VHF channels for marine operator? 24 - 28 and 84 - 87
 

I was testing my radios by talking back an forth thru each channel. On
channels 24 thru 28 and 84 thru 87 the radios do not respond to each other.
Is this what you would expect ?

I notice these are public correspondance channels are the marine operators
no longer in business? Are these channels ever used anymore?

VHF channels for marine operator? 24 - 28 and 84 - 87
 

They are duplex channels. Shore side transmits on one freq, boat side on
another. Both can talk at once.

--
Chuck Tribolet

http://www.almaden.ibm.com/cs/people/triblet

Silicon Valley: STILL the best day job in the world.


"Scott Downey" wrote in message ...
I was testing my radios by talking back an forth thru each channel. On
channels 24 thru 28 and 84 thru 87 the radios do not respond to each other.
Is this what you would expect ?

I notice these are public correspondance channels are the marine operators
no longer in business? Are these channels ever used anymore?

VHF channels for marine operator? 24 - 28 and 84 - 87
 

On Tue, 17 Feb 2004 17:44:40 -0500, "Scott Downey"
wrote:
I was testing my radios by talking back an forth thru each channel. On
channels 24 thru 28 and 84 thru 87 the radios do not respond to each other.
Is this what you would expect ?

I notice these are public correspondance channels are the marine operators
no longer in business? Are these channels ever used anymore?
================================================== ==

Those channels are in "full duplex" mode which means that they
transmit and receive are on different frequencies. They were designed
to communicate with the old marine operator shore stations, not in
"ship-to-ship" mode.

Marine operators have become obsolete in most areas since cell phones
became widely available. I haven't heard one in years but it's
possible that they still exist in some places. Too bad in a way
because some of them had very high antennas and could be heard a long
way out. We could frequently communicate with the Camden, Maine
operator from over 50 miles offshore.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

So that means two ship radios cant talk together on these channels?
FCC and boaters I would think do not like wasted frequencies. I wonder what
the plan is for them.

"Wayne.B" wrote in message
...
On Tue, 17 Feb 2004 17:44:40 -0500, "Scott Downey"
wrote:
I was testing my radios by talking back an forth thru each channel. On
channels 24 thru 28 and 84 thru 87 the radios do not respond to each
other.
Is this what you would expect ?

I notice these are public correspondance channels are the marine
operators
no longer in business? Are these channels ever used anymore?
================================================== ==

Those channels are in "full duplex" mode which means that they
transmit and receive are on different frequencies. They were designed
to communicate with the old marine operator shore stations, not in
"ship-to-ship" mode.

Marine operators have become obsolete in most areas since cell phones
became widely available. I haven't heard one in years but it's
possible that they still exist in some places. Too bad in a way
because some of them had very high antennas and could be heard a long
way out. We could frequently communicate with the Camden, Maine
operator from over 50 miles offshore.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

Ships can talk on them. Just need two radios.
"Scott Downey" wrote in message
...
So that means two ship radios cant talk together on these channels?
FCC and boaters I would think do not like wasted frequencies. I wonder
what
the plan is for them.

"Wayne.B" wrote in message
...
On Tue, 17 Feb 2004 17:44:40 -0500, "Scott Downey"
wrote:
I was testing my radios by talking back an forth thru each channel. On
channels 24 thru 28 and 84 thru 87 the radios do not respond to each
other.
Is this what you would expect ?

I notice these are public correspondance channels are the marine
operators
no longer in business? Are these channels ever used anymore?
================================================== ==

Those channels are in "full duplex" mode which means that they
transmit and receive are on different frequencies. They were designed
to communicate with the old marine operator shore stations, not in
"ship-to-ship" mode.

Marine operators have become obsolete in most areas since cell phones
became widely available. I haven't heard one in years but it's
possible that they still exist in some places. Too bad in a way
because some of them had very high antennas and could be heard a long
way out. We could frequently communicate with the Camden, Maine
operator from over 50 miles offshore.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

On Wed, 18 Feb 2004 18:56:41 GMT, "Calif Bill"
wrote:

Ships can talk on them. Just need two radios.

================================================== ==

Not really true unless one of the radios is set up as a "land" station
with the transmit and receive frequencies reversed.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

"Scott Downey" wrote in message ...
So that means two ship radios cant talk together on these channels?
FCC and boaters I would think do not like wasted frequencies. I wonder what
the plan is for them.

Yes that means that two ships/boats cannot talk to eachother. They
are intended for ship to shore communications (between ships and
public/private coast stations).

