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NOAA Weather Radio (NWR; also known as NOAA Weather Radio All Hazards) is a network of radio stations in the United States that broadcast continuous weather information directly from a nearby Weather Forecast Office of the service's operator, National Weather Service (NWS), an agency of the National Oceanic and Atmospheric Administration (NOAA) within the United States Department of Commerce. NOAA Weather Radio broadcasts National Weather Service warnings, watches, forecasts, weather observations and other hazard information 24 hours a day. It also broadcasts alerts of non-weather emergencies such as national security, natural, environmental and public safety (such as an AMBER Alert) through the U.S. Federal Communications Commission's (FCC) Emergency Alert System. ==Operations== Known as "The Voice of NOAA's National Weather Service", NOAA Weather Radio (NWR) is provided as a public service by the National Oceanic and Atmospheric Administration. By the end of 2014, NWR had about 1025 transmitters〔(【引用サイトリンク】url=http://www.nws.noaa.gov/nwr/coverage/station_listing.html )〕 serving 95% of the United States' population, covering all 50 U.S. states, adjacent coastal waters, and the territories of Puerto Rico, the U.S. Virgin Islands, Guam, American Samoa and Saipan. The radio service continuously transmits weather and marine forecasts (where applicable) and other related information. In addition, NWR works in cooperation with the FCC's Emergency Alert System (EAS), providing comprehensive severe weather alerts and civil emergency information. In conjunction with federal, state and local emergency managers and other public officials, NWR can broadcast alerts and post-event information for all types of hazards, including natural (such as earthquakes or avalanches), man-made (such as chemical releases or oil spills), technological (such as nuclear power plant emergencies) and public safety (such as "AMBER alerts" or 9-1-1 telephone outages). Many television stations which have the capability (both commercial and public) may simulcast a local NWR station's audio content on their second audio program channel if they are not carrying a program which features either a Spanish language translation or a Descriptive Video Service track for the visually impaired. Some digital subchannels which carry weather information may also have a local NWR audio feed airing in the background, while conventional television stations carry the audio during off-air periods while transmitting a test pattern, in lieu of a reference tone. Many cable television systems and some commercial television and radio stations will, during EAS activation, rebroadcast the audio of a warning message first heard on their local NWR station, to alert viewers of a severe weather event or civil emergency, usually with the issuance of a tornado warning or tornado emergency, especially in tornado-prone areas of the country. Listening to a NOAA Weather Radio station requires a special radio receiver or scanner capable of receiving at least one of seven specific channels within the frequency range of 162.4 MHz through 162.55 MHz, collectively known as "weather band". For example, a receiver that only tunes in standard FM or AM broadcast stations will not suffice. The seven FM channels, reserