Kinemetrics 468-DC-MRS Operating And Service Manual
TRUETIME
OPERATING
AND
SERVICE
MANUAL
"MODEL
468-DC-MRS"
Satellite Synchronized Clock
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TIME
KINEMETRICS/TRUETIME: 3243 SANTA ROSA AVE., SANTA ROSA,
CA
95407 (707) 528-1230 - TELEX 176687 - FAX (707) 527-6640
MANUAL DATED 10/86
~
KINEMETRICS
"References
this
manual
468-DC
A-468MS
A-468RK
KINEMETRICS I TRUETIME
3243
Santa
Rosa
Ave.
Santa
Rosa,
CA
95407
May
in
to:
be
replaced
'by:
468-DC/MM
A-468MS/RK/MM-2
A-468RK/MM-2
11
TRUETIME
KINEMETRICS
MARTIN MARIETTA CORPORATION
SAT
.RS
OP..DER
NO.
In
1982
Kinemetrics/TrueTime
redesigned
the
Models
A-468MS/RK
and
A-468RK
GOES
antenna
system.
The
newer
MK
II
version
of
the
Model
A-468MS/RK
has
a
different
circuit
card
and
has
different
dimensions
than
the
MK
I.
The
MK
II
antenna
is
still
compatible
with
the
MK I Remote
Kit,
and
the
MK
II
Remote
Kit
is
still
com-
patible
with
the
MK I antenna
as
far
as
function
is
concerned.
The
MK
II
version
of
the
Remote
Kit
also
has
a
different
circuit
card
and
different
dimensions.
When we
supplied
GOES
antennas
to
Martin
Marietta
in
1984,
we
were
able
to
remanufacture
MK
I
kits
from
resources
that
were
still
available
to
us.
Those
resources
are
no
longer
available.
Producing
MK I antennas
at
this
point
in
time
would
entail
an
ex-
tremely
prohibitive
expense
for
Martin
Marietta.
The
MK
II
GOES
antenna
system
is
now
the
only
version
available
to
us.
However,
we
can
still
accommodate
Martin
Marietta
van
application
by
providing
a
special
adapter
plate
to
be
installed
on
the
MK
II
Remote
Kit.
This
plate
will
allow
the
user
to
interchange
both
MK I and
MK
II
Remote
Kits.
Both
units
as
far
as
input/outputs
are
concerned.
are
The
mounting
holes
in
the
antenna
pedestal
baseplate
have
been
drilled
out
to
0.
459",
and
the
upright
mounting
stanchion
has
been
shorted
to
9.5"
to
conform
to
Martin
Marietta
Drawing
No.
850MROR0026.
Applicable
drawings
follow
this
page.
KINEMETRICS/TRUETIME: 3243 SANTA ROSA AVE., SANTA ROSA, CA 95407 (707) 528-1230 - TELEX 176687 - FAX (707) 527-6640
·468DC-MRS
SYSTEM
DESCRIPTION
ITEM
-
l
2.
3
4
5
6
7
8
9
WARRANTY
PART
468~DC
NUMBER
MM
A-468MS/RK
A-468RK
MM
A-468Br/MM
A-468
A-468
MM -1.5
MM
- 20
A-468BC/MM
A-468AP1/MM
A-468PP1/MM
INFORMATION:
MM
2
DESCRIPTION
GOES
Satellite
GOES
Antenna Mark
Antenna Remote
Base
Plate
Cable Assembly
Cable
RG
214
"N" Bulkhead
Paint
Paint
Adapter
Assembly 20
with
"N"
Connector
Code 17925
Code 17925
Synchronized
II
Kit
for
Item
1.5
foot
length
Foot
length
Connectors
for
Item
for
Item
Clock
3
2 (White)
4 (White)
The
Kinemetrics/TrueTime
Kinemetrics/TrueTime's
perform
to
details.
their
warranty
end
user.
repairs.
Santa
Refer
design
to
of
the
468-DC-MRS
Rosa
factory
This
warranty
pages 1 through 3 of
is
the
is
transferable
is
considered
only
this
facility
from
manual
proprietary.
authorized
Martin
for
additional
to
Marietta
APPENDIX
•A"
PAGE
DESCRIPTION
1
468-DC{MM ·
2
A-468MS/
~MM
3
A-468RK/MM· ·
4
A-468
BP/"·
MM·
~
10.00
MAX
"'
<
T
MODEL
GOES
.22
TYP
468-DC/MM
SATELLITE
CLOCK
TO
A-468RK/MM-2
REMOlE KIT
"N•
CONNECTOR
~Annc-1
/\_.A~QU~
/DLt lt..At..A-?
IVIVLJLL
I\
IVUIVl....J/
l'I'/
1v11v1
'-
GOES
ANTENNA
WITH
MOUNTING
HARDWARE
TO
468-DC/MM
·aNc·
CONNECTOR
FROM
A-468MS/RK/MM-2
•N•
CONNECTOR
MODEL
A-468RK/MM-2
REMOTE
KIT
•
fV\._
··-
.050·
RIVNUTS
(HOLE
PATIERN
TO
MATCH
NEW
REMOTE
Kil)
FITS
5/16•
BOLT
ADAPTER
7
r
COUNTERSUNK
HOLES
PLATE
FOR
ATTACHMENT
TO
VAN
{HOLE
PATTERN
TO
MATCH
OLD
REMOTE
KIT)
FITS
10-32
FLATHEAD
SCREWS
10.00·
I I
1.00·
0.75•
......_------13.00•
-----------4
....
NOTE:
DRAWING
NOT
TO
SCALE
MATERIAL:
1/8•
PLATE
ALUMINUM,
PAINTED
MODEL
A-468BP
/MM
MK
I
TO
MK
II
REMOTE
ADAPTER
PLATE
TABLE
OF
CONTENTS
SECTION
PAGE
I
GENERAL
INFORMATION
1-1
INTRODUCTION...................................
1-1
1-7
WARRANTY
.......................................
1-3
1-8
SPECIFICATIONS.................................
1-4
II
INSTALLATION
2-1
ANTENNA
INSTALLATION
................
~
..........
2-1
2-7
RACK
MOUNTING..................................
2-4
2-9
INSTRUMENT
START-UP
............................
