TIM-5H
-
Hardware
Integration
Manual
Design-In
GPS.G5-MS5-07015-A-1
u-blox
proprietary
Page 27
your position is our focus
Open Circuit Detection (OCD)
The
open
circuit
detection
circuit
uses
the
current
flow
to
detect
an
open
circuit
in
the
antenna.
The
threshold
current
is
2.5mA
(at
2.7V)
and
5.1mA
(at
5.5V)
respectively
(applies
to
resistor
values
according
to
and
at
room
temperature).
If
the
current
through
T2
is
large,
the
voltage
drop
through
R4
and
therefore
AADET_N
will
be
high,
indicating
an
open
connection.
On
the
other
hand,
if
the
current
is
small,
AADET_N
will
be
low.
Status Reporting
At
startup
and
on
every
change
of
the
antenna
supervisor
configuration
the
u-blox
5
GPS/GALILEO
module
will
output
a
NMEA
($GPTXT)
or
UBX
(INF-NOTICE)
message
with
the
internal
status
of
the
antenna
supervisor
(disabled,
short
detection
only,
enabled).
None,
one
or
several
of
the
strings
below
are
part
of
this
message
to
inform
about
the
status
of
the
active
antenna
supervisor
circuitry
(e.g.
“ANTSUPERV=
AC
SD
OD
PdoS”).
Abbreviation
Description
AC
Antenna
Control
(e.g.
the
antenna
will
be
switched
on/
off
controlled
by
the
GPS
receiver)
SD
Short
Circuit
Detection
Enabled
OD
Open
Circuit
Detection
Enabled
PdoS
Power
Down
on
short
Table 6: Active Antenna Supervisor Message on startup (UBX binary protocol)
To
activate
the
antenna
supervisor
use
the
UBX-CFG-ANT
message.
For
further
information
refer
to
the
u-blox 5 Protocol Specifications [1].
Similar
to
the
antenna
supervisor
configuration,
the
status
of
the
antenna
supervisor
will
be
reported
in
a
NMEA
($GPTXT)
or
UBX
(INF-NOTICE)
message
at
start-up
and
on
every
change.
Message
Description
ANTSTATUS=DONTKNOW
Active
antenna
supervisor
is
not
configured
and
deactivated.
ANTSTATUS=OK
Active
antenna
connected
and
powered
ANTSTATUS=SHORT
Antenna
short
ANTSTATUS=OPEN
Antenna
not
connected
or
antenna
defective
Table 7: Active Antenna Supervisor Message on startup (NMEA protocol)
The
open
circuit
supervisor
circuitry
has
a
quiescent
current
of
approximately
2mA.
This
current
may
be
reduced
with
an
advanced
circuitry,
which
fulfils
the
same
function
as
the
u-blox
suggested
circuitry.
