DSC PROCEDURE
After the initial distress alert and acknowledgement subsequent communications are made by radio telephony or narrow band printing ( nbdp ) as indicated in the distress message. Note that voice transmissions are not permitted on the DSC channels
You need to tune your receiver 1.7 khz below the assigned frequency, unless you are using a receiver that has a different ofset/display method, the target communication receiver springs to mind with the dial reading 2khz higher than actual frequency. You do need a good receiver for this mode.
|
Frequency |
DSC Frequency |
RX Displayed |
R/T |
NBDP |
RX Displayed |
|
4 MHZ |
4207.5 kHz |
4205.8 kHz |
4125.0 kHz |
4210.0 kHz |
4208.3 kHz |
|
6 MHZ |
6312.0 kHz |
6310.5 kHz |
6215.0 kHz |
6314.0 kHz |
6213.3 kHz |
|
8 MHZ |
8414.5 kHz |
8412.8 kHz |
8291.0 kHz |
8416.5 kHz |
8414.8 kHz |
|
12 MHZ |
12,577.0 kHz |
12575.3 kHz |
12,290.0 kHz |
12,579.0 kHz |
12577.3kHz |
|
16 MHZ |
16,804.5 kHz |
16802.8 kHz |
16,420.0 kHz |
16,806.5 kHz |
16804.8 kHz |
|
22 MHZ |
- |
|
- |
22,376.0 kHZ |
22374.3 kHz |
|
|
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VHF
Ships operating within VHF range can use the DSC calling frequency, 156.525 MHZ (channel 70) for distress alerts and safety calls, and 156.8 mhz (channel 16) for radiotelephone distress and safety traffic
DISTRESS FREQUENCIES
2182 kHz mf
international distress frequency for ship, aircraft and survival craft.
3023 kHz intercommunications between mobile stations engaged in coordination of search and rescue
4125 kHz distress and safety traffic by radiotelephone
5680 kHz intercommunications between mobile stations engaged in coordination of search and rescue
6125 kHz distress and safety traffic by radiotelephone
8364 kHz designated for use by survival craft stations.
DISTRESS
BEACONS
GMDSS makes use of the COSPAS-SARSAT SATELLITE system which provides global detection of 406.025 GHZ EPIRBS.
Some EPIRBS also transmit on 121.5mhz the equipment that detects the 121.5 MHZ signal is due to be phased out shortly, but it will remain an aircraft distress frequency
NAVTEX
NAVTEX which operates on 518 kHz is the chief means of transmitting short range maritime safety information (msi) including navigational warnings, meteorological forecasts and warnings, ice reports, search and rescue information, pilot messages and details of changes to navigational aids. All ships of 300 gross tonnages and above are required to carry a receiver, capable of receiving international navtex broadcasts
