u-blox ANTARIS 4 User Manual

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your position is our focus
4.6.5 Degraded Navigation
ednavigationdeDegrad vi uselessthan4satellites.
4.6.5.1 2D Navigatio
IftheGPSreceiveronly s3satellite calculatea sition,the vigationa u acon altitude
keu emissi e),
thealtitudeiskeptcons
 Note TheANTAR
GPSTechn gydoesnot lculateany lutionwith numbe fSVsle 3SV.
ANTARIS
®
4TimingReceiverscancalculatetimingsolutionwithonlyoneSV.
 Note s during acquisition, the initial altitude is set to 500m. To
changethe tialaltitudeu UBX–CFG onfig)-NAV2(Navigatio 2)mess .
4.6.5.2 Dead Reckon g/ extrapo ing position g
plementedextra
rdoes nolonger achieve apositionfix
with a sufficient position accuracy or DOP value (can be configured in UBX-CFG-NAV2). It keeps a fix track
(heading i til the Dead Reckoning Timeout is reached. The position is
extrapolatedbut
it’sindicatedas“NoFix”(exceptforNMEAV2.1).
 Note ForsensorbasedDeadReckoningGPSsolutions,u-bloxoffersDeadReckoningenabledGPSmodules
racy position solutions for automotive applications at places
with poor or no GPS coverage. This technology relies on additional inputs from a turn rate
 sensor
(gyro)andaspeedsensor(odometer orwheeltick).
T bit information  less accurate than the information retrieved
f ng available,(e.g.whiletheephemeris
s the
Withalmanacnavigation
enabl
iltheephemerisisfully  retrieved.Bydisabling
almanac navigation, the receiver does not use the almanac for navigation, but will always wait to
collect the
With an almanac only solution the position will only have an accuracy of a few kilometers. Normal GPS
performancerequiresatleast4satellitesincludedinthenavigationsolution,whichhaveephemerisinformation
available.
Almanacnavigationallowsmuch
fasterstartup,asthereisnoneedtowaitforthecompletionoftheephemeris
download (>18s). This is useful whenever an inaccurate position is better than no position (e.g. emergency or
securitydevices).
 Note The almanac information is NOT used for calculating a  position, if valid ephemeris information
is
present,regardlessofthesetting ofthisflag.Butthealmanacinformationisneededtoacquirethe
SVwhenthereisnoephemerisdataavailable.
scribesallna
n
gationmodes,which
ha sto po na lgorithm ses stant
toma pforth ngfourthsatellite.Whenlosingasatelliteafterasuccessful3Dfix(min.4SVavailabl
tanttothelastknownaltitude.Thisiscalleda2Dfix.
IS
®
4 olo ca so a ro ssthan
Only
If the receiver makes initial 2D LSQ  fixe
ini se (C n age
in lat in
Theim polationalgorithmkicks in
as soon asthe receive
s equal to the last calculated heading) un
(LEA-4R/TIM-4R). They allow high accu
4.6.6 Almanac Navigation
he satellite or  retrieved from an almanac is much
astartupperiod,onlyalmanacinforromtheephemeris.Ifduri mationis
receiverstillisabletonavigatebasedonalmantillisbeingdownloaded) acorbits.
ed,whenanewsatelliterisesanditsreceptionjusthasstarted,thereceivermight
useanalmanactousethissatelliteinthenavigationsolution unt
entireephemerisinformationbeforeincludingasatelliteinthenavigationsolution.
GPSModules-SystemIntegrationManual(SIM)(incl.ReferenceDesign) ReceiverDescription
GPS.G4-MS4-05007-A1
  Page 99

u-blox ANTARIS 4 Specifications

General

Brand	u-blox
Model	ANTARIS 4
Category	GPS
Language	English