Coast Guard using US mode on radio

[deblen]

Originally Posted by stewie

All maritime VHF channels have the same range.

Not necessarily. Some countries restrict output to 1watt on certain channels.
Therefore, your VHF will automatically restrict output to 1W,depending on the mode(US/Int) that you have set. Ch 67 used to be that way-in US mode.
Leave your VHF in US mode at all times,while in USA or Canada.


Len

[deblen]

https://www.amc.edu.au/__data/assets...obile-Band.pdf




https://en.wikipedia.org/wiki/Marine...nd_frequencies

[Alan Mighty]

Originally Posted by Alan Mighty

* in around 1947, by agreement at an international conference held in New Jersey, three chunks of the VHF spectrum were allocated to maritime mobile use for safety. But the bottom line always was that individual jurisdictions (i.e. nation states) had to exert their political will to safeguard the spectrum allocation for maritime mobile.

* in the US, in 1948 the USCG did deals with the US FCC, surrendering some spectrum and getting the 21A thru 24A channels in return.

* in other jurisdictions (i.e. outside the US), different nation-states did slightly different things, but generally three chunks of VHF spectrum were allocated to maritime mobile. In truth, VHF 16 is the minimum that is protected around the world. Some jurisdictions don't like their citizens having access to VHF transceivers at all. Not mentioning any names now.

* in the US, the several railway companies were politically much more powerful than the unorganised users of maritime mobile. So the US ended up with only two of those three chunks of VHF spectrum allocated to maritime mobile. And one of the two chunks was made thinner than elsewhere. Railways and other commercial uses took what in non-US jurisdictions is maritime mobile spectrum.

* back in the 1980s, there was a marine incident. A foreign flagged ship was navigating in US waters. The USCG had broadcast a warning (on 21A or one of those other USA-only channels) that a barge carrying flammable petrochemicals (petrol or gasoline, depending what side of the creek you went to school) was adrift. The foreign flagged ship was, not surprisingly, not monitoring the US channels and so received not that warning broadcast. The captain of the foreign flagged ship was not happy. The eventual result was that the US Houses of Congress legislated that all foreign-flagged ships in US waters must carry a VHF transceiver with a switch that changed from "international mode" to the more restricted (but with the 21A - 24A channels that the USCG had bartered from the US FCC) "US mode". Although not governed by US law, most all of this planet's manufacturers of VHF sets have installed that switch. No one specified that that switch should be easy to use - quite the contrary.

To add to and to clarify the above, at the request of a couple-three CF members:

* the first crucial period for the maritime mobile service in the US was 1947 - 59, the period between the 1947 international conference held in Atlantic City, New Jersey, and the 1959 ITU World Administrative Radio Conference. A good internet search might reveal the documents from both conferences (e.g. using a search item such as "1959 WARC"). My understanding - because I'm not old enough to have held a radio license in '47-'59 - is based on the experience of an ex-USCG Comms officer who lives aboard in my home marina. Story is that the companies & govt agencies controlling US ports were not well organised and could not get together with US shipping firms or the representatives of recreational boaters. The various railway companies (called 'railroad' companies by the same people who call petrol 'gas') could present a loud united voice to high levels of US politics and administration (meaning the White House, Congress, and the FCC). VHF sets are less expensive than many of the alternatives. The railway companies used VHF to communicate between a locomotive pushing a train from behind and a guard up front, and lots of other similar uses. My ex-USCG source reckons that an unnamed railway company may have 'manufactured' a 'Gulf of Tonkin-like incident' to claim that interference by a marine VHF transmission may have contributed to what the railway company called an 'incident'. The USCG and shipping and boating interests wanted the US to push for those three blocks of VHF spectrum to be reserved for the Maritime Mobile Service (MMS). The US railway companies argued to the US FCC that it should have a big chunk of that spectrum. I'm not clear on what position the US put to the 1959 WARC, but the USCG was very disappointed and recorded that only two or three other jurisdictions supported the stance that those 3 blocks of VHF spectrum should be reserved internationally for MMS. The 1959 WARC was the last chance to reserve the blocks. No reservation was made; the 1959 WARC ended with it being up to each individual jurisdiction to do its best efforts.

* after the 1959 WARC, jurisdictions with maritime interests did what they could to reserve the spectrum blocks for the VHF MMS. In the US, the railway companies won. So the US was left with only 2 of the 3 blocks, plus the 20A-24A block that the USCG had traded other spectrum to gain.