Marine operators service started going by the wayside in the USA in
just the last 10 years. Prior to that, cellphones were widely
available but still pricey enough that not everyone had them.

How marine channels are used is a international issue. In many parts
of the world these duplex channels are still used more than they are
in the US. There are a couple of channels that have different uses in
the U.S. than in the rest of the world. This is why you have a
International / U.S. mode on your set. When foriegn vessels enter
U.S. waters they want to be able to use their "international" radios.
Likewise, if you take your boat to another country, you may want to be
able to contact a coast station on one of those international
channels. So just because marine operators are used as much here,
doesn't mean the international channel designations should be changed.

And in my opinion (worth something to me, but perhaps not you - your
call) we don't have a shortage of frequencies. If you can't find an
appropriate, clear, working channel it is most likely because many are
being used for communications that don't realy belong on them anyway.
The marine radio service is not there for bull**** sessions between
boaters and drunk fishermen. It should be used for communications
that are relative to the safe and efficient operation of vessel,
ports, etc.


"Wayne.B" wrote in message
...
On Tue, 17 Feb 2004 17:44:40 -0500, "Scott Downey"
wrote:
I was testing my radios by talking back an forth thru each channel. On
channels 24 thru 28 and 84 thru 87 the radios do not respond to each
other.
Is this what you would expect ?

I notice these are public correspondance channels are the marine
operators
no longer in business? Are these channels ever used anymore?
================================================== ==

Those channels are in "full duplex" mode which means that they
transmit and receive are on different frequencies. They were designed
to communicate with the old marine operator shore stations, not in
"ship-to-ship" mode.

Marine operators have become obsolete in most areas since cell phones
became widely available. I haven't heard one in years but it's
possible that they still exist in some places. Too bad in a way
because some of them had very high antennas and could be heard a long
way out. We could frequently communicate with the Camden, Maine
operator from over 50 miles offshore.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

There's a US/International mode on radios not because the channels
have different USES, but because they have different FREQUENCIES.
For example, international Ch 22 is a full duplex channel on 157.100/161.700
while US 22A is a simplex channel on 157.100.

I think that over time the marine telephone channels will be freed for other
uses.

--
Chuck Tribolet

http://www.almaden.ibm.com/cs/people/triblet

Silicon Valley: STILL the best day job in the world.


"Curtis CCR" wrote in message om...
"Scott Downey" wrote in message ...
So that means two ship radios cant talk together on these channels?
FCC and boaters I would think do not like wasted frequencies. I wonder what
the plan is for them.

Yes that means that two ships/boats cannot talk to eachother. They
are intended for ship to shore communications (between ships and
public/private coast stations).

Marine operators service started going by the wayside in the USA in
just the last 10 years. Prior to that, cellphones were widely
available but still pricey enough that not everyone had them.

How marine channels are used is a international issue. In many parts
of the world these duplex channels are still used more than they are
in the US. There are a couple of channels that have different uses in
the U.S. than in the rest of the world. This is why you have a
International / U.S. mode on your set. When foriegn vessels enter
U.S. waters they want to be able to use their "international" radios.
Likewise, if you take your boat to another country, you may want to be
able to contact a coast station on one of those international
channels. So just because marine operators are used as much here,
doesn't mean the international channel designations should be changed.

And in my opinion (worth something to me, but perhaps not you - your
call) we don't have a shortage of frequencies. If you can't find an
appropriate, clear, working channel it is most likely because many are
being used for communications that don't realy belong on them anyway.
The marine radio service is not there for bull**** sessions between
boaters and drunk fishermen. It should be used for communications
that are relative to the safe and efficient operation of vessel,
ports, etc.


"Wayne.B" wrote in message
...
On Tue, 17 Feb 2004 17:44:40 -0500, "Scott Downey"
wrote:
I was testing my radios by talking back an forth thru each channel. On
channels 24 thru 28 and 84 thru 87 the radios do not respond to each
other.
Is this what you would expect ?

I notice these are public correspondance channels are the marine
operators
no longer in business? Are these channels ever used anymore?
================================================== ==

Those channels are in "full duplex" mode which means that they
transmit and receive are on different frequencies. They were designed
to communicate with the old marine operator shore stations, not in
"ship-to-ship" mode.

Marine operators have become obsolete in most areas since cell phones
became widely available. I haven't heard one in years but it's
possible that they still exist in some places. Too bad in a way
because some of them had very high antennas and could be heard a long
way out. We could frequently communicate with the Camden, Maine
operator from over 50 miles offshore.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

"Chuck Tribolet" wrote in message ...
There's a US/International mode on radios not because the channels
have different USES, but because they have different FREQUENCIES.
For example, international Ch 22 is a full duplex channel on 157.100/161.700
while US 22A is a simplex channel on 157.100.