2-4
III
OPERATION
3-1
3-3
3-7
3-11
3-13
3-16
3-18
3-24
3-26
3-28
3-36
3-41
3-45
3-51
3-55
3-66
3-74
3-7 5
3-79
3-84
3-88
3-92
3-94
3-97
3-98
3-104
3-106
3-114
3-123
3-125
'"\ 1 '"\
/""\
.)-1.)U
3-133
3-134
3-135
INTRODUCTION
..................................
.
SATELLITE
EAST-WEST
LED
.......................
.
DISPLAY
.......................................
.
HOURS
OFFSET
..................................
.
12/24
HOUR
CLOCK
OPERATION
....................
.
AUTOMATIC/MANUAL
SATELLITE
SELECTION
..........
.
PROPAGATION
DELAY
.............................
.
1 Hz
•••••••••••••••••••••••••••••••••••••••••••
1 KHz
•.•••••••••••.••••.....•.•.•••••••••••••••
IRIG-B
(REMOTE
DISPLAY
DRIVING
OUTPUT)
........
.
SLOW
CODE
.....................................
.
C..()
u~
vu
11~
•
•••••••••••••••••••••••••••••••••••••••••
EXTERNAL
OSCILLATOR
(Option)
..................
.
IRIG-H
(Opt
ion)
...............................
.
PARALLEL
BCD
TIME
OUTPUT
(Option)
.............
.
RS-232
TIME
OUTPUT
(Option)
...................
.
RS-232
MODE
DESCRIPTIONS
......................
.
MODE C ........................................
.
MO
DE
T
•••••••••••••••••••••••••••••••••••••••••
M 0
DE
F
•••••••••••••••••••••••••••••••••••••••••
MODE M ........................................
.
MODE P ........................................
.
MODE R ........................................
.
NOTES
.........................................
.
MODE
U -
DUT1
MODE
............................
.
M
0
DE
E . . . . . . . . .
...............................
.
I
-MODE
- (Opt
ion)
.............................
.
DAMS/HEALTH
MESSAGE
SOFTWARE
(Option)
.........
.
DAMS/HEALTH
MESSAGE
SET
UP
KEY
STROKESo••······
VERIFICATION
KEY
STROKES
......................
.
3-1
3-1
3-4
3-4
3-5
3-5
3'.'""5
3-7
3-8
3-8
3-9
3=9
3-10
3-10
3-11
3-15
3-19
3-19
3-19
3-20
3-21
3-21
3-22
3-22
3-23
3-24
3-24
3-25
3-27
3-27
DAMS/HEALTH
MESSAGE
INFORMATION
KEY
STROKES
....
3-29
OPERATING
NOTES
................................
3-29
IEEE-488
OUTPUT
(Option)
.......................
3-30
INTRODUCTION
...................................
3-30
1
TABLE
OF
CONTENTS
(cont.)
SECTION
PAGE
III
OPERATION
(cont.)
3-137
3-140
3-142
3-146
3-151
3-156
3-158
3-161
3-165
3-167
3-170
3-173
3-177
3-179
HARDWARE.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-30
EXTERNAL
TRIGGER
...............................
3-31
SOFTWARE.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-31
MODE
F
.........................................
3-31
MODE M .........................................
3-32
MODE N .........................................
3-33
MODE P .........................................
3-33
MODE T .........................................
3-34
SAMPLE
PROGRAMS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-
3 5
D.C.
POWER
INPUT
(Option)
......................
3-37
SOus
TIMING
(Option)
...........................
3-37
DAYLIGHT
SAVINGS
TIME
CORRECTION
.......•.......
3-38
RS-232
STANDARD
MODES
.........................
3-38
ADVANCED
PERFORMANCE
OPTION
....................
3-39
IV
THEORY
OF
OPERATION
4-1
4-16
4-17
4-19
4-21
4-26
4-31
4-34
4-36
4-38
4-42
4-47
4-52
4-58
4-61
4-64
4-68
4-71
4-75
4-77
4-81
4-84
4-87
4-90
4-102
4-103
4-105
4-107
4-119
THEORY
OF
OPERATION
MODEL
468-DC
..............
.
DETAILED
DESCRIPTION
OF
OPERATION
.............
.
ACTIVE
ANTENNA
ASSEMBLY
86-170
................
.
PRE -AMP
L I F
IE
R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
lST L.O.
MUL'NPLIER/MIXER
.....................
.
INTERMEDIATE
FREQUENCY
AMPLIFIER
..............
.
DETECTOR
BOARD
ASSEMBLY
86-73
.................
.
ANALOG
BOARD
ASSEMBLY
86-74
...................
.
RF
LOCK
DETECTOR
..............................
.
RF
LOCK
LOOP
..................................
.
DATA
DETECTOR
.................................
.
DATA
LOCK
DETECTOR
............................
.
COARSE
PHASE
LOCKED
LOOP
.......•...............
FINE
DATA
PHASE
LOCKED
LOOP
...................
.
EXTERNAL
OSCILLATOR
INPUT
(Option)
............
.
TIMING
CHAIN
..........................•......•.
DIGITAL
BOARD -ASSEMBLY
86-42
................
.
POWER
SUPPLY -ASSEMBLY
86-52
...............•..
DISPLAY
BOARD -ASSEMBLY
86-43
....•............
PARALLEL
BCD
TIME
OUTPUT
(Option)
-
ASSY.
86-44
RS-232
INTERFACE
(Option)
-
ASSEMBLY
86-46
.....
DAMS/HEALTH
MESSAGE
(Option)
..................•
IEEE-488
INTERFACE
(Option)
-
ASSEMBLY
86-47
..
.
D.C.
POWER
INPUT
(Option)
.....................
.
SOFTWARE
......................................
.
PROGRAM
DESCRIPTION
...........................
.
RECEIVER
CONTROL
AND
DATA
PROCESSING
..........
.
DESCRIPTION
OF
THE
STATE
DIAGRAMS
...•........•.
TIMING
OUTPUTS
................................
.
2
4-1
4-6
4-6
4-6
4-6
4-7
4-8
4-8
4-8
4-8
4-9
4-11
4-13
4-14
4-15
4-16
4-16
4-17
4-17
4-17
4-18
4-18
4-18
4-18
4-20
4-20
4-20
4-20
4-26
V
MAINTENANCE
AND
TROUBLESHOOTING
5-1
MAINTENANCE
MODEL
468-DC
.......................
5-1
5-4
THIRD
I.F.
TRIM
-
AS~EMBLY
86-73
...............
