CHNG I

CHNG ITNG QUAN V IN I THNG TIN SNG CC NGN

CP CHIN THUTTrong Qun i ta, in i () thng tin sng cc ngn cp chin thut c s lng kh ln ln n hng vn chic, xut pht t hai ngun cung cp chnh, mt l ngun t cc nc XHCN trong ni bt l cc loi in i ca Lin X (c) nh P105, P108, P109, P123-M, hai l t ngun chin li phm thu c trong chin tranh ca cc nc TBCN, ch yu l ca M nh AN/PRC 10, AN/PRC 25, RT 524. Cc loi in i ny tuy c mc v kh nng hot ng khc nhau, tnh nng k chin thut cng khc nhau, nhng u c mt s c im chung ch yu. Sau y, chng ta tm hiu mt s c im chung ca chng trn phng din k thut v bo m thng tin trong chin u cp chin thut xut kh nng ci tin hin i ho cc loi in i trn.1.1. c im ca thng tin v tuyn qun s sng cc ngn cp chin thut

1.1.1. Nhim v, yu cu ca thng tin v tuyn sng cc ngn cp chin thut

Nhim v:

Do tnh cht ca chin u cp chin thut nn thng tin v tuyn (TTVT) qun s sng cc ngn (SCN) cp chin thut (CCT) c nhim v m bo thng tin trong chin u cho cc phn i nh, cc cp c s (thp nht) t cc c nhn, nhm nh, tiu i, trung i, i i n tiu on trong tc chin c lp v c trong chin u hip ng binh chng.

Yu cu:

Xut pht t nhim v trn, cc yu cu c th i vi TTVT qun s SCN CCT l:

Lm vic vi cng sut nh, c ly lin lc ngn, thng thng ti a ch t 10 30 Km. C kch thc nh gn, trng lng nh, d mang xch.

S dng n gin, thun tin, t khu iu chnh.

Kh nng lm vic tin cy, nhanh chng, chnh xc.

1.1.2. Dng cng tc v di tn lm vic

Vi u im l di tn rng, di SCN khng t ra yu cu cht ch i vi b rng ph tn hiu c dng. Bi vy ch thoi iu tn FM (vi b rng ph ) vi u im l chng nhiu tt, thc hin n gin, t gy nhiu ln nhau gia cc c chn lm dng cng tc c bn ca SCN CCT. Bn cnh , cc ny cn c trang b thm cc dng cng tc ph na nh ch bo (iu bin AM, n bin SSB, iu tn FM) cho ph hp vi trong cc trng hp tc chin khc nhau.V di tn lm vic, bng VHF - nm trong di sng SCN c gi tr nm trong phm vi 30MHz 300MHz, thng dng cho v tuyn di ng, thng tin hng hi, hng khng, pht thanh FM thng mi (88MHz n 108MHz), truyn hnh thng mi (t 54MHz n 216MHz). Tuy nhin, trong lnh vc qun s thng s dng di t 30MHz n 88MHz. Bn cnh , li dng mt s cc u im ca di sng ngn th mt s loi qun s CCT cn cng tc on sau ca di sng ngn, t 20 MHz tr ln. Trong di tn ny, tu thuc vo quan im thit k, trnh k thut v cng ngh, li c chia thnh on nh.

V d: Lin X (c) c cc P105, P108, P109. Mi ch bao trm mt on nh (t 21,5 46,1 MHz), gia cc on nh ny li c mt phn nh tn s trm nhau lin lc vi nhau khi cn thit. i vi P123-M th c di tn lm vic rng hn (t 20 51,5 MHz), tuy nhin, li phi chia thnh hai bng sng. Trong khi , M s dng AN/PRC 25 vi di tn bao ht c di (t 30 75,95 MHz) ph hp vi xu hng hin nay l ch to cc c di tn bao ht c di.1.1.3. c im truyn sng v c ly lin lcDo khng c s phn x u n t tng ion, thng tin SCN ch yu da trn sng t v sng trc tip.

Cng sut ca tn hiu ti v tr thu c tnh bng cng thc:

(1.1)Trong :

P1 l cng sut ca tn hiu pht.

D1, D2 l h s nh hng ca cc anten.

l bc sng.

r l c ly lin lc.

F l h s suy hao ph thuc vo mi trng, a hnh thc t.

Vi bc sng nh, cho php thu gn kch thc anten ca thit b, do SCN l s la chn thch hp cho lin lc di ng trong phm vi hp ca chin u cp chin thut. Tuy nhin, c ly lin lc trong di SCN b hn ch, ph thuc nhiu vo a hnh, a vt v thng thng s dng phng php thu pht sng thng trong phm vi ngn. Do vy m bo c ly lin lc cng nh m bo tnh an ton, b mt thng la chn lm vic ch cng sut nh, t mt vi n vi chc W.1.1.4. Thit b thng tin v tuyn sng cc ngn cp chin thutThit b TTVT SCN CCT hay c th l cc in i SCN CCT bao gm my thu v my pht l chnh. Tuy nhin do in i SCN cp chin thut yu cu ti thiu v kch thc, trng lng thit b v ch cn lin lc bn song cng nn thng thit k c phn thu, phn pht trong cng mt thit b v c th dng chung mt s khi my thu v my pht, v d nh: khi t hp tn s, mch vo my thu v mch ra my pht, mt s b lc* My pht gm: Micro, khuch i iu ch, b kch thch, khuch i cng sut, phi hp anten v h thng iu khin, ngun cung cp. ( Hnh 1.1)

Chc nng chnh ca my pht l:

To dao ng cao tn (RF). iu ch dao ng. Khuch i v bc x. Nhim v ca cc thnh phn nh sau: - Khuch i iu ch: L b khuch i mc tn hiu Audio a vo iu ch (thng l FM).

- Kch thch: Lm nhim v to dao ng RF thc hin iu ch tn hiu. i vi in i SCN cp chin thut c th dng b dao ng ngoi sai my thu lm b dao ng kch thch hoc lm chun cho b kch thch n gin v gn nh.- Khuch i cng sut v tin khuch i cng sut: c nhim v khuch i tn hiu cng sut yu cu, v vy KCS c th gm mt hay nhiu tng. Do iu kin c ng ca chin u cp chin thut phi dng ngun nui cho thit b thng tin l pin hoc acquy nn khi KCS phi m bo hiu sut khuch i ln gim tiu hao nng lng ti a nht.

- Phi hp anten: Lm nhim v phi hp tr khng gia khi KCS vi anten.

- H thng iu khin: Dng chung cho c my thu v my pht, n gm phn giao din vi ngi s dng v phn to ra cc tn hiu iu khin cc hot ng ca in i.

- Khi ngun: To ra cc mc in p yu cu cho ton b thit b.

* My thu gm: Anten, mch vo, khuch i cao tn, trn tn, dao ng ngoi sai, khuch i trung gian, hn bin, tch sng, khuch i m tn, tai nghe ( Hnh 1.2).

Chc nng chnh ca my thu bao gm chn lc, khuch i, bin i v tch sng (gii iu ch).- Chc nng chn lc: L kh nng tch tn hiu c ch khi tp hp nhiu v tp m ca my thu. c kh nng chn lc cao, trong my thu cn c nhng mch lc cc loi nhng tn s lm vic khc nhau v c c tnh khc nhau, t vo nhng v tr ph hp trn ton tuyn thu. V vy u ra my thu ta nhn c tn hiu c ch t b nh hng ca cc tn hiu khc.