I think that over time the marine telephone channels will be freed for other
uses.

Yes - they are simplex in the US and duplex on international...
because they have different uses. 22A in the US is a Coast Guard
"liason" channel that you can use to talk to the CG ship-to-ship
(talking to a CG vessel) or ship-to-shore (talking to a CG station).

In in other parts of the world 22 (the duplex channel) is used for
port operations.

Not to say that 22A is not used outside the US. Doesn't Canada use
22A for the same thing we do?


"Curtis CCR" wrote in message om...

How marine channels are used is a international issue. In many parts
of the world these duplex channels are still used more than they are
in the US. There are a couple of channels that have different uses in
the U.S. than in the rest of the world. This is why you have a
International / U.S. mode on your set. When foriegn vessels enter
U.S. waters they want to be able to use their "international" radios.
Likewise, if you take your boat to another country, you may want to be
able to contact a coast station on one of those international
channels.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

9 channels designated for duplex use ties up 18 frequecies or 18 potential
channels
The marine operator is obsolete and yes it is a waste not being able to use
these channels.

"Curtis CCR" wrote in message
om...
"Scott Downey" wrote in message
...
So that means two ship radios cant talk together on these channels?
FCC and boaters I would think do not like wasted frequencies. I wonder
what
the plan is for them.

Yes that means that two ships/boats cannot talk to eachother. They
are intended for ship to shore communications (between ships and
public/private coast stations).

Marine operators service started going by the wayside in the USA in
just the last 10 years. Prior to that, cellphones were widely
available but still pricey enough that not everyone had them.

How marine channels are used is a international issue. In many parts
of the world these duplex channels are still used more than they are
in the US. There are a couple of channels that have different uses in
the U.S. than in the rest of the world. This is why you have a
International / U.S. mode on your set. When foriegn vessels enter
U.S. waters they want to be able to use their "international" radios.
Likewise, if you take your boat to another country, you may want to be
able to contact a coast station on one of those international
channels. So just because marine operators are used as much here,
doesn't mean the international channel designations should be changed.

And in my opinion (worth something to me, but perhaps not you - your
call) we don't have a shortage of frequencies. If you can't find an
appropriate, clear, working channel it is most likely because many are
being used for communications that don't realy belong on them anyway.
The marine radio service is not there for bull**** sessions between
boaters and drunk fishermen. It should be used for communications
that are relative to the safe and efficient operation of vessel,
ports, etc.


"Wayne.B" wrote in message
...
On Tue, 17 Feb 2004 17:44:40 -0500, "Scott Downey"
wrote:
I was testing my radios by talking back an forth thru each channel.
On
channels 24 thru 28 and 84 thru 87 the radios do not respond to each
other.
Is this what you would expect ?

I notice these are public correspondance channels are the marine
operators
no longer in business? Are these channels ever used anymore?
================================================== ==

Those channels are in "full duplex" mode which means that they
transmit and receive are on different frequencies. They were designed
to communicate with the old marine operator shore stations, not in
"ship-to-ship" mode.

Marine operators have become obsolete in most areas since cell phones
became widely available. I haven't heard one in years but it's
possible that they still exist in some places. Too bad in a way
because some of them had very high antennas and could be heard a long
way out. We could frequently communicate with the Camden, Maine
operator from over 50 miles offshore.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

"Scott Downey" wrote in message ...
9 channels designated for duplex use ties up 18 frequecies or 18 potential
channels
The marine operator is obsolete and yes it is a waste not being able to use
these channels.

I will not argue that there isn't a better use for these frequencies.
My point was that we don't need any more channels for recreational
boater bull****. I'd guess that three quarters of the recreational
boater radio traffic I hear on working channels in this area is stuff
that shouldn't be tying up those channels in the first place.



"Curtis CCR" wrote in message
om...
"Scott Downey" wrote in message
...
So that means two ship radios cant talk together on these channels?
FCC and boaters I would think do not like wasted frequencies. I wonder
what
the plan is for them.

Yes that means that two ships/boats cannot talk to eachother. They
are intended for ship to shore communications (between ships and
public/private coast stations).

Marine operators service started going by the wayside in the USA in
just the last 10 years. Prior to that, cellphones were widely
available but still pricey enough that not everyone had them.

