9.4.
NMEA Interface Connection
Using the FMD15 as navigation log or NMEA printer, the NMEA
interface must be connected with an external NMEA device (e.g.
GPS) The TX+ / TX- of the external unit must be connected to the
RX+ / RX- of the FMD15.
9.5.
Antenna and earth connection
The antenna socket is designed to be fitted to a coaxial cable
connection with a BNC plug and impedance of 50
Ω
. No provision
has been made for the connection of high impedance,
unshielded antennæ.
The reception quality depends, to a high degree, on the quality of
the antenna used. A good antenna guarantees good reception.
We recommend the use of a well tuned passive antenna or a high
performance active antenna. Cheap active antenna do not
provide the desired results due to bad cross-modulation
characteristics.
Long wire antenna (e.g. on the back-stay) should be used in
connection with an impedance matching balun transformer.
Important for good reception is of course good earthing of the
ship's power supply and the FMD15. An adequately dimensioned
grounding sponge and properly matched antenna will result in
optimum performance.
For installation recommendations, see the following pages:
