Nera F77 User manual

Nera F77
Installation Manual
May 01 09:15
4.8 Speech
ALPHA
ISDN
Saturn F
Nera F77
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© Nera SatCom AS, 2002
A MEMBER OF CIRM
Safety Warnings, Cautions and Warranty
General
To avoid interference, do not run cables parallel to AC wiring, or near fluorescent lights or
other high magnetic or electrical fields. Interference from this kind of sources causing
equipment to be faulty or fail working properly will automatically void warranty conditions.
Access to the interior of the equipment shall be made by a Nera qualified technician only.
The equipment shall be installed by a Nera SatCom approved Installation & Service Agent.
Warranty is not valid until the "Nera Satcom AS Warranty Certificate" (at the back of the
Registration and Warranty Certificate booklet enclosed with the equipment) is signed by the
approved Installation & Service Agent, and returned to Nera SatCom.
Grounding
Grounded AC power socket shall be installed near the equipment and shall be easily acces-
sible. Connection to all type of equipment meant for operation of the unit must be done
while the unit is powered off. Peripheral equipment using mains shall be connected to a
grounded AC power socket.
Cables and connections
Cables must be shielded. The shield must be grounded at both ends. All peripheral equip-
ment must be grounded.
Cable lengths exceeding those specified for the equipment interface and connectors, will
automatically void warranty conditions.
- ISDN telephone 100 m 0.22 mm2 min
- Analogue telephone 150 m 0.22 mm2 min
- USB
- RS-232 3 m
- RS-422
Cable lengths beyond their maximum require special arrangements, cable extenders, short
haul modems etc.
Connection of two (2) analogue telephone instruments in parallel is not acceptable.
Ventilation of the Below Deck Equipment
Ambient temperature range: 0 - 45oC.
To ensure adequate cooling of the MCU a 10 cm unobstructed space must be
maintained above and below the unit.
When wallmounted, ensure sufficient space above the MCU to permit removal of the
Modem Unit and Power Supply Unit. See "Placing the Main Communication Unit (MCU)".
Failure to comply with the above rules for installation will automatically void the
warranty.

3
Nera F77
Continuing the Saturn tradition
Nera SatCom AS reserves the right to change the design and specifications of the equipment without notice.
Below Deck Equipment - BDE .................................................................. 4
Above Deck Equipment - ADE .................................................................. 5
Placing the Antenna .................................................................................. 6
Designing the Antenna mast ..................................................................... 8
Outline dimensions of Antenna radome (mast mounted version) ............. 9
Outline dimensions of Antenna radome (deck mounted version) ............ 10
Physical characteristics of main units ..................................................... 11
MCU connectors ..................................................................................... 13
Upper connector panel ........................................................................... 13
MCU connectors ..................................................................................... 14
Lower connector panel ........................................................................... 14
Example of BDE installation ................................................................... 15
Example of Nera F77 installation cabling arrangement ........................... 16
Placing the Main Communication Unit (MCU) ......................................... 17
Placing the Distress Alarm Unit & ISDN Handset ................................... 17
Placing the ISDN Handset as a standard telephone ............................... 17
Placing the telefax (option) ..................................................................... 18
Placing the PC (option) ........................................................................... 18
Placing analogue telephones (option) ..................................................... 18
Grounding considerations ....................................................................... 19
Laying cables .......................................................................................... 21
Telephone wiring .................................................................................... 22
Unpacking .............................................................................................. 23
Installing the Above Deck Equipment (ADE) ........................................... 23
Mast mounted version ............................................................................ 23
Deck mounted version ............................................................................ 24
ADE - Connecting coaxial cable to Mast Mounted Antenna .................... 25
ADE - Connecting coaxial cable to Deck Mounted Antenna ................... 26
Installing the Below Deck Equipment (BDE) ........................................... 27
Location and grounding of units .............................................................. 27
BDE - Example of local or near-by installation ........................................ 28
BDE - Example of remote installation ..................................................... 29
Connection Box QUFC 911 918 (option) ................................................ 30
Nera ISDN Handset ................................................................................ 31
Handset holder/cradle ............................................................................ 31
Mounting the Main Communication Unit (MCU) ...................................... 32
BDE - Connecting the coaxial cable to the MCU..................................... 33
Examples of Below Deck Equipment ...................................................... 34
ISDN telephones/equipment ................................................................... 35
ISDN cable lengths ................................................................................. 35
ISDN wall socket .................................................................................... 36
Distress Alarm Unit ................................................................................. 37
ISDN bus termination ............................................................................. 37
Analogue telephones .............................................................................. 38
Wall socket for analogue telephone/telefax gr.3 (option) ........................ 38
PC - asynchronous data communication ................................................ 39
NMEA-0183 input sources (complies with IEC 61162-1) ........................ 40
Mounting connector type 11N-50-3-54 (for cable RG223/U) ................... 41
Mounting connector type 11N-50-7-5 (for cables RG214/Ethernet 06230) .......... 42
Mounting connector type 11N-50-10-4 (for cable S10172 B-11) ............. 43
Mounting connector type 11N-50-12-10 (for cable RF 1/2" 50) ............... 44
Mounting connector type 11N-50-23-10 (for cable RF 7/8" 50) ............... 45
Mounting connector type 11N-50-32-2/11N-50-42-2 ............................... 46
(for cables RF 1 1/4"/15/8" 50) ................................................................ 46
Main items .............................................................................................. 47
Cable pinouts .......................................................................................... 49
Reception of L-band Broadcast signals .................................................. 51
Azimuth Angle Map ................................................................................. 52
Elevation Angle Map ............................................................................... 52
SYSTEM
PLANNING
INSTALLATION
CONTENTS
Rev Date: October 2002 Publication No.: 101442 (PA11)
APPENDIX 1-6
APPENDIX 7
APPENDIX 8
APPENDIX 9
APPENDIX 10

4
Installation Manual
Nera F77
Continuing the Saturn tradition
SYSTEM
ISDN Handset
Main Communication Unit MCU
7
4
1
3
6
9
DEL
2
5
8
0
DIAL 00+INTL
TEL.NO.+
ON
SHIFT
asic Equipment
Accessories
Distress Alarm
Additional
ISDN Handsets
7
4
1
3
6
9
DEL
2
5
8
0
DIAL 00+INTL
TEL.NO.+
ON
SHIFT
Analogue telephones
(wall or desk)
Telefax
(Group 3 or 4)
ISDN telephones Additional
Distress Alarm
DISTRESS
Saturn F
PC
DISTRESS
Saturn F
Below Deck Equipment - BDE
Main Control Unit The Nera F77 Main Communication Unit (MCU) - which
constitutes the major electronic part - is designed for wall or
desktop installation. The MCU supplies 48 VDC power to the
ADE through the coaxial cable.
The MCU mains input is 100 - 240 VAC ±10%. The power
requirement is approx. 40 W in receive/idle mode, and
approx. 150 W in transmit mode.
A CD supplied with the equipment contains a program for
control and operation from PC. See the Nera F77 - User
Manual.
ISDN Handset The ISDN Handset keypad and built-in display allows dialing
and control of the MCU and antenna.
Distress Alarm The Distress Alarm Unit provides remote activation of an
alert transmission and indication of incoming distress calls.
Options •Additional ISDN Handsets
•ISDN telephones
•Analogue DTMF telephones
•Group 3 and Group 4 telefax
•PC
•Additional Distress Alarm Unit (DA)

5
SYSTEM
Nera F77
Continuing the Saturn tradition
Antenna Dish
Servo Stabilized
Pedestal
GPS Receiver
Rotary Joint
Access Hatch
(mast mounted
version only)
RF-Transceiver
Above Deck Equipment - ADE
The Nera F77 Above Deck Equipment consists of:
• Servo stabilized antenna dish with RF-Transceiver
• Mast mounted radome, or
• Deck mounted radome
BDE - ADE Coaxial Cable
Mast mounted radome
(cutaway view)
Deck mounted radome
(cutaway view)
Total of equipment connected:
7ISDN devices
2 Distress Alarm Units
4 Analogue devices
2 Serial PCs
1 USB device