How marine channels are used is a international issue. In many parts
of the world these duplex channels are still used more than they are
in the US. There are a couple of channels that have different uses in
the U.S. than in the rest of the world. This is why you have a
International / U.S. mode on your set. When foriegn vessels enter
U.S. waters they want to be able to use their "international" radios.
Likewise, if you take your boat to another country, you may want to be
able to contact a coast station on one of those international
channels. So just because marine operators are used as much here,
doesn't mean the international channel designations should be changed.

And in my opinion (worth something to me, but perhaps not you - your
call) we don't have a shortage of frequencies. If you can't find an
appropriate, clear, working channel it is most likely because many are
being used for communications that don't realy belong on them anyway.
The marine radio service is not there for bull**** sessions between
boaters and drunk fishermen. It should be used for communications
that are relative to the safe and efficient operation of vessel,
ports, etc.


"Wayne.B" wrote in message
...
On Tue, 17 Feb 2004 17:44:40 -0500, "Scott Downey"
wrote:
I was testing my radios by talking back an forth thru each channel.
On
channels 24 thru 28 and 84 thru 87 the radios do not respond to each
other.
Is this what you would expect ?

I notice these are public correspondance channels are the marine
operators
no longer in business? Are these channels ever used anymore?
================================================== ==

Those channels are in "full duplex" mode which means that they
transmit and receive are on different frequencies. They were designed
to communicate with the old marine operator shore stations, not in
"ship-to-ship" mode.

Marine operators have become obsolete in most areas since cell phones
became widely available. I haven't heard one in years but it's
possible that they still exist in some places. Too bad in a way
because some of them had very high antennas and could be heard a long
way out. We could frequently communicate with the Camden, Maine
operator from over 50 miles offshore.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

I disagree. It's OK for the fishermen to lie about what they caught, where
they caught it, and what they caught it with ;-), and the divers to chat about
dive conditions. Fortunately in Monterey, we have few enough boaters that
it's not a problem (except maybe the first couple of weekends of Salmon
season), but I can see how it could be a real problem in an area like South
Florida that's wall to wall boats.


--
Chuck Tribolet

http://www.almaden.ibm.com/cs/people/triblet

Silicon Valley: STILL the best day job in the world.


"Curtis CCR" wrote in message m...
I'd guess that three quarters of the recreational
boater radio traffic I hear on working channels in this area is stuff
that shouldn't be tying up those channels in the first place.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

you are the new type of boater that has a new toy and knows
nothing about how to use it and what it is all about. How
nice boating was before your type came on the water. Capt.
boots
"Chuck Tribolet" wrote in message
...
I disagree. It's OK for the fishermen to lie about what
they caught, where
they caught it, and what they caught it with ;-), and the
divers to chat about
dive conditions. Fortunately in Monterey, we have few
enough boaters that
it's not a problem (except maybe the first couple of
weekends of Salmon
season), but I can see how it could be a real problem in an
area like South
Florida that's wall to wall boats.


--
Chuck Tribolet

http://www.almaden.ibm.com/cs/people/triblet

Silicon Valley: STILL the best day job in the world.


"Curtis CCR" wrote in message
m...
I'd guess that three quarters of the recreational
boater radio traffic I hear on working channels in this
area is stuff
that shouldn't be tying up those channels in the first
place.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

OK, then, just what is appropriate on the VHF?

--
Chuck Tribolet

http://www.almaden.ibm.com/cs/people/triblet

Silicon Valley: STILL the best day job in the world.


"Boots Crofoot" wrote in message . ..
you are the new type of boater that has a new toy and knows
nothing about how to use it and what it is all about. How
nice boating was before your type came on the water. Capt.
boots
"Chuck Tribolet" wrote in message
...
I disagree. It's OK for the fishermen to lie about what
they caught, where
they caught it, and what they caught it with ;-), and the
divers to chat about
dive conditions. Fortunately in Monterey, we have few
enough boaters that
it's not a problem (except maybe the first couple of
weekends of Salmon
season), but I can see how it could be a real problem in an
area like South
Florida that's wall to wall boats.


--
Chuck Tribolet

http://www.almaden.ibm.com/cs/people/triblet

Silicon Valley: STILL the best day job in the world.


"Curtis CCR" wrote in message
m...
I'd guess that three quarters of the recreational
boater radio traffic I hear on working channels in this
area is stuff
that shouldn't be tying up those channels in the first
place.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

Then point the OP in the right direction for help.

