HC VIN HNG KHNG VIT NAMKHOA IN T VIN THNG

THIT B DN NG MT T TI: THIT B DN NG NDB

GING VIN: Nguyn Thanh DngSinh Vin: L Vn TuynLp DV1-K4

Mc LcI. GII THIU4II.TNH NNG K THUT41. Di tn lm vic 42. Cng sut pht 43. iu ch 44. Tn hiu nhn dng 55. H thng kim tra v iu khin56. H thng cp ngun 57. Anten 58. Tm hot ng 59. i hiu 6III.NGUYN TC HOT NG61. Anten 62. Nguyn tc hot ng63. Cng dng ca i NDB64. c im ca NDB 7IV.THIT B NDB SA 100071.Gii thiu71.1. M t tng qut71.2. c tnh71.3. c tnh ca b ghp anten PC-1 Kilo91.4. M t tng qut v b chuyn i t ng SA92.Nguyn l hot ng102.1. M t chc nng cc khi trong SA1000102.2. M t nhim v ca h thng chuyn i t ng SA113.Phn tch mch chi tit my pht SA 1000123.1. Mch tng hp tn s KWOSYN123.2. Tng li RF123.3. m tn i hiu133.4. Mch thoi 133.5. Tng li iu ch143.6. Mch to i hiu ( Kecyer)143.6.1. M ha i hiu143.6.2. Card ghi dch143.7. Tng iu ch ( DMOD)153.8. Khuch i cng sut switching ( SPA)163.9. B lc163.10. Mch kim tra163.11. Mch tch b cc khi cng sut( MDC)183.12. Ngun in184.Phn tch mch chi tit mch chuyn i t ng194.1. Mch iu khin chuyn i t ng194.2. Mch logic t ng chuyn i194.3. Mch t ng ngt b DC (DCAD)20V.Anten211.Anten ch T i xng212.Anten tr21

I DN NG V TUYN SNG DI V HNG NDB(Non Directional Radio Beacon)I.GII THIU NDB l mt my pht thanh trn tn s thp,trung bnh v ra mi hng,km theo i hiu nhm gip my bay c th bay hng v cc i NDB c t trong cc khng l trong nc v quc t. NDB l thit b dn ng ph tr bng radio m trm pht mt t pht ra mi hng trn my bay s ch th cho phi cng bit hng bay ti i.Khi ngi li trn my bay nhn tn hiu i NDB bng cch nghe tn hiu nhn dng ca i pht 2 ln trong 1 chu k trn tn s 1020kHz.Theo kim ch th ca b nh hng phi cng c th li theo hng ch ca kim ti i NDB.Khi my bay vt qua i NDB th kim ch th ca b nh hng quay ngc 1800 bo hiu cho ngi li bit my bay qua i. i NDB c th dng lm nhim v dn ng di,dn ng tip cn ti sn bay v dng lm i ch hng cho thit b ILS.II.TNH NNG K THUT.1.Di tn lm vic. Di tn lm vic ca cc i NDB nm trong khong ( 190- 1750) KHz ( Annex 10). Vi sai s cho php so vi tn s lm vic.Trong trng hp i NDB c cng sut pht ln hn 200W v tn s lm vic ln hn 1606,5 KHz th Vi cc i Locator lm nhim v kt hp b tr cho h thng ILS th tn s lm vic gia hai i phi cch nhau 1 khong v c qui nh: 2.Cng sut pht Cng sut pht ca i NDB phi c m bo ph sng ng vi mt c ly nht nh ty thuc vo nhim v ca i. Trong ch landing: t 15-20 nautical mile. Trong ch enroute: t 25- 150 nautical mile. Cng sut pht ca mt i NDB khng c vt qu 2dB so vi mc cn thit m bo tm ph sng ca c ly cho php. Vit Nam cc i NDB pht tn s 220- 550 KHz3.iu ch. Phn iu ch ca i NDB trong qu trnh iu chnh cn ch n 2 tham s:a.Tn s m thanh iu ch Tiu chun Tiu chun su iu ch 4.Tn hiu nhn dng S dng m Morse quc t. Tc 7 t/1 pht Ni dung: ti a l 3 t (ch hoc s) Thi gian c php mt tn hiu nhn dng khng qu 1 pht.5.H thng kim tra v iu khin Tiu chun ti thiu ca h thng kim tra v iu khin ca mt i NDB gm: Cng sut: khi cng sut gim -3dB phi t chuyn my ( hoc tt my). Mt tn hiu nhn dng: Phi t chuyn my( hoc tt my). H thng Monitor c s c: Phi t chuyn my (hoc tt my).6.H thng cp ngun H thng cp ngun y cho 1 i NDB gm 3 dng th t u tin sau: in mng cng nghip AC in my n AC c quy DC Khi mt ngun thi gian chuyn i t ngun ny sang ngun khc ty thuc vo chc nng ca thit b ( thng thng t 8s 20s) H thng chuyn i l tng l h thng chuyn i t ng7.Anten Thng thng cc i NDB s dng anten nh sau: Anten ch T Anten ch I Anten c h s phm cht cao- Polestar. Anten c nh gi qua mt tham s gi l h s bc x ca anten. H s c nh ngha: H s bc x ca anten ph thuc vo cng sut u vo ca anten( cng sut ca my pht).Cng sut u vo cng ln i hi h s bc x ca anten cng ln tc phm cht ca anten cng cao.8.Tm hot ng Tm hot ng ti a ca NDB l 1000Km ph thuc vo 4 yu t: Ph thuc vo truyn sng vo ban ngy hay ban m Truyn sng trn mt t hoc mt nc Cng sut my pht: nh nht 20W ln nht l 5KW V tuyn t i.9.i hiu: c pht theo m lut Morse i hiu chia lm 2 loi: i quc ni gm 2 ch ci. i quc t: i hiu gm 3 ch ci Ch u tin X biu th i quc t Ch th hai V tn nc t i Ch th ba D ni t i. Tn s pht i hiu :

