Understanding marine channels

[52to12]

Some marine channel numbers are followed by the letter A. Does the A have any special significance?

 

[fmon]

I believe the A is for navigating US waters only.

 

[LarrySC]

Frequency pairs. If it has an "A" then the system has a cross talk freq like a repeater. With ship to shore phone, it would be a repeater.

 

[jack103]

Frequency pairs. If it has an "A" then the system has a cross talk freq like a repeater. With ship to shore phone, it would be a repeater.

A=USA!!!!!!

 

[nd5y]

This is from the Coast Guard communications web site

Note that the letter "A" indicates simplex use of the ship station transmit side of an international duplex channel, and that operations are different than international operations on that channel. Some VHF transceivers are equipped with an "International - U.S." switch for that purpose. "A" channels are generally only used in the United States, and use is normally not recognized or allowed outside the U.S. The letter "B" indicates simplex use of the coast station transmit side of an international duplex channel. The U.S. does not currently use "B" channels for simplex communications in this band.

 

[seamusg]

This is from the Coast Guard communications web site

Note that the letter "A" indicates simplex use of the ship station transmit side of an international duplex channel, and that operations are different than international operations on that channel. Some VHF transceivers are equipped with an "International - U.S." switch for that purpose. "A" channels are generally only used in the United States, and use is normally not recognized or allowed outside the U.S. The letter "B" indicates simplex use of the coast station transmit side of an international duplex channel. The U.S. does not currently use "B" channels for simplex communications in this band.

In US boarder areas with Canada B could be in use. B channels are usually duplex. The US to get more freqs took a lot of the Marine duplex freqs and gave the other half to rail roads along with changing the bandwidth requirements for marine in US waters.

 

[sean_kd4adv]

There is no repeater in the VHF marine band.
There may be onboard ship repeaters in the UHF 457.xxx band.

Ship-to-Shore means exactly that.
*There is no such repeater.*
Used for telephone interconnect/ "phone patches"
It is a "cross-talk" method that is built into the VHF Marine Mobile transceivers.

Simplex ship to ship comms and ship to shore comms mean exactly that!
157.1000 - 22A for example :
When a vessel has established comms on VHF CH.16 with the US COAST GUARD CAMSLANT - Hampton Roads Group (NMN) on the East Coast near Virginia then they move to 22A and that is Direct Comms.

Sean, KD4ADV

 

[jpryor]

And I've heard the USCG refer to Channel 23C "Charlie" when using encryption . . .

 

[seamusg]

.

Ship-to-Shore means exactly that.
*There is no such repeater.*
Used for telephone interconnect/ "phone patches"
It is a "cross-talk" method that is built into the VHF Marine Mobile transceivers.

Simplex ship to ship comms and ship to shore comms mean exactly that!
157.1000 - 22A for example :
When a vessel has established comms on VHF CH.16 with the US COAST GUARD CAMSLANT - Hampton Roads Group (NMN) on the East Coast near Virginia then they move to 22A and that is Direct Comms.

Sean, KD4ADV

There is duplex coms on marine, cell phones have almost replaced Ship to Shore phone calls, ie ch's 26 and 28 in the Detroit area. The ALPHA channels that the USCG uses came from taking the second freq of a duplex channel and making it simplex, ie 21A simplex or 21B duplex.

 

[CapnJon]

And I've heard the USCG refer to Channel 23C "Charlie" when using encryption . . .

I've been out for a few years but it prolly means using coded or secure comm's...

 

[Mozilla]

Marine channels

Instead of guessing or throwing in another opinion, here's the gospel.
Read the section right under the frequency charts, it will give you the actual situation.
This is a great site for Marine stuff including more than radio, so enjoy.

http://www.navcen.uscg.gov/marcomms/vhf.htm


As to the encrypted, the term varies , but includes "C" behind the channel for coded aka encrypted, also includes " go red " "flip the switch" " scramble" " go hyper" and many others. Even within sectors there seems to be variations.