On Fri, 20 Feb 2004 15:51:19 -0600, "Boots Crofoot"
wrote:

you are the new type of boater that has a new toy and knows
nothing about how to use it and what it is all about. How
nice boating was before your type came on the water. Capt.
boots
"Chuck Tribolet" wrote in message
...
I disagree. It's OK for the fishermen to lie about what
they caught, where
they caught it, and what they caught it with ;-), and the
divers to chat about
dive conditions. Fortunately in Monterey, we have few
enough boaters that
it's not a problem (except maybe the first couple of
weekends of Salmon
season), but I can see how it could be a real problem in an
area like South
Florida that's wall to wall boats.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

Chuck, I wouldn't worry about "Capt." Boots - he sure sounded grumpy about a
boater asking questions. It's the ones who don't ask questions he should
worry about.

Here in Canada, the appropriate authorities have a list of what channels are
allowable for what purposes, which varies geographically, and I was able,
much to my surprise, to get them to say in writing that unassigned channels
could be used at will! Perhaps such a list is available in the U.S. as
well - I would be surprised were it not.

Duplex channels for recreational boaters here are generally used for
communicating with the Canadian Coast Guard, in which case the "duplex"
nature of the channel is transparent. It's just that other boaters can only
hear the Coast Guard side of the interchange.

We also have VHF courses, and I'm sure you do too. The ones I'm familiar
with are offered through the Power Squadron, sanctioned by the appropriate
government department, and passing the test gives us a life-long restricted
operator's certificate. In the U.S. of course it's www.usps.org, and I
suspect the Coast Guard Auxiliary (www.cgaux.org/) also offers similar
courses.

====

Charles T. Low
- remove "UN"
www.boatdocking.com/BDPhoto.html - Photo Contest
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Chuck Tribolet" wrote in message
...
OK, then, just what is appropriate on the VHF?

--
Chuck Tribolet

http://www.almaden.ibm.com/cs/people/triblet

VHF channels for marine operator? 24 - 28 and 84 - 87
 

Ok that makes sense that other boaters would only hear the coast guard shore
station, BUT what about the guy on the boat the CG shore station is talking
to?
Isn't he in the same position as anyone else listening? If another boater is
on the same frequency as the one the CG is talking to wont he hear both
sides? Is the duplex send frequency at the shore station different for each
duplex channel?
I have heard this before and still dont understand it.

"Charles T. Low" wrote in message
.. .
Chuck, I wouldn't worry about "Capt." Boots - he sure sounded grumpy about
a
boater asking questions. It's the ones who don't ask questions he should
worry about.

Here in Canada, the appropriate authorities have a list of what channels
are
allowable for what purposes, which varies geographically, and I was able,
much to my surprise, to get them to say in writing that unassigned
channels
could be used at will! Perhaps such a list is available in the U.S. as
well - I would be surprised were it not.

Duplex channels for recreational boaters here are generally used for
communicating with the Canadian Coast Guard, in which case the "duplex"
nature of the channel is transparent. It's just that other boaters can
only
hear the Coast Guard side of the interchange.

We also have VHF courses, and I'm sure you do too. The ones I'm familiar
with are offered through the Power Squadron, sanctioned by the appropriate
government department, and passing the test gives us a life-long
restricted
operator's certificate. In the U.S. of course it's www.usps.org, and I
suspect the Coast Guard Auxiliary (www.cgaux.org/) also offers similar
courses.

====

Charles T. Low
- remove "UN"
www.boatdocking.com/BDPhoto.html - Photo Contest
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Chuck Tribolet" wrote in message
...
OK, then, just what is appropriate on the VHF?

--
Chuck Tribolet

http://www.almaden.ibm.com/cs/people/triblet

VHF channels for marine operator? 24 - 28 and 84 - 87
 

No, here's how it goes with duplex:

All of the boaters' radios listen to channel 4017 (hypothetical) on
frequency 200.150 MHz (hypothetical) and transmit on 200.220 (I'm just
making these numbers up).

The land station does the reverse. Follow that information on to its logical
conclusion and I think you'll see what I mean. A boater and a land station
can carry on a conversation just fine, but two boaters cannot.

The question is why, and I think it's because more highly-qualified radio
operators can use duplex to carry on a two-way conversation, like on a
conventional telephone, using a different radio for receiving than
transmitting (although the two radios could both be in the same box - like a
telephone!). The way we recreational boaters do it, at least to my knowledge
and in my experience, is to carry on a one-way conversation, e.g. transmit,
then another one-way conversation on another frequency, i.e. receive,
although you don't have to change your channel setting to do that - the
radio changed frequencies for you, but without changing the same channel
number, when you switch back and forth between transmitting and receiving.
But one radio can't receive and transmit simultaneously, whether in simplex
or duplex mode, so it doesn't make any difference, to the recreational
marine VHF radio operator, whether it's duplex or simplex - except for other
eavesdropping boaters.