6
Installation Manual PLANNING
Nera F77
Continuing the Saturn tradition
FREE ADMITTANCE AT
DECK LEVEL AT LEAST
2 M ELOW RADOME
MICROWAVE RADIATION !
NO ADMITTANCE WITHIN 5 M
Based on
8 W/m
2
Placing the Antenna
Radome type Nera F77 is delivered either with mast mounted or deck
mounted radome. See previous page.
The mast mounted version includes a hatch which provides
access for service and repair, whereas the deck mounted
version must be lifted down.
Avoiding obstructions The antenna has a beamwidth of ±7.5 degrees (at 3 dB points)
and ideally requires a free line of sight in all directions above an
elevation angle of +5 degrees.
Any obstruction will cause blind sectors, resulting in signal
degradation or even loss of communication with the satellite.
Degradation of the satellite signal can only be completely
avoided by placing the antenna higher than any obstructions.
This is often not feasible and a compromise must be made to
reduce the number of blind sectors and cost of installation.
The degree of signal degradation depends on the size of the
obstructions; the distance to them must therefore be consid-
ered.
Preferably, all obstructions within 3 m of the antenna should be
avoided. Obstructions less than 15 cm in diameter can be
ignored beyond this distance.
Radiation precautions Passengers should not be admitted in areas closer than 5 m
from the antenna.
However, no restrictions are required when the antenna radome
is installed at least 2 m above the highest point accessible to
passengers.
Personnel should not be close to the antenna for periods of
more than 1 hour per day without switching off the RF transmit-
ter.

7
PLANNING
Nera F77
Continuing the Saturn tradition
Avoiding interference Do not locate the antenna close to interfering signal sources, or
in such a position that the source (e.g. radar-antenna) radiates
directly into the Saturn antenna.
The Above Deck Equipment (ADE) should be separated as far
as possible from other transmitters, and preferably by at least
5 m from the antenna of other communication or navigation
equipment, such as the antenna of the satellite navigator, the
VHF antenna or radar equipment.
Compass safe distance For installation on British or Norwegian vessels, the antenna
should be located at a distance of at least 1.0 metres from the
magnetic steering compass. Be aware that requirements may
vary from one country to another.
Other precautions Do not place the antenna close to the funnel, as smoke depos-
its will then eventually degrade antenna performance.
The antenna should be installed so that severe vibration and
shock are avoided.
If installed on top of a signal and radar mast, the mast must be
supported by stays.
10 CM
RADAR
AVOID INTERFERENCE
E.G. FROM THE RADAR
10°
10°

8
Installation Manual PLANNING
Nera F77
Continuing the Saturn tradition
HOLE
DIA 22 MM
LONGITUDINAL
AXIS OF SHIP
10 MM STEEL PLATE
ANTENNA
UNIT
ACCESS
HATCH
MAST
FLANGE
330MM247.5MM
350 MM
247.5MM
330 MM
Antenna Unit Mounted on Mast
Designing the Antenna mast
The mast must be designed to carry the weight of the antenna
unit, approximately 65 kgs. It must be able to withstand wind
forces of up to 120 knots on the radome as well as the onboard
vibration levels. The radome is 1.080 m high and has a maxi-
mum diameter of 1.312 m.
The top end of the mast should be fitted with a flange with holes
matching the bolts extending from the bottom of the radome.
See figure below. The flange must not be so large as to inter-
fere with the hatch at the bottom of the antenna unit. The holes
through the mast flange must be positioned symmetrically
about the ship’s longitudinal axis.
NOTE: On ships with excessive vibration the mast must be
supported by stays or other adequate means.
If the height of the mast makes it necessary to climb up to the
antenna unit, a ladder must be provided on the mast column. A
guard rail must be attached to the upper section for safety
purposes. If the height of the mast exceeds approximately 4.5
metres, an access platform should be attached to the mast
approximately 1 metre below the radome bottom.
Be aware that requirements may vary from one country to
another.