5-1
5-8
DATA
SYMMETR~
ADJUSTMENT -ASSEMBLY
86-74
......
5-2
5-10
EAST
SWEEP
TRIM -ASSEMBLY
86-74
...............
5-2
5-12
WEST
SWEE?
TRIM -ASSEMBLY
86-74
...............
5-3
5-14
10
MHz
FINE
TIMEBASE
TRIM -ASSEMBLY
86-74
.....
5-3
5-16
1
MHz
COARSE
TIMEBASE,
ASSEMBLY
86-74
..........
5-3
5-18
FIRST
LOCAL
OSCILLATOR
PEAKING,
ASSEMBLY
86-74.
5-3
5-22
TROUBLESHOOTING
................................
5-4
5-49
TROUBLESHOOTING
THE
EXTERNAL
OSCILLATOR
(Opt.).
5-8
5-51
TROUBLESHOOTING
THE
D.C.
SUPPLY
(Option)
.......
5-8
VI
SCHEMATICS
AND
PARTS
LISTS
6-1
6-2
6-3
6-4
6-5
6-6
6-7
6-8
6-9
6-10
6-11
6-12
6-13
6-14
6-15
6-16
6-17
6-18
6-19
6-20
6-21
6-22
6-23
6-24
6-25
6-26
6-27
6-28
6-29
6-30
6-31
6-32
6-33
PARTS
LOCATION -ASSEMBLY
86-170
..............
.
SCHEMATIC -ASSEMBLY
86-170
...................
.
SYMBOL
DESIGNATION
REFERENCE
86-170
...........
.
PARTS
LOCATION -ASSEMBLY
86-173
..............
.
SYMBOL
DESIGNATION
REFERENCE
86-173
...........
.
SCHEMATIC -ASSEMBLY
86-173
...................
.
PARTS
LOCATION -ASSEMBLY
86-73
...............
.
SYMBOL
DESIGNATION
REFERENCE
8r
~1
............
.
SCHEMATIC -ASSEMBLY
86-73
....................
.
PARTS
LOCATION -ASSEMBLY
86-74
...............
.
SCHEMATIC -ASSEMBL'-
96-74
....................
.
SYMBOL
DESIGNATION
R~iERENCE
86-74
............
.
PARTS
10CATION -ASSEMBLY
86-42
.............
.
SYMBOL
DESIGNATION
REFERENCE
86-42
............
.
SCHEMATIC -ASSEMBLY
86-42
....................
.
PA~TS
LOCATION -ASSEMBLY
86-43
.........
~-
.....
.
SYMBOL
G:SIGNATION
REFERENCE
86-43
............
.
SCHEMATIC -ASSEMBLY
86-43
....................
.
PARTS
LOCATION -ASSEMBLY
86-44
...............
.
SYMBOL
DESIGNATI0N
REFERENCE
86-44
............
.
SCHEMATIC -ASSEMBLY
86-44
....................
.
PARTS
LOCATION -ASSEMBLY
86-46
...............
.
SYMBOL
DESIGNATION
REFERENCC
86-46
............
.
SCHEMATIC -ASSEMBLY
86-46.
,
................
.
PARTS
LOCATION
-
ASSEMBLY~:
-47
...............
.
SYMBOL
DESIGNATION
REFERENCE
86-47
............
.
SCHEMATIC -ASSEMBLY
86-47
....................
.
PARTS
LOCATION -ASSEMBLY
86-52
...............
.
SYMBOL
DESIGNATION
REFERENCE
86-52
............
.
SCHEMATIC -ASSEMBLY
86-52
....................
.
PARTS
LOCATION -ASSEMBLY
86-147
..............
.
SYMBOL
DESIGNATION
REFERENCE
86-147
...........
.
SCHEMATIC -ASSEMBLY
86-147
...................
.
3
6-2
6-3
6-4
6-6
6-6
6-7
6-8
6-8
6-9
6-10
6-11
6-12
6-14
6-14
6-15
6-16
6-16
6-17
6-18
6-18
6-19
6-20
6-20
6-21
6-22
6-22
6-23
6-24
6-24
6-25
6-26
6-26
6-27
VI
SCHEMATICS
AND
PARTS
LISTS
(cont.)
VII
6-34
6-35
6-36
6-37
6-38
6-39
6-40
6-41
6-42
6-43
6-44
6-45
6-46
6-47
6-48
6-49
6-50
6-51 A-468
ANTENNA
A-468Rtc,
7-1
7-4
7
-9
7-10
7-14
7 - 1 5 M 0
21
7 7-27
PARTS
SYMBOL
SCHEMATIC -ASSEMBLY
REAR
PARTS
SUBCHASSIS
PARTS
MODEL
PARTS
MODEL
PARTS
MODEL
PARTS
MODEL
PARTS
MODEL
PARTS
INSTALLATION
EXTERNAL
GENERAL
MODEL
I
NS
TALLA
MODEL
INSTALLATION...................................
DEL
M 0
DEL A-4 6 8
EXTERNAL
LOCATION -ASSEMBLY
DESIGNATION
PANEL
LIST 220-30
LIST 221-30
468-DC
LIST
A-468MS
A-468MS
LIST 141-170
A-468HX
LIST 141-171
A-468HX
LIST 142-171
ANTENNA
ASSEMBLY
ASSEMBLY
151-70
LIST
FINAL
FINAL
142-170
SUB-ASSEMBLY
SUB-ASSEMBLY
FINAL
SYSTEMS
FOR
ANTENNA
INFORMATION
A-468MS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 -1
TI
ON.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 -3
A-468HX..................................
A -4 6 8
RK
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 -6
RK
C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 -8
ANTENNA
REFERENCE
86-53
220-30
..............................
221-30
..............................
ASSEMBLY
..............................
ASSEMBLY
.............................
.............................
.............................
ASSEMBLY
ASSEMBLY
..........................
MODELS
INPUT
............................
INPUT
86-53
.....................
.....................
.....................
A-468MS, A-468HX,A-468RK,
.........................
................
86-53
151-70
142-170
141-170
141-171
142-171
142-171
.............
.............
...........
.............
.............
...........
............
6-28
6-28
6-30
6-31
6-31
6-31
6-31
6-32
6-32
6-33
6-33
6-33
6-33
6-34
6-34
6-34
6-34
6-35
7-1
7-3
7-4
7-8
VIII
IRIG-B
8-1
8-4
8-11
AND
IRIG-H
INTRODUCTION...................................
