u-blox ANTARIS 4 User Manual

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1 GPS Fundamentals
1.1 Theory of operation
Basic Signal Processing (ANTARIS
®
GPS Technology)
DataOutput
Downconversion
Filtering
A/DConversion
Navigation
Calculation
Acquisition
Correlator1
Correlator2
.
.
.
Correlator16
RFInput
Anal ogSignal
1.575 GHz
DigitalIF
si gnal
Pseudorange
Carrie rphase
OrbitInforma tion
per SV
Position,Velocity
TimeSolution
SerialOutput
RF Section GPS Channels Navigation Interface
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Figure 1: Basic Signal Processing
The ANTARIS
®
4 GPS receiver is an L1 Frequency (C/A Code) GPS receiver and performs the entire GPS signal
processing,fromantennainputtoserialpositiondataoutput.
Theprocessingstepsinvolvedare:
1. RFSection
In the RF Section the GPS signal received by the antenna is amplified, filtered and converted to
 an
intermediate frequency (IF). An A/D converter changes the  analog intermediate frequency into a digital IF
signal.
2. GPSChannels
ThedigitalIFsignalbitstreamispassedtothebasebandsection,whereitisfedintothecorrelators.Itisthe
functionof thecorrelatorstoacquireand track
thesatellite signals.Thereare16channels usedin parallel,
with each correlator looking for a characteristic PRN code sequenceinthebitstream. Oncethe correlator
has identified a valid signal, Pseudorange, Carrier Phase and Orbit Information can be extracted from the
GPSsignal.
3. Navigation
Theon-boardprocessorruns
analgorithmthatcalculatesthe position,velocityandtime.This calculationis
called the navigation solution. Once the navigation solution is calculated, it can be transformed into the
desiredcoordinatesystem,e.g.Latitude/Longitude/Altitude.
4. Interface
ThedataofthenavigationsolutionisavailableattheserialRS232or
USBinterface.
GPSModules-SystemIntegrationManual(SIM)(incl.ReferenceDesign) GPSFundamentals
GPS.G4-MS4-05007-A1
  Page 11

u-blox ANTARIS 4 Specifications

General

Brand	u-blox
Model	ANTARIS 4
Category	GPS
Language	English