DSC Test Calls to USCG MMSI 003669999

VHF Marine Band radios, protocol, radio communication theory, practical advice; AIS; DSC; MMSI; EPIRB.
jimh
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DSC Test Calls to USCG MMSI 003669999

Postby jimh » Fri Mar 16, 2018 12:32 pm

The USCG NavCen website notes (with some emphasis added by me):

USCG_website wrote:For VHF DSC radios equipped with the Test Call feature, test transmissions should be made to the US Coast Guard MMSI 003669999 to receive an automated VHF DSC test response. You must use the “Test Call” category of your radio because “Individual” category calls to this address will not receive an automated response....

Source: https://www.navcen.uscg.gov/dsc-testing

In order for this procedure to produce an ACK (acknowledgement) reply from the USCG radio system, the CALL TYPE must be set to "TEST CALL."

Routine calls to MMSI 003669999 will NOT produce an ACK response. I just tested this with my CLASS-D DSC radio and verified this behavior:

  • a call of category TEST to MMSI 003669999 immediately produced an ACK response
  • a call of category INDIVIDUAL to MMSI 003669999 produced NO ACK response.

The USCG RESCUE-21 radio system behaved just as described in the USCG NavCen website announcement.

The typical CLASS-D DSC radio should be able to make DSC routine calls of the following CATEGORIES:

  • INDIVIDUAL
  • GROUP
  • ALL SHIPS
  • POSITION REQUEST
  • POSITION SEND
  • TEST

In a particular DSC radio user interface, the operator may need to scroll through a listing of call categories to reach the TEST call category.

The USCG maintains a radio watch for DSC calls with their RESCUE 21 radio system. At every RESCUE 21 site there is a receiver dedicated to monitoring the digital selective calling frequency (156.525-MHz Channel 70) and a ICS Electronic V4 Marine Communication System for digital selective calling and logging. For more information on communication facilities at RESCUE 21 sites, see my article

Rescue 21 Radio Installations
http://continuouswave.com/whaler/reference/Rescue21Stations.html

The article identifies a number of sites in the Great Lakes, provides illustrations of the towers and antennas, and discusses in detail the equipment used and the operational practices.

ASIDE: finding the webpage about DSC Testing on the USCG NavCen website is an exercise in diligent site navigation. The path to that page is five layers below the top page of the USCG website, as follows:

[UPDATED on July 26, 2022 when the USCG website organization changed (again).]
  • go to the top page of http://www.navcen.uscg.gov
  • ignore all the blue bottons near the middle of the page, and locate and click on a square box with the legend "Maritime Safety Information (MMSI) near the bottom of the page; a new page appears;
  • on the new page locate, ignore all the blue buttons, and locate a series of short horizontal lines which apparently is indented to represent a menu; click on the menu, and a new window appears;
  • in the new window that has just appears an click on the button "Marine Telecomms" and another new window appears;
  • on new window again find the three short horizontal bars on the upper right and click on them; another new window appears in left panel of links under heading "Digital Selective Calling"; another window opens;
  • in the new page under the heading "DSC Procedures for Ships" find and select "DSC Testing"
  • new page appears with information on DSC testing

The path is thus:
  1. HOME
  2. MARINE SAFETY INFORMATION
  3. MARINE TELECOMMS
  4. DIGITAL SELECTIVE CALLING
  5. DSC PROC(edures) SHIPS
  6. DSC TESTING