your position is our focus
5.3 System Sensitivity Test
The
best
approach
to
test
the
sensitivity
of
a
GPS
device
is
the
use
of
a
1-channel
GPS
simulator.
It
assures
reliable
and
constant
signals
at
every
measurement.
Figure 18: 1-channel GPS simulator
u-blox
recommends
the
following
Single-Channel
GPS
Simulator:
•
Spirent
GSS6100
Spirent
Communications
Positioning
Technology
(previously
GSS
Global
Simulation
Systems)
www.positioningtechnology.co.uk
5.3.1 Guidelines for Sensitivity Tests
1.
Connect
a
1-channel
GPS
simulator
to
the
OEM
product
2.
Choose
the
power
level
in
a
way
that
the
“Golden
Device”
would
report
a
C/No
ratio
of
45
dBHz
3.
Power
up
the
DUT
(Device
Under
Test)
and
allow
enough
time
for
the
acquisition
4.
Read
the
C/No
value
from
the
NMEA
GSV
or
the
UBX-NAV-SVINFO
message
(e.g.
with
u-center
AE)
5.
Reduce
the
power
level
by
10dB
and
read
the
C/No
value
again
6.
Compare
the
results
to
a
“Golden
Device”
or
an
ANTARIS
®
4
GPS
EvalKit.
5.3.2 ‘Go/No go’ tests for integrated devices
The
best
test
is
to
bring
the
device
to
an
outdoor
position
with excellent visibility
(HDOP
<
3.0).
Let
the
receiver
acquire
satellites
and
compare
the
signal
strength
with
a
“Golden
Device”.
!
Note
As
the
electro-magnetic
field
of
a
redistribution
antenna
is
not
homogenous,
indoor
tests
are
in
most
cases
not
reliable.
This
kind
of
tests
may
be
useful
as
a
‘go/no
go’
test
but
not
for
sensitivity
measurements.
LEA-4R
/
TIM-4R
-
System
Integration
Manual
/
Reference
Design
Product
Testing
GPS.G4-MS4-05043
Page 33
