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Because Ordinary GPS is not enough.

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Global Navigation Satellite

System

GPS is United States System - NAVSTAR GPSSystem

GNSS is a new world-wide term that has beenadopted to inl!de all satellite navigationsystems"

GPS #US$% Glonass #R!ssia$% Galileo #&U$

G'(NASS is R!ssian )ederation System

Short *or GLObal Navigation And S!rveying System

GPS is Topon+s system% adopted bea!se o!rsystems are designed to !se more than GPSalone"

GNSSGNSS

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GPS+ Signal TriangulationGPS+ Signal Triangulation

How do we Compute a 3D GPS position?

Triangulate!

Distance from satellites to receiverMeasured by the receiver by tracking the satellite signals

and carrier frequency

X,Y,Z ocation of satellite in s!ace

A Special information file with this information is

received from each satellite.

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" # or more satellites re$uired for %asic non&moving

'D !ositioning (om!ute atitude, ongitude, )levation, * +ime Offset

X,Y, Z, +ime-

" Precision eal&+ime +/- !ositioning re$uires a

minimum of 0 satellites

How many satellites doesHow many satellites doesa system need toa system need to

operate?operate?

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Satellite Availability & PreisionSatellite Availability & Preision

!inimum o" # satellites are re$uired%but tat's not all(

" +he location of the satellites overhead,

and ho1 many you have availa%lema2es a %ig difference

" Satellite triangulation 3strength of figure4

" 5uality of satellite s!acing overhead iscalled DOP Dilution of Precision-

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Satellite 6vaila%ility * Precision

"7inimum Satellite

(overage

"Poor Satellite Distri%ution

"8igher DOP

"o1er Precision

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Satellite 6vaila%ility * Precisio

"7inimum Satellite (overage

"Good Satellite Distri%ution

"Better DOP

"Better Precision

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Satellite 6vaila%ility * Precision

"6dditional Satellite (overage

"Great Satellite Distri%ution

"o1est DOP

"Best Precision

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GPS Satellite AvailabilityGPS Satellite Availability

Site in )* Cali"ornia )o ,bstrutions

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Satellite ,bstrutionsSatellite ,bstrutions

"9ot all sites are 1ide o!en

"O%structions to the signal

eliminate satellitesSystem "alls below

minimum satellite level and

loses ig auray

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-y Topon GPS not dependent on one

system only ? .t's beause/0" ." one system is down te positions an still beobtain "rom te oter system*

" Tis is one o" te reasons wy 1uropean unionsetup teir own system 0 GA2.21,*

" And we are ready to support it*

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4GPS G2,)ASS

+ 56

476ours days

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7inimum e$uired

9um%er of S:s

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Speed !

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Accuracy

Deviation

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-i is better ?

!ore satellites ?

!ore options "rom a single satellite ?

;25% 2% 2C and 2#

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;hy 37ore4is Betternitiali?ation, no

1ait time and more

!roductivity

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- Different signals within the receiver require overcoming technical

hurdles. Topcon offer dual-frequency GPS+Glonass for complete

surveying applications

- Different frequencies allow for better atmospheric modeling- ndependent solutions between GPS ! Glonass systems ensure

improved reliability " an e#tra chec$ %&ore is always better'

- (ll of this is transparent to the user - (ll said and done)

You simply track more satellites!