III.NGUYN TC HOT NG1.AnteanMy pht c : Cng sut nh hn 1KW th dng anten hnh ch T. Cng sut ln hn hoc bng 1KW th dng anten tr2.Nguyn tc hot ng: Dng in cao tn t my pht truyn ti anten bc x ra ngoi khng gian theo mi hng. Trang thit b t trn my bay: My thu ADF ( Automatic Direction Finder): dng tn s thp v trung bnh c 3 di tn s: Bng 1 t 190-400KHz. Bng 2 t 400-800KHz. Bng 3 t 800-1750KHz. i km vi ADF c 2 loi anten: Anten v hng c 1 si dy di. Anten nh hng: Anten khung c th l hnh trn,vung hoc ch nht.3.Cng dng ca NDB C 4 cng dng: Dng bay quy hng bay ti i NDB: Sau khi ct cnh ti sn bay A ngi li m my ADF tn s ca i dng Head phone nghe i hiu nhn ng h RMI hoc radio compass (dng anten v hng) t cng tc anten v hng bt sang cng tc anten nh hng,chuyn qua khung.Xoay kim ln RMI hoc radio compass sau khng nghe c i hiu.Phng ca my bay ang bay so vi phng ca sng anten mt gc 600: khi bay qua nh i kim ng h i 1800 khi kim ng h ch v s 0 Xc nh v tr ang bay: dng 2 i NDB.Gi hng bay c,m ADF trn tn s i NDB2,nghe i hiu.Xoay anten thu cho ti khi khng nghe c i hiu ca i s 2. Dng vng ch: chiu lch ca kim ng h c thay i hay khng. lch: c thay i,chiu lch kim v v tr ca my bay lun lun lch nhau. Dng p xung sn bay: anten ca i NDB phi nm trn trc ng bng khi h xung sn bay tm nhn r phi 1km th mi c h cnh.4.Cc c im ca i NDB u im: Cc thao tc rt quen thuc vi cc phi cng H thng mt t n gin Gi thnh r Nhc im: Chu nh hng rt mnh ca a vt,a hnh v cc nhiu tp ca thi tit,ca my thu ADF thu c ch th sai lm kim ch th lch qu xa gy nguy him cho my bay St nh hoc nhiu x sng in t vo ban m gy ra li i NDBIV.SA 10001.Gii thiu:1.1. M t tng qut: L 1 my pht AM, c cng sut sng mang iu chnh c t 200W n 1000W. My pht dng cng ngh Switching cc tng cng sut v cc khi iu ch, n p, lm cho h thng t c hiu sut cao trong 1 kch thc nh gn. Phn kch thch RF gm 1 mch tng hp tn s t 190KHz n 535KHz, iu khin bng thch anh , mt mch dao ng ra 2 tn s m tn 1020Hz hoc 400Hz dng cho i hiu, 1 b to m i hiu theo m Morse c th ci t c bng cc cng tc, 1 mch kim tra v 1 mch x l thoi (ty chn). Phn cng sut ca my pht gm 4 h thng 250W c lp nhau. Mi h thng c 1 b lc ng ra , 1 tng khuch i cng sut switching, b iu ch n p switching. Ng ra RF ca mi h thng c kt ni li v cung cp tn hiu 1000W n b ghp anten. i NDB gm 2 my pht SA 1000 v 1 b chuyn i t ng c t trong 1 t my duy nht.1.2.c tnh: Cht lng: Tha mn cc i hi p dng ca ICAO v FCC. Tn s: 190535KHz, tng hp tn s iu khin bng thch anh, la chn tn s bng cch thay i cng tc vi cc bc cch l 500Hz. n nh tt hn 0,005 (nhit t -40oC +70oC). Cng sut ra: Cng sut sng mang trn ti 50 chnh c lin tc t 200W n 1000W. iu ch : Mch iu ch/ n p cung cp mc iu ch t 0 95. m tn 400Hz hoc 1020Hz trong my c la chn bng cch t jumper. B to a hiu: trong my hot ng bnh thng tc 8 baud (khong 7 vng/pht), c th chnh c t 5 n 16 baud. Ngun in vo: 115/230VAC 10%, 50/60 Hz 1 pha v 144 VDC. Cng sut tiu th danh nh l 1800W vi 1000W cng sut sng mang pht ra v iu ch mc 95. Ngun in bnh: Khi s dng in bnh vo lc mt in, cn phi c 2 loi in th 144VDC v 24VDC. Cng sut i hi cho 144V l 8A v 2,5A cho 24V. Cng sut gim khong 15 hoc nh hn. o c: Cc ng h trn mt my s o cng sut ra, cng sut sng di, in th cp cho tng cng sut, dng in cng sut, phn trm bin iu, mc m tn ng vo (khi dung thoi). i hiu: B keyer bng bn dn cung cp 95 cng tc c cc khong tng ng. Trong m Morse, mt khong ny chnh c t 63 ms n 1666 ms. Bo v mch: Cc cu ch ring bit c dung bo v cc mch AC v DC. Mt mch sng di VSWR s dng my pht nu VSWR vt qu 1 gi tr chnh trc . iu kin hot ng: Nhit t -50oC +70 oC, m t 0100. Kim tra gim st: My pht s ngng hot ng khi b mt i hiu, iu ch xung thp hn mc chnh trc, tone i hiu b dnh, cng sut xung thp hn mc chnh trc, sng phn x tng ln hn mc chnh trc. Vi h thng c my d phng, tn hiu ngng my s khi ng my d phng lm vic . Ng vo thoi (ty chn): Cn bng, 60020, -17dBm (-28dBm +5dBm), dng DC khng c vt qu 3 mADC. M t tng qut b ghp anten PC-1Kilo: B ghp anten dung ghp cng sut ra ca my pht c tr khng 50 vi anten hoc ch T, hoc anten tr. B ghp gm c 1 bin th phi hp tr khng, 1 cun dy ln c cc u ra vi 1 vng iu chnh cng hng quay c do mch t ng iu chnh cng hng iu khin bng motor