Is that any clearer?

====

Charles T. Low
- remove "UN"
www.boatdocking.com/BDPhoto.html - Photo Contest
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Scott Downey" wrote in message
...
Ok that makes sense that other boaters would only hear the coast guard
shore
station, BUT what about the guy on the boat the CG shore station is
talking
to?
Isn't he in the same position as anyone else listening? If another boater
is
on the same frequency as the one the CG is talking to wont he hear both
sides? Is the duplex send frequency at the shore station different for
each
duplex channel?
I have heard this before and still dont understand it.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

sure, the duplex channels are separated so each person transmitting does not
step on the other persons transmission, therefore both could talk and be
heard if you had 2 radios or a special radio where you could hear and talk
at the same time.

But if you have 2 boaters both on the same duplex channel talking to one
shore station on its own complemntary channel, each boater should be part of
the same conversation. There would be no difference between them as they
would both be using the same duplex channel. So therefore another boater
ought to be able to listen in if tuned to the same duplex channel that the
other boater was using talking to the shore station.

Does anyone sell a special radio that allows one to hear and talk at the
same time? I dont see that in the catalogs. Using 2 radios is a work around,
I suppose.

"Charles T. Low" wrote in message
.. .
No, here's how it goes with duplex:

All of the boaters' radios listen to channel 4017 (hypothetical) on
frequency 200.150 MHz (hypothetical) and transmit on 200.220 (I'm just
making these numbers up).

The land station does the reverse. Follow that information on to its
logical
conclusion and I think you'll see what I mean. A boater and a land station
can carry on a conversation just fine, but two boaters cannot.

The question is why, and I think it's because more highly-qualified radio
operators can use duplex to carry on a two-way conversation, like on a
conventional telephone, using a different radio for receiving than
transmitting (although the two radios could both be in the same box - like
a
telephone!). The way we recreational boaters do it, at least to my
knowledge
and in my experience, is to carry on a one-way conversation, e.g.
transmit,
then another one-way conversation on another frequency, i.e. receive,
although you don't have to change your channel setting to do that - the
radio changed frequencies for you, but without changing the same channel
number, when you switch back and forth between transmitting and receiving.
But one radio can't receive and transmit simultaneously, whether in
simplex
or duplex mode, so it doesn't make any difference, to the recreational
marine VHF radio operator, whether it's duplex or simplex - except for
other
eavesdropping boaters.

Is that any clearer?

====

Charles T. Low
- remove "UN"
www.boatdocking.com/BDPhoto.html - Photo Contest
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Scott Downey" wrote in message
...
Ok that makes sense that other boaters would only hear the coast guard
shore
station, BUT what about the guy on the boat the CG shore station is
talking
to?
Isn't he in the same position as anyone else listening? If another
boater
is
on the same frequency as the one the CG is talking to wont he hear both
sides? Is the duplex send frequency at the shore station different for
each
duplex channel?
I have heard this before and still dont understand it.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

You only hear the shore station side. Your and the other boaters radio
transmit on a frequency that the radios do not receive.
Bill

"Scott Downey" wrote in message
...
sure, the duplex channels are separated so each person transmitting does
not
step on the other persons transmission, therefore both could talk and be
heard if you had 2 radios or a special radio where you could hear and talk
at the same time.

But if you have 2 boaters both on the same duplex channel talking to one
shore station on its own complemntary channel, each boater should be part
of
the same conversation. There would be no difference between them as they
would both be using the same duplex channel. So therefore another boater
ought to be able to listen in if tuned to the same duplex channel that the
other boater was using talking to the shore station.

Does anyone sell a special radio that allows one to hear and talk at the
same time? I dont see that in the catalogs. Using 2 radios is a work
around,
I suppose.

"Charles T. Low" wrote in message
.. .
No, here's how it goes with duplex:

All of the boaters' radios listen to channel 4017 (hypothetical) on
frequency 200.150 MHz (hypothetical) and transmit on 200.220 (I'm just
making these numbers up).

The land station does the reverse. Follow that information on to its
logical
conclusion and I think you'll see what I mean. A boater and a land
station
can carry on a conversation just fine, but two boaters cannot.