9
PLANNING
Nera F77
Continuing the Saturn tradition
ANTENNA
MOUNTING
STUDS (4), M16
1312 MM
1080 MM
1200 MM
ACCESS
HATCH
SEEN FROM ELOW
480MM
330MM
60MM
DRAIN
HOLE
LIFTING
LUGS (4)
Outline dimensions of Antenna radome (mast mounted version)
2000MM
6 00MM
DIA 140MM
CA LE
SUPPORT
Optional steel
Antenna Mast, R906569
Weight: 85 kgs
For welding onto deck
Weight: approx. 65 kgs

10
Installation Manual PLANNING
Nera F77
Continuing the Saturn tradition
Outline dimensions of Antenna radome (deck mounted version)
925 MM
1047 MM
SEEN FROM BELOW
350 MM
247.5MM
247.5MM
ANTENNA
MOUNTING
STUDS (4), M12
DRAIN HOLE
COAXIAL
CABLE ENTRY
Weight: approx. 45 kgs

11
PLANNING
Nera F77
Continuing the Saturn tradition
Nera F77
ISDN Handset
101654
Handset holder/cradle
QSXA911394
(for ISDN Handset)
22.5
40
37.5
15 1530
61 mm
22 mm
100 mm
FUNC
ALPHA
ENTER
SHIFT
MORE/
HELP
LES
PTT
ESC
7
STU
DATA
Ø.
4
JKL
1
ABC
LIST
LIST
3
GHI
6
PQR
9
LIGHT
YZÆ
SPC
ON/OFF
DEL
2
DEF
PLAY
5
MNO
8
VWX
TAX
0
ÄÖÜ
ON
SHIFT BAT
ALPHA
DIA 00+INT
TE .NO.+
56 mm
2000 mm
215 mm
RJ45
45
mm
Distress Alarm Unit
100154
45
45
56.5 56.5115
35 mm
90 mm
228 mm
DISTRESS
Saturn F
372.5mm
380mm
70mm
Weight: 0.3 kg Weight: 0.06 kg
Weight: 4 kg
Main Communication Unit (MCU)
100141
Weight: 0.3 kg
25
165
25
165
Dia 6mm
322.5 25
25
Physical characteristics of main units

12
Installation Manual PLANNING
Nera F77
Continuing the Saturn tradition
Physical characteristics of main units cont'd
Analogue telephone/telefax
wall socket
(option)
R 906 676/1
20
20
125
2020 160
Connection box
(option)
QUFC 911 918
200 mm
50 mm
170 mm
ISDN wall socket
(option)
102176
70 mm
82 mm
30 mm
ISDN junction box
(option)
102124
Nera Ter inal Adapter
Analogue-to-ISDN TA with
2 analogue lines (option)
QDGY911914
TEL1 POWER TEL2
142mm
148mm
30mm
50 mm
57 mm
20 mm
9
0 mm
90 mm
48 mm
Weight: 0.6 kg
Weight: 0.1 kg

13
PLANNING
Nera F77
Continuing the Saturn tradition
O I
100-240 VAC
RF
SIM CARD ROAD AND
(DGPS)
WHEN CHANGING MODEM UNIT
AND TAKE OUT SIM CARD
REMOVE COVER
SIM CARD INSIDE
POWER ON/OFF SWITCH FUSES
INDICATOR
100-240 AC MAINS SIM CARD L- AND ANTENNA
CONNECTOR (inside cover) OUTPUT CONNECTOR
MCU connectors
Upper connector panel
For lower panel,
see next page

