Posted:
October 14, 2016
As reported by the U.S. Coast Guard's Navigation Center, the International Telecommunications Union has amended the VHF maritime radio channel numbering scheme, which will affect 18 channels used in the U.S. New VHF radios will eventually begin using this scheme. Changes to U.S. channel numbers are shown on the U.S. VHF Channels page.
As noted on the Navigation Center website, "the four-digit channel number beginning with the digits '10' indicates simplex use of the ship station transmit side of what had been an international duplex channel. These new channel numbers, now recognized internationally, were previously designated in the U.S. by the two-digit channel number ending with the letter 'A'. That is, the international channel 1005 has been designated in the U.S. by channel 05A, and the U.S. Coast Guard channel 1022 has been designated in the U.S. as channel 22A. Four-digit channels beginning with '20', sometimes shown by the two-digit channel number ending with the letter 'B', indicates simplex use of the coast station transmit side of what normally was an international duplex channel. The U.S. does not currently use 'B' or '20NN' channels in the VHF maritime band. Some VHF transceivers are equipped with an 'International/U.S.' switch to avoid conflicting use of these channels."
Changes to VHF maritime radio channel numbering scheme
As reported by the U.S. Coast Guard's Navigation Center, the International Telecommunications Union has amended the VHF maritime radio channel numbering scheme, which will affect 18 channels used in the U.S. New VHF radios will eventually begin using this scheme. Changes to U.S. channel numbers are shown on the U.S. VHF Channels page.
As noted on the Navigation Center website, "the four-digit channel number beginning with the digits '10' indicates simplex use of the ship station transmit side of what had been an international duplex channel. These new channel numbers, now recognized internationally, were previously designated in the U.S. by the two-digit channel number ending with the letter 'A'. That is, the international channel 1005 has been designated in the U.S. by channel 05A, and the U.S. Coast Guard channel 1022 has been designated in the U.S. as channel 22A. Four-digit channels beginning with '20', sometimes shown by the two-digit channel number ending with the letter 'B', indicates simplex use of the coast station transmit side of what normally was an international duplex channel. The U.S. does not currently use 'B' or '20NN' channels in the VHF maritime band. Some VHF transceivers are equipped with an 'International/U.S.' switch to avoid conflicting use of these channels."