- Chc nng khuch i: Tn hiu c ch u vo my thu nhn c rt nh, c gi tr t vi micro vn ti vi trm micro vn. cho thit b cui cng lm vic bnh thng th tn hiu c ch cn c khuch i ln, nh vy my thu phi c h s khuch i rt ln c 106 hoc cao hn na. thc hin chc nng khuch i, my thu cn c nhng b khuch i vi nhng c tnh khc nhau cao tn (KCT), trung tn (KTG), thp tn (KAT), di dng khuch i di rng hoc khuch i cng hng.

Thng thng chc nng khuch i trong my thu gn lin vi chc nng chn lc, bi v cc mch chn lc khi c khuch i km theo s cho ta tnh cht chn lc tt hn.

- Chc nng bin i tn hiu: Gm bin tn t RF v IF v bin i tm li quy lut iu ch ca tn hiu. gi l qu trnh tch sng hay gii iu ch. Qu trnh ny c thc hin trn cc b tch sng.1.2. in i sng cc ngn cp chin thut trong tc chin hin i ca Qun i ta1.2.1. Tnh trng hot ng, mt s bn lun xung quanh cht lng ca in i th h c v hng gii quyt

S lng SCN CCT th h c cn li trong bin ch ca Qun i ta ln n hng vn chic, trong phn ln gp phi cc loi hng hc khc nhau vi iu kin sa cha rt kh khn do cc linh kin s dng qu tui th v hng hc, gi ho, bn cnh l s khan him vt t, linh kin d tr do ngng sn xut ch to.

V nhim v bo m TTLL trong tc chin c t ln hng u, duy tr TTLL bng cc th h c l mt yu cu thc tin ca Qun i ta trong giai on hin ti. gii quyt c th thc hin bng cc gii php nh: Mua mi, t sn xut hay ci tin. Tuy nhin, thc t cho thy, vic mua mi cc loi thay th hon ton cc th h in i c cn gp nhiu kh khn do kh khn v kinh ph, nn kinh t nc ta cha th m bo c vic u t mi hon ton. Vic t sn xut cc loi mi t trang b c coi l hng pht trin ng n ca Qun i trong tng lai, nhng thi im hin ti, trnh khoa hc, k thut v cng ngh nc ta cha cho php. Ch c hng ci tin, hin i ho l ph hp nht trong giai on hin nay nhm tip tc duy tr thng tin lin lc (TTLL) bng cc th h in i c sn, cho php chng ta tn dng c hng vn c cn li trong bin ch, tit kim ti a cho ngn sch Quc phng v nn kinh t t nc m vn m bo c yu cu v TTLL .Mt s nh gi ca cc chuyn gia hng u trong lnh vc TTVT v cc SCN CCT th h c nh sau:- Mt s b phn c cng sut ln (nh b KCS trong PRC-25, RT 524) hay thm ch ton b in i (nh trong P123-M, P105, P108, P109) s dng cc phn t khuch i l cc n in t (n chn khng). y l cc linh kin c cht lng v tin cy khng cao, c tui th thp nn hin nay a phn b gi ho v khng cn vt t linh kin thay th do cc nh ch to ngng sn xut t lu.- Cc tng khuch i ch yu vn dng mch cng hng (di hp) sau thi gian s dng qu lu d sinh ra hin tng lch cng hng, y l nguyn nhn gim st tin cy ca , khin cc lm vic khng n nh v vic khi phc sa cha l kh phc tp.- Cc mch lc trong m ch yu l trong cc tng KTG vn s dng phng php lc phn b, mi tng khuch i c mt b lc ring, khin s lng cc b cng hng tng r rt, s cng tr nn phc tp hn v lch cng hng sau thi gian s dng di ca chm cc b lc ny dn ti cht lng ca cng gim st i hn na.- Cc b to dao ng, ch sng v ngoi sai ch yu vn l cc b dao ng LC, vic hiu chnh bng thch anh ch dng mt s tn s quan trng . Cc phng php t hp tn s (THTS) n gin, c bn s dng trn linh kin tng t, c mt s loi kt hp s dng s kt hp, dng vng so tn, so pha (nh trong AN/PRC 25), tuy nhin ch mc n gin. Cc l do ny khin kh nng THTS trong cc th h c cn nhiu hn ch, kh nng n nh tn s km, vic t v thay i tn s l kh phc tp phc tp.

