DSC Radio and Pushbutton Distress Calls

Marine DSC radio has several advantages over traditional voice communication, such as:

• It can transmit data digitally, which means it has a longer range, faster speed and clearer quality than analog signals;

• It can send a distress alert with a single button press, which includes your vessel's identity, position and time. This can save precious time and provide accurate information to rescuers in an emergency;

• It can make ship-to-ship calls using a unique 9-digit code called Maritime Mobile Service Identity (MMSI), which allows you to contact a specific vessel without broadcasting over an open channel;

• It can scan multiple channels for distress, urgency and safety messages, and alert you when a message is received.

All new VHF radios sold in the market are equipped with DSC capabilities. You can also buy MF/HF radios that have DSC functions. However, before you use a marine DSC radio, you need to register for a MMSI number and program it into your radio.

You can obtain a MMSI number from various organizations, such as the Federal Communications Commission (FCC), Boat US, Sea Tow, the Power Squadron, and Shine Micro. The registration process may vary depending on the organization, but generally you need to provide some basic information about your vessel, such as its name, type, size, colour, owner and contact details. You also need to specify the type of radio equipment you have on board and the areas where you operate.

FCC MMSI numbers are valid worldwide and are entered into an international database. Non-FCC MMSI numbers are only valid in the US and are entered into a national database. If you plan to travel outside the US waters, you need to have an FCC MMSI number. Otherwise, you can use a non-FCC MMSI number.

The procedure for programming your MMSI number into your radio may differ depending on the model and manufacturer of your radio. You should consult your radio's manual for specific instructions. However, in general, you need to access the menu or setup mode of your radio, select the option for entering or editing your MMSI number, enter the 9-digit code using the keypad or buttons, and confirm or save your entry.

The range of marine DSC radio depends on several factors, such as the transmission power, the frequency band, the antenna height, the weather conditions and the terrain. In general, marine DSC radio has a longer range than traditional voice communication, with up to 25% more distance and faster speed.

For VHF DSC radio, the transmission power ranges between 1 and 25 watts, giving a maximum range of up to about 60 nautical miles between aerials mounted on tall ships and hills, and 5 nautical miles between aerials mounted on small boats at sea level.

For MF/HF DSC radio, the transmission power ranges between 60 and 150 watts, giving a maximum range of up to several thousand nautical miles depending on the frequency band and the atmospheric conditions. MF/HF DSC radio monitors multiple distress, urgency and safety bands in the 2, 4, 6, 8, 12 and 16 MHz bands.

To send a distress alert using marine DSC radio, you need to press and hold the red distress button on your radio for at least 5 seconds. This will automatically send a digital message containing your MMSI number, position and time to all nearby vessels and coast stations on channel 70 (VHF) or 2187.5 kHz (MF/HF). You should also switch to channel 16 (VHF) or 2182 kHz (MF/HF) and make a voice mayday call following the standard procedure.

To make a ship-to-ship call using marine DSC radio, you need to know the MMSI number of the vessel you want to contact. You can either enter it manually using the keypad or buttons on your radio, or select it from a stored list if your radio has that feature. Then you need to choose a working channel where you want to have the voice conversation. After that, you need to press the call button on your radio, which will send a digital request to the other vessel on channel 70 (VHF) or one of the MF/HF calling frequencies. If the other vessel accepts your request, both radios will automatically switch to the working channel and you can start talking.

To receive a call using marine DSC radio, you need to have your radio turned on and set to scan mode. This means that your radio will monitor channel 70 (VHF) or multiple MF/HF calling frequencies for incoming digital messages. When someone calls you, your radio will alert you with a sound or a display. You can then accept or reject the call using the buttons on your radio. If you accept the call, your radio will automatically switch to the working channel where you can have the voice conversation.

To test your marine DSC radio, you can perform a self-test or a test call. A self-test is a function that allows you to check the internal operation of your radio. You can access it from the menu or setup mode of your radio. A test call is a function that allows you to check the transmission and reception of your radio. You can make a test call to another vessel or a coast station that has DSC capabilities. You need to enter their MMSI number and select a test category, such as routine, position or distress. Then you need to press the call button on your radio, which will send a digital message to the other party. If they receive your message, they will send back an acknowledgment, which will confirm that your radio is working properly.