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Hotngca cc hthngGNSS v b thu GNSS

Sinh vin:NguynVn LongNguynTrng Ton

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Ni dung

Hotng chung camththng GNSS.

So snh cc hthng GPS, GLONASS, Galileo.

Cuto chung v hotngcab thu GNSS.

Nguyn tc xc nhv tr.

27/20/2012

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3/11

Hotng chung camththngGNSS

Hthnggm 3 phn:

Khu khng gian: lm nhimv pht nhngbn tin nhv(vv trcav tinh, thi gian) n cc my thu v cctrmiukhin.

Khu iukhin: Cpnhttrng thi cav tinh v phtthng tin iukhinv tinh.

Khu ngi dng: cc mythu xc nh, tnh ton v trngisdng.

37/20/2012

Khu khng

gian

Khu iu

khinKhu ngi

dng

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So snh cc hthng GPS ,GLONASS

,Galileo

GPS GLONASS Galileo

Khu khng

gian

24 v tinh phn b trn 6 mtphng nghing vimtphngxch o gc 55 o, cao 20200 km.

24 v tinh phn b trn 3 mtphng nghing vimtphngxch o gc 64.8, cao 19130km

30 v tinh phn b trn 3 mtphng nghing vimtphngxch o 56 o, cao 23222 k m

Khu iukhin

Gmmttrmch, 5 trmgim st, 4 anten mtt

Gmmt trung tm iukhinhthng SCC v cctrm TT&C (Telementary,Tracking and control)

Ngoi ra cn c hthng tnla khng gian phcv cngtc phng b sung v tinh

Gm 2 trung tm iukhin:Trmmtt (GCS) (5 trmTTC) v trmiukhindnnghthng (30 trm GSS)

Dchv SPS: dn s ,tns L1 =1575.42 Mhz

PPS: qun s ,tns L2 =1227.6 Mhz

Sdng cng ngh CDMA thu nhn tn hiut cc v tinhkhc nhau qua m PRN (C/A

hoc P(Y))

G1 = 1602 + 0.5625*n Mhz

G2 = 1246 + 0.4375*n Mhz

n l s knh ngvisv tinh

OS: dchvm, tns E5a=1176 Mhz v L1, chnh xc= 4m

CS: Dchvthngmi, tns E6 = 1279MHz, chnh xc

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cim tn hiuca cc hthngGNSS

7/20/2012 5

GPS sdng 3 sng mang: L1, L2, L5 Galileo sdng 3 sng mang: E1, E5, E6 Bng cc tham sca cc sng mang:

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Dng tn hiuca cc hthng GNSS

7/20/2012 6

Bng thng ca cc sng mang

Tns cc sng mang quytnhtns lm vicca LNA, anten v bng thngca cc sng mang quytnhblc thng di ph hp.

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7/11

Cuto chung v hotngcab

thu GNSS

Cu trc ca tn hiu GNSS Mt tn hiu GNSS bao gm 2 thnh phn: sng mang v bn tin,

bn tin gmbn tin dnng v m PRN okhong cch tngisdngnv tinh v sng mang.

M PRN v bn tin dnngsi qua khi Data spreading (cng 2tn hiu) riciuchs tn scbnbng cc phngphp iuchs(BPSK ,BOC )

Tn hiu sau khi i qua biuchs ci qua b ghp knh vchuyn ln tns RF pht i .

77/20/2012

Nav.Message

Multiplexing and

Modulation

(RF )

Data

spreading

(modulo-2

adding)PRN code

Signal

Shaping

(Base band

modulation)

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8/11

Cuto chung v hotngcabthu GNSS

Skhica my thu GNSS Gm c 5 khichcnng chnh:

Tn hiut anten ctinx l trc khi vo khinhndin.

Tikhinhndin, tn hiusc phn bit l do v tinh no phtngthitr m v dchtn Doppler scnh gi th.

Sau khinhndin l khi tm kim v giiiuchbn tin nhv.

Cc thng tin sau ca vo khix l tnh ton xc nhvtrcangisdng.

87/20/2012

Front-End Acquisition

Tracking &

Demodulatio

n

Navigationprocessing

Antena

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Nguyn tc xc nhv tr.

Trong iukin l tng, khng c li, xc nhv trcamtvt, ngi ta sdng 3v tinh vihphng trnh sau:

Trong : 1, 2, 3 l khong cch tv tinh nimcn xc nh (c xc nhbngphng php TOA (time of arrival))

(x1,y1,z1); (x2,y2,z2); (x3,y3,z3) l taca cc v tinh.

(xu,yu,zu) l tachabitcaimcn xc nh.

Thphng trnh trn, ta s xc nhc cc tham svtangisdng.

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Nguyn tc xc nhv tr.

107/20/2012

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11/11

Nguyn tc xc nhv tr.

Tuy nhin, trong iukinthct, th khong cch tv tinh nv trcnxc nhs l :

Di l sai sv trv tinh , bi l sai snghv tinh, Ti l sai strtng bnh lu , Ii l sai strtngin ly, but l sai s ngh mythu, vi sai s do nhiuoc my thu.

Do cc sai s ny, nn xc nhv tr, ngi ta cn cn thm mt thams: bu (sai svkhong cch do nghngi dng) v 4 v tinh cs

dng bu = c * but .

Hphng trnh xc nhv tr :

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