311
Figure 3. Scheme of experiment
Taking into account that binary version of MMSI
requires 30 bits [6], an arbitrary word with a length of
32 bits was selected as an embedded data. The word
was continuously transmitted by IC-M330 radio
every second on the background of arbitrarily voice
messages or just pressed PTT button without any
speech accompaniment.
Sampling frequency was chosen to be Fs = 8192 Hz
to get 32 frames per second with a length of one
frame 256 samples.
Voice messages at the receiving side were received
without perceptible distortions. Various
combinations of MMSI data during multiple
transmissions were detected without errors.
5 CONCLUSION
The addressed, properly identified VHF
radiotelephone communication plays an important
role in general maritime safety. Automatic
identification, in turn, ensures efficient messaging
from the very beginning of a radio transmission,
while eliminating the human factor inherent in voice
identification.
AI allows you to identify anonymous,
intentionally compromised and harmful
transmissions such as PTT button falling back in a
VHF transceiver. AI makes possible integrating MMSI
detected data and AIS data for graphic display of the
transmitting station.
The proposed audio watermarking algorithm in
cooperation with GPS synchronization made it
possible practical AI implementation of
radiotelephone messages using standard VHF marine
installations.
Watermark rate 32 bit/s give the possibility
transmitting MMSI every second during the entire
time the push-button is pressed. The transfer of other
data, such as coordinates, is also possible with the
appropriate input.
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