14
Installation Manual PLANNING
Nera F77
Continuing the Saturn tradition
MCU connectors
Lower connector panel
TEL 4
ISDN
RS-422
TEL 2
ISDN
ISDN ISDN
ISDN
SILENCE
SW
IND
NMEA
NMEA
TEL 1
TEL 3
ISDN ISDN
TEL 3 USB
TEL 4
ISDN
TX
TX
RX
RX
TEL 4
TX
TX
RX
RX
TX
TX
RX
RX
TX
TX
RX
RX
TX
TX
RX
RX
RS-232
B
RS-232
A
RS-232:
9-pin serial data ports for:
 operation and
configuration from PC.
 software download
 64kbps data service ( DI)
 MPDS
USB:
serial data port for:
 operation and configuration
from PC.
 64kbps data service ( DI)
 MPDS
ISDN:
Connectors/RJ45
Services:
 4.8kbps compressed speech
 64kbps speech
 64kbps data service ( DI)
 56kbps data service (V110)
 64kbps audio service (3.1kHz)
Note! Use shielded ISDN cable
Screw terminal locks TEL 1 - 4, and
RJ45 connectors TEL 3 - 4:
Connection of 2W analogue telephones and
G3 fax
NMEA:
Connection of
NMEA-183
heading input
SILENCE:
Connection of
"Radio Silence
Box"
RS-422:
serial port for
connection of
data equipment
with up to 100
metres cables.

15
PLANNING
Nera F77
Continuing the Saturn tradition
Telefax
Distress
Alarm
PC
Ground foil
ISDN bus
Analogue tel/fax
ISDN
Handset
Distress
Alarm
Analogue
Telephone
Remote installations Remote installations
RF cable
to/from
Antenna
Main
Communication
Unit
ISDN
Handset
DISTRESS
Saturn F
DISTRESS
Saturn F
7
4
1
3
6
9
DEL
2
5
8
0
DIAL 00+INTL
TEL.NO.+
ON
SHIFT
7
4
1
3
6
9
DEL
2
5
8
0
DIAL 00+INTL
TEL.NO.+
ON
SHIFT
Example of BDE installation

16
Installation Manual PLANNING
Nera F77
Continuing the Saturn tradition
Example of Nera F77 installation cabling arrangement
The installation includes five Nera ISDN Handsets (two w/Distress Alarm Unit), Group 3 and 4
telefaxes, PC w/printer, Data Equipment and two Analogue Telephones.
TEL 4
ISDN
RS-422
TEL 2
ISDN
ISDN ISDN
ISDN
SILENCE
SW
IND
NMEA
NMEA
TEL 1
TEL 3
ISDN ISDN
TEL 3 US RS-232
TEL 4
RS-232
A
ISDN
TX
TX
RX
RX
TEL 4
TX
TX
RX
RX
TX
TX
RX
RX
TX
TX
RX
RX
TX
TX
RX
RX
FUNC
ALPHA
ENTER
SHIFT
MORE/
HELP
LES
PTT
ESC
7
STU
DATA
ØÅ.
4
JKL
1
A C
LIST
LIST
3
GHI
6
PQR
9
LIGHT
YZÆ
SPC
ON/OFF
DEL
2
DEF
PLAY
5
MNO
8
VWX
TAX
0
ÄÖÜ
ON
SHIFT AT
ALPHA
DIAL 00+INTL
TEL.NO.+
FUNC
ALPHA
ENTER
SHIFT
MORE/
HELP
LES
PTT
ESC
7
STU
DATA
ØÅ.
4
JKL
1
A C
LIST
LIST
3
GHI
6
PQR
9
LIGHT
YZÆ
SPC
ON/OFF
DEL
2
DEF
PLAY
5
MNO
8
VWX
TAX
0
ÄÖÜ
ON
SHIFT AT
ALPHA
DIAL 00+INTL
TEL.NO.+
FUNC
ALPHA
ENTER
SHIFT
MORE/
HELP
LES
PTT
ESC
7
STU
DATA
ØÅ.
4
JKL
1
A C
LIST
LIST
3
GHI
6
PQR
9
LIGHT
YZÆ
SPC
ON/OFF
DEL
2
DEF
PLAY
5
MNO
8
VWX
TAX
0
ÄÖÜ
ON
SHIFT AT
ALPHA
DIAL 00+INTL
TEL.NO.+
FUNC
ALPHA
ENTER
SHIFT
MORE/
HELP
LES
PTT
ESC
7
STU
DATA
ØÅ.
4
JKL
1
A C
LIST
LIST
3
GHI
6
PQR
9
LIGHT
YZÆ
SPC
ON/OFF
DEL
2
DEF
PLAY
5
MNO
8
VWX
TAX
0
ÄÖÜ
ON
SHIFT AT
ALPHA
DIAL 00+INTL
TEL.NO.+
PCPC
Radio Room
ridge
Owner's Cabin Captain's Cabin
Saloon
Analogue
telephone
Connection ox
QUFC 911 918
Nera ISDN Handset
Analogue
telefax (G3)
MCU CONNECTOR PANEL
Analogue
telephone
Nera
ISDN
Handset
Nera
ISDN
Handset
Nera
ISDN
Handset
Digital
telefax (G4)
Digital
telefax (G4)
PC
X
X
X
X
Nera
ISDN
Handset
Saturn F
DIAL 00+INTL
TEL. NO.+
13
456
789
0
A C
2
DEF
DATA
GHI
JKL MNO PQR
STU VWX
TAX LIGHT
YZÆ
SPCØÅ.
PLAY
ÄÖÜ
ESC
DEL
ON/OFF LIST
LIST
FUNC ALPHA ENTER
SHIFT MORE/
HELP LES PTT
ON
SHIFT AT
ALPHA
Distress Alarm
Distress Alarm
Nera ISDN
Nera ISDN
Saturn F

