What are the common errors or pitfalls of using DSC on VHF channels?

1 Wrong MMSI number

MMSI or maritime mobile service identity is a unique nine-digit number that identifies your vessel and radio equipment. It is like a phone number for your radio. You need to register your MMSI number with the appropriate authority and program it into your radio. If you enter the wrong MMSI number, you may not be able to send or receive DSC calls correctly. You may also cause confusion or interference to other vessels or stations. Make sure you check your MMSI number before using DSC and update it if you change your radio or vessel.

2 No GPS input

DSC relies on GPS or global positioning system to provide your location and time information. This is especially important for distress calls, as it allows the coast guard and other vessels to locate you quickly and accurately. If your radio does not have a GPS input, you need to connect it to an external GPS device. If your GPS input is not working, you need to check the wiring, the settings and the antenna. You also need to update your position manually every four hours if you are moving.

3 Wrong channel selection

DSC uses different VHF channels for different types of calls. Channel 70 is reserved for distress, urgency and safety calls. Channel 13 is used for bridge-to-bridge communication. Channels 6, 8, 72 and 77 are used for ship-to-ship communication. Channels 9, 16, 67 and 73 are used for calling and switching. You need to select the appropriate channel for your DSC call and follow the instructions on your radio. If you select the wrong channel, you may not be able to reach your intended recipient or you may interfere with other users.

4 No acknowledgement

When you receive a DSC call, you need to acknowledge it by pressing the appropriate button on your radio. This lets the caller know that you have received their message and that you are ready to communicate. If you do not acknowledge a DSC call, the caller may think that you have not received their message and may repeat it or try another channel. This may cause congestion or confusion on the VHF network. You also need to acknowledge a distress call even if you cannot assist, as this helps the coast guard to coordinate the response.

5 No testing

Like any other radio equipment, you need to test your DSC function regularly to ensure that it is working properly. You can do this by sending a test call to a coast station, a nearby vessel or a DSC test box. You should receive a positive acknowledgement or a test reply within a few seconds. If you do not, you need to check your radio settings, your antenna and your power supply. You should also check the battery level of your radio and replace it if necessary. You should not use DSC for testing on channel 70, as this may cause false alarms or interfere with distress calls.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?