hoc quay bng tay. B ghp c lp t trong 1 hp bng nhm, c bo v cc tc ng ca thi tit v c thit k lp ngoi tri.1.3.c tnh ca b ghp anten PC-1 Kilo: Tr khng vo: 50. Tr khng ti: 2 25 in tr, 700pF 1500 pF in dung. Tn s: 190KHz 535KHz vi ti 700pF 1500 pF. Cng sut RF ng vo: 2000W trung bnh, 4000W nh. ng h o: Dng anten, cng sut sng di, 1 ng h vi cng tc 4 vtr: OFF, cng sut sng di, 0-20A, 0-10A. Cng hng: Cun dy ln vi cc u chn th, cc u chn tinh v 1 vng chnh cng hng quay c. Cc u chn th v chn tinh c la chn bng cc mi hn phi sau bng thao tc. H thng t ng iu chnh s iu chnh vng cng hng n v tr cng hng chnh xc. Tm in cm ca cun dy l 25H1mH iu kin lm vic: Nhit t -50oC +70 oC, m ln n 95%, cao ln n 4000m. B ghp anten c thit k lp t ngoi tri. Ngun in vo: 12VDC, 50mA, do my pht cung cp hoc 110/220VAC (ty chn) khi dng vi cc my pht khc. Kch thc: Di 120cm, ng knh 76cm.1.4.M t tng qut v b chuyn i t ng SA: T ng chuyn hot ng ca my pht chnh sang my pht d phng nu cng sut RF xung thp hn gi tr t trc, hoc mc iu ch xung thp hn mc nh trc, hoc tone i hiu mt, b mt, hoc cng sut sng di tng cao hn mc nh trc. T ng chuyn my trong trng hp cc tn hiu gim st ni b trong 1 my pht bo hng. Cho php my pht ph c test th trn ti gi m khng lam ngng hot ng ca my pht chnh. Ng ra RF ca my pht ph c ly ra t bng iu khin chuyn i t ng (5A1). an ton, hot ng chuyn i s b cp trong thi gian test.1.5.c tnh ca b chuyn i t ng: Nhim v iu khin: Tt m h thng, tt m my pht, la chn my pht chnh, reset li my chnh, normal/test. Cc ch bo: Trng thi h thng: PRIMARY: My pht no c chn l my chnh. SECONDARY: My pht chnh hng, my ph ang hot ng. FAIL: C 2 my hng, 1 tip im relay c cung cp sau bng I/O. iu kin lm vic: Nhit t -40oC +70 oC, m t 0100. Bo v mch: Cc cu ch AC, DC, cc ng vo logic c cch ly bi cc tr khng ni tip v cc diode kp.2.Nguyn l hot ng:2.1M t chc nng cc khi trong SA1000: B tng hp tn s: Tn hiu RF c to ra trn card KWOSYN bng 1 mch dao ng LC iu khin c bng in p, hot ng tn s gp i tn s hot ng. Tn hiu ny sau c chia to ra tn hiu 1KHz a n 1 mch vng kha pha PLL so snh vi tn hiu 1KHz chun to ra dao ng thch anh 4096MHz chia xung. in p ra ca mch kha pha s iu chnh tr s t ca diode bin dung trong mch dao ng LC. Tn hiu RF ng ra ca dao ng LC c chia 2 to ra sng vung ng ra cho b la chn tn s bng 3 cng tc loi trn xoay trn card. Tng li RF: Sng vung tn s hot ng t card tng hp tn s c m vi 1 cng o trn card chnh b kch thch trc khi a n ng vo ca tng khuch i cng sut . m tn i hiu: Card to m tn i hiu to ra 2 tn hiu m tn 400Hz v 1020Hz. Mt trong 2 tn hiu ny c la chn v a qua 1 cng do mch to i hiu kim sot , 1 cng do mch m tn kim sot v nt chnh Modulation Level Control trn mt my kim sot. B to i hiu: 1 card m ha i hiu, 1 hoc 2 card thanh ghi dch m ha ty thuc vo chiu di i hiu cc bits m ha c cha trong card thanh ghi dch m ha n cng cho php m tn qua bng xung nhp 8 MHz iu chnh c.i hiu c sp c bng cc cng tc dip trn card thanh ghi dch m ha nh sau: 1 chm (tt) tng ng vi 1 cng tc c ng, 1 gch (te) tng ng 3 cng tc lin tip c ng. Khong cch gia cc ch l 3 cng tc c m. Tt l 1 m di 125ms v te l 1 m di 375ms. Phn thoi (ty chn): Khi c yu cu s dng thoi trn NDB.., n s c x l tr6n card m tn, gm c: mch lc m tn, mch kim tra li t ng (AGC), iu khin ting n (squelch), v mch ct nh. Tng li iu ch: Cc tn hiu i hiu,mt mc DC, v thoi c cng li, m v iu chnh mc trn card chnh b kch thch trc khi a n ng vo tng iu ch. Tng iu ch: Tn hiu tng hp t tng li iu ch s c a vo 1 mch iu ch rng xung to ra 1 chui xung 120160 KHz vi cc rng xung tng ng vi in p ng vo. Nhng xung ny s iu khin 1 mch n p switching to in p iu ch cho tng cng sut. Tng iu ch GPS (ty chn): i vi h thng NDB pht ra tn hiu sa sai DGPS, ngi ta s dng card giao tip iu ch GPS thay cho card tng hp tn s KWOSYN. Khuch i cng sut: Cc b khuch i cng sut loi switching ton cu s khuch i tn hiu RF t tng li RF v cung cp tn hiu iu ch n cc khi lc. Mch lc: Cc khi lc bao gm tn s 190KHz 535KHz trong 5 bng. Cc bng c la chn bng cc jumper. Kim tra: Tn hiu ng ra ca b lc c a qua card KWRF n ng ra RF 50. Cng sut ra, cng sut sng di v iu ch c ly mu trn card ny