5.79A When establishing coast stations in the NAVTEX service on the frequencies 490 kHz, 518 kHz and 4 209.5 kHz, administrations are strongly recommended to coordinate the operating characteristics in accordance with the procedures of the International Maritime Organization (IMO) (see Resolution 339 (Rev.WRC 07)). (WRC 07)
5.109 The frequencies 2 187.5 kHz, 4 207.5 kHz, 6 312 kHz, 8 414.5 kHz, 12 577 kHz and 16 804.5 kHz are international distress frequencies for digital selective calling. The conditions for the use of these frequencies are prescribed in Article 31.
5.110 The frequencies 2 174.5 kHz, 4 177.5 kHz, 6 268 kHz, 8 376.5 kHz, 12 520 kHz and 16 695 kHz are international distress frequencies for narrow-band direct-printing telegraphy. The conditions for the use of these frequencies are prescribed in Article 31.
5.128 Frequencies in the frequency bands 4 063-4 123 kHz and 4 130-4 438 kHz may be used exceptionally by stations in the fixed service, communicating only within the boundary of the country in which they are located, with a mean power not exceeding 50 W, on condition that harmful interference is not caused to the maritime mobile service. In addition, in Afghanistan, Argentina, Armenia, Belarus, Botswana, Burkina Faso, the Central African Rep., China, the Russian Federation, Georgia, India, Kazakhstan, Mali, Niger, Pakistan, Kyrgyzstan, Tajikistan, Chad, Turkmenistan and Ukraine, in the frequency bands 4 063-4 123 kHz, 4 130-4 133 kHz and 4 408-4 438 kHz, stations in the fixed service, with a mean power not exceeding 1 kW, can be operated on condition that they are situated at least 600 km from the coast and that harmful interference is not caused to the maritime mobile service. (WRC 19)
5.130
5.131
5.132
US82 In the bands 4146-4152 kHz, 6224-6233 kHz, 8294-8300 kHz, 12 353-12 368 kHz, 16 528-16 549 kHz, 18 825-18 846 kHz, 22 159-22 180 kHz, and 25 100-25 121 kHz, the assignable frequencies may be authorized on a shared non-priority basis to Federal and non-Federal ship and coast stations (SSB telephony, with peak envelope power not to exceed 1 kW).
US296 In the bands designated for ship wide-band telegraphy, facsimile and special transmission systems, the following assignable frequencies are available to non-Federal stations on a shared basis with Federal stations: 2070.5 kHz, 2072.5 kHz, 2074.5 kHz, 2076.5 kHz, 4154 kHz, 4170 kHz, 6235 kHz, 6259 kHz, 8302 kHz, 8338 kHz, 12 370 kHz, 12 418 kHz, 16 551 kHz, 16 615 kHz, 18 848 kHz, 18 868 kHz, 22 182 kHz, 22 238 kHz, 25 123 kHz, and 25 159 kHz.
US340 The band 2-30 MHz is available on a non-interference basis to Federal and non-Federal maritime and aeronautical stations for the purposes of measuring the quality of reception on radio channels. See 47 CFR 87.149 for the list of protected frequencies and bands within this frequency range. Actual communications shall be limited to those frequencies specifically allocated to the maritime mobile and aeronautical mobile services.

Wiki entries

Access Broadband over Power Line (Access BPL)

Current Use 3.5–4.65 MHz Access BPL

According to the FCC's definition, Access BPL is "a carrier current system installed and operated on an electric utility service as an unintentional radiator that sends radio frequency energy on frequencies between 1.705 MHz and 80 MHz over medium voltage lines or over low voltage lines to provide broadband communications and is located on the supply side of the utility service’s points of interconnection with customer premises. Access BPL does not include power line carrier systems as defined in § 15.3(t) or In-House BPL as defined in § 15.3(gg)."

Low voltage lines are defined as lines carrying, for example, 240/120 volts from a distribution transformer to a customer's premises. Medium voltage lines carry between 1,000 and 40,000 volts from a power substation to neighborhoods, and may be overhead or underground.

Access BPL is an unlicensed service operated under Subpart G of Part 15 of the FCC's rules. Radiated emission limits from medium voltage lines in the 1.705-30 MHz range must not exceed the limits in 47 CFR 15.209, and those from 30-80 MHz must not exceed the limits in 15.109(b). Systems that operate on low voltage lines must comply with 15.109(a) limits across the entire 1.705-80 MHz range.

When Access BPL systems must use notch filters to protect licensed services, the notch must be at least 25 dB below applicable Part 15 limits in the 1.705-30 MHz band, and at least 10 dB below the limits in the 30-80 MHz band.

There are 12 sub-bands in which Access BPL systems are not allowed to operate anywhere to protect aeronautical (land) stations and aircraft receivers. Those excluded bands are listed in 15.615(f), and are excluded in the list of Access BPL bands in this entry.

Access BPL systems are not allowed to operate within the sub-band 2173.5-2190.5 kHz within 1 km of coast station facilities listed in 47 CFR 15.615(f)(2)(i), to protect the internationally-recognized standard maritime calling frequency of 2182 kHz.

No Access BPL emissions are allowed in the 73.0-74.6 MHz radio astronomy band on overhead medium voltage lines within 65 km of the Very Large Array radio telescope in New Mexico (34 04 43.5N, 107 37 03.82W), or within 47 km of the VLA on underground power lines or overhead low voltage lines.

Access BPL operators must consult at least 30 days in advance when deploying systems near various FCC field offices, aeronautical and maritime stations, radar systems, radio astronomy stations, and research areas. Details are in 47 CFR 15.615(f)(3).