your position is our focus
!
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.
4.1.7 Navigation Input Filters
The
navigation
input
filters
mask
the
input
data
of
the
navigation
engine.
These
settings
are
optimized
already.
It
is
not
recommended
that
changes
to
any
parameters
be
made
unless
advised
by
u-blox
support
engineers.
Parameter
Description
Fix Mode
By
default,
the
receiver
calculates
a
3D
position
fix
if
possible
but
reverts
to
a
2D
position
if
necessary
(
Automatic 2D/3D
).
It’s
possible
to
force
the
receiver
to
permanently
calculate
2D
(
2D-only
)
or
3D
(
3D-only
)
positions.
Fix Altitude
Initial
altitude
used
for
2D
navigation
output
The
fix
altitude
is
used
if
Fix
Mode
is
set
to
2D-only
or
in
case
of
a
2D
fix
after
a
Coldstart.
Min SVs
Restricts
the
navigation
solution
to
be
calculated
with
at
least
n
satellites.
This
could
be
used
to
inhibit
a
solution
with
only
3
satellites.
Set
this
value
to
1
single
satellite
for
timing
applications
(LEA-4T
only).
Max SVs
Uses
at
most
‘n’
satellites
for
a
navigation
solution.
Initial Min SV
Minimum
number
of
satellites,
which
must
be
available
before
the
first
position
fix
will
be
calculated.
Min C/No
A
satellite
with
a
C/N0
below
this
limit
is
not
used
for
navigation.
Initial Min C/No
Minimum
C/N0
for
the
initial
fix.
Only
satellites
exceed
this
threshold
will
be
used
for
the
calculation
of
the
first
position
fix.
This
parameter
may
be
set
to
a
higher
value
than
"Min
C/No
(Nav)"
in
order
to
achieve
a
higher
confidence
in
the
accuracy
of
the
first
position
fix.
Min SV Elevation
Minimum
elevation
of
a
satellite
above
the
horizon
in
order
to
be
used
in
the
navigation
solution.
Low
elevation
satellites
may
provide
degraded
accuracy,
because
of
the
long
signal
path
through
the
atmosphere.
DR (Dead Reckoning)
Timeout
4
The
time
during
which
the
receiver
provides
an
extrapolated
solution.
After
the
DR
timeout
has
expired
no
GPS
solution
is
provided
at
all.
Don
not
change
for
LEA-4R/TIM-4R.
Table 11: Navigation Input Filter parameters (UBX-CFG-NAV2)
4
Does
not
apply
to
DR
enabled
receivers
(like
TIM-LR)
LEA-4R
/
TIM-4R
-
System
Integration
Manual
/
Reference
Design
Navigation
GPS.G4-MS4-05043
Page 27