IRIG
CONTROL
CODE
TIME
FORMAT
FUNCTIONS
CODE
...............................
FORMAT
..............................
4
8-1
8-1
8-2
SECTION
I
GENERAL
INFORMATION
1-1
INTRODUCTION
1-2
This
manual
has
been
designed
and
written
to
provide
the
owner
of
the
Model 468-DC 'GOES'
Satellite
Synchronized
Clock
r.1 ; t- h a 1 1
/"\
f f- h o rt
!l t-!l
!l
n rt ; n f
/"\
r m
!l
t- ;
/"\
n n o o rt o rt t-
/"\ /"\
no
r
!l
t- o
!l
n rt 1 1 f- ; -
VY
...L.
'-
L J
\.A
..L ..L
'-J
.L.
'-
L J
"-
..._...
'-" '-\.A
\.A
L
J.
'"4
..&..
.L
J.
.L
..._,,
.L
l..l.J.
\.A
'-
.L
'-J
L J.
1.
.I
""-'" '-..._...
'-
"-& '-.._,.
'-'
t'
""""
.L.
'-" '-"-'
\.A
L J.
'-.&
\A
'-
..L
lize
all
its
features.
1-3
The
information
included
in
this
manual
is
as
complete
as
possible
and
includes
normal
maintenance
and
adjustment
data
that
may
be
required
to
facilitate
field
repair
of
the
unit.
1-4
The Model 468-DC
has
been
designed
to
receive
the
NOAA
"GOES"
Satellite
which
transmits
on a frequency
of
468
MHz
and
decode
the
time
information
from
the
broadcasts
as
well
as
dis-
play
outputs
for
supplying
the
time
information
to
other
equip-
ment.
The
Synchronized
Clock
in
its
standard
configuration
pro-
vides
a
front
panel
display
of
days,
hours,
minutes,
and
seconds
with
five
rear
panel
BNC
connectors
with
IRIG
B,
1
Hz,
1
kHz,
Precision
60 Hz, and
Slow
Code
locked
to
the
electrically
output-
ted
time
(and
options
if
ordered),
may
be
in
either
Universal
Coordinated
Time
(UTC),
more
commonly
referred
to
as
Greenwich
Mean
Time
(GMT),
or
in
local
time.
This
is
done
through
the
proper
time
zone
offset
selected
by
the
rear
panel
thumbwheel
switches.
The
Model
468-DC
is
shipped
to
display
the
time
of
year
in
the
twenty-four
hour
format.
By
simply
removing
the
cover
and
switching
the
position
of
the
small
switch
on
the
microprocessor
circuit
board,
the
unit
can
be
converted
to
dis-
play
and
output
time
in
the
more
conventional
twelve
hour
format.
1-5
This
instrument
has
been
designed
to
be
completely
automatic
requiring
only
antenna
installation
and
connection
of
the
unit
to
the
power
source.
Once
the
instrument
is
installed
and
turned
on,
the
microprocessor
will
lock
to
the
signal
from
the
"GOES"
Satellite
(either
East
or
West
Satellite
by
sweeping
for
lock),
decode
and
display
the
time.
From
that
point
on,
the
unit
will
require
no
further
attention
and
will
provide
time
to
an
accuracy
of
+1.0
ms,
continually
updated
by
and
phase
locked
to
the
transmissions
of
the
"GOES"
Satellite.
In
the
event
of
loss
of
signal,
the
unit
will
continue
operation
on
its
internal
crystal
time
base.
If
power
should
fail,
upon
restoration,
the
unit
will
again
read
the
time
signals
and
start
displaying
the
time
transmitted.
1-6
The Model 468-DC
Satellite
Svnchronized
Dis:dtal
Clock.
when
using
the
A-468MS
Antenna,
is
gu~ranteed
to
op~rate
~t
any
location
within
the
5°
viewing
angle
of
the
satellite
as
shown
on
the
map
enclosed.
For
viewing
angles
of
0°
- 5°
the
Model
468-HX
should
be
utilized.
1-1
150° 180°
150°
120°
900
~o ~o
~
EAST WEST
+ IN-ORBIT
SPARE
LOCATED
AT
105° W
FIGURE
1-1
GOES
SATELLITE
COVERAGE
MAP
1-2
1-7
WARRANTY
KINEMETRICS/TRUETIME
warrants
each
instrument
it
manufactures
to
be
free
from
defects
in
material
and
workmanship
for
a
period
of
one
year
from
the
date
of
delivery
to
the
original
purchaser.
Under
this
warranty,
any
instrument
which
is
returned
to
us
(freight
pre-paid)
and
is
found
by
us
to
be
defective
in
material
or
workmanship
will
be
repaired
or
replaced
(at
our op-
tion)
at
no
charge
to
the
customer
and
returned
freight
pre-paid.
Our
obligation
under
this
warranty
is
limited
to
servicing
or
adjust-
ment
of
any
instrument
returned.
Items
not
covered
by
this
warranty
are:
fuses,
batteries,
and
any
illuminated
parts
or
damage
caused
by
accident
or
physical
destruction
of
the
instrument.
This
warranty
is
expressly
in
lieu
of
all
other
obligations
or
liabil-
ities
on
the
part
of
TrueTime.
TrueTime
neither
assumes
nor
autho-
rizes
any
other
person
to
assume
for
them
any
other
liability
in
connection
with
our
sales.
1-3
1-8
SPECIFICATIONS
RECEIVER
FREQUENCY:
SYSTEM
SENSITIVITY:
SYSTEM
NOISE
MARGIN:
TIMING
ACCURACY:
PROPAGATION
DELAY
CORRECTION:
TIME
BASE
STABILITY:
DISPLAY:
DISPLAY
ACCURACY:
NOMINAL
TURN-ON
TIME:
OPERATING
TEMP:
1-4
468.8250
and
468.8375
MHz
Automatic
or
Manual
select.
The
sensitivity
is
suitable
for
proper
operation
with
satellite
viewing
angle
5°
or
more
above
the
horizon
when
using
the
A-468MS
Antenna.
(approximately
.2uV/m)
Operates
with
9db
attenuator
inserted
between
A-468MS
flat
plate
and
preamp
input
in
locations
which
have
a
satel-
lite
elevation
of
greater
than
15°.
