u-blox ANTARIS 4 User Manual

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your position is our focus
4.5.2 Warmstart Strategy
InWarmstart,thereceiverreadstheapproximatetime(fromRTCclock),position andalmanacinformationfrom
4.5.3 Hotstart Strategy
te time (from RTC clock), position, almanac and ephemeris
rtstonavigate.
ith poor/limited sky view or does not have a
backup battery. Depending on the information provided, the receiver will perform the best possible startup
scenario.
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Battery Backup RAM, assigns up to 12 channels with currently visible SVs and tries to acquire them. The
remainingchannelswillbeassignedtonon-visibleSVsasthereceivermayhavebeenmovedtoanother
location
duringofftime.
OncesufficientSVsarefoundandephemerisisdecoded,thereceiverstartstonavigate.
In Hotstart, the receiver reads the approxima
informationfromBatteryBackupRAM,assignsupto12channelswithcurrentlyvisibleSVsandtriestoacquire
them. The remaining channels will be assigned to non-visible SVs as the receiver may have been moved to

anotherlocationduringofftime.
OncesufficientSVsarefoundthereceiversta
4.5.4 Aiding / Assisted GPS (AGPS)
TheANTARIS
®
4 aidingfeatureallows supplying external informationto improveTime ToFirst Fix (TTFF).This is
particularly useful if a receiver is operated in an environment w
Acquisition
Sync/
Confirm
Tracking
best case typ :
6-12 secs
Start
Receiver
First
Position
(TTFF)
Time
C
h
an
n
el
s
Signal Level
Aiding Data
received
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Figure 74: GP n isition with Ai ng
ites can improve the TTFF in urban canyons (downloading the
ephemerisrequiresadirectline-of-sighttoeachsatelliteforatleast18s,whichisdifficulttoachieveforthelow
 areas). If not only the ephemeris but also  current
 time and
 thealmanac too)are downloadedto the receiver, the TTFF can be
S Sig al Acqu di
Providing ephemeris data for the visible satell
elevation satellites in urban or  mountainous
approximatereceiver position (and possibly
furtherreducedasthereceivercanskipcertainstepsduringtheacquisitionprocedure.
TheminimalTTFFofabout4sisachievedbyprovidingprecisehardwaretimesynchronization.
GPSModules-SystemIntegrationManual(SIM)(incl.ReferenceDesign) ReceiverDescription
GPS.G4-MS4-05007-A1
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u-blox ANTARIS 4 Specifications

General

Brand	u-blox
Model	ANTARIS 4
Category	GPS
Language	English