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Digital Marine Radio Service

Sail Boat
Curve of the earth

Marine radios, which are typically installed on boats, operate on the Very High Frequency (VHF) Marine band. These radios play an indispensable role in maritime safety, greatly contributing to emergency rescue operations and general navigation on the water. They allow for essential communication between vessels and with shore stations, providing up-to-date weather reports, distress signal broadcasts, and a means for vessels to keep in touch with one another. However, while these radios are a critical component of boating safety, they are not without their associated shortcomings. Their performance is greatly influenced by a range of factors; the most critical of these is line of sight. Essentially, for a radio signal to be received, the transmitting and receiving antennas must be within sight of each other. This is often a limiting factor for these radios. Despite the vast expanses of open waters devoid of typical obstructions such as buildings or mountain ranges, another natural obstacle comes into play. This obstacle is the curvature of the earth itself. The earth’s curvature and the closer-than-perceived horizon significantly limit the range of the marine radio. Radio waves will go about 10% beyond the visual horizon. For most power boats, the marine radio has an effective operational range of about 14 miles from boat to boat. This is insufficient to even reach from Los Angeles to Catalina Island. This is because the radio waves travel in a straight path, and beyond certain distances, they simply move past the receiver due to the Earth’s curved surface. Hence, the 14-mile range is essentially a function of the height of the boat’s antenna above the waterline. However, sailboats often have the advantage in this scenario. They usually mount their antennas at the top of their high masts, elevating them above the typical antenna height on power boats. As a result, sailboats can extend the range of their radios to approximately 28 miles from sailboat to sailboat, effectively doubling the communication range of their power boat counterparts. To overcome the limitations of marine VHF radios, services like the Coast Guard, Marine Exchange, and Vessel Assist often utilize strategic locations for their base stations. These organizations typically set up their radio equipment at higher altitudes on land. By doing so, they achieve a significantly greater line of sight, enabling them to extend their communication range considerably further than the typical marine radio. This expanded reach is invaluable in ensuring the safety and efficiency of maritime operations.

Over the years, we have been developing radio systems to overcome the line-of-sight limitations intrinsic to terrestrial mobile and portable radios, commonly imposed by obstructions such as mountains, buildings, and the earth’s curvature. To circumvent these hindrances, we have forged a web of interconnected mountaintop sites. During the creation of this terrestrial network, we extended significant coverage into the Pacific Ocean. A multitude of these mountaintop sites now provide coverage roughly 70 miles seaward and stretch approximately 300 miles from north of Morro Bay to the south of the Mexican border. (We do not recommend using our network south of the Mexican border as we are not licensed to operate in Mexican waters.)

In addition to these advantages, our networked radios provide:
1. The capability to communicate on land, unlike marine radios which are restricted to specific marine entities.
2. Extended communication range into the ocean, beyond the scope of cell phone coverage.
3. Access to private channels, offering a clear line without the need to filter through unrelated stations or handle interference.
4. Conversation encryption to ensure privacy and prevent unauthorized monitoring.
5. GPS tracking for both marine and land based stations.
6. A tailored emergency alert function.
7. The capacity to manage commercial or personal communications without monopolizing a marine frequency.

MRA Channel List

1Calling ChannelGeneral calls to other vessels
2Vessel Assist
3Coast GuardNon-emergency calls
4Yacht club 1Communication directly with clubs
5Yacht club 2
6Yacht club 3
7Yacht club 4
8Yacht club 5
9Yacht club 6
10Yacht club 7
11Yacht club 8
12Yacht club 9
13Yacht club 10
14Commercial 1General purpose commercial traffic
15Commercial 2
16Commercial 3
17Commercial 4
18Commercial 5
19Commercial 6
20Commercial 7
21Commercial 8
22Commercial 9
23Commercial 10
24Talk group 1General conversations
25Talk group 2
26Talk group 3
27Talk group 4
28Talk group 5
29Talk group 6
30Talk group 7
31Talk group 8
32Talk group 9
33Talk group 10
34Marina 1Communications with Marinas
35Marina 2
36Marina 3
37Marina 4
38Marina 5
39Marina 6
40Marina 7
41Marina 8
42Marina 9
43Marina 10
44Private 1Private channels can be configured for exclusive use of a group. Encryption is also available.
45Private 2
46Private 3
47Event 1Channel for a particular event.
48Event 2
49Event 3
50Event 4

Signal Level Map

Diga-Talk Network Nautical Coverage 8 Level

Mobile and Portable Coverage Map

Diga-Talk Network Nautical Coverage 2 Level

Google Earth Maps

The maps below can be viewed in Google Earth. These maps contain greater detail than those above.

