LI M U
LI M U Ngy nay, th gii thng tin ngy cng pht trin mt cch a dng
vphong ph.Nhucuvthngtinlinlctrong cuc sng cngtngcvs lng v cht lng,
i hi cc dch v ca ngnh Vin Thng cng m rng.Trong nhng nm gn y thng
tin v tinh trn th gii c nhng bc tinvt bc p ng nhu cu i sng, a con
nginhanh chng tip cn vi cc tin b khoa hc k thut. S ra i ca nhiu loi
phng tin tin tin nh my bay, tu v tr i hi 1 k thut m cc h thng c
khng th p ng c l nh v trong khng gian 3 chiu, ng trc s i hi chnh ph
M ti tr 1 chng trnh nghin cu h thng nh v trong v tr. Vi mc tm hiu
cc h thng nh v ny . Do em chn ti nh v s dng module thu GPS cho bi
tp ln ca mnh.
MC LC2Chng 1:tng quan v h thng nh v ton cu GPS
21.1.Tng qut v nh v ton cu gps
21.1.1. Lch s ra i cua GPS
21.1.2. GPS l g?
31.2. Gii thiu mt s thnh phn ca GPS
31.2.1. Phn khng gian (space segment)
41.2.2. Phn iu khin (control segment)
41.2.3. Phn s dng (user segment)
51.3 Qu o ca v tinh GPS
61.4 Tn hiu GPS:
71.5 chnh xc ca h thng:
8Chng 2 :Gii thiu thit b thu module SIM548C GPS
82.1. Module SIM548C v cc thit b i km
132.2. Phn cng module SIM548C
132.2.1 Phn cng ng dng GSM ca SIM548C
142.2.1.1 Bng m t cc chn ca module
152.2.2 Bt ng GSM ca module SIM548
172.2.3 Tt ng dng GSM ca module SIM548
192.2.4 Kt ni SIM card
212.3 Phn cng ng dng GPS ca module SIM548 Giao tip vi ng dng GPS
thng qua chun giao tip ni tip RS-232.
212.3.1 Chi tit cc chn dng cho ng dng GPS
212.3.2 Bt ng dng GPS
222.3.3Chun giai tip ni tip ca ng dng GPS
222.4. Lp t thit b module pha khch hng
222.4.1 V d v lp t module dng cho theo di & gim st phng tin
vn ti ti u
242.4.2 Li ch s dng
26Chng 3: Mt s ng dng ca module GPS
263.1. Xy dng phng n ng dng GPS trong bi ton qun ly xe bu
chnh
263.1.1. Xy dng phng n qun ly xe bu chnh bng GPS
273.1.1.1. Qun ly bng phng php trc tuyn
283.1.1.2. Qun ly bng phng php khng trc tuyn
283.1.2. Thit k thit b v xy dng chng trnh qun l vn chuyn bu chnh
bng cng ngh GPS.
293.1.2.1. Module GPS
303.1.2.2. Mch vi s ly thu nhp d liu GPS
313.1.2.3. H thng qun ly cua trung tm iu khin
313.1.2.4. H thng qun ly d liu trn xe bu chnh
Kt lunTi liu tham khoChng 1:tng quan v h thng nh v ton cu
GPS
1.1.Tng qut v nh v ton cu gps
1.1.1. Lch s ra i cua GPS
T thi xa xa, con ngi s dng thin vn, la bn v bn xcnh v tr v tm ng
trong cc chuyn thm him khai ph cc min t l. Tuy nhin phi n nm 1995,
khi cc h thng v tinhnh v ton cu GPS ca M v GLONASS ca Nga chnh thc
i vo hot ng, nhu cu nh v dn ng mi c gii quyt mt cch c bn.
Ngoi mc tiu qun s nh tng thit k ban u, cc h thng v tinh nh v c
ng dng rng ri v hiu qu trong nhiu lnh vc dn s. Ngy nay, cng ngh nh
v ton cu tr thnh mt ngnh cng nghip c doanh s hng chc t USD/nm v ang
c pht trin mnh m.
H thng v tinh nh v ton cu l mt v d tiu biu cho s kt hp gia nghin
cu c bn vi nghin cu ng dng v pht trin cng ngh.
1.1.2. GPS l g?
nh nghaNASTAR Global Positioning System (GPS) l h thng nh v da
vo cc v tinh. N c nhiu u im sau: chnh xc nh v cao, t decamet n
milimet C sn cho ngi s dng bt c u trn tri t Hot ng lin tc 24h/ngy,
trong mi iu kin thi titGPS trc tin l mt h thng hng hi phc v cho mc
ch qun s. N c thit k, h tr ti chnh, khai thc v iu khin bi B quc
phng M. Tuy nhin GPS c cung cp min ph cho ngi s dng dn s mt mc gii
hn.GPS c thit k thay th cho h thng v tinh Doppler TRANSIT phc v tt
cho cng ng trc a v hng hi trn 20 nm. Vic xy dng thnh cng GPS l nh
vo nhng thnh tu khoa hc v k thut sau: tin cy cao ca h thng khng
gian Cng ngh ng h nguyn t chnh xc cao Kh nng xc nh v theo di v tinh
mt cch chnh xc Cng ngh VLSI v quang ph rng
1.2. Gii thiu mt s thnh phn ca GPS H thng nh v ton cu GPS bao gm
3b phn cu thnh, l phn khng gian (space segment), phn iu khin
(control segment), phn ngi sdng (user segment). Chng ta s ln lt tm
hiu c th v tng b phn cuthnh ca h thng v chc nng ca chng.
Hnh 1.1: Cc thnh phn cu to ca h thng GPS
1.2.1. Phn khng gian (space segment)
Trm khng gian bao gm 24 v tinh nhn to lin tc pht tn hiu qung b
khp ton cu v c v nh tri tim ca ton h thng. Cc v tinh c cp ngun hot
ng bi cc tm pin mt tri v c thit k hot ng trong vng gn 8 nm. Nu cc
tm pin mt tri b hng th v tinh s hot ng nh cc c quy d phng c gn sn
trn v tinh. Ngoi ra trn v tinh cn c mt h thng tn la nh hiu chnh qu
o bay ca v tinh. M phng v tinh GPS u tin vo nhng nm 1978 v tip tc
hon thin vic phng 24 v tinh ln qu o vo nm 1994
1.2.2. Phn iu khin (control segment) Phn iu khin l duy tr hot ng
ca ton b h thng GPS cng nhhiu chnh tn hiu thng tin ca v tinh h thng
GPS.Phn ny bao gm 8 trm mt t trong c 4 trm theo di
(MonitorStation): Diego Garcia (n Dng ), Ascension Islend (i Ty Dng
),Kwajalein (Ty Thi Bnh Dng ) v Hawaii (Thi Bnh Dng ); mt trm iu
khin trung tm (MasterControlStation) v 3 trm hiu chnh s liu(Upload
Station). Li trc a t trn 4 trm ny c xc nh bng
phngphpgiaothoangydi(VLBI).Trmtrungtmlmnhim vtnh ton li ta ca cc v
tinh theo s liu ca 4 trm theo di thu c t v tinh.Sau tnh ton cc s
liu c gi t trm trung tm ti 3 trm hiu chnh s liuv t gi tip ti cc v
tinh. Nh vy trong vng 1 gi cc v tinh u cmt s liu c hiu chnh pht cho
cc my thu1.2.3. Phn s dng (user segment)
Phn s dng bao gm cc my thu tn hiu t v tinh trn t lin, mybay v tu
thy.Cc my thu ny phn lm 2loi: my thu 1 tn s v my thu 2tn s. Mythu 1
tn s ch nhn c cc m pht i vi sng mang L1- Cc my thu 2tns nhn c c 2
sng mang L1v L2- Cc my thu 1tn s pht huy tc dng trong o ta tuyt i
vi chnh xc 10 m v ta tng i vi chnh xc t 1 n 5cm trong khong cch nh
hn 50km. Vi khong cch ln hn 50 km chnh xc s gim i ng k( chnh xc c
dm). o c trn nhng khong cch di n vi nghn km chng ta phi s dng my 2
tn s kh i nh hng ca tng ion trong kh quyn tri t. Ton b phn cng
GPShot ng trongh thng ta WGS-84 vikch thc elipsoida=6378137.0m
v=1:29825722.