17
PLANNING
Nera F77
Continuing the Saturn tradition
Placing the Main Communication Unit (MCU)
The Main Communication Unit should be placed in a ventilated
area. To ensure adequate cooling of the MCU a 10 cm unob-
structed space must be maintained above and below the unit.
A space of 10 cm above the
MCU is also required to
allow removal of units.
For grounding, see
"Grounding considera-
tions" and "Location and
grounding of units".
Ambient temperature range
0O-45
OC.
The MCU is manufactured as
a cabinet for wall or desktop
installation with dimensions
as shown. Six holes through
the MCU mounting plate
allows the unit to be secured
to the wall or desk top.
Placing the Distress Alarm Unit & ISDN Handset
The Distress Alarm Unit is operated in
conjunction with an ISDN Handset.
The ISDN Handset functions as a display
and communication unit for alert trans-
mission. It may also be used for normal
voice communication.
Up to two (2) Distress Alarm Units &
ISDN Handsets may be connected in
series. The units may be installed any-
where onboard the vessel.
Four separate ISDN ports are available
on the MCU as RJ45 jacks or screw
terminal blocks.
Max cable length: 100 m, 4 x 0.22 mm2.
See "ISDN telephones/equipment"
Placing the ISDN Handset as a standard telephone
The Nera ISDN Handsets may be installed as
standard telephones. The units may be in-
stalled anywhere onboard the vessel.
Four separate ISDN ports are available on the
MCU as RJ45 jacks or screw terminal blocks.
372.5mm
380mm
70mm
10 cm
free
space
10 cm
free
space
DISTRESS
Saturn F
FUNC
ALPHA
ENTER
SHIFT
MORE/
HELP
LES
PTT
ESC
7
STU
DATA
ØÅ.
4
JKL
1
A C
LIST
LIST
3
GHI
6
PQR
9
LIGHT
YZÆ
SPC
ON/OFF
DEL
2
DEF
PLAY
5
MNO
8
VWX
TAX
0
ÄÖÜ
DIAL 00+INTL
TEL.NO.+
ON
SHIFT AT
ALPHA
FUNC
ALPHA
ENTER
SHIFT
MORE/
HELP
LES
PTT
ESC
7
STU
DATA
ØÅ.
4
JKL
1
A C
LIST
LIST
3
GHI
6
PQR
9
LIGHT
YZÆ
SPC
ON/OFF
DEL
2
DEF
PLAY
5
MNO
8
VWX
TAX
0
ÄÖÜ
DIAL 00+INTL
TEL.NO.+
ON
SHIFT AT
ALPHA