v c dng cung cp cho ng h o trn mt my. Ngoi ra cc tn hiu ny cng c x l trn cc card kim tra cung cp tn hiu ngng my trong trng hp cng sut pht gim, mc i hiu thp, m i hiu b dnh, sng di cao. Ngun cp in: Ngun pht cho my pht c th c cung cp t 115/230 VAC hoc 24 VDC v 144 VDC hoc c hai. Ngun AC cho mi nhm RF l loi nn in cu thng thng, lc bng t. Khi h thng dng c 2 ngun cung cp AC, DC, ngun DC s cung cp khng b gin on khi b mt in AC. B np bnh (ty chn): H thng np s t ng np bnh theo 2 cch, np nhanh v np chm thy thuc vo iu kin ca bnh. Mch bo v s m bo bnh khng np hoc x qu mc an ton.2.2.M t nhim v ca h thng chuyn i t ng SA: H thng my pht i gm c 2 my pht ging nhau, hot ng c lp v 1 b chuyn i t ng. Bnh thng b chuyn i cung cp cc kt ni tn hiu v ngun in n 1 trong 2 my pht. Bt c my pht no cng c th l my pht chnh ty thuc vo cng tc chn trn mt my. My pht chnh c gi l PRIMARY. Khi xy ra hng hc trn my pht chnh do card kim tra trong my pht hin (cc hng hc ny c th l: iu ch thp, cng sut thp, sng di cao, i hiu mt hoc b dnh), n s ra lnh ngng my. B chuyn i s pht hin ra tnh trng ny v x l chuyn i bt u. Card logic t ng chuyn i u tin s ngng cp in cho relay cp in n my pht chnh. Sau 1 khong ch ngn, cc ghp ni n b ghp naten s c chuyn sang my pht ph. Sau 1 khong ch ngn na, relay tip in cho my pht ph s c cp in . Hot ng ca my pht ph s do card kim tra trong my pht ph gim st, n khi pht hin li trong my pht ph hoc n khi c 1 lnh reset tr li my pht chnh bng cch n nt reset trn b chuyn i. Trng thi ca my pht i c th hin bng 3 n LED trc mt my v 1 relay bo ng. n xanh bo my pht chnh ang hot ng, n vng bo my pht ph ang hot ng (c i my t my chnh sang my ph), n bo my pht ph hng. Relay bo ng hng my s nh khi n LED bo hng sng. Ngun cung cp in cho b chuyn i c th l AC hoc DC. Chn la in p AC hot ng bng cch thay i jumper ti card iu khin chuyn i bn trong mt trc my (5A1). Cng tc ngun h thng c t trc mt my hot ng nh cng tc cp in chnh cho h thng my pht i bng cch iu khin ngun n cc relay cp in v logic chuyn i. Cng tc Normal/Test t trn bng iu khin ca h thng chuyn i (5A1) s a in v ti gi n my pht ph. iu ny cho php my pht ph c test vi ti gi 50 gn bn ngoi t my.3.Phn tch mch chi tit my pht SA 1000:3.1.Mch tng hp tn s KWOSYN: Xem s nguyn l hnh 13-1. Transistor Q1 v mch kt hp ca n hnh thnh 1 mch dao ng 3 im in dung COLPPITS vi tn s thay i c t 2 ln 190KHz n 2 ln 535KHz. Nu dng c 2 cun dy L1 v L2 tn s c th chnh c t 2 ln 190KHz n 2 ln 320KHz. Nu ch dng cun dy L1, tn s c th chnh c t 2 ln 320KHz n 2 ln 535KHz ty thuc vo in p iu khin t chn 9 v chn 13 ca IC mch kha pha PLL U2 v vic iu chnh cc cun dy L1, L2. Tn s hot ng mong mun c chn bng 3 cng tc S2, S3, S4. Ni J1 s cng thm 0,5KHz vo tn s hot ng chn trn S2, S3, S4, lm cho b chia U4 s chia 2 ln tn s hot ng, to ra tn hiu 1 KHz ng ra chn 23. U1 chia tn hiu 4096MHz dao ng bng thch anh vi h s chia 4096 to ra tn hiu chun 1KHz ng ra chn 1. Nhng tn hiu 1KHz ny c a vo IC kha pha PLL U2 so snh v kha pha 2 tn hiu ny bng cch thay i in p ra ti chn 9 v 13 iu khin diode bin dung CR1. Tn hiu dao ng c U3 chia 2 v to ra sng vung ng ra c tn s bng vi tn s hot ng c la chn trn cc cng tc S2, S3, S4. Tn hiu ny c a ra chn s 7 ca card n tng li RF. Kim tra tn hiu ny ti im th TP1. TP2 dng kim tra in p iu khin, nm trong khon t 18V. Q3 v Q4 iu khin n LED DS1, sng khi PLL trng thi kha.3.2.Tng li RF:L 1 cng o (P/O U2) trn mch chnh khi kch thch. Sng vung RF c khuch i m, c a n tng khuch i cng sut switching (SPA) chn 1. S ca tng li RF nm chung trong s tng th my pht SA v s mch chnh khi kch thch.3.3.m tn i hiu: Xem hnh 13-2, mch ny dng to tn hiu m tn dng cho i hiu v mc DC cung cp cho mch li iu ch (DMOD) iu khin in p iu ch. U1D v mch kt hp to ra tn hiu 400Hz hoc 1020Hz ty thuc vo v tr ca jumper. U1A v mch kt hp to thnh b lc tch cc 1020Hz. U1C v mch kt hp to thnh b lc tch cc 400Hz. Tn s m tn la chn c a n cng U2A c iu khin bi tn hiu squelch trong trng hp c s dng thoi. Nu khng s dng thoi, chn 13 ca U2 s mc cao 12 V v khng ni jumper, s m cng cho tn hiu m tn i qua. Trng hp c s dng thoi ng thi vi i