Hnh 1.2: Phn thit b s dng dn ng GPRS
1.3 Qu o ca v tinh GPS H thng GPS bao gm 24 v tinh a tnh, trong
c 03 v tinh dnh cho d phng, trong tng lai M s tip tc phng thm 04 v
tinh GPS na ln qu o bo m d phng 1:3 cho ton b h thng. V tinh GPS
bay theo su qu o, mi qu o c 04 v tinh, mt phng qu o bay nghing 550
so vi mt phng xch o tri t v cc gc xun phn ca qu o lch nhau s ln
nguyn ca 600. V tinh GPS bay quanh tri t vi qu o trn, c tm trng vi
tm ca tri t vi bn knh 26.500km v quay ht mt vng quanh tri t trong
na ngy thin vn (tng ng 11,96 gi).Tt c cc v tinh GPS th h I (Block
I) bt u c phng ln qu o t nhng nm 1978 n nay khng cn hot ng na. n nm
1985 M bt u phng v tinh GPS th h II (Block II) bng phi thuyn con
thoi v tn la y Delta II. Cc thng s chnh ca v tinh th h th II nh
sau:
- Khi lng trn qu o: 930Kg.
- ng knh: 5,1m.
- Tc bay: 4km/s.
- Tn s sng mang ng xung bng L1: 1575,42MHz; bng L2:
1227,6MHz.
- Tn s sng mang ng ln 1783,74MHz.
- ng h: 02 ng h nguyn t Cesium; 02 ng h nguyn t Rubidium.
- Thi gian hot ng trn qu o: 78 nm.
V l thuyt mt my thu GPS ti bt c mt a im no trn tri t v trong mi
iu kin thi tit u c th nhn thy t nht 3 v tinh GPS v khi pht hin c v
tinh th t l hon ton c th xc nh c v tr ca mnh nh cc php o khong cch
t v tinh n my thu
Hnh 1.3: Cc qu o ca v tinh trong h thng GPS
1.4 Tn hiu GPS: Mi v tinh GPS th h II u c mang theo hai loi ng h
nguyn t a thng tin thi gian vo trong tn hiu pht. V tinh GPS s dng
tn hiu ng xung bng L v c chia thnh hai bng con l L1 v L2 vi tn s
sng mang tng ng l f1=1575,42MHz v f2=1227,6MHz. Vi tn s c s
f0=1,023MHz, ngi ta to ra cc tn s sng mang bng cc b nhn tn:
f1=1540f0; f2=1200f0.
Tn hiu L1 t mi v tinh s dng kho dch pha nh phn (BPSK - Binary
Phase Shift Keying) c iu ch bi hai m gii tp ngu nhin PRN. Thnh phn
ng pha c gi l m km hay m C/A (Coarse/Acquistion Code) c dng cho mc
ch dn s. Thnh phn trc pha (dch pha 90o) c gi l m chnh xc hay m P
(Precision Code) c s dng trong qun i M v cc nc ng minh vi M. Tn hiu
bng L2 cng l tn hiu BPSK c iu ch bng m P.
