GMDSS (Global Maritime Distress and Safety System) is a worldwide system for handling maritime emergency and safety transmissions. Part of the system is the DSC (Digital Selective Calling).
Each user of the GMDSS is assigned a nine-digit number (MMSI – Maritime Mobile Service Identity) from the mobile maritime service. 3 digits of this number are used as a country code.
|
Parameter |
Value |
|
Frequency range |
VHF/UHF |
|
Operation modes |
Broadcast/Simplex |
|
Modulation |
FM, SUB FSK |
|
Symbol rate |
1200 Bd |
|
Center frequency |
1700 Hz |
|
Shift/Bandwidth |
800 Hz |
|
Receiver settings |
FM, BW = 12 kHz |
|
Input format(s) |
AF, IF |
|
Additional Info |
ITA-5 |
DSC is used on HF and VHF. On VHF the symbol rate is 1200 baud and the center frequency is 1700 Hz and the shift is 800 Hz.
Selecting Options/Display offers the option of an ASCII or RAW bits display.
The complex structures of the DSC are described in detail in the ITU-Rec. M.493-11.