hu, khi c tn hiu thoi, cng s ng do tn hiu sqelch iu khin, tn hiu m tn i hiu i qua R11 thay v cng do bin b suy gim. Tn hiu m tn i hiu t cng U2A c a n cng U2B, c iu khin bng tn hiu to i hiu (Keyer).3.4.Mch thoi (ty chn): Xem hnh 13-3, ng vo mch thoi 600 cn bng c a n b suy gim S1, R47, R48, R49 cho php la chn cc tn hiu ng vo hot ng mc cao hay thp. Tn hiu sau c ghp qua bin th v b lc thng cao C1, R2, C2 v bin tr iu chnh mc R6 n tng khuch i U1A v cng squelch U3. Ng ra ca U1A cung cp tn hiu cho mch o ng h U1B v mch iu khin squelch U1C v U1D. Vi R6 v cng tc S1 c chnh mc nhy cao nht, in p logic chn 7 U1D s mc 1, hay 12V, khi mc tn hiu vo ln n trn -28dBm Mc in p chn 7 lm cng sqelch U3 ng v a tn hiu thoi n mch AGC gm U2A, Q1, Q2, v Q3. Q1 hot ng nh 1 in tr thay i vi ng vo ca U2A. in tr ny c kim sot bi mc tn hiu hi tip t chn 1 ca U2A. Khi mc tn hiu tng ln, in p trn cng Q1 gim, in tr gim, lm gim mc tn hiu thoi n ng vo chn 3 ca U2A v gi mc ra thoi n nh. Cng tc S2 s cm AGC nu mun. Ng ra thoi ca U2A c khuch i bi U2C v c a vo mch ct i xng CR7, CR8 ngn nga iu ch qu mc. R44 dng chnh mc ct. Tn hiu sau c khuch i v lc cho U2D v U2B, iu chnh c bng R20 v a ra khi mch bng chn 9. i vi cc ng dng c bit, tn hiu thoi c th a ra 1 mch lc t bit v cc mch sa dng sng trn 1 card khc ngoi ni vi mch bng cc chn 7 v 9. Tn hiu squelch chn 13 c dng kim sot vic t ng suy gim mc m tn i hiu khi c ng thi iu ch tn hiu thoi v m tn i hiu. nh th tr v iu ch i hiu mc cao c th c iu chnh bng cch thay i gi tr ca R34 nh bng sau:Thi gianGa trGhi ch

5 giy470KGa tr mc nh

8giy820K

11 giy1.2M

3.5.Tng li iu ch Tn hiu m tn i hiu t mch to m i hiu c iu chnh bng bin tr MOD mt trc my trn card ACTRL v cng vi mt in p DC v tn hiu thoi nu c,a n ng vo ca tng li iu ch Q1 v Q2 trn mch chnh khi kch thch.Ng ra ca tng li iu ch c chnh bng bin tr RF Level trn mch ACTRL v a n mch chnh RF.S ca tng li iu ch nm chung trong s tng th mch chnh khi khch thch3.6.Mch to i hiu ( Kecyer) Gm 1 card m ha i hiu v mt hoc nhiu thanh ghi dch.Mi card thanh ghi dch c lp trnh bng cc cng tc dip,mi cng tc v tr ON tng ng vi 1 ting tt c thi gian iu chnh c t 60ms n 200ms ( tiu chun l 125ms,tng ng vi tc 8 baud). Cc k t chun l :1 tt = 1 bit, 1 te = 3 bits1 khong trng gia cc k t = 3 bits1 khong trng ca nguyn i hiu = 5 bits3.6.1. M ha i hiu Xem hnh 13-5 (Gio trnh thit b dn ng mt t trang 259) U1D,U1E,R3,R4,R5 v C1 to thnh mt mch dao ng sng vung vi tn s iu chnh c trong khong 6-18Hz ,bnh thng chnh mc 8Hz, tng ng vi tc 8 baud.Tn hiu ng h ny c a n card ghi dch v n,ng vo xung nhp ca thanh ghi U2.U2 nhn tn hiu i hiu dng ni tip t card ghi dch sau khi qua cng o U1A. Trong trng hp 4 bits lin tip ca i hiu l 0 ( ht mt chu k i hiu),ng ra song song ca 2 u l 1, cng U3 s kch hot dao ng n n U4 to ra mt xung xa cho U2 v a n card ghi dch mt lnh np li. Ch : R6 v C2 c th thay i chnh thi gian ngng gia cc ln lp li i hiu.3.6.2.Card ghi dch i hiu c np vo thng qua cc cng tc U2 n U6, bt u U6 v theo chiu n U1.Cng tc s 1 ca U6 lun mc 0.Nu khng dng ht cc cng tc, 4 cng tc k tip bit cui cng phi mc 0.Khi mt lnh np/dch nhn c t card m ha( ng ra ca mch dao ng n n U4), thng tin lu tr trn cc cng tc c dch chuyn ni tip n chn 2 ca card ghi dch v chn 2 ca card m ha.Vo cui chu k i hiu, 4 bit 0 lin tip s c U2 trn card m ha pht hin v mt chu k mi c lp li. 4 bits 0 cui chu k cng vi mt bit 0 u to thnh khong trng 5 bit gia cc ln lp li i hiu. Mc 0 c np vo chn 10 ca U13 mi khi mt bit c dch qua. Nh vy trong trng hp s dng ht cc cng tc khi ht mt chu k i hiu,iu kin 4 bits cui l 0 vn c bo m. Trong trng hp i hiu qu di phi s dng 2 card ghi dch,ng ra cc card th 2 ( chn 2) c ni n chn m rng( chn 22) ca card th nht.3.7 .Tng iu ch ( DMOD) Tn hiu tng hp gm mc DC, m tn i hiu,thoi( nu c)t tng li iu ch c a vo chn 10 ca U1C trn card DMOD. Ng ra ca U1C c ni n ng vo so snh ca IC iu ch rng xung U2.Ng vo cn li chn 7 l mt tn hiu rng ca c to ra trong U2 v hot ng tn s xc nh bi R13,R14 v C7( danh nh l 150 KHz). Cc ng ra chn 11 v 14 l nhng xung vi rng tng ng vi in p vo chn 9. R14 s c tho b