1)
+1.5
ms
of
UTC/NBS
Time when
cor-
rected
for
propagation
delay
through
on-board
switches
and
using
the
A-468MS
Antenna.
2) The
time
difference
between
neigh-
boring
clocks
locked
to
the
same
satellite
is
considerably
improved
over
UTC
timing
accuracy.
Consult
the
factory
for
specification
and
conditions.
Two
internal
decade
switches
provide
+50
ms
correction
capability
in
1
ms
steps.
When
not
phase
locked,
crystal
controls
to
+l
x
10-6.
For
higher
stability
time
base
when
not
phase
locked
to
satellite,
see
"External
Oscillator
Input"
Option.
1/2"
high
planar
gas
discharge.
plays
day
of
year,
hours,
minutes
seconds.
Dis-
and
-0
to
+100
ms,
anytime
colons
are
not
flashing.
Three
minutes
from power on and
reception
with
90%
confidence
average
signal
conditions.
0°
to
50°
C.
signal
under
REAR
PANEL
OUTPUTS:
1 Hz:
KHz:
1
DRM()'l'R
.l\..LU:J
\J
..L
.U
DRIVING
SLOW
CODE:
f\T
~
LI.LU
(IRIG
DT
L.
.UC:J.
AV
.&..
B):
Rising
loads
SECTION
Rising
loads
SECTION
or
or
edge
CMOS.
III,
edge
CMOS.
III,
IRIG B Time
panel
Time
KHz
easily
D.C.
III,
DRIVING
BNC
1
pulse
day
and
mark,
seconds
sourcing
pulled
See
BNC
Code
carrier.
field
level
entitled
OUTPUT)".
output
per
(lppd).
remain
4
seconds
for
40
to
SECTION
on
time,
High
entitled
on
time,
High
entitled
Code
connector.
is
an
amplitude
This
converted
shift
time
"IRIG-B
of
1
pulse
hour
(lpph),
The
high
for
day
MA
at
4.0
ground
III,
entitled
10%,
"l
10%,
"l
is
provided
Standard
output
to
code.
(REMOTE
per
pulses
2
seconds
for
hour
mark.
volts
by a lk
drives
Low
Hz".
drives
Low
KHz".
modulated
can
TTL
See
minute
and 1
go
high
mark
Capable
minimum,
ohm
"SLOW
ten
90%.
two
90%.
on
a
TTL
See
TTL
See
rear
IRIG B
also
be
compatible
Section
DISPLAY
(lppm),
pulse
on
for
per
time
minute
and
of
and
resistor.
CODE".
1
6
60
HZ:
EXTERNAL
OSCILLATOR
(Option):
Provided
source
through
driving
wave
Hz
has
is
cycles).
See
SECTION
Input
than
wave
100
KHz
is
as
to
level
2.4
is
KHz
is
needed
clock
the
entitled
on
BNC
connector
to
drive
a
power
10
an
a
50%
Cycle
Cycle
Cycle
TTL
unusual
amplifier..
loads.
duty
#1
#2
#3
III,
of
less
volts
(TTL)
required.
to
10
MHz
satisfactory.
regardless
time-base
satellite~
"EXTERNAL
a
synchronous
The
duty
cycle
cycle.
over
High 9ms,
High 8ms,
High 8ms,
entitled
than
sine
Any
in
of
when
4V
wave
frequency
multiples
No
unit
frequency.
not
See
OSCILLATOR".
as
frequency
Capable
output
50
Low
8ms
Low
9ms
Low
8ms
"60
Hz".
and
greater
or
adjustment
phase
SECTION
motor
of
square
The 60
ms
(3
square
from
of
100
Used
locked
III.
.
1-5
IRIG H
(Option):
PARALLEL
BCD
TIME
(Option):
RS-232
(Option):
I-MODE
(Option):
S-MODE
(Option):
BNC
output
of
standard
IRIG H
format
TTL
DC
level
shift
supplied
unless
otherwise
requested.
If
1
KHz
amplitude
modulated
carrier
requested,
IRIG B
will
automati-
cally
be
supplied
in
D.C.
Level
Shift
format.
See
SECTION
III,
entitled
"IRIG-H
(Special
Order
Option)".
If
ordered,
Parallel
BCD
time
of
year
is
provided
on
rear
panel
50
pin
"D"
con-
nector.
Days,
hours,
minutes,
seconds
and
milliseconds
are
provided.
Lines
indicating
worst-case
time
error
of
+l,
+5,
+50 and +500ms
drives
15
"LST'T"L"
Toads-or
'CMOS': See
SECTION
III,
enti-
tled
"PARALLEL
BCD
TIME
OUTPUT
(Special
Order
Option)".
The High
Capacity
Parallel
BCD
drives
100
LSTTL
loads.
The
displayed
time
of
year
is
outputted
in
EIA
Standard
RS-232C
configuration
via
a
"Motorola
ACIA".
Output
format
is
D D D H H M M S S
and an
indicator
of
the
time
quality,
CR/LF. Baud
Rate
and "ACIA"
opt
ions
are
dip
switch
selectable.
See
SECTION
III,
entitled
"RS-232
TIME
OUTPUT
(Options)".
Time
can
be
preset
and
displayed
without
synchronization
to
NBS
transmissions.
DAMS/Health Message
Software.
Assists
users
of
NESS
data
collection
system
to
check
the
quality
of
uplink
transmis-
sions.
IEEE-488
(Option):
IEEE
Buss
interface
is
also
available.
HOURS
OFFSET:
1-6
The
time
is
outputted
in
ASCII
format,
with
the
most
significant
digit
first
(lOO's
of
days).
Among
operating
modes
is
time
on demand
to
the
millisecond
level,
or
marked
time
to
the
millisec-
onds
level.
See
SECTION
III,
entitled
"IEEE-488
OUTPUT
(Option)".
•
Rear
panel
thumbwheel
switch
allows
adjustment
of
+
or
- "O"
to
"11"
hours
from
transmitted
UTC
time.
See
SECTION
III,
entitled
"HOURS
OFFSET
11
•
12/24-HR.
OPERATION:
Dip
use
Switch
as
format
entitled
located
12
hour
as
clock
shipped.
"12/24-HOUR
inside
in
place
See
CLOCK
unit
SECTION
of
allows
24
hour
III,
OPERATION".
468-DC
SIZE:
WEIGHT:
POWER
D.C.
