New VHF Channel Numbers; New Services

VHF Marine Band radios, protocol, radio communication theory, practical advice; AIS; DSC; MMSI; EPIRB.
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New VHF Channel Numbers; New Services

Postby jimh » Fri Oct 14, 2016 1:29 pm

The International Telecommunications Union (ITU) has changed the channel number assignment in the VHF Marine Band. An announcement on the Coast Guard Navigation Center website says:

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 our U.S. VHF Channels page.

I don't know exactly when the USCG posted that. Their website notes the most recent update was October 6, 2016. I believe that the recommended changes will take place on January 1, 2017.

The changes appear to affect 18 channels which were formerly assigned as split channels for duplex or semi-duplex operation between ship stations and shore stations, mostly for public correspondence and coast guard use. The reassignment appears to end the use of the lower-frequency of the pair, and creates new simplex channels using those frequencies. Several of these channels were already in use in the USA as simplex on the lower frequency pair, designated by the old channel number with an "A" appended. The changed channels and their new numbering scheme are described below:

CH    TX-MHz   RX-MHz   Notes
1001 156.050 156.050 Lower frequency of duplex CH-1, was 01A
1005 156.250 156.250 Lower frequency of duplex CH-5, was 05A
1007 156.350 156.350 Lower frequency of duplex CH-7, was 07A
1018 156.900 156.900 Lower frequency of duplex CH-18, was 18A
1019 156.950 156.950 Lower frequency of duplex CH-19
1020 157.000 157/000 Lower frequency of duplex CH-20
1021 157.050 156.050 Lower frequency of duplex CH-21, was 21A
1022 157.100 157.100 Lower frequency of duplex CH-22, was 22A
1023 157.150 157.150 Lower frequency of duplex CH-23, was 23A
1063 156.175 157.175 Lower frequency of duplex CH-63, was 63A
1065 156.275 157.275 Lower frequency of duplex CH-65, was 65A
1066 156.387 157.375 Lower frequency of duplex CH-66, was 66A
1078 156.935 156.925 Lower frequency of duplex CH-78
1079 156.975 156.975 Lower frequency of duplex CH-79
1080 157.025 157.025 Lower frequency of duplex CH-80, was 80A
1081 157.075 157.075 Lower frequency of duplex CH-81, was 81A
1082 157.125 157.125 Lower frequency of duplex CH-82, was 82A
1083 157.175 157.175 Lower frequency of duplex CH-83, was 83A

The Coast Guard Navigation Center page continues to list a second 1020 as a split channel, but I suspect that is perhaps a mistake on the web presentation. [Update; that error has been corrected on the USCG website--jimh] It is hard to have one channel number be designated to two different uses of the channel. The Navigation Page for channel assignments also gives the permitted uses of all the channels, including these new ones. See for more details.

The new channels that will be created by this change are really just the new lower frequency pair of old channels 19, 20, 79, and 80. The new channel numbers have been assigned uses as follows:

1001 Port Operations and Commercial, VTS. New Orleans/Lower Mississippi area
1005 Port Operations or VTS. Houston, New Orleans and Seattle areas
1007 Commercial. VHF Digital Small Message Services
1018 Commercial. VHF Digital Small Message Services
1019 Commercial. VHF Digital Small Message Services
1020 Port Operations
1021 U.S. Coast Guard only
1022 Coast Guard Liaison and Maritime Safety Information Broadcasts
1023 U.S. Coast Guard only
1063 Port Operations and Commercial, VTS. New Orleans/Lower Mississippi area
1065 Port Operations
1066 Port Operations
1078 Non-Commercial. VHF Digital Small Message Services
1079 Non-Commercial. VHF Digital Small Message Services
1080 Non-Commercial. VHF Digital Small Message Services
1081 U.S. Government only--Environmental protection operations
1082 U.S. Government only
1083 U.S. Government only

As you can see, most of the new channels have remained in their original use for vessel traffic services (VTS), for use by commercial ships, and for use by Coast Guard or other government users. Only new channels 1078, 1079, and 1080 are available for non-commercial use.

