VHF Marine Band Transmitter Power

VHF Marine Band radios, protocol, radio communication theory, practical advice; AIS; DSC; MMSI; EPIRB.
jimh
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VHF Marine Band Transmitter Power

Postby jimh » Wed Jun 15, 2016 8:40 am

Operation of radio transmitters in the Maritime Radio Service in the United States of America is regulated by the Federal Communications Commission in Part 80, STATIONS IN THE MARITIME SERVICES

Maximum power for a ship station transmitter is given in 47 CFR 80.215 - Transmitter power. Subpart (e) applies to the VHF Marine Band

(e) Ship stations frequencies above 27500 kHz. The maximum power must not exceed the values listed below.

(1) Ship stations 156-162 MHz—25W.

Marine utility stations and hand-held portable transmitters: 156-162 MHz-10W

Footnotes:

Reducible to 1 watt or less, except for transmitters limited to public correspondence channels and used in an automated system.

The frequencies 156.775 and 156.825 MHz are available for navigation-related port operations or ship movement only, and all precautions must be taken to avoid harmful interference to channel 16. Transmitter output power is limited to 1 watt for ship stations, and 10 watts for coast stations.

jimh
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Re: VHF Marine Band Transmitters

Postby jimh » Wed Jun 15, 2016 8:43 am

Transmitters used in the VHF Marine Band must provide for controls to adjust the transmitter as specified in 47 CFR 80.80 - Operating controls for ship stations.

§ 80.80 Operating controls for ship stations.

(a) Each control point must be capable of:

(1) Starting and discontinuing operation of the station;
(2) Changing frequencies within the same sub-band;
(3) Changing from transmission to reception and vice versa.
(4) In the case of stations operating in the 156-162 MHz bands, reducing power output to one watt or less in accordance with § 80.215(e).(Note 1)

Note 1: Ship station transmitters, except hand-held portable transmitters, manufactured after January 21, 1987 must automatically reduce the carrier power to one watt or less when turned to the frequency 156.375 MHz or 156.650 MHz. All ship station transmitters, except hand-held portable transmitters, used after January 21, 1997, must automatically reduce power as described above. A manual override device must be provided which when held by the operator will permit full carrier power operation on channels 13 and 67. Hand-held portable transmitters must be capable of reducing power to one watt, but need not do so automatically.

jimh
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Re: VHF Marine Band Transmitters

Postby jimh » Wed Jun 15, 2016 8:57 am

Summary of transmitter power limit for ship stations with channel designators instead of frequencies:

NEVER MORE THAN 1-Watt: Channel 75 and 76. (These are the channels adjacent to Channel 16.)

AUTOMATIC REDUCTION TO 1-Watt but can be overridden: Channel 13 and 67.

jimh
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Re: VHF Marine Band Transmitters

Postby jimh » Wed Jun 15, 2016 9:02 am

Transmitter power is further regulated by 47 CFR 80.63 - Maintenance of transmitter power.

§ 80.63 Maintenance of transmitter power.

(a) The power of each radio transmitter must not be more than that necessary to carry on the service for which the station is licensed.


The inference here is that stations should reduce power to 1-Watt if that power provides sufficient communication.