your position is our focus
8 Troubleshooting
The ANTARI
®
GPS receiver does not F ati
M urantennahasag skyview. bstructedviewleadstoprolonge startuptimes.
In igned system, thea of the C/No ratio high eleva satellites shouldbe inthe range of
4 o about50dBHz. Wit standard ff-the-shelf ctive antenna, 47 dBHz
should easily be achieved.
L valuesleadtoaprolon startuptime.
The position drifts heavily
M rantennahasag skyview. uctedv leadsto tion rift.Checkthecurrentsatellite
c fore starting st tests in er to make sure it matches e test specifications (typically
H Check
every test dr r critical positions (minimal number of SV in view) and monitor the DOP
( IfusingUBXprotoc on’tforge tocheckth positionaccuracyestimation.
The position is off by a few dozen meters
T IS
GPSTechnologys differ ntdatums. default,it artsup withtheWGS84standardGPS
d your application expe different datum, you’ll most likely find the positions to be off by a few
d rs.Findoutwhatkin datumyourapplicatio requiresan config retheEvalKit
accordingly.And
d gettocheckthecalibrationofu-cen rAEmapfiles.
The position is off by hundreds of meters
P mayalsooccurwh lmanacnavigationis bled.The tellite rbitinformationretrievedfrom
an c is much less accura an the information re eved from the ephemeris. With an almanac only
s e sition
willonlyh accura ofa fewkilometersbut may artupfasterorstillnavigatein
a scuredvisibilitywh eephem risfromon orseveralsatellites avenotyetbeenreceived.The
a rmationisNOTuse calculati gaposition ifvalidephe erisin rmationispresent,
regardless
o ofthisflag.
In tocol, position sol s with high deviatio .g. due to enabli almanac navigation) can be
f the PositionAccura ask.UBX tocoldoe notdirectly port thissinceitprovidesaposition
a mation, which allo user t filter the
p ition according to is requirements. However, the
‘ withinLimits’flagofth -NAV-S ATUSmessa eindicatewhether econfiguredthresholds(i.e.P
AccuracyMaskandPDOP)areex d.
The ANTARIS
®
GPS does not preserve the configuration in case of a reset
Th ARIS
®
GPStechnologyuses aslightlydifferentconceptthanmostofthe herGPSreceiversdo.Settings
y. In order to save them permanently, sending a second command is
required. This allows testing the new settings and reverting to the old settings by resetting the receiver
if the
new settings are no good. This is some kind of a safety procedure as it's no longer possible to accidentally
programabadconfiguration(e.g.disablingthemaincommunicationport).SeeSection 4.9.2forthedetails.
On my GPS receiver with external power management, the Hotstart TTFF times are much longer than
specified
Onstartup(afterthefirst position fix)theGPSreceiver performsa RTC
calibrationto haveanaccurateinternal
timesource.AcalibratedRTCisrequiredtoachieveminimalstartuptime.
Before shutting down the receiver externally, check the status in MON-HW in field ‘Real Time Clock Status’.
Don’tshutdownthereceiveriftheRTCisnotcalibrated.
S meet the TT F specific on
akesureyo ood O d
a well es-d
4dBHz t
verage of tion
owC/No
h a o a
ged
akesureyou ood Obstr iew posi d
onstellation be atic ord th
DOP<2.0).
ive fo
e.g.HDOP). ol,d t e
®
upports e By st
heANTAR
atum. If cts a
ozenmete dof n d u
onotfor te
osition drift
an
ena ena sa o
alm a
olutionth
te th
avean
tri
it
po
reaswith b
cy st
o
lmanacinf
enth e e h
o
fthesetting
dfor n , m fo
NMEA pro ution n (e ng
ilteredwith cyM pro s sup
ws the o
os h
ccuracy esti
Position eUBX T g th
ceede
ot
eANT
are initially stored to volatile memor
GPSModules-SystemIntegrationManual(SIM)(incl.ReferenceDesign) Troubleshooting
GPS.G4-MS4-05007-A1
Page 144
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