VDSMS or VHF Digital Small Message Services

The VHF Digital Small Message Services (VDSMS) is a new use that permits transmission of short digital messages in accordance with RTCM Standard 12301.1. I am sure most boaters have never heard of this standard, so here is a brief summary of it:

RTCM 12301.1, Standard for VHF-FM Digital Small Message Services,
July 2009

This 4-page standard specifies the minimum functional and technical requirements for VHF-FM Digital Small Message Services (VDSMS). VDSMS are designed to be embodied within an item of equipment capable of receiving and transmitting VHF communication. This is not an equipment standard. VDSMS are intended to provide for short messaging from ship-to-ship, shore-to-ship and ship-to-shore.

VDSMS are intended to operate on frequencies in the international VHF Marine Band defined in Appendix 18 of the International Radio Regulations (RR Ap 18), unless otherwise restricted by regulation. VDSMS may share channels with other services (e.g. voice services) on a non-interference basis. The VHF Data Link (VDL) access method for VDSMS is intended to ensure that a call in progress is not disrupted. VDSMS transmissions have a limited duration and a limited duty cycle to ensure the availability of the channel for other users. VDSMS transmitter emissions masking is intended to protect the users of the adjacent channels.

The body of this standard includes general requirements for VDSMS. Requirements for specific technology implementations will be contained in future separate Annexes that will include packet data structure, message types, error detection/correction and other technical details associated with each technology.

This sounds like the same sort of text messaging as the SMS service used on cellular telephones. Note that the three new channels available to non-commercial users also permit use of VDSMS transmission. Perhaps soon boaters can send short text messages to other boaters. Won't that make life grand?

An astute reader might now ask, "What will happen to the upper-frequency pair of all those duplex channels?" That is a good question. I believe the ITU recommendation includes creating new simplex channels from those higher-frequency pairs, and the naming convention would prefix "20" to the old channel number. There would thus be a bunch of new higher-frequency simplex channels in the VHF Marine Band. For example, the old duplex CH-1 had the ship station transmitting on 156.050 and the shore station transmitting on 160.650. When CH-1 was dissolved into 1001 for simplex at 156.050, that left 160.650 available for simplex, too. That channel would be designated 2001. (A Space Odyssey channel?) The big frequency jump is a problem with using this for ships. Formerly ship transmit channels were all grouped at the very low end of the band, and the typical ship antenna is tuned for that range. Most ship antennas do not have wide VSWR bandwidth, and if you try to transmit into a ship antenna tuned for the low end now at a frequency of 160.650 the VSWR is likely to be above 2:1. It is typical a recreational grade VHF radio will try to shut down transmitter power output if it sees a high VSWR.

For even more details about the new frequencies and the possibilities of even more channels sometime in the future, enjoy reading these two documents:

ITU-R M.1084-5
Interim solutions for improved efficiency
in the use of the band 156-174 MHz by
stations in the maritime mobile service!!PDF-E.pdf

ITU-R M.1842-1
Characteristics of VHF radio systems and equipment for
the exchange of data and electronic mail in the maritime
mobile service RR Appendix 18 channels!!PDF-E.pdf

Finally, in case you were wondering if the FCC was interested in your opinion on any of this, you missed the boat. A notice of requests for comments was published in April 2016. See


The request for comments concerns changes proposed to PART 80 of the commission's rules (Maritime Radio Services) by the Radio Technical Commission for Maritime Services (RTCM) that were included in their petition to the FCC, "Petition for rulemaking to rewrite Part 80 of the Commission’s rules for Stations in the Maritime Services," filed in February 2016. You can obtain a copy of their petition from

Summary of petition

Full petition with complete details of all proposed changes

RTCM explained their reason for their petition to change the Part 80 rules:

Since the last FCC revision of Part 80 of the rules, these standards and relevant maritime radio technologies have undergone additional changes, revisions and advances. This Petition for Rulemaking is intended to revise Part 80 in response to these changes.

By this Petition, changes have been proposed throughout Part 80 to simplify regulations and to eliminate equipment and procedures which are no longer used.