* the USCG (and other interests) tried to get the US FCC to re-assign the missing VHF spectrum block in the late 1970s (in preparation for the 1979 WARC). Apparently the peak body of US railway companies admitted that given 7 years, they could vacate that block of spectrum. But the railway capitalists continued to argue that VHF was a safety issue. So the FCC did not favour the USCG (it's only a 2nd class branch of the US military, right? US capitalists always get the ear of govt and govt agencies, not chappies in uniform). The railway companies argued that for their safety, they had to have sole use of the VHF spectrum block for 190 statue miles each side of a railway. That sort of ruled out any coastal or riverine use of that contentious VHF block (the grudging offer by the railway corporations to give up the spectrum block if given a 7-year transition period was never followed).

* the 1980s incident with the wayward petrol barge, leading to the "international/US" mode switch on VHF sets happened in Long Island Sound.

* in the 1990s, there were other incidents after the introduction of pagers (remember those? before smartphones?). Apparently FCC received reports of interference between maritime VHF transmissions (apparently on the Mississippi) and a page company. Guess who won - the pager company or the maritime mobile service? That's right. And that's the reason that most all VHF sets now carry a LOcal/DX (Distance) switch. Wouldn't want a bridge to bridge conversation about whether to pass red to red or green to green on the Mississippi to interfere with pager messages to set up a customer with a hooker or a drug dealer, would you?

* in the 1990s, the USCG (plus some shipping and boating interests such as Boating US) realised they had a chance to get the US FCC to reallocate the VHF 20-24 spectrum block (which of course includes VHF 84-86 and comes right close the AIS channels) to the MMS. That would have brought one of the two remaining US VHF MMS spectrum blocks almost to match the 'international' block. So what did the US FCC do? (note: US CF members can work out who was president at the time, who ran FCC, and who did the lobbying). A company bid for the VHF 20-24 block claiming it was going to set up a US-wide maritime telephone network. And so the FCC dutifully allocated that spectrum block to said company. Said company never did what it promised (and instead on-sold chunks of that block to other commercial uses). Depending on your POV, that was THE last chance for the US to become internationally operable with the rest of the world VHF MMS.

* What's more alarming is that VHF 28 and VHF 88 overlap the two frequencies allocated to AIS. If you take into account how the US FCC has decided in the past if any commercial user (pager companies, railway corporations) reports interference from VHF MMS, then you'd have sleepless nights about the integrity of AIS1 and AIS2 in US waters.

I think good searching of the internet will give anyone interested chapter and verse on the history of VHF MMS in the US. Start with USCG Telecommunications people. They know all the dirty story.

[Alan Mighty]

Originally Posted by Alan Mighty

* back in the 1980s, there was a marine incident. A foreign flagged ship was navigating in US waters. The USCG had broadcast a warning (on 21A or one of those other USA-only channels) that a barge carrying flammable petrochemicals (petrol or gasoline, depending what side of the creek you went to school) was adrift.

Jef Mallet sent a comment yesterday:

[Stu Jackson]

Originally Posted by stormalong

Huh??? Just leave it in U.S. mode. Canada uses U.S. mode for it's comms. No need to keep the radio in international mode for Canada.

Which is what I have been suggesting all along.
Look, it's simple: the frequencies for 22A and 83A ARE THE SAME for U (USA) and C (Canadian).

I just got back on the boat and checked the frequencies in my VHF manual.

What is so bleepin' hard about this?

Just don't use I. Done.



I moved from the US to Canada three years ago. Figured out what channels to scan and have never had any issues.

[wedivebc]

Originally Posted by Stu Jackson

Which is what I have been suggesting all along.
Look, it's simple: the frequencies for 22A and 83A ARE THE SAME for U (USA) and C (Canadian).

I just got back on the boat and checked the frequencies in my VHF manual.

What is so bleepin' hard about this?

Just don't use I. Done.



I moved from the US to Canada three years ago. Figured out what channels to scan and have never had any issues.

I'm sorry but you are wrong. When CCG has you switch channels they insist you also switch to US mode, if you stay in int mode or whatever the default for our radios are you can't hear them until you switch.

[stormalong]

Originally Posted by wedivebc

I'm sorry but you are wrong. When CCG has you switch channels they insist you also switch to US mode, if you stay in int mode or whatever the default for our radios are you can't hear them until you switch.

I don't think you understood what Stu and I are saying. You do not need to "switch" to U.S. mode if you simply stay in U.S. mode. All of the normal frequencies are the same in U.S. and international modes.

[Stu Jackson]

Originally Posted by wedivebc

I'm sorry but you are wrong. When CCG has you switch channels they insist you also switch to US mode, if you stay in int mode or whatever the default for our radios are you can't hear them until you switch.

That's not how my radio (SH) works. The operator chooses the I, C or U. There is no default setting, but even if there is, it does not revert to that when turned off, it remains at what it was last set to. The operator must set it, but only needs to do so once.



Like I said, forget I.


For these two channels, 22A and 83A, the frequencies in C and U are identical.


