh biy tdm tat vi nguySn /y hoat dpng, kha ning phit hien edng trinh ngam eua thiet bj Radar xuySn di't RAMAC/X3M. Day la loai thiit bi nhip khiu phue vu cho cic dff in thinh lap ban dd cdng trinh ngim khu vuc do thi. Do die diim dia ehat vi diiu kien tu nhien cua Viet Nam, viec khao sit, danh gii kha nang do tim eua thiit bj trong dliu kiSn ffng dung d ntfdc ta la rit ein thiit Ndi dung cua bii bao se neu mpt sd kit qua nghien cffu ban dau vi tinh ning tic dung cua thiit bj RAMAC/X3M, kha ning phat hiSn cdng trinh ngim, cic thdng sd sff dung may trong diiu kien Viet Nam vi dp ehinh xic do tim edng trinh ngim dat duge khi sff dung thiit bj niy di thanh tip ban dd cong trinh ngam khu vtfC dd thj.Mddau
Hien nay, viec xay dimg cac cdng frinh co sd ha tdng d cdc khu virc dd lhj dang phdt trien rdt manh: Cde cau vo0 tai cdc nut giao, ham eho ngodi di bd, cdng trinh cap thoat node... nen nhu cau thdnh ldp ban do cdng trinh ngam d cde khu vyc do thj la rat cap thiet Trong khi dd, hd so lai lieu vd cdng trinh ngam d node ta tQ tnidc den nay ehim dope quan ly mdt cdch ddng bd (chQ yeu la quan ly theo nganh: Cap node, dien thoai...) vd cdn rat nhieu dang cdng frinh ngam dope xdy dyng IQ cac giai doan Irodc, cac tdi lieu luu Irii phan Idn da that thodt. Trdn thtic te, d node la ehoa
Ailgtai lOOMBz
Hinh 1 : Miy dd cdng trinh ngam Ramac X3M cd ban do cdng ttinh ngam dd lhj.
Ddy cung chfnh Id khd khdn rdi ldn eho cdc don vj thiet ke va thi edng eac cdng trinh quan Irpng trong khu vyc do thj. Td't cae edc yeu td da neu tren ddt ra mdi ydu cau mang tfnh cap bdeh, dd la phai Ihdnh lap ban dd cdng trinh ngam d khu vye dd lhj.
Didm khde biet quan Irpng khi do ve Ihdnh lap ban do edng Irinh ngam va do ve thdnh lap ban do dia hinh Id d eho: Cdc dd'i topng do ve ddu nim chim d dodi mat dal, d nhQng dp sau khae nhau.
Cac edng trinh ngam lai dope xdy dyng rat da dang bing nhieu loai vdt lieu nho gach, b§ tdng, dng 2 0 Tdi nguySn vd Mdi trudng | Ky 2-Thing 8/2015
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VAI pnAfi ).a pnin^
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•fM,Hinh 2: Nguyen ly hoat dpng c(5a may /?AMAC X3M thep, dng nhya PVC... Do do, van
de quydt djnh trong edng tdc thdnh lap ban dd edng trinh ngam Id thiet bj dd tim va phat hien cdng trinh ngam. TQ tnidc den nay chQng ta chim ed loai thiet bj dd tim cdng trinh ngam hidn dai. Tai bd mdn Trac dja cdng trinh (Trodng Oai hpc Md -Oja chat) chi cd loai may dd edng frinh ngam theo nguydn tic cam Qng dien tQ IT-4 (Lien Xd cu san xuat). Loai thiel bj nay ehi dd tim dope eac edng trinh ngdm bang kim loai (cd tfnh dan didn), vd ede cdng trinh ngam dang dan dien d dp sau 3 m so vdi mdi ddt. Od ddp Qng ydu clu Ihanh ldp ban dd cdng trinh ngam TP. Ha Ndi, mdt thidt bj radar xuydn dat FV\MAC X3M da dope nhdp. Day Id loai thidt bi do hang MALA Geoseieence (Thuy Didn) san xuat Trong thdi gian qua, ehQng ldi dd liep nhan thiel bl va triln khai edng tac thQ nghiem dd tim edng ngam bang thiel bj F?AMAC X3M tai khu vye Ha Ndi.
CO sd ly thuyet vd phirong phdp nghiSn cQu
ciu tao vi nguyen /y hoat dpng cua thiet bj RAMAC X3M
Ciu tao miy
Cdu lao cQa thiet bt RAMAC X3M nho (Hinhl),
Bao gdm cac bd phan sau ddy:
- Ang len thu phdt sdng
- Bd dieu khien tmng ldm - May tt'nh.
Nguyen ly hoat dpng cOa thiit bi
Nguyen ly hoat ddng cQa thidt bi RAMAC X3M nhO sau:
Sdng didn tQ d dai lan sd eao IQ 1-1000 MHz dope phat vdo trong long dat dodi dang xung.
Khi gdp cac mdt ranh gidi hay eac dj vdt trong mdi trodng, chung bi phan xa trd Iai mat da't Tai day, anten thu cQa he thdng se ghi lai xung phan xa va lou glQ vao may tinh. Thdng qua eac phep xQ ly, phan lfch, minh giai ta ed the giai doan dope ngudn gay ra dj thodng. Cac phan xa dang dilm dope ghi nhdn dodi dang hypeebol la do so phdn tan hinh eau Clia tfn hieu tao ra. Trong khi dd, eae phan xa phing vln glQ nguyen hinh dang ciia nd (Hinh 2). Tan sd cang eao, dp phan giai cdng cao va dp xuyen sau cang giam.
Phuang phap nghien effu De ddnh gia kha ndng Qng dung cQa thidt bj F^MAC X3M, can phai khao sat mdt sd tfnh ndng sau day cOa mdy:
Kha ndng phat hien cac loai cdng Irinh ngam (dope xay dt^g bang edc loai vat lieu khac nhau).
Dp chi'nh xac dd tim, phat hien edng trinh ngam (dp cht'nh xdc vj frf mdt bang va dp sdu cQa cdng trinh ngam dd dope).
Oja ban thyc hien edng tae khao sat dope chpn la khu voc 23 pho ed quanh hd Hoan Kiem.
Tai khu vye nay chung toi da tie'n hanh edng viec theo trinh to sau day:
Khao sat thffc dia:
Dya vao cae diem Id cQa cdng trinh ngam (edc hd ga:
Thoat node, cap node, dien thoai...) tien hanh xae dinh dp sau thoe te, vj frf ehfnh xac, vat lieu xdy dong, hodng di ciia cac tuydn cong frinh ngam.
SQ dung may loan dae didn tQ lien hanh do nd'i cae diem Id eCia edng trinh ngam (nham xac dinh vj tri mdt bang, eao dp mat dat, eao dp eCia edng trinh ngam) va coi day la sd lieu thoe cQa edc dilm edng frinh ngam.
Dd cdng trinh ngam bang thiit bi RAMAC X3M
SQ dung thiet bi RAMAC X3M d l dd lim cdng trinh ngam theo eae mdt cat vudng gdc vdi hodng di cQa cac tuyen cdng trinh ngam.
Khi phat hien cdng trinh ngam tien hanh danh dd'u tren mat dat vi Iri mat bing va dpe sd Tdi nguydn vg Mdi trudng | Ky 2-Thing 6/2015 2 1 -
dp sdu cOa cdng trinh Iren gian dd sdng radar.
SQ dung may loan dae dien IQ do xdc dinh loa dp va dp eao eQa cac dilm edng frinh ngam bang dd 6ddc bing thiet bj RAMAC X3M.
Phan lich kel qua dd lim tren gian dd sdng va danh gia dd chi'nh xae dd tim vd phat hien cdng trinh ngam cCia thiel bj.
Ket qua nghidn cQu Trong qua frinh khao sal lai thoe dja, ehting ldi da tien hanh dieu tra va do 430 dilm Id edng trinh ngam (bao gdm cac dang cdng trinh: Cap node, thodt node, dien thoai, tfn hieu giao thdng) va lien hdnh dung Ihiel bi RAMAC X3M dd lim tren 170 mdt cat vudng gdc vdi hodng di ciia luyen cdng trinh ngam. Kel qua do IhQ nghiem cho thay:
Sau khi da l i ^ ehpn dope eac thdng sd cai ddt tren mdy phu hpp vdi dde dilm dja ehat, dja hinh ctia IQng khu vyc thie't bj F?AMAC X3M eho phep phat hien dope tat ca cae loai cdng trinh ngam hien cd d trong khu vyc can
do ve (bao gdm eac loai chat lieu xdy dyng va kich thodc khdc nhau (Hinh 3).
Dp sau va kieh thude cOa edng trinh ngdm phat hien dope phu thupc vdo loai anten sQ dyng khi dd tim edng Irinh ngam:
Loai anten tan sd 800 MHz eho phep phat hien dope ede loai cdng trinh nglm cd kfch thodc nhd (2 cm) va nam d dd sdu khoang 0.5 m so vdi mdt da't.
Loai anten lan sd 500 MHz eho phep phai hidn tat ea ede loai edng frinh ngam ed kfch thOdc (0.06m - 0.6 m) vd nam d dp sau khoang 1.0 - 3.5 m so vdi mdt dat Day cung chfnh la ^ a tang cd ChQa nhieu loai edng Irinh ngam nhat
Loai anten ldn sd 100 MHz cho phep phat hien tat ca ede loai cdng frinh ngam cd kich thodc (0.06 m 1.5 m)va nim d dp sdu khoang 1.0 -15 m so vdi mdt dat
Nho vdy, di ed Ihd phdt hien day dQ cde loai edng trinh ngdm tren ciing khu vyc can phai sQ dung nhieu loai anten de dd tim
OislEmce [m]
nhieu lan d nhong dp sdu khac nhau.
Dp chfnh xae dd lim vd phat hidn cdng frinh nglm cDa ttiilt bj RAMAC X3M Iheo danh gia ban dau ed t h i dat nho sau:
Sal sd frung phoong xae djnh vj frf mdi bing edng trinh ngam:
mp = 7 - 1 0 (cm).
Sai sd trung phOdng xac djnh dd sdu cdng trinh ngam: m^^ = 9 - 12(em).
Kha ndng phat hien va do chfnh xde dd lim edng trinh ngam ctia thiel bj RAMAC X3M edn phu Ihudc vao dilu kien ^a chat oia khu vyc do ve. Cae khu voc ngap node (ddc biel la node mdn ) dal set, dja chat khdng ddng nhdl e6 anh hodng rdt Idn den ket qua do tim cQa thidt bj.
Ke't ludn
TQ nhQng kel qua do dae thQ nghiem ngodi hien trodng cho thay thidi bi radar xuyen dat RAMAC X3M hoan loan cd the ddp l>ng ede yeu cau ddt ra cho cdng tae dd lim phat hien eong trinh ngdm khi lien hanh lap ban dd edng trinh ngam khu vyc dd lhj.
Tai liSu tham khao [1] Tii lieu hifi^ng dan s&
dung thiit bj RAMAC X3M (ban tieng Anh). 2004
[2] Nguyen Vdn Giang. Sao cio kit qui nghien cffu nguyen ly ciu tao vi hoat ddng cda may rada xuy§n dit RAMAC X3M.2003
[3] Phan Vdn Hien. Xiy ddng phffdng in diSu tra do ve ban d6 cdng ttinh ngim dan dung thinh phd Hi Ndi. Od tdi nghien cQu cap Thdnh phd. 1996.B 2 2 Tdi nguydn yg Mdi trudng | K^2- Thing 6/2015
