3. Decoding of Messages
The FMD15 can store and decipher NAVTEX, MORSE, RTTY and
SITOR codes, which then can be read and/or printed out in plain
language. In radio signal traffic there are many other kinds of
keyed codes. As they are not for use by the general public, they
cannot be decoded by the FMD15.
Weather and navigational warnings for shipping are transmitted
in one of the above-mentioned codes, which can be decoded
by the FMD15.
The signal tone (NF) received is fed to a PLL signal Decoder,
which filters out the audio signals and transforms them into digital
information. This in turn will be converted into legible symbols by
the integrated microprocessor.
The type of code used by the individual station, can be found in
the appropriate manuals for marine radio stations. The codes
used vary:
for MORSE also : CW,A1,A1A, telegraphy
for RTTY also : F1B, telex
for SITOR also : FEC,F1B
3.1Selecting Mode and Decoding
In various manuals, the type of code used by a station is shown
mostly as A1A, F1B etc. The following list is an oversight of types of
transmission generally used in marine radio transmission. The
required adjustments to receiver and Decoder are also listed
