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1st3001001 EN 1_14.docx
1
st
-Relief GmbH
Bank: UniCredit Bank Austria AG
FN: 206478w, HG Wien
Handelskai 388 / Top 632
Swift/BIC: BKAUATWW
VAT No.: ATU 51115305
1020 Vienna, Austria, Europe
IBAN: AT24 1100 0085 7396 5400
Tax No. 014/3645
www.1st-Relief.com
EORI: ATEOS1000001609
2.8
Antenna Installation
2.8.1
GPS Antenna
This is a TNC female bulkhead connector that mounts to the back of the case. This port
provides the 5V DC feed for the active GPS antenna required by the NAUTICAST B2 unit (i.e.
it should incorporate an LNA) and must be suitable for marine shipboard applications (index
of protection, ruggedness, means of mounting, etc.). An antenna should be selected with a
gain (in dB) depending on the length of cable between the antenna and the AIS unit; after
subtraction of cable and connector losses a minimum total gain of 20 dB should be available
at the NAUTICAST B2 unit GPS antenna connector. The GPS antenna to be used for AIS use,
must be a dedicated antenna, i.e. not shared with any other GPS receiver. Installation of the
GPS antenna is critical for the performance of the built in GPS receiver which is used for
timing of the transmitted time slots and for the supply of navigational information should the
main navigational GPS fail.
We strongly recommend that:
The GPS antenna is mounted in an elevated position and free of shadow effect from
the ship’s superstructure.
The GPS antenna has a free view through 360 degrees with a vertical angle of 5 to 90
degrees above the horizon.
As the received GPS signal is very sensitive to noise and interference generated by
other onboard transmitters, ensure that the GNSS antenna is placed as far away as
possible from radar, Inmarsat and Iridium transmitters and that the GPS antenna is
free from direct view of the radar and the Inmarsat beam.
It is also important that the MF/HF and other VHF transmitter antennas are kept as far
away as possible from the GNSS antenna. It is good practice never to install a GNSS
antenna within a radius of 2 meters from these antennas.
2.8.2
VHF Antenna
This is a UHF female bulkhead connector that mounts to the back of the case.
The VHF antenna employed for AIS use:
Must be a dedicated antenna, i.e. not shared with any other VHF transmitter/receiver.
Must be suitable for marine shipboard applications (index of protection, ruggedness,
means of mounting, etc.).
Should be omni-directional and vertically polarized with unity gain (0 dB) with a
bandwidth sufficient to maintain VSWR <1.5 over the frequency range 156 – 163 MHz.
As a minimum the 3dB bandwidth must cover the two AIS channels and the DSC
Channel.
Should be mounted with at least a two meter vertical separation distance from any
other VHF antenna used for speech or DCS communication but see also the section
“Radio Frequency Exposure Warning” below.
2.9
Warnings
Connecting a badly mismatched VHF antenna, leaving the VHF antenna port disconnected,
or shorting the VHF antenna port will activate the VSWR alarm, cause the unit to stop
sending position reports or cause damage to the transponder and activating the red LED.
To meet the requirements for Radio Frequency Exposure it is necessary to install the VHF
antenna correctly and operate the AIS equipment according to the instructions.
The GPS, VHF, power and data cables need to be secured to the bulkhead within 6” to 12”
from the connectors.
