GX1256S Page 59
11. CHANNEL ASSIGNMENTS
Tables on the following columns list the VHF Marine Channel assignments
for U.S.A. and International use. Below are listed some data about the charts.
1. VTS. Where indicated, these channels are part of the U.S. Coast Guard’s
Vessel Traffic System.
2. Alpha channel numbers, that is, channel numbers followed by the letter
A (such as Channel 07A) are simplex channels on the U.S.A. or Cana-
dian channel assignments whose counterparts in the International as-
signments are duplex channels. International channels do not use “al-
pha” numbers. If you call the Coast Guard on Channel 16, they will some-
times ask you to “go to channel 22 Alpha.” This is a channel assigned
to U.S.A, and Canadian Coast Guards for handling distress and other
calls. If your radio is set for International operation you will go to Chan-
nel 22 instead of 22A, and will not be able to communicate with the
Coast Guard. To use Channel 22A, your radio must be set for USA or
Canada operation, usually by a U/I/C (USA/International/Canada) con-
trol or combination of controls. Channel 22 (without an “A”) is an Inter-
national duplex channel for port operations. Some radios indicate an
“A” adjacent to the alpha channels on the display; on others “alpha” is
not indicated but the proper channel is selected based on the U/I/C set-
ting.
3. Bridge-to-Bridge channels (for example, Channel 13) are for use by bridge
operators on intercoastal waterways and rivers. It is also used by marine
vessels in the vicinity of these bridges for navigation and for communi-
cating with the bridge operators. Note that a limit of 1 Watt is specified
for these channels. See page 25 for additional information.
4. The S/D column on the chart indicates either S (simplex) or D (duplex).
Simplex means transmitting and receiving on the same frequency. Only
one party at a time can talk, unlike a telephone. Be sure to say “over”
and release your microphone push-to-talk switch at the end of each trans-
mission. Duplex operation involves the use of one frequency for trans-
mitting and a separate frequency for receiving. On channels specified
as duplex on the charts, correct mode of operation is established auto-
matically by your radio when you select a channel; you cannot change
the mode. And you still must release the push-to-talk switch after each
transmission in order to listen to the radio.