Flotilla 11

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RESCUE 21   -  Coast Guard's new technology

Technology Update - Digital Selective Calling Radios

Digital Selective Calling (DSC) radio is the latest in marine radio technology. Digital Selective Calling is part of a global upgrade in maritime distress communications. Satellite and digital technology used for several years on commercial ships is now available to the recreational boater. DSC radios allow boaters to make ship-to-ship private calls and the DSC distress channel is currently being monitored by commercial ships.

Since 1996 recreational boaters were no longer required to have a ship's station license issued by the FCC in order to operate a VHF radio. The new DSC radios however have to be registered to work properly in emergency situations. They are also encoded with a unique nine digit FCC identification number that allows the ship-to-ship calling feature. This unique number called a Maritime Mobile Service Identity or MMSI, is much like your cell phone number. Once the radio is registered with the FCC, that information and your boat's information is entered in the US Coast Guard's national distress database.

The major advantage of the DSC radio is its ability to send an automatic "mayday" that identifies the vessel and also, when connected to a LORAN or GPS, can send the vessels location. The DSC radio operates much like an EPIRB that sends encoded "maydays" directly to satellites. The DSC radio will also continue sending the emergency signal if the skipper is disabled.

Another feature of the DSC radio is the ability to place private ship-to-ship calls to other vessels equipped with DSC radio. Basically if you know the MMSI number of the radio you are calling only that vessel will receive you message. Just like using your cell phone.

Although commercial ships over 300 tons are now required to monitor the DSC Radio reserved Channel 70 for distress calls, the US Coast Guard is still monitoring Channel 16. As the Coast Guard updates and upgrades there equipment, they should be monitoring DSC Channel 70 in many areas by 2002-3 and be fully functional and compliant by 2005-6. The USCG's equipment up grade will include:

  • DSC capability to send or receive calls on channel 70

  • Eliminate the 65 gaps in current VHF coverage in the US
  • Provide direction finding capability to trace a garbled radio signal to within 25 miles
  • Provide playback of VHF voice or digital calls
  • Provide automatic tracking of USCG ships and aircraft on search and rescue missions

There have been recent incidences where commercial ships have picked up the "mayday" calls on Channel 70 and relayed them to the USCG.

The DSC radio feature is part of the Global Maritime Distress and Safety System (GMDSS). This system was put in place by international treaty in 1988 and all seagoing nations including the US will be GMDSS compliant by 2005-6.


No new equipment is needed for you to benefit from Rescue 21. The Coast Guard will continue responding to distress calls from marine-band radios, as well as cell phones, flares, lights, and flags.

However, you can help us improve response time by using a marine-band radio equipped with DSC. If properly registered with a Maritime Mobile Service Identity (MMSI) number and interfaced with GPS, the DSC radio signal transmits vital vessel information, position, and the nature of distress (if entered) at the push of a button. In an emergency, one push of a button and your DSC radio will send an automated digital distress alert containing your MMSI number and position to other DSC-equipped vessels and rescue facilities. DSC will provide a quicker and more accurate response by the Coast Guard.

The Boat U.S. and Sea Tow MMSI Programs have been certified by both the Federal Communications Commission (FCC) and the Coast Guard to assign MMSI numbers to vessels with DSC capable radios. To obtain and register your MMSI number, the Coast Guard recommends logging onto or and following the instructions. The Coast Guard Auxiliary is also available to help local boaters ensure their radios are in good working order.

DSC emergency signals will only be received by the Coast Guard when Rescue 21 is fully operational in your area.



21st Century Technology

To address the limitations of the current communications system, the National Distress and Response System (NDRS), the Coast Guard has implemented a recapitalization program entitled Rescue 21. When finished, Rescue 21 will replace a wide range of aging, obsolete radio communications equipment to include:

  • Consoles at all Coast Guard Activities, Sectors, Stations, and Marine Safety Offices (about 270 facilities)
  • All remote transceiver sites (antenna towers), as well as the network connecting them to the facilities above
  • Approximately 3,000 portable radios
  • Outfit Coast Guard smallboats with robust and upgraded communications suite

A quantum leap forward

Rescue 21 revolutionizes how the Coast Guard uses command, control, and communications for all missions within the coastal zone. The system:

  • incorporates direction-finding equipment to improve locating mariners in distress
  • improves interoperability amongst federal, state, and local agencies
  • enhances clarity of distress calls
  • allows simultaneous channel monitoring
  • upgrades playback and recording feature of distress calls
  • reduces coverage gaps for coastal communications and along navigable rivers and waterways
  • supports Digital Selective Calling for registered users
  • provides portable towers for restoration of communications during emergencies or natural disasters

Search and Rescue (SAR)

The U.S. Coast Guard is best known worldwide for its Search and Rescue (SAR) expertise, which dates back more than 200 years to the earliest days of the Revenue Cutter Service and the Life-Saving Service. Today, despite the nation's best efforts to prevent maritime accidents, the Coast Guard responds to about 60,000 emergency calls and saves nearly 5,000 lives annually. During Hurricane Katrina, the Coast Guard saved over 33,000 lives in a two week period!

The Coast Guard's SAR response involves multi-mission stations, cutters (ships), aircraft, and boats linked by communications networks. The National SAR Plan divides the U.S. into regions, with the Coast Guard acting as the maritime SAR coordinator. To meet this responsibility, the Coast Guard maintains facilities on the East, West and Gulf coasts; in Alaska, Hawaii, Guam, and Puerto Rico; and on the Great Lakes and inland U.S. waterways.

Current Limitations of NDRS

The NDRS was established more than 30 years ago as a VHF-FM-based radio communication system that has a range of up to 20 nautical miles along most of the U.S. shoreline. While this system has served the Coast Guard well over the years, it consists of out-of-date and non-standard equipment with many limitations. These include:

  • No direction finding capability.
  • Numerous geographic communication's coverage gaps.
  • Limited interoperability with other emergency response services.
  • Single-channel radio operation, which prohibits the ability to receive multiple radio calls.

Increasing Future SAR Demands

The Coast Guard's SAR mission is likely to become even more challenging in the years ahead. Trends indicate:

  • Dramatic increases in recreational boating, with many more personal watercraft congesting the nation's waterways.
  • Increased maritime trade, resulting in unparalleled growth in the size and numbers of ships using inland, coastal, and international waterways.
  • The natural consequence of this expanded use of our coastal waterways will result in increased mission demands for enforcing laws and protecting the marine environment.

Homeland Security Demands

Securing the maritime border of the United States is in the Coast Guard's charter as the lead federal agency for maritime homeland security. The Coast Guard has three tenets: Preparedness, Awareness, and Capability to address maritime homeland security challenges. Rescue 21 provides the command, control, and communications that will give the Coast Guard the "Capability" to defend the Nation's coastal waterways. It will improve "Awareness" through its contribution to Maritime Domain Awareness. Rescue 21 is the tool that will keep the Coast Guard "Prepared" and assist the Coast Guard fleet in meeting its coastal mission demands.

Rescue 21 will provide the United States with a 21st century maritime command, control, and communications (C3) system that encompasses the entire United States. By replacing outdated technology with a fully integrated C3 system that improves interoperability, Rescue 21 will protect mariners and help defend the nation's coasts.



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