Diga-Talk Network Nautical Coverage 8 Level
Signal Level Map
Diga-Talk Network 72 Site Mobile Coverage Nautical Coverage
Mobile Coverage
Diga-Talk Network 72 Site Portable Coverage Nautical Coverage
Handheld Coverage
Diga-Talk Network Nautical Coverage 2 Level
VHF Marine Frequencies
New Channel NumberOld Channel NumberShip Transmit MHzShip Receive MHzUse
100101A156.050156.050Port Operations and Commercial, VTS. Available only in New Orleans / Lower Mississippi area.
100505A156.250156.250Port Operations or VTS in the Houston, New Orleans and Seattle areas.
0606156.300156.300Intership Safety
100707A156.350156.350Commercial. VDSMS
0808156.400156.400Commercial (Intership only). VDSMS
0909156.450156.450Boater Calling. Commercial and Non-Commercial. VDSMS
1010156.500156.500Commercial. VDSMS
1111156.550156.550Commercial. VTS in selected areas. VDSMS
1212156.600156.600Port Operations. VTS in selected areas.
1313156.650156.650Intership Navigation Safety (Bridge-to-bridge). Ships >20m length maintain a listening watch on this channel in US waters.
1414156.700156.700Port Operations. VTS in selected areas.
1515156.750Environmental (Receive only). Used by Class C EPIRBs.
1616156.800156.800International Distress, Safety and Calling. Ships required to carry radio, USCG, and most coast stations maintain a listening watch on this channel. 
1717156.850156.850State & local govt maritime control
101818A156.900156.900Commercial. VDSMS
101919A156.950156.950Commercial. VDSMS
2020157.000161.600Port Operations (duplex)
102020A157.000157.000Port Operations
102121A157.050157.050U.S. Coast Guard only
102222A157.100157.100Coast Guard Liaison and Maritime Safety Information Broadcasts. Broadcasts announced on channel 16.
102323A157.150157.150U.S. Coast Guard only
2424157.200161.800Public Correspondence (Marine Operator). VDSMS
2525157.250161.850Public Correspondence (Marine Operator). VDSMS
2626157.300161.900Public Correspondence (Marine Operator). VDSMS
2727157.350161.950Public Correspondence (Marine Operator). VDSMS
2828157.400162.000Public Correspondence (Marine Operator). VDSMS
106363A156.175156.175Port Operations and Commercial, VTS. Available only in New Orleans / Lower Mississippi area.
106565A156.275156.275Port Operations
106666A156.325156.325Port Operations
6767156.375156.375Commercial. Used for Bridge-to-bridge communications in lower Mississippi River. Intership only.
6868156.425156.425Non-Commercial. VDSMS
6969156.475156.475Non-Commercial. VDSMS
7070156.525156.525Digital Selective Calling (voice communications not allowed)
7171156.575156.575Non-Commercial. VDSMS
7272156.625156.625Non-Commercial (Intership only). VDSMS
7373156.675156.675Port Operations
7474156.725156.725Port Operations
7777156.875156.875Port Operations (Intership only)
107878A156.925156.925Non-Commercial. VDSMS
107979A156.975156.975Commercial. Non-Commercial in Great Lakes only. VDSMS
108080A157.025157.025Commercial. Non-Commercial in Great Lakes only. VDSMS
108181A157.075157.075U.S. Government only – Environmental protection operations.
108282A157.125157.125U.S. Government only
108383A157.175157.175U.S. Coast Guard only
8484157.225161.825Public Correspondence (Marine Operator). VDSMS
8585157.275161.875Public Correspondence (Marine Operator). VDSMS
8686157.325161.925Public Correspondence (Marine Operator). VDSMS
8787157.375157.375Public Correspondence (Marine Operator). VDSMS
8888157.425157.425Commercial, Intership only. VDSMS
AIS 1AIS 1161.975161.975Automatic Identification System (AIS)
AIS 2AIS 2162.025162.025Automatic Identification System (AIS)
Conventional VHF Marine Frequencies