Masterclock
GMR
User
Manual
v2
–
2016.12
47
GPS
Option
With
the
GPS
option
the
GMR
derives
precision
UTC
time
from
satellites.
The
GMR
includes
an
internal
receiver
that
requires
a
pre
‐
amplified
GPS
antenna.
GPS
ANTENNA
CONNECTIONS
1.
Disconnect
power
from
the
unit.
2.
Provide
the
antenna
with
a
clear
view
of
the
sky.
Do
not
move
it
again
until
after
the
GMR
has
achieved
satellite
lock
(explained
below).
Route
the
antenna
cable
to
the
back
of
the
GMR.
3.
Connect
the
antenna
cable
coaxial
connector
to
the
gold
SMA
female
connector
on
the
rear
of
the
unit
(labeled
ANT
in
image
at
left).
4.
Reapply
power
to
the
GMR.
START
‐
UP
AND
GPS
SATELLITE
ACQUISITION
When
the
GMR
is
initially
powered
up
the
time
to
acquire
satellites
and
extract
correct
time
is
typically
5
to
15
minutes.
In
less
than
optimal
conditions
this
could
extend
to
25
minutes.
Atmospheric
conditions,
type
of
antenna,
antenna
location
and
antenna
cable
length
will
affect
acquisition
time.
When
restarting,
if
the
location,
time
and
number
of
satellites
have
not
significantly
changed
since
last
power
down,
the
GPS
should
lock
much
faster.
The
green
lock
LED
on
the
front
of
the
GMR
will
blink
once
per
second
when
locked
to
a
reference,
twice
per
second
when
not
locked.
Verify
the
active
reference
using
device
status
available
with
WinDiscovery,
SSH,
or
telnet.
ANTENNA
CABLE
LENGTH
COMPENSATION
Nanosecond
offsets
can
be
added
to
compensate
for
cable
length
under
Input
Control
‐
GPS/GNSS
.
GPS
ANTENNA
–
SMA
FEMALE
Note:
All
components
of
the
GPS
system
(including
the
GMR
unit
with
GPS
receiver,
power
supply,
GPS
antenna
and
antenna
cable)
are
tested
as
a
system
at
the
factory
before
shipment.
Be
sure:
1)
The
GPS
antenna,
the
GMR
and
the
supplied
coaxial
antenna
cable
have
not
been
damaged;
2)
The
GPS
antenna
has
an
unobstructed
view
of
the
sky;
3)
The
power
connector
is
properly
installed;
4)
The
front
panel
LED
follows
the
startup
sequence
described
earlier
(on,
off
and
then
on).