The question is why, and I think it's because more highly-qualified
radio
operators can use duplex to carry on a two-way conversation, like on a
conventional telephone, using a different radio for receiving than
transmitting (although the two radios could both be in the same box -
like
a
telephone!). The way we recreational boaters do it, at least to my
knowledge
and in my experience, is to carry on a one-way conversation, e.g.
transmit,
then another one-way conversation on another frequency, i.e. receive,
although you don't have to change your channel setting to do that - the
radio changed frequencies for you, but without changing the same channel
number, when you switch back and forth between transmitting and
receiving.
But one radio can't receive and transmit simultaneously, whether in
simplex
or duplex mode, so it doesn't make any difference, to the recreational
marine VHF radio operator, whether it's duplex or simplex - except for
other
eavesdropping boaters.

Is that any clearer?

====

Charles T. Low
- remove "UN"
www.boatdocking.com/BDPhoto.html - Photo Contest
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Scott Downey" wrote in message
...
Ok that makes sense that other boaters would only hear the coast guard
shore
station, BUT what about the guy on the boat the CG shore station is
talking
to?
Isn't he in the same position as anyone else listening? If another
boater
is
on the same frequency as the one the CG is talking to wont he hear
both
sides? Is the duplex send frequency at the shore station different for
each
duplex channel?
I have heard this before and still dont understand it.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

"Scott Downey" wrote in message
...
Ok that makes sense that other boaters would only hear the coast guard
shore
station, BUT what about the guy on the boat the CG shore station is
talking
to?

It is common for the shore station to rebroadcast the ships signal so that
all can hear it. This technique is often referred to as a "repeater".

I don't know about any other country, but here is a link to the US Coast
Guard's web page that provides information regarding what channels are used
for what:

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


There are 51 channels in this list. One of these is a "receive only" (with
respect to the boat) channel. Ten of these are "duplex" channels, where the
transmit and receive frequencies are different. Of these 10, 8 are
designated as "Public Correspondence (Marine Operator)". One is designated
"Automatic Identification System duplex repeater". Only one, channel 20, is
used for official use: "Port Operations (duplex)"

I haven't listened in on the port operations much, but I suspect that they
would operate in the "repeater" mode. On this channel, the ship transmits on
a frequency of 157.000 MHz. The port office has a radio that is listening
on 157.000 MHz, and transmits on 161.600 MHz. The port office can transmit
directly, or it can take the signal it received and transmit it again on
161.600. If it is in repeat mode, all the ships within range can hear the
entire conversation. This would be very helpful in coordinating traffic
between ships that might be out of range with each other but within range of
the port (which would have the benefit of a much taller antenna and possibly
a better receiver and more powerful transmitter).

It has been a number of years since I have heard any Marine Operator traffic
on VHF. Before cell phones, marine operator traffic was fairly common. If
a ship wanted to place a call, they would contact the marine operator on
channel 16. The operator would instruct them to go to a specific duplex
channel where the call would be made. Let's say that the operator directed
you to channel 28. The boat would transmit on frequency 157.400 and receive
on 162.000. The marine operator would do the opposite. Since the person at
the other end of the phone line can't "push to talk" the marine operators
transmitter is going all the time, transmitting whatever it gets from the
phone line.

When the call was connected, the very nature of the telephone line "repeats"
the boats signal. Just like you hear your own voice in the earpiece when
you talk on the phone, the marine operators transmitter will hear the
skipper's voice after it has looped through the telephone central office. A
third party eavesdropping on the channel will be able to hear the entire
conversation.

Rod McInnis

VHF channels for marine operator? 24 - 28 and 84 - 87
 

"Scott Downey" wrote in message ...
sure, the duplex channels are separated so each person transmitting does not
step on the other persons transmission, therefore both could talk and be
heard if you had 2 radios or a special radio where you could hear and talk
at the same time.

But if you have 2 boaters both on the same duplex channel talking to one
shore station on its own complemntary channel, each boater should be part of
the same conversation. There would be no difference between them as they
would both be using the same duplex channel. So therefore another boater
ought to be able to listen in if tuned to the same duplex channel that the
other boater was using talking to the shore station.

Yeah. You can listen in on the transmissions from the shore station,
not the other boats.

If two boats are talking to a shore station on, say, channel 84. both
of the boats will only hear the shore station, not eachother.

Think off a tin can telephone system. With one string (frequency) you
are simplex. In theory you can't hear the other guy talking when you
are talking because you have the can to your mouth instead of your
ear. Only one person can talk at a time, but only one string is
needed for a two-way comm.

With duplex there are two strings (frequencies). The string from your
transmitter is connected to shore station's receiver. That string
only goes one way. The other string goes from the shore station's
transmitter to your receiver. Again it's only one way on each string.

The other boats' strings are set up the same way. The only way to
hear other boats would be to swap the strings on your radio. You
can't do that.