khi tn s hot ng l bi tn ca tn s ny.Cc xung ra t 2 ng ra s c gi ra lun phin mi ng ra hot ng tn s khong 75KHz vi chu k lm vic ti a l 50%,Mi ng ra c a n cc mch li in p cao ring bit U3 v U4,c nhim v a cc xung t cc cng vo cc ngun ca Q1 v Q2 ngc vi in p ti cc ngun.V th Q1 v Q2 c ni song song ch c th c m lun phin nhau mt khong thi gian cht ngn gia cc xung c U2 pht ra chu k lm vic nh hn 100% mt t Q1 v Q2 khng bao gi lm vic trng nhau.Cc cc mng ca Q1 v Q2 c ni n ngun ip p cao mt chiu 170V DC nu do ngun AC cung cp v 144 VDC nu do bnh in cung cp.in p ti ngun ca Q1 v Q2 l 1 chui xung 150KHz, bin 170V, chu k nhim v thay i t 0 n gn 100%. rng xung ny tng ng vi in p vo ti chn 9 ca U2. Q1,Q2,CR4,L2 v C15 hnh thnh 1 mch n p switching h p.L1 l mch lc c nhim v cn bt tn hiu tn s switching,Ng ra ngang qua C15 tng ng tuyn tnh vi in p chn 9 ca U2.Hi tip c thc hin qua R16,R17 v C10 gim bt mo m tn. Khi hot ng bnh thng,in p ra l mt chiu,khong 60V trong trng hp khng c iu ch,gp i in p nh trong trng hp iu ch 100%. Chn 11 ca U3 v U4 l ng vo shutdown c dng tt in p PA vi cng tc RF ON/OFF hoc tn hiu ra lnh shutdown nhn c t card iu khin gim st.Mc 1 chn ny s cm IC.3.8.Khuch i cng sut switching ( SPA) Xem hnh 13-8 ( trang 266) . in p ra t tng iu ch c a vo cc transistor FET Q2, Q4, Q7, Q8 khuch i switching cung cp vic iu ch bin mc cao. Ng vo RF cho tng cng sut switching n t tng li RF trn mch chnh khi kch thch, gm c mt sng vung mc TTL hot ng tn s la chn trn card tng hp tn s. Tn hiu ny c m bi U1v t vo cc cp transistor khuch i b ph Q1, Q3 v Q5, Q6. Mi cp transistor ny s lun phin dn cc na chu k ca tn hiu RF, to ra dng sng vung trn cc cun dy s cp T1, T2. Tn hiu trn T2 ngc pha 180 vi tn hiu trn T1 khi Q2 v Q8 dn, Q4 v Q7 tt v ngc li, ngn nga cc transistor ny dn cng lc. Ng ra dng sng vung c t vo T3, c phi hp vi tr khng ng vo 50 Ohm ca mch lc. in p PA v dng in PA ly mu t tng khuch i cng sut c a n mch AMTR, ty vo cng tc chn la, s c ni n ng h o trn mt my. S ca mch AMTR xem s tng qut SA.3.9.B lc Xem hnh 13-9 ( tr. 267). Tn hiu sng vung ca mi tng khuch i cng sut switching c lc trn mch lc 5 bng. B lc ny l dng b lc ci tin t b lc Butterworth 50Ohm- 7 phn t i xng. Cc bng tn s c la chn bng jumper l: 190 220 KHz, 220-280 KHz, 280-360 Khz, 360-440 KHz, 440-535 Khz. Ng ra ca b lc khi khc c kt hp vi nhau to ra cng sut 500W trn mch kt hp/lc. Xem hnh 13-10 ( tr.268). c c cng sut 1000W, 2 mch kt hp/lc s c ni vi nhau ti khi KWRF. Mi ng ra ca b lc ca khi 200W c th c ngt ra khi h thng bng mt mch trn cc card kt hp/ lc trong trng hp khi hng duy tr my pht vn hot ng ch gim cng sut.3.10.Mch kim tra Mch kim tra gm 3 b mch khc nhau. Xem hnh 13-11( tr. 267). Tn hiu RF ra t cc mch kt hp/lc c a n mch KWRF n ng ra my pht. Cng sut pht v cng sut sng di c ly mu bng T1, T2, C1,C2 v R1, tch sng v a n mch MONITOR CTRL v mch AMTR1. Mt mu in p cng c ly trn R6 o phn tram iu ch. Cc tn hiu cng sut pht v cng sut sng di trn mch AMTR1 s ch bo trn ng h qua cc in tr nh chun ( xem hnh 13-12). Tn hiu iu ch c phn ra thnh tn hiu trung bnh v tn hiu mc m tn v ch bo trn ng h phn o phn trm iu ch. Tn hiu cng sut sng di t mch KWRF c a vo chn 2 ca b so snh U5 trn mch MONITOR CTRL, so snh vi mt in p chnh c chn 3. Nu tn hiu cng sut sng di ln hn in p chnh trc ny, chn 7 ln mc cao, t mch cht U3A ln 1, a tn hiu mc cao n mt trong cc ng vo cng NOR U4A, to ra mt tn hiu tt my ng ra ca mch. Reset bng cch chp mass chn 18 ca mch MONITOR s t mc cao n chn reset ca U3B v U3C, reset ng ra U3B v U3C v 0 nu ng vo l 0. Tn hiu cng sut pht t mch KWRF c t vo R6 trn mch MONITOR R6 c chnh in p chn 3 ca U1A thp hn in p chn 2 mc tt my nu cng sut thp. Vic ny lm cho chn 1 ca U1A mc 0 v gi in p ti TP3 vo khong 0.5VDC, gy ra tt my sau mt thi gian tr hon. Cc tn hiu m tn i hiu v thoi a vo b tch sng ng b U2 phn ra v tch sng. U2 s tt hoc m gia chn 1 v 2 ng b vi tone chun t U1B ca mch m tn i hiu. Ng ra chn 2 ca U2 l mt in p DC tng ng vi mc iu ch ca i hiu. Mc DC ny c a n chn 10 ca U1 so snh vi mc chun sng mang chn 9 ca U1. Ng ra chn s 8 ca U1 nu l mc