Chnh t tnh hnh v cc nh gi v th h c nh trn, nn vic tin hnh ci tin, hin i ho cc SCN CCT th h c tr ln cp bch.1.2.2. Cc yu cu c bn i vi SCN CCT trong tc chin hin iTrong phn ny, s gii thiu mt s yu cu quan trng i vi th h in i hin i rt ra cc yu cu i vi vic ci tin hin i ho cc loi th h c.Cc th h SCN CCT hin i cn c cc yu cu v tnh nng k thut c bn nh sau:1.2.2.1. SCN CCT phi c cu trc linh hot, c kh nng thch nghi trong cc iu kin chin u khc nhau

Xy dng thit b in t c nhiu tnh nng, vi mt tch hp cao, trn mt cu trc m ngi s dng c th la chn cu hnh thch hp l xu hng chung ca cc thit k hin i hin nay. i vi SCN CCT nhim v chnh ca n l bo m thng tin thng sut trong thi gian xy ra tc chin. i tng quan tm nht l thit b gy nhiu ch p, trinh st in t v thng tin gi t pha i phng. Trong trng hp i phng trinh st bng cc thit b v tuyn hin i ly trm tin tc hoc pht nhiu ch p th ngi ta thng s dng cc bin php sau phng chng:

- iu chnh cng sut ph hp.

- S dng phng thc truyn tin nhanh rt ngn thi gian lin lc.

- S dng b m thoi.

- Thay i tn s lin tc (nhy tn).

- Thay i iu ch.

- Thay i phn cc.

- nh hng anten.

i vi SCN CCT khng cn thit phi s dng ht cc phng php trn m ch tp trung vo 3 phng php u.

Trong trng hp i phng gy nhiu chn (hoc nhiu ton di), cng sut nhiu s khng qu ln nhng bo m lin lc c th yu cu cng sut my pht phi ln. Mt khc, c nhng iu kin chin u yu cu cng sut ln tng c ly lin lc, nhng cng c trng hp c ly lin lc li ngn yu cu cng xut va phi chng trinh st in t ca i phng. Do yu cu v tnh nng thay i cng xut cng l mt yu cu cn thit i vi in i SCN cp chin thut. Nu modul khuch i cng sut c t trong in i th s lm cho thit b ny tng khi lng v kch thc ng k v khng cn thit trong cc iu kin chin u thng thng cp chin thut. Gii php thch hp cc in i hin i l thit k modul khuch i cng sut lp ngoi. Vi s la chn ny cng sut my pht c la chn theo mc v t l thun vi khi lng, kch thc ca in i.

Trong trng hp i phng trinh st ly cp tin tc, th thi gian truyn tin cng nh bao nhiu th tnh bo mt s cng cao by nhiu. Phng php truyn tin bng tn hiu thoi rt d b l, lc ny s dng phng php truyn tin di dng d liu s rt nhanh v hiu qu hn. Nhng dng lnh ngn gn c son tho trc tip nh mt modul lp ngoi hoc c nhp t trc trn chin u vo b nh theo quy nh ca ngi ch huy. T cng c th d dng m ho bo mt thng tin hn.

Trng hp bt buc phi dng tn hiu thoi, hin nay nc ta cng nghin cu ch to c b m thoi cho thit b v tuyn. Vi in i mang xch cp chin thut th lp modul m thoi bn ngoi khi cn thit s ph hp hn l thit k cng trong my.