Does anyone sell a special radio that allows one to hear and talk at the
same time? I dont see that in the catalogs. Using 2 radios is a work around,
I suppose.

The only thing that would allow is for you to transmit and receive
simultaneously (full duplex as opposed to half duplex). It will not
change the frequency set and allow you to talk to other boats on a
duplex channel.

VHF channels for marine operator? 24 - 28 and 84 - 87
 

"Rod McInnis" wrote in message ...
"Scott Downey" wrote in message
...
Ok that makes sense that other boaters would only hear the coast guard
shore
station, BUT what about the guy on the boat the CG shore station is
talking
to?

It is common for the shore station to rebroadcast the ships signal so that
all can hear it. This technique is often referred to as a "repeater".

I don't know about any other country, but here is a link to the US Coast
Guard's web page that provides information regarding what channels are used
for what:

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


There are 51 channels in this list. One of these is a "receive only" (with
respect to the boat) channel. Ten of these are "duplex" channels, where the
transmit and receive frequencies are different. Of these 10, 8 are
designated as "Public Correspondence (Marine Operator)". One is designated
"Automatic Identification System duplex repeater". Only one, channel 20, is
used for official use: "Port Operations (duplex)"

I haven't listened in on the port operations much, but I suspect that they
would operate in the "repeater" mode. On this channel, the ship transmits on
a frequency of 157.000 MHz. The port office has a radio that is listening
on 157.000 MHz, and transmits on 161.600 MHz. The port office can transmit
directly, or it can take the signal it received and transmit it again on
161.600. If it is in repeat mode, all the ships within range can hear the
entire conversation. This would be very helpful in coordinating traffic
between ships that might be out of range with each other but within range of
the port (which would have the benefit of a much taller antenna and possibly
a better receiver and more powerful transmitter).

It has been a number of years since I have heard any Marine Operator traffic
on VHF. Before cell phones, marine operator traffic was fairly common. If
a ship wanted to place a call, they would contact the marine operator on
channel 16. The operator would instruct them to go to a specific duplex
channel where the call would be made. Let's say that the operator directed
you to channel 28. The boat would transmit on frequency 157.400 and receive
on 162.000. The marine operator would do the opposite. Since the person at
the other end of the phone line can't "push to talk" the marine operators
transmitter is going all the time, transmitting whatever it gets from the
phone line.

When the call was connected, the very nature of the telephone line "repeats"
the boats signal. Just like you hear your own voice in the earpiece when
you talk on the phone, the marine operators transmitter will hear the
skipper's voice after it has looped through the telephone central office. A
third party eavesdropping on the channel will be able to hear the entire
conversation.

Hearing youself on the telephone receiver is called sidetone. Phone
connection made through trunks don't necessarily have sidetone.
However you are correct that you could often hear the ship side of the
call on the receive side of the channel.

Rod McInnis

VHF channels for marine operator? 24 - 28 and 84 - 87
 

Thanks for all the good help.

I believe, now I understand .


"Curtis CCR" wrote in message
om...
"Scott Downey" wrote in message
...
sure, the duplex channels are separated so each person transmitting does
not
step on the other persons transmission, therefore both could talk and be
heard if you had 2 radios or a special radio where you could hear and
talk
at the same time.

But if you have 2 boaters both on the same duplex channel talking to one
shore station on its own complemntary channel, each boater should be
part of
the same conversation. There would be no difference between them as they
would both be using the same duplex channel. So therefore another boater
ought to be able to listen in if tuned to the same duplex channel that
the
other boater was using talking to the shore station.

Yeah. You can listen in on the transmissions from the shore station,
not the other boats.

If two boats are talking to a shore station on, say, channel 84. both
of the boats will only hear the shore station, not eachother.

Think off a tin can telephone system. With one string (frequency) you
are simplex. In theory you can't hear the other guy talking when you
are talking because you have the can to your mouth instead of your
ear. Only one person can talk at a time, but only one string is
needed for a two-way comm.

With duplex there are two strings (frequencies). The string from your
transmitter is connected to shore station's receiver. That string
only goes one way. The other string goes from the shore station's
transmitter to your receiver. Again it's only one way on each string.

The other boats' strings are set up the same way. The only way to
hear other boats would be to swap the strings on your radio. You
can't do that.

Does anyone sell a special radio that allows one to hear and talk at the
same time? I dont see that in the catalogs. Using 2 radios is a work
around,
I suppose.

The only thing that would allow is for you to transmit and receive
simultaneously (full duplex as opposed to half duplex). It will not
change the frequency set and allow you to talk to other boats on a
duplex channel.