Searching for any news about RM-11765, I found that many interested parties had filed comments, including:

--the USCG
--Steve Spitzer (of the NMEA)

You can read their comments (and more comments from others) by downloading them from the FCC website at,DESC&proceedings_name=RM-11765

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Re: New VHF Channel Numbers, New Services

Postby jimh » Sat Oct 15, 2016 9:41 am

Based on a footnote in the USCG website international VHF Marine Band frequency chart, it appears the upper frequency of old channels 27 and 28, which under the new number scheme would be known as 2027 and 2028, are going to be allocated for use for possible future AIS channels. They are given new channel designations as ASM 1 and ASM 2. This creates a nice group of adjacent AIS channels at the high end of the VHF Marine Band, as follows

ASM-1 161.950
AIS-1 161.975
ASM-2 162.000
AIS-2 162.025

Footnote "z'" says:

Until 1 January 2019, these channels may be used for possible testing of future AIS applications without causing harmful interference to, or claiming protection from, existing applications and stations operating in the fixed and mobile services.

From 1 January 2019, these channels are each split into two simplex channels. The channels 2027 and 2028 designated as ASM 1 and ASM 2 are used for application specific messages (ASM) as described in the most recent version of Recommendation ITU-R M.2092.


For the referenced M.2092, see

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Re: New VHF Channel Numbers

Postby jimh » Mon Oct 17, 2016 5:00 pm

Via some correspondence with Standard-Horizon, I learned they will soon be implementing the new four-digit channel designator scheme in their radios. This may occur in a few weeks. I think these new channel numbers will take most boaters by surprise. I have not seen any discussion of this on any boating-oriented website. There is some talk about this, but mostly on radio-oriented websites.

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Re: New VHF Channel Numbers

Postby jimh » Tue Oct 18, 2016 12:51 pm

I finally found the holy grail of these new channel assignments and numbering:

Report ITU-R M.2231-1
Use of Appendix 18 to the Radio Regulations for the maritime mobile service

This explains several puzzling things. First, the phrase "RR Appendix 18" means Radio Regulations Appendix 18." This apparently refers to some sort of master frequency allocation listing in the formal treaty regulations. Next, the planned use of the VHF Marine Band is very nicely shown in a colorful and well done illustration titled "Figure 1." Consult this diagram to understand more about frequency use plans and allocations. Also, there is a very interesting section titled "Considerations for the maritime use of RR Appendix 18 in the United States." This section explains in detail the unique situation of many of the frequencies in the marine band having been allocated to other services in the USA.

Actually, the new channel number seems to not be mentioned here. I am still looking for the authoritative source document on that action.

The above document makes many references to ITU REGIONS by number. The Americas are considered as ITU REGION 2. For a map of the regions see

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Re: New VHF Channel Numbers; New Services

Postby jimh » Tue Oct 18, 2016 2:09 pm

Reviewing the most recent channel assignments available to recreational boats, that is, not commercial, not coast guard, not government, not VTS, not port-operations,and not public correspondence, we find the available channels are as follows;

06--Intership safety
09--Boater Calling. Commercial and Non-commercial. VDSMS
13--Intership navigation safety. Bridge-to-Bridge
16--International distress, safety, and calling
68--Non-commerical, VDSMS
69--Non-commercial. VDSMS
71--Non-commercial. VDSMS
72--Non-commercial, inter-ship only. VDSMS
1078--Non-commercial. VDSMS
1079--Non-commercial, Great Lakes only. VDSMS
1080--Non-commercial, Great Lakes only. VDSMS

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Re: New VHF Channel Numbers: New Services

Postby jimh » Sat Mar 18, 2017 10:14 am

Revisiting the USCG webpage with the new channel number listing, I see they corrected the error regarding having chanel 1020 listed twice. The USCG webpage now correctly shows Channel 1020 as simplex channel for "Port Operations."

The USCG also notes:

These new channel numbers should eventually begin to be displayed on new models of VHF marine radios.

If anyone has purchased a new VHF Marine Band radio, check to see if the channel numbering conforms to the new four-digit scheme and post a follow-up.