DSC Radio Check: Fast, Easy, and Automatic
Since the discontinuation of SeaTow's radio check service, the US Coast Guard recommends all VHF checks be held by DSC test call to their Rescue 21 system on digital channel 70 (the only all-digital channel). All fixed marine radios since 1999 have DSC capability. Since 2011 these radios must also have a DSC test call capability. Marine radios transmitting and successfully receiving a response from a DSC test call can be expected to operate acceptably in the voice mode as well.
They detail the procedure:
To perform a DSC Test Call, enter the U.S. Coast Guard’s coast station group identity “003669999” into the radio’s DSC station memory. This does not get entered into the group memory since you do not want to be part of the Coast Guard shore station group. Once entered and stored, a DSC test call can be made by executing the following three steps:
- Select “Test Call” from the radio’s DSC menu,
- Select the USCG number entered into memory, and
- Transmit the call.
The radio display should indicate when that test call is acknowledged and display the acknowledging station’s nine-digit identity. That identity may be different than the group identity previously entered into memory. The DSC call was to the group of all Rescue 21 stations, only a local individual station will answer and that MMSI will be displayed.
While you're at it, it would pay to enter the Coast Guard ship’s group MMSI, 036699999 into your single (not group) memory. In an emergency, you can put out a call that goes to all Coast Guard ships and all Coast Guard shore stations in range.
The Coast Guard specifically recommends against using channel 16 for VHF checks. 16 is for emergency traffic. VHF 9 may be used for radio checks but is discouraged in favor of using automatic DSC test calls for radio checks.