cao bo mc m tn cao hoc ngc lai. Nu my pht hot ng ng, chn 1 ca U1 s vo khong 12V, chn s 8 s thay i hoc 0,5V hoc 12V tng ng vi cc xung i hiu. TP3 s thay i hoc 12V hoc 6V. S thay i chuyn tip cc mc in p TP3 c ghp qua t C5 n Q1 lm Q1 dn, khng cho t C6 np in qua R12, R13. Nu dng RF hoc phn tram iu ch gim di mc nh trc bi R6 v R22 TP3 s c gi mc +0,5V v 6V tng ng, cho php C6 np in qua R12, R13 kch transistor UJT Q2 sau thi gian tr hon 25 giy. Nu i hiu b dnh, C5 s c np in v Q1 khng dn, gy ra cng kt qu nh trn. Xung trn R15 t mch cht U3C ln cao, pht ra mt tn hiu ngng my ng ra ca mch. Cng tc MONITOR v tr ENBL, tn hiu ngng my s c a n khi DMOD, tt in p cao cung cp cho tng cng sut. v tr DSBL, ng vo ngng my ca khi DMOD c ni t, cm chc nng lm ngng my. RF OFF tc ng bng vic a 12V vo ng ngng my ca khi DMOD, iu ny tng t nh lnh ngng my. RF ON tho b 12V ra khi ng ngng my v ni n n ng ra iu khin ngng my ca mch MONITOR. Tn hiu ngng my TP3 c x l qua U6, U7, U8 v c dng iu khin n LED mch trc my, bo tnh trng ngng my. Xem s monitor trn hnh 13-13.3.11.Mch tch b cc khi cng sut( MDC) Mch ny kim tra mc in p ngang qua cu ch ca khi iu ch (DMOD) v cu ch ca tng khuch i cng sut switching (SPA). Mi nhm RF c mch tch b ring, lien tc kim tra trng thi ca cc cu ch. Khi hot ng bnh thng, s khng c in p trn cc cu ch, cc B ca Q1 v Q2 c ni t qua cc in tr R1 v R3 tng ng. Nu cu ch b t, in p s c pht hin, transistor Q1 v Q2 dn. Cc diode zener CR5, CR10 gi in p n nh mc 24V ng cc relay trn khi kt hp/lc phn kch thch ca my pht. ng thi, n LED ch trng thi cng sut PA STATUS trn mt my sang , bo nhm RF hng. Hot ng ny tho b nhm RF hng ra khi ng ra RF cui cng ca my pht v cng sut ng ra RF suy gim vi cng sut ca nhm RF c g b. Xem s hnh 13-14.3.12.Ngun in Mt bin th ngun in lp di y ca t my, cp cc mc 115VAC(HVAC) v 18 VAC(LVAC) n cc mch nn v lc khc nhau cho cc khi khuch i RF250W. HVAC cng c cung cp cho mch ngun ca khi kch thch. in p vo 115 hoc 230 VAC cung cp cho bin th qua cc cu ch mt trc my v cc relay iu khin. Xem hnh 13-15. HVAC c ni n cu nn in CR4. Ng ra 170VDC danh nh c lc bng cc t C3 v C4 v a n ng vo HVIN trn mch iu ch DMOD. Relay K1 ni R1 n b ngun x in trn C3 v C4 khi tt in. Ng vo 144VDC c dng khi s dng bnh. LVAC c nn n cu nn in kt hp vi U1 trn mch cp in cho tng kch thch. Ng ra DC c ni n mch n p 12V. Ng vo 24VDC c dng khi s dng in bnh. LVAC c ni n cu nn in trn cc mch cp in PA. Ng ra DC c lc v n p 12V, a n cc mch in p thp trn khi iu ch DMOD v cng sut SPA. in p 24VDC t bn ngoi cng c th cung cp cho cc mch h th ny.( hnh 13-16) Ngun in bnh 24 VDC v 144VDC nu s dng s t ng cung cp in cho my pht trong trng hp mt in AC. Do ngun cao th thp hn khi dng in AC, cng sut ra RF gim khong 15% so vi khi dng in AC. Mch bo v bnh s ngt b bnh ra khi mch khi in p gim xung thp hn 20% tr s danh nh.4.Phn tch mch chi tit mch chuyn i t ng4.1 Mch iu khin chuyn i t ng Xem hnh 13-17. Mch ny hot ng nh mt b ngun v giao tip gia mch logic chuyn i t ng vi cc relay iu khin. T1 v C1 i in p 115 VAC hoc 230 VAC sang 24 VDC hoc 48 VDC ty thuc vo cu hnh ca cc jumper. in p DC cp in cho mch logic chuyn i t ng v cung cp ngun ( CTRL+V). n bo DS1, DS2 v DS3 ch bo trng thi ca h thng: DS1 ch my chnh hot ng, DS2 ch my chnh hng, my ph hot ng, DS3 ch c my chnh v my ph hng. Cc cng tc S1-S5 c cc nhim v sau: S1- M in ton my SYSTEM Power ON/OFF S2- M in my pht TRANSMITTER Power ON/OFF : cho php mch logic t ng chuyn i lm vic. S3- La chn my pht chnh l my 1 hoc my 2. S4- RESET: reset h thng v li my pht chnh S5-TEST/NORMAL: NORMAL, ch mt my pht hot ng v ng ra ca my c ni n b ghp anten. ch TEST, my pht ph c hot ng trn ti gi.4.2.Mch logic t ng chuyn i Xem hnh 13-18. Ty thuc vo khi mi m my hoc reset tr v my chnh, h thng s bt u mt chu k hot ng nh sau: tho in ra khi my pht ph, ng relay anten vo my pht chnh, cui cng l cp in vo my pht chnh. iu ny c thc hin qua logic trong mch chuyn i t ng. Chn 3 ca U2 mc 0V khi bt u, khin cho chn 1 ca U3 ln mc 1 (5V). U3 l mt vi mch c bit dng to mt khong tr c nh. Sau khong 0,6s, tn hiu logic a vo chn 1 ca U3 