You are mixing MODE and channel.


They are both S, simplex channels.


My radio manual says, for both: US govt, Canadian coast guard under description.


Neither one of them has a check mark next to I for either of those channels. No wonder they make you switch!


Like I said, forget I.

[Shrew]

Originally Posted by Brian.D

As an example, take channel 22 and 22A. Most of the channels assigned in VHF Maritime are duplex frequencies. This means (and I am not talking down to anyone) that the transmit and receive frequencies are different. In the US, the "A" designation, as in 22A, means the channel is a simplex channel where the transmit frequency and receive frequency are the same. Here, I believe the 161.7 MHz frequency (the other half of the channel 22 pair) is used somewhere else.

This holds true for geostationary satellites. There are three different sets of down link frequencies. This because some of the downlink frequencies are used by microwave system throughout the world. The satellite downlink could interfere with the microwave links.

As for the dissertation above, I too have never hear that story. It sounds plausible.

I am not familiar with your description. Here is how I understand it to work:

Simplex: One Direction, One channel

Half-Duplex: Two directions, one channel (one direction at a time)

Full-Duplex: Two directions, two channels. (both directions simultaneous.)

[Kelkara]

Originally Posted by wedivebc

I'm sorry but you are wrong. When CCG has you switch channels they insist you also switch to US mode, if you stay in int mode or whatever the default for our radios are you can't hear them until you switch.

Here in BC what the CCG say is "switch to channel 8 3 alpha, that's channel 8 3 in the US mode"

So you can stay in Canada mode on channel 83A, or if you've got your radio set in USA mode I presume the same frequency is called channel 83 ... No need to change mode ( unless maybe you've just crossed an ocean and have your radio in International mode) ... Just go to 83A or 83 accordingly.

[requiem]

Originally Posted by Shrew

I am not familiar with your description. Here is how I understand it to work:

Simplex: One Direction, One channel

Half-Duplex: Two directions, one channel (one direction at a time)

Full-Duplex: Two directions, two channels. (both directions simultaneous.)

What radio people call simplex is really “half duplex”.

As to the radio modes, this link may be relevant for some: https://ccga-pacific.org/news/?action=view&nid=107

Some radios that should use simplex on certain channels in Canada mode don’t; for those you’d need to stay in US mode. A problem with staying in US mode is that you might want to use non-US channels at times as well.

[Perfect Ride]

Thank you Alan Mighty, very informative history and useful tips.

[stormalong]

Originally Posted by Brian.D

As an example, take channel 22 and 22A. Most of the channels assigned in VHF Maritime are duplex frequencies. This means (and I am not talking down to anyone) that the transmit and receive frequencies are different. In the US, the "A" designation, as in 22A, means the channel is a simplex channel where the transmit frequency and receive frequency are the same. Here, I believe the 161.7 MHz frequency (the other half of the channel 22 pair) is used somewhere else.

This holds true for geostationary satellites. There are three different sets of down link frequencies. This because some of the downlink frequencies are used by microwave system throughout the world. The satellite downlink could interfere with the microwave links.

As for the dissertation above, I too have never hear that story. It sounds plausible.

Nope, not right. Most of the VHF marine channels are simplex - One frequency for transmit and receive. Only the old public correspondence channels are duplex - different channels for transmit and receive.

If the normal channels were duplex you could not hear both sides of the conversation on a simple receiver. The old public correspondence channels were duplex specifically so that most eavesdroppers could not hear both sides of the conversation.

[Stu Jackson]

I just did a quick search Google and can't find a chart as simple and clear as the one in my Standard Horizon HX270S radio manual.

I also have it saved on my computer as a PDF file, but it is 1,500KB and I think too big to post here.

I am sure that if ANYONE was interested in facts that they could download ANY SH radio manual and read the frequency chart.

It's very good and answers all these questions and many incorrect statements that have been made.

This is a c&p from the table for channels 22, 22A, 83 and 83A. Formatting won't let me line stuff up the way the table does, so I've annotated it.


22 I only Duplex 157.100 161.700 Port operation, ship movement
22A C & U not I Simplex 157.100 US and Canadian Coast Guard Liaison and Maritime
Safety Information Broadcasts announced on channel 16


83 Not U, C & I only Duplex 157.175 161.775 Canadian Coast Guard Only
83A U & C, not I Simplex 157.175 U.S. Government Only, Canadian Coast Guard Only


Is that enough to convince you?

[requiem]

Originally Posted by Stu Jackson

83 Not U, C & I only Duplex 157.175 161.775 Canadian Coast Guard Only
83A U & C, not I Simplex 157.175 U.S. Government Only, Canadian Coast Guard Only

My Uniden handheld lacks an 83A, but its idea of channel 83 aligns with what your radio calls 83A.