A-468MS
SYNCHRONIZED
(Standard):
POWER
INPUT:
ANTENNA
DIGITAL
1-3/4"
26.7cm)
dard
ware
available.
7-1/4
(5.4kg).
96-135VAC,
amps.
When
replaced
centers,
tive.
used.
vdc.
depending
CLOCK
19"
included.
lbs.
Others
ordered,
Input
Power
x
17" x 10-1/2"
behind
panel.
(48.9cm)
(3.5kg)
60-400Hz,
available
with
red
Common
binding
is
"Banana
voltage
is
upon
option.
(4.4
Mounts
EIA
rack
24"
Ship
(60.
Wt. 12
less
on
the
standard
posts
positive,
Plugs"
may
be
approximately
x
system,
9)
than
request.
AC
black
11
43.2
in
stanhard-
hardware
lbs.
25
volt
input
on
3/4"
is
nega-
can
vdc
to
20
watts
x
is
be
32
CT7"R.
u.Lu:J.J•
WEIGHT:
A-468HX
SIZE:
WEIGHT:
A-468RK
SIZE:
WEIGHT:
ANTENNA
DOWN
CONVERTER
x
l 0
10"
cm).
10
lbs(4.5
17"
x
x 109
mounting
22
lbs
10
..
x
6.
1
cm)
10
LBS
(7
1.
...,,,
lro'i
..
~b
' , •
hi
oh
II
••
~b
..
kg)
Ship
17" x 43"
cm)
Provided
system
(10
kg)
13"
x
2.4"
.
(4.5
,/ •
KG)
(25.4
high
and
Ship
Ship
cm x
Wt. 16
(4'.1.2
with
hardware.
Wt. 66
(2.54
cm x 33.0
Wt. 16
25
..
4 cm x
lbs.(7.3kg.)
cm x 43.2
a
universal
lbs.
(30
lbs.
30.5
cm
cm
kg)
x
1-7
17.00
---------------·
15.00
17.00
FIGURE
1-2
MODEL
468-DC
DIMENSIONS
1-8
SECTION
II
INSTALLATION
2-1
ANTENNA
INSTALLATION
2-2
The Model 468-DC
Synchronized
Clock
is
shipped
ready
for
operation
and
will
require
no
adjustments.
The
first
step
in
set-up
and
operation
of
the
unit
is
to
install
the
antenna
in-
cluded
with
the
unit.
An
antenna
supplied
by
KINEMETRICS/TRUETIME
for
use
with
the
Model
468-DC
must
be
used
in
conjunction
with
this
receiver/clock
as
the
antenna
includes
not
only
a
preamp,
but
receiver
controlled
frequency
conversion
circuits.
The
use
of
"in
antenna
conversion"
of
the
468
MHz
frequency
to a lower
frequency
for
transmission
down
the
coax
allows
up
to
1000
feet
of
RG-58/U
lead
in
coax
to
be
used.
2-3
Satellite
selection
in
the
Model
468-DC
can
be
either
automatic
or
manual.
Maximum
time
accuracy
is
obtained
in
the
manual
mode
where
the
operator
selects
either
the
East
or
West
satellite
then
sets
the
propagation
delay
switches.
In
the
automatic
mode
the
Model 468-DC
will
try
for
the
East
satellite
first
then
the
West
satellite.
If
only
basic
time
is
required
and
a
change
in
the
received
satellite,
which
can
result
in
a
worst
case
error
in
propagation
delay
of
9
milliseconds,
is
acceptable
then
the
automatic
mode
can
be
used
and
the
advantage
of
automatic
scanning
is
achieved.
This
scanning
allows
the
receiver
to
select
either
receivable
satellite
in
the
case
of
poor
or
no
reception
from
one.
The
automatic
mode
can
be
used
only
if
a
common
pointing
direction
will
allow
the
antenna
to
receive
signals
from
both
satellites.
This
can
be
evaluated
by
the
use
of
the
pointing
angle
maps,
FIGURES
2-1
and
2-2.
The
beamwidth
of
the
A-468MS
antenna
is
approximately
90%.
Both
satellites
can
be
received
by
the
A-468MS
antenna
in
most
areas
where
there
are
no
obstructions
from
buildings,
trees
or
moun-
tains.
If
maximum
time
accuracy
is
required
with
respect
to
UTC
or
another
468-DC
in
the
field
then
either
the
East
or
West
satellite
must
be
selected,
the
antenna
pointed
at
the
selected
satellite,
the
propagation
delay
calculated
and
the
internal
switches
set.
SECTION
III,
PROPAGATION
DELAY,
gives
switch
set-
t i ng
instr
u c t
ions.
2-4
Once
it
is
determined
which
satellite
will
be
received
(or
if
both
are
to
be
received)
the
attached
maps
can
be
used
to
determine
the
best
pointing
direction
for
the
users
location.
In
the
case
of
the
A-468MS,
the
antenna
should
be
physically
pointed
such
that
the
signal
from
the
satellite
comes
onto
the
antenna
receiving
plate
through
the
top
of
the
plastic
bubble.
The
axis
of
the
A-468HX.
the
Helix,
should
be
pointed
at
the
satellite
for
best
results.
Thus,
if
the
user
was
d~irectly
under
the
satellite,
the
antenna
would
be
set
with
it
facing
straight
up.
If
the
satellite
was
at
a 5°
angle
above
the
horizon,
the
antenna
must
be
tipped
at
83°.
2-1
N
'"1'.I
I
II-«
N
Cl
LONGITUDE
c::
~
tl;l
100 120 140 160
E 180
w
160
140 120 100
80 60 40 20
0 20
40
90
.-.z
TH
.-.z
H
90
~
I
,......
80
80
0
70
70
0
pj
(/)
60
60
t:zj
>
50
50
{/)
-1
40
40
>
z
30
30
t-i
t:zj
z
20
20
z
>
w
10
10
w
l'l:J
Cl
Cl
0
:::i
=>
1-4
~--
0
0
.....
z
I-
.....
1--J
c:(
10
10
<(
t-4
_J
....J
z
0
?O
20
>
z
30
30
0
t""4
40
40
1:11
50
50
60
60
lO
70
80
80
AZ
H
90
90
100
120 140
160
E 180 w 160
140 120
100 80
60
t~O
20
0 20
40
LONGITUDE
EASTERN
SATELLITE
POINTING
ANGLES.
N
1
l;..)