Khi bit m gi tp ngu nhin PRN, chng ta c th c lp truy nhp n nhng
tn hiu t nhiu v tinh GPS trong cng mt tn s sng mang. Tn hiu c truyn
bi mi v tinh GPS s c tch mi my thu bng cch to m PRN tng ng. Sau ghp
hoc tng quan ho m PRN ny vi tn hiu thu c t v tinh, chng ta s c c
thng tin dn ng. Tt c cc m PRN u c bit t trc, n c to hoc lu trong my
thu GPS1.5 chnh xc ca h thng: B Quc phng Hoa K s dng ro chn SA
(Selective Availability) nhm lm gim chnh xc ca nhng ngi s dng my
thu GPS phi qun s. y l ro chn c xy dng bng s kt hp ca cc phng thc
iu ch, cc cu hnh khc nhau v chia GPS thnh 3 cp dch v vi chnh xc khc
nhau: dch v nh v chnh xc (PPS - Precise Positioning Service), dch v
nh v chun khng ro chn( SPS without SA - Standard Positioning
Service without SA) v dch v nh v chun c ro chn (SPS with SA).
PPS l dch v c chnh xc cao nht. Dch v ny ch c cung cp cho qun i M
v qun i cc nc ng minh thn cn ca M. Dch v ny c kh nng truy nhp m P v
c d b tt c cc ro chn SA. Cc dch v nh v chun SPS c chnh xc thp hn v
ch truy nhp ti m C/A bng tn L1
=>Tng kt chng 1Chng 1 nu racu trc, c im k thut ca h thng GPS,
ccphng phpo GPS.Trong chngny cng nuc cck thutnh vthu bao trong mng
GSM/GPRS, cc ch tiu nh gi ca cc phng php nh v. So snh c n nh, chnh
xc, kh nng m rng ..... Kt hp cc phngphp nyli vinhau lmtng chnh
xckhi nhv cngnh gipcc nh khai thc cung cp a dng cc dch v da trn v
tr. Chng 2 : Gii thiu thit b thu module SIM548C GPS
2.1. Module SIM548C v cc thit b i km SIM548C m-un l mt m-un nh
gnhot ng 4 bng tn GSM/GPRS, ng thi sn phm ny cng c tch hp k thut
GPS cho nh v v tinh. Thit k gn gip SIM548C d tch hp GSM/GPRS &
GPS thnh gii php all-in-one. Bn s tit kim c thi gian v tin bc vi
thit b phn cng tch hp ny. c trang b vi cng ngh GPS nh v v tinh.
Thit k nh gn ca SIM548C lm cho n d dng tch hp GSM / GPRS & GPS
nh l mt gii php tt c trong mt. Bn s tit kim ng k c thi gian v chi
ph cho s hi nhp ca cc thnh phn phn cng b sung.Vi mt giao din tiu
chun cng nghip v chc nng GPS, s kt hp ca c hai cng ngh cho php ti
sn c gi tr c theo di lin tc bt k v tr no vbt c lc no vi vng ph sng.
Nhng tnh nng tng qut:- Quad-Band GSM 850/900/1800/1900MHz
- GPRS multi-slot class 10
- GPRS trm di ng loi B
- Tng thch vi GSM giai on 2 / 2 +
- Class 4 (2W GSM850/900MHz)
- Class 1 (1W @ GSM1800/1900MHz)
- Kim sot thng qua lnh AT (GSM 07,07 v 07,05 v SIMCom tng cng
lnhAT)
- B cng c ng dng SIM
- Tiu th in nng thp
- Cung cp in p khong 3,4 ... 4,5 V
- Nhit hot ng bnh thng: -30 C n +80 C- B hn ch Nhit hot ng: -40
C n -30 C v +80 C n +85 C
- Nhit bo qun: -45 C n 90 C
- Kch thc: 50 * 33 * 8.8mm
Thng s k thut cho GPS
- Thu 20 knh, L1 1575,42 MHz, C / code Mt con chip tc 1.023
MHz
- chnh xc v tr 2,5 m CEP-
M khng c SA / vn tc 0,1 m / s,M khng c SA / Thi gian 1 msng b
GPS thi gian
- Chc v vi DGPS / SBAS: 2.0 CEP
- Ngy WGS-84- Mua t l (TTFF c xc nh mc 95% ca trm a phng v tr u
tin)
- Hot bt u