18
Installation Manual PLANNING
Nera F77
Continuing the Saturn tradition
Placing the telefax (option)
A digital telefax (Group 4) can be con-
nected to one of the ISDN outlets, or to
an ISDN bus for transfer at 64 kbps rate.
An analogue telefax (Group 3) should
be connected to the FAX (GR3) outlet,
providing up to 28.8 kbps transfer
speed.
Placing the PC (option)
A PC w/ISDN card can be con-
nected to one of the ISDN outlets,
or to an ISDN bus for 64 kbps rate
data communication for installation
up to 100 m away from the MCU.
With the PC connected to the USB/
RS-232/RS-422 port it can also be
used for control and configuration
of the Main Communication Unit.
This requires that the vtLite Marine
program accessible on the Nera F77 CD is installed.
Connection to the USB/RS-232/RS-422 port also allows
64 kbps data transmission.
See the User Manual.
Cable lengths:
• ISDN port: see "ISDN telephones/equipment"
• USB port: 1.5 m, see "Appendix 8"
• RS-232 ports: 3 m, see "Appendix 8"
• RS-422 port: 100 m
Placing analogue telephones (option)
Analogue 2-wire telephones can be installed
anywhere onboard the vessel.
Four separate analogue ports TEL1-TEL3
and FAX (GR.3) are available on the MCU.
TEL3 and FAX (Gr.3) are in addition avail-
able as RJ45 jacks.

19
PLANNING
Nera F77
Continuing the Saturn tradition
Grounding considerations
A successful installation of a maritime satellite terminal must take
into account the noisy environment in which the equipment shall
operate.
Electrical noise The electrical environment on board a ship is usually quite noisy.
Powerful electrical installations cause voltage variations and
transients, as well as low and high frequency noise. Radio and
radar equipment radiate radio frequency signals which frequently
impregnate cables on board with unwanted interference.
Ground plane Most ships have a steel hull. One should think that the steel
construction of the ship would constitute a good ground plane.
This is often not quite true. Rust, other forms of corrosion, paint
and grease, often prevent a good ground connection. A conse-
quence of this is that high energy power distribution on board a
ship can cause significant ground potential differences.
Antenna unit Adequate grounding of the Antenna Unit depends on the
fastening bolts making good contact with the top flange of
the mast. This is obtained by removing paint and using
enclosed toothed washers and nuts.
Antenna cable The antenna coaxial cable normally has a solid or meshed metal
screen which must be terminated to ground both at the antenna
pedestal and at the MCU. The length of the cable can often be
more than 40 metres. If the ground potential level at the two
points differ, the current passing through the screen of the co-
axial cable can be quite strong. The antenna cable screen consti-
tutes a heavy gauge wire, which is capable of conducting large
amounts of current.
Below Deck Equipment The MCU must be provided with a good electrical connection to
the ship’s hull for grounding. This is obtained by using copper
foil. (See Installation: "Location and grounding of units".)
Length of copper foil/10 cm should not exceed 300 cm. The foil
should be connected to ship's hull (deck or roof) by hard-solder-
ing (or screws) to steel.
Mains power/ground Mains ground is secured to the common grounding point through
the external supply. It is therefore important to use the same
mains branch for additional equipment connected to the MCU
(Fax, PC w/printer etc.).

20
Installation Manual PLANNING
Nera F77
Continuing the Saturn tradition
ma .3m
Desktop
MCU
min.
10 cm
Grounding considerations cont'd
Location of the Below Deck Unit for best possible grounding.
See also INSTALLATION: "Location and grounding of
Units".