N
I
N
0
0
~
en
w
Cl
::::>
II-
c:(
.....J
LONGITUDE
100
120
140 160 E
180
W
160
140 120
100
80
60
40
20 0
9
0.-
..
,_.~,._
......
..mi
.......................
A.Z
....
TH
..........................................
A.Z
.... H ..
.,.
.............
.,.
...........................
-~_.llliilp
.........
....,
.....
S'O
80
70
60
50
40
30
20
10
20
30
40
50
60
70
80
AZ
TH
dO
70
to
40
.30
10
Lu
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0
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l·-
1 ()
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30
AZ
H
90._
..........
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...........
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......... .-... .-... .-.. .-........ .-........
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90
100
120
140
160
E
180 W 160
140
120
100
80
60
40
20
0
20
40
LONGITUDE
WESTERN
SATELLITE
POINTING
ANGLES.
2-5
Included
with
the
antenna
is
a
mounting
flange
with
a
shaft
attached
to
allow
versatile
tipping
as
well
as
rotation
for
proper
antenna
pointing.
The
stand
also
allows
attachment
of
this
antenna
to
a
flat
surface
for
mounting.
See
Section
VII.
2-6
Once
the
mounting
and
pointing
of
the
antenna
is
com-
plete,
attach
a
lead
in
coax.
For
this
purpose
RG-58/U
is
avail-
able
from
Kinemetrics/Truetime
in
50'
and
100'
lengths.
2-7
RACK
MOUNTING
2-8
If
it
is
desired
to
mount
the
Model 468-DC
in
a
stan-
dard
19"
rack
system,
use
the
rack
mounting
ears
provided
with
the
unit.
These
ears
may
be
attached
to
the
side
of
the
cabinet
~y
removing
the
two
8-32
flat
head
screws
on
the
side
of
the
instrument
and
placing
the
screws
through
the
counter-sunk
hole
in
the
bracket
and
re-installing
the
screw.
The
unit
now
may
be
mounted
in
a
1-3/4"
opening
in
any
EIA
standard
19"
rack
system.
2-9
INSTRUMENT
START-UP
2-10
After
the
antenna
installation
is
complete,
as
de-
scribed
in
SECTION
II,
entitled
"Antenna
Installation"
above,
the
lead-in
coax
should
be
connected
to
the
rear
panel
BNC
connector
labeled
"ANTENNA".
Connect
the
power
cord
to
the
socket
on
the
rear
panel
and
plug
the
unit
into
an
appropriate
power
source.
The power
switch
on
the
front
panel
may
now
be
turned
on.
2-11
When
the
power
is
turned
on,
the
initial
indication
of
proper
operation
of
the
Model 468-DC
is
the
colons
on
the
display.
The
colons
will
blink
off
and on
at
about
once
per
second.
This
indicates
to
the
user
that
the
unit
is
operating
properly
and
that
the
receiver
is
looking
for
phase
lock
to
the
carrier
of
the
signql
and
then
to
the
100
Hz
data
rate
of
the
information
broadcast.
Next,
after
the
468-DC
has
read
and
recognized
the
maximum
length
sequence
(MLS)
transmitted
each
1/2
second,
the
colons
will
be
locked
on
solid.
2-12
Following
this
data
lock,
the
synchronized
clock
will
recognize
that
it
is
reading
data,
a
satellite
location
(as
transmitted
in
the
message)
will
be
read.
From
this
information,
the
468-DC
can
determine
if
it
is
locked
to
the
"EAST"
OR
"WEST"
Satellite
and 1
ight
the
appropriate
"LED" on
the
front
panel.
2-13
Finally,
after
two 30
second
long
time
frames
of
infor-
mation
of
the
time
of
year
have
been
read
which
agree
as
to
the
time,
the
front
panel
display
will
light
indicating
the
correct
time
of
year.
At
this
same
time,
any
options
which
have
been
ordered
to
electrically
output
the
time
will
begin
to
function.
2-14
One
of
the
most
often
overlooked
and
yet
most
important
factors
in
the
installation
and
operation
of
the
Model 468-DC
is
proper
antenna
installation.
Without
a
proper
antenna
installation,
the
signal
from
the
satellite
will
not
be
received
and
thus
the
unit
cannot
possibly
function
properly.
In
many
2-4
case
s
11
j us t
to
tr
y
it
out
11
, an
at
tempt
w i 11
be
mad e to
ope r ate
the
unit
with
the
antenna
inside
a
building
or
without
determining
the
proper
antenna
pointing
angle.
This,
as
often
as
not,
results
in
inability
to
lock
to
the
satellite
signal,
and
failure
to
decode
the
time.
2-5
3-1
INTRODUCTION
SECTION
III
OPERATION
3-2
The
Model
468-DC
Synchronized
Clock
provides
the
user
with
a
means
of
obtaining
time
traceable
to
the
U.S.
National
Bureau
of
Standards
with
an
accuracy
of
+L5msy
For
stability,
the
time
base
is
phase-locked
to
the
satellite
data
rate.
The
time-of-year
information
broadcast
by
The
National
Oceanic
and
Atmospheric
Administration
through
the 11GOES
11
Satellite
is
dis-
played
in
days,
hours,
minutes
and
seconds
on
the
front
pan~l.
Also
available
are
outputs
of
this
time
information
in
the
form
of
Remote
Display
Driving
Output
(IRIG-B,
Parallel
BCD
Time,
or
RS-232C
compatible
interface,
or
IEEE-488
compatibility).
The
Model 468-DC
has
been
specifically
designed
to
minimize
operator
set-up
and
will
provide
many
years
of
service
without
attention.
3-3
SATELLITE
EAST-WEST
LED
3-4
Located
on
the
lower
left
hand
corner
of
the
front
panel
are
two LED's
labeled
"Satellite",
"WEST"
or
"EAST".
These
green
LEDs
will
light
anytime
the
unit
is
receiving
a
sufficient
signal
from
one
of
the
satellites
to
allow
the
internal
time
base
to
phase
lock
to
data
frequency
of
100
Hz. When
the
unit
is
initially
turned
on,
if
adequate
signal
is
present,
this
LED
will
light
within
30
to
45
seconds.
If,
during
the
course
of
opera-
tion,
phase
lock
with
the
satellite
is
lost
long
enough
for
the
R.F.
Circuits
to
sweep
for
phase
lock,
(about
150
seconds),
this
light
will
go
out.