s xut hin trn cc chn 12, 13 ca U3. Sau khong 0,6s na, tn hiu logic xut hin trn chn 6 ca U3. Cc tn hiu logic trn cc chn 1,12,6 c a n cc cng U4C, U4B, U4D. Ti y tn hiu s o nu my pht 2 c chn l my pht chnh v khng o nu my 1 l my chnh. Cc tn hiu logic t cng U4B v U4C a n U7 set v reset cc flip-flop do cc cng U7A, U7B,U7C v U7D, to cc tn hiu ra cho cc relay iu khin cc relay cp in cho my pht 1 v 2. Ng vo cho php, chn 5 ca U7, c kch thch bi U5D v Q11. Mch ny c tc dng ngn nga vic chuyn my tc thi khi bt cng tc chn la my pht chnh. Khi c mt cng tc no thay i v tr, tn hiu ti chn 15 ca mch logic lm chn 5 ca U7 gi mc 0 trong khong thi gian c xc nh bi R40 v C6, cm tm thi cc relay cp ngun cho my pht. Ng ra ca U4D a qua cng o U6 qua Q3 kch relay anten K7. R9,C3 v R27, C5 thc hin ng b relay anten vi cc relay cp ngun khi bt cng tc chn my pht chnh. Sau khi my pht chnh nhn c in p hot ng, n s p ng vi mt tn hiu ngng my +12V ch rng hot ng ca my pht ng. Tn hiu ny hin din chn 12 hoc 13 ca mch logic chuyn i t ng, c ghp n U1A,U1B, U1C n U2 chn 5. Vi mc 1 chn 5 ca U2, mc 0 s xut hin chn 3,4 v mc 1 chn 2. H thng s c cht ti trng thi my pht chnh hot ng. Nu my pht chnh hng, tn hiu ngng my +12V s xung 0, gy ra mc 0 chn 5 U2, mc 1 chn 3,4 v mc 0 chn 2. Khi mc 0 xut hin chn 1 U3 c a n 2 mch tr hon ca U3, logic chuyn i s bt u bng vic ngt in cp cho my pht chnh, chuyn cc ghp ni anten sang my pht ph, sau cp in cho my pht ph. Vic ngt in cp cho my pht chnh ngn nga tn hiu 12V ngng my c li, cht h thng ti trng thi my ph hot ng. Cc cng ca U2 v U5 s thc hin vic ch bo tnh trng my ti cc n LED trn mt my. Relay bo hng my K1 trn mch logic chuyn i t ng cung cp kh nng bo ng bng cc cp cng tc ca relay. ch hot ng my pht chnh hoc my pht ph, relay ng. My hng hoc mt in, relay nh. Cc cng tc ca relay chu c in p 115VAC,1A vi ti thun tr. Cng tc NORM/TEST t my pht chnh ni ra anten v my pht ph ni n ti gi. Cng tc la chn my pht chnh phi c xc nh r trc khi cng tc NORM/TEST c chn v tr TEST v ti gi l do ngi s dng ni vo u ni ti gi trn b chuyn i.4.3.Mch t ng ngt b DC (DCAD) Xem hnh 13-19. Mch ny nhm mc ch bo v khi in p xung thp hn mc quy nh. DCAD hot ng bng cch ly mu in p 24 VDC do c quy cung cp chn 7 ca TB1. Khi mc in p DC xung thp hn mc quy nh chnh trc bng R4, ng ra U1D chn 14 ln cao, m Q1, tc ng cc relay K1,K2 lm ngt in cp cho my pht. Trong trng thi ny, ngun DC t c quy s phc hi mc 23-24 VDC v tip tc cung cp cho DCAD mc 30mA cho n khi c in AC hoc DCAD c reset. R4 c chnh trc nh my c tc ng mc 19 VDC. DCAD bnh thng c reset do bnh c np in li v t n mc 26,2 VDC hoc do tho b bnh ra khi my.V.Anten Tm hot ng ca mt i NDB ph thuc vo nhiu yu t v khng th ni chc chn c. cng trng c th tnh ton c nu bit dn in ca mt t. Tuy nhin cng trng cn thit li ph thuc vo iu kin nhiu mi trng, ph thuc vo v tr t i. Mt cng trng khong 70 V/m th th M hoc chu u nhng li khng cho nhng vng trong v gia 300N v 300S.1.Anten ch T i xng Thng c dng vi cc my pht t 500 n 1000W nu t xy dng, anten loi ny i hi mt din tch t vo khong 46mx122m i vi chiu cao anten 18m, v 46m x 152m vi anten 36m. Anten ch T i xng chun gm 2 ct cao 60 feet (18m) t cch nhau 300 feet (100m), thnh phn bc x ng cao 55 feet (16m) v 2 dy di 280 feet (85m) nm ngang trn nh. in dung ng vo thay i trong khong 480pF tn s 190KHz v ln n 1150pF 535KHz. Chiu cao hiu dng vo khong 49 feet (15m). in tr ng vo gm in tr bc x cng in tr tiu hao. in tr bc x thay i trong khong 0,14 190KHz n1,13 535KHz. in tr tiu hao ty thuc vo nhiu iu kin m nh sn xut khng lng c, thng thng t khong 2-5. Tm hot ng ph thuc vo cng trng, iu kin t v cng sut bc x. Cng sut bc x tng theo tn s tuy nhin mt mt truyn sng do nh hng mt t gim theo tn s. vi cng trng 70 V/m, t tt, tm hot ng dao ng trong khong 165 dm tn s 190KHz v 150 dm 535KHz vi my pht 500W v khong 220 dm tn s 190KHz2.Anten tr Anten tr c dng nhng ni khng t lm anten ch T. Mt s nhnh nm ngang trn nh anten tr c gn thm nhm 2 mc ch: gim in khng ng vo v dn n gim in p trn anten v tng cao hiu dng. Anten tr v mt in km hn anten ch T vi cng cao v b gim ti trn nh.

4