Trong chin u, cc b phn ca in i mang xch thng do in i vin mang trc tip i theo ngi ch huy b phn, cn in i ca b phn s ch huy thng c t ln mt v tr cao . trnh ha lc ca ch, bo v sinh mng cho b i khi ch trinh st v tuyn pht hin v tr ca in i th in i cn c tnh nng iu khin xa bng i dy cp c th t in i mt v tr cch xa ngi ch huy.Bn cnh trong cc in i th h c, tuy c kh nng chuyn tip. nhng hu nh u hot ng ch nhn cng. Trong iu kin tc chin thng thng cng nh trong iu kin trc canh, yu cu v kh nng chuyn tip t ng cc in i l rt cn thit thit hi v con ngi khi gp ho lc ch p ca ch, cng nh m bo kh nng chuyn tip nhanh chng.1.2.2.2. in i SCN cp chin thut cn c di tn rng, c nhiu knh sng cng tc, c kh nng thay i tn s cng tc nhanh chng

Xut pht t thc tin hin nay, k ch c trang b cc phng tin trinh st, tc chin in t hin i. i phng c th gy nhiu ch p, trinh st pht hin nghe trm thng tin ca ta. Do vy, trnh c nhiu, gi b mt tin tc qun s m vn duy tr c lin lc thng sut th i hi cng tc t chc hip ng thng tin cng phi cht ch, cn phi t chc cng nhiu ng thng tin vu hi, d tr. Trng hp i phng gy nhiu ngm, nhiu trt, ngi chin s s dng in i phi lin tc thay i tn s hot ng trn mt di tn rng.

Tnh cht khn trng ca chin u CCT yu cu thao tc chuyn i tn s l n gin, thun li nht cho ngi s dng. y l yu cu khi thit k ci tin cc loi in i SCN sao cho phi ti u ho v giao din s dng, nhng phi ti a v kh nng t ng iu chnh tn s, t thit lp cc ch thch nghi, t chn bng tn cng tc1.2.2.3. SCN CCT phi c kh nng sa cha v thay th nhanh chng, d dng, lm vic vi tin cy caoYu cu ny xut pht t thc tin hin nay, s lng SCN CCT cn li trong bin ch ca Qun i ta ln n hng vn chic, trong phn ln gp phi cc loi hng hc khc nhau vi iu kin sa cha rt kh khn do cc linh kin s dng qu gi ho, bn cnh l s khan him vt t, linh kin trong giai on hin nay. Do , yu cu ln nht trong vic ci tin cc th h ny l phi m bo vic sa cha, thay th cc n v ( ni trc tip nm gi trang b ) din ra cng n gin, cng d dng cng tt. Nu m bo c yu cu ny, vic m bo thng tin lin lc s thng sut hn. tin cy ca c quyt nh ch yu bi nhy v chn lc. Do yu cu i vi tin cy trong qu trnh lm vic ca chng ng ngha vi vic m bo nhy v chn lc ca in i theo yu cu. Cc th h in i c tuy p ng c yu cu v tin cy trong giai on trc, nhng trong giai on hin nay, vi s pht trin ca khoa hc, k thut c bit l khoa hc k thut Quc phng, cc in i ny dn dn khng p ng c yu cu ngy cng cao. Nng cao tin cy ca in i SCN v vy tr thnh mt yu cu cp bch trong giai on hin nay.Bng cc bin php k thut mi, ng dng cng ngh cao, ngy nay chng ta c th ci tin c SCN p ng c cc yu cu trn.

1.2.2.4. in i c kt cu c kh vng chc, thit k n gin gn nh,c kh nng c ng cao, trin khai nhanh, c bn trc iu kin mi trng kh hu nhit i. Mi trng lm vic ca in i SCN cp chin thut ch yu l ngoi tri. Trong thc t, trn chin u c th din ra bt k iu kin thi tit no v i phng cng dng mi cch ph hu cc thit b thng tin ca ta. Do vy, mt thit b d c tnh nng k thut cao nhng khng p ng c yu cu v vng chc th cng khng th hot ng c trong chin u. Thit k n gin gn nh qu trnh s dng v mang xch c ng ca ngi chin s tr nn d dng hn, qu trnh trin khai din ra nhanh chng hn, m bo tc chin tt hn. iu ny l cn thit v trong th h in i c u c kt cu kh cng knh v phc tp. Do mi thit k ci tin cc tnh nng cho in i u phi tnh ton n yu cu ny. Tm li, xut pht t yu cu chin thut thng tin ca b i ta c th rt ra nhng yu cu tnh nng c bn i vi SCN CCT trong chin tranh hin i nh sau:

- Modul ho vi mt tch hp cao c th d dng sa cha thay th.- Nng cao nhy v chn lc cho ph hp vi yu cu bo m thng tin lin lc ngy nay.- C th thay i cng sut pht tng ng vi c ly lin lc.

- C th kt hp 2 my to thnh mt trm chuyn tip t ng.

- C tnh nng iu khin xa.

- Truyn tin nhanh di dng tin ngn khi lp thm modul truyn d liu.

- C kh nng m ha, bo mt tn hiu thoi khi lp thm modul m thoi.

- Giao din n gin, trin khai tin li nhanh chng, d dng cho thao tc ca ngi s dng.

- Kch thc, trng lng gn nh. Kt cu c kh vng chc, chng c rung, va p v nh hng ca iu kin kh hu mi trng khc nghit.

- Tiu th ngun tit kim.

Trn y l cc yu cu khng bt buc i vi mt my thu pht v tuyn SCN bnh thng nhng vi cc qun s, trong cc trn nh khc nhau, c nhng yu cu chin thut khc nhau vi tnh cht c lit ni chung, th cc yu cu ny ngy nay tr thnh nhng yu cu thit yu c th p ng c nhim v bo m lin lc thng sut. Cc yu cu ci tin, hin i ho cc SCN CCT th h c cng phi c din ra trn c s ca cc yu cu trn, c vy cc th h c c ci tin mi p ng c yu cu trong tc chin hin i. Tuy nhin, trong khun kh ca mt n tt nghip, ch xin trnh by mt s gii php ch yu ci tin hin i ho SCN CCT cc chng tip theo.1.3. Kt lun chng IT vic nghin cu cc c im v yu cu ca thng tin qun s SCN nh nu trn, ta nhn thy vai tr quan trng ca cc th h ang v s c s dng trong Qun i ta. Tuy nhin, p ng c yu cu ngy cng cao i vi th h hin i ngy nay th bi ton cn phi gii l mt nhim v kh khn v cp bch. Vic nghin cu gii quyt bi ton ny c nhiu c quan chc nng bt tay vo nghin cu thc hin, t cp Cc Khoa hc - Cng ngh - Mi trng, Tng cc K thut n cc t chc nghin cu ca Qun i khc nh Trung tm Khoa hc Qun s Quc phng, HVKTQS v c s quan tm ca nhiu nh nghin cu, cc cn b k thut n cc hc vin, sinh vin lm vic, hc tp trong lnh vc in t vin thng T xut hin nhiu ti cc cp t thp n cao nghin cu v vn .Vi ngha khoa hc v thc tin nh nu trn, n xin c a ra mt vi sut v phng php ci tin, hin i ho c th cho mt s loi SCN CCT. Chng II gii thiu v l lun xy dng phng n ci tin ph hp, chng III s trnh by cch thc ci tin thc t, vi hy vng gp phn no vo vic gii quyt bi ton hin nay, nhm m bo cho nhim v TTLL trong chin u v sn sng chin u ca Qun i ta. Kch thch

Tin K CS

K CS

Phi hp anten

Khi ngun

Khuych i iu ch

H thng iu khin

Hnh 1.1: S khi my pht v tuyn in.

Mch vo

KCT

Trn tn

KTG, Lc

HB, Tch sng

KAT

DNS

H thng iu khin

Khi ngun

Hnh 1.2: S khi my thu v tuyn

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