When
phase
lock
is
regained
and a satellite
position
is
recognized
in
the
data,
the
appropriate
LED
will
again 1 ight.
3-5
Phase
lock
will
be
maintained
continually
in
most
areas
and
the
only
occasion
for
loss
of
lock
will
be
experienced
due
to
local
noise
interference.
The
most
common
source
is
"land
mobile"
transmitters
on
a
frequency
of
468.8250
MHz
which
is
directly
on
the
Western
Satellite
frequency.
3-6
The
Satellite
LED
also
provides
information
as
to
the
Satellite
position.
If
the
468-DC
is
able
to
read
the
time
of
ye
a r
in
for
m a t
ion
b u t t
he
s a t e
11
i t e po s i t i
on
in
form
a t i o nr e ad
in
code
does
not
agree
with
the
position
shown
on
the
propagation
determination
maps,
(FIGURES
3-1
and
3-2),
the
LED
will
blink.
If
the
R.
F.
carrier
on
which
the
time
data
was
found
is
on
the
468.8250
MHz
frequency,
the
West
LED
will
blink,
if
on
468.8375
MHz,
the
East
LED
will
blink.
This
indicates
to
the
user
which
S3tellite
is
being
received,
but
that
propagation
delay
informa-
tion
may
be
incorrect
and
exact
satellite
position
should
be
determined
if
accuracies
to
the
millisecond
level
are
desired.
Satellite
LED
blinking
also
occurs
when
the
unit
is
in
"Auto-
matic"
satellite
selection,
the
468-DC
has
swept
to
the
other
3-1
L.U
I
N
w
Cl
:::>
tt-
c:(
_J
LONGITUDE
100 120 140
160
E 180 W 160 140 120 100 80
60
40
20
0
20
40
90
...........................................................................................................................................................................
.,.
..........
90
50
20
10
w
Cl
::::>
0
I-
l-
*---l+---+-~-+--fll~-++--+--++~~~+-+--4f---+~-+-~-+-~~~+--~t----1'-~--
1 o
:3
20
50
90
...........................................................................................
1111111111
...................................................................................
90
100 120
140
160 E 180 W 160 140
120
100 80
60
40
20
0
20 40
LONGITUDE
FIGURE
3-1
WESTERN
SATELLITE
MEAN
DELAYS
VJ
I
VJ
LaJ
0
:::;:)
II-
c(
....J
LONGITUDE
100
120
140
160 E 180 W 160
JL40
120
100
80
bO
40
0 20
40
90
.......................
--i,_.
......
..,.
................
,...
........................................................
,...
.............................. ~ ..................
l
.....................
~.90
80
60
50
40
10
40
10
LaJ
0
:::;:)
0
I-
40
50
60
90
.........................................................................................................................................................
l
.............................................
90
100
120
140
160 E 180 W 160 140 120 100 80 60 40 20 0 20 40
LONGITUDE
FIGURE
3-2
EASTERN
SATELLITE
MEAN
DELAYS
satellite,
but
complete
time
synchronization
is
not
complete.
This
usually
requires
less
than
15
minutes
to
accomplish
and
then
clears
the
blinking.
3-7
DISPLAY
3-8
The
front
panel
display
of
time
is
blank
when
the
unit
is
initially
turned
on,
because
the
correct
time
is
not
known.
The
time
information
broadcast
by
the
"GOES"
Satellite
is
repeated
every
30
seconds.
The
time
in
format
ion
is
broadcast
in
the
first
11
seconds
of
each
half
minute.
Requirements
for
the
display
to
light
are:
1)
the
unit
must
obtain
phase
lock
with
the
carrier
of
satellite,
2)
phase
lock
with
the
lOOHz
data
rate
must
be
obtained,
and 3)
two
consecutive
frames
of
time
code
must
be
read
which
agree
as
to
the
time.
When
these
three
er
iter
ia
are
met,
the
display
will
light
showing
the
correct
time
in
days,
hours,
minutes,
and
seconds,
Universal
Coordinated
Time
(UTC)
more
commonly
referred
to
as
Greenwich
Mean Time
(GMT).
Correc-
t
ion
to
local
time,
conversion
to
a
12-hour
clock
in
place
of
the
24-hour
time
base
as
transmitted
and
correct
ion
for
propagation
delay
are
covered
in
the
following
sections.
3-9
The
display
has
been
designed
to
indicate
to
the
user
the
accuracy
of
the
time
information
being
displayed
and on
the
time
output
lines
if
ordered.
After
the
display
turns
on
it
will
indicate
the
worst
case
accumulated
drift
of
the
time
information
should
phase
lock
with
the
satellite
be
lost.
When
the
unit
has
accumulated
loss
of
lock
for
13.9
hours
since
the
last
synchro-
nization
to
+Sms.,
the
colons
will
flash.
The
flashing
colons
indicate
that-the
estimate
of
the
worst-case
error
of
the
display
and
outputted
time
is
+SOms.
of
N.8.S.
time.
When
the
unit
has
been
in
operation
for
T38.9
hours
without
phase
lock
since
the
last
synchronization,
the
complete
display
will
flash.
This
flashing
is
certain
to
attract
the
operators
attention
and
indi-
cates
that
the
time
as
displayed
and
outputted
may
have
a
worst-
case
error
of
more
than
~SOOms.
(1/2
second).
3-10
Display
or
colon
flashing
will
stop
when
the
signal
from
the
satellite
is
regained,
phase
locked
to
and
the
time
code
is
read.
Under
normal
operation
this
will
occur
without
operator
attention.
It
is
very
unlikely
that
either
of
these
conditions
will
occur
under
normal
conditions.
Due
to
the
ability
of
the
unit
to
phase
lock
to
the
carrier
frequency
down
to
very
low
signal
levels,
persistent
flashing
of
the
colons
or
di
splay
may
be
an
indication
of
poor
reception
due
to
local
interference
or
antenna
location
and/
or
installation.
Refer
to
SECTION V "Ma
in-
tenance
and
Troubleshooting"
for
additional
information
on
this
subject.
3-11
HOURS
OFFSET
3-12
Located
on
the
rear
panel
is
a
thumbwheel
switch
la-
beled
"HOURS
OFFSET".
This
switch
is
set
for
"O"
at
the
factory
which
means
that
the
displayed
time
will
be
Coordinated
Universal
Time
as
broadcast.
To
change
the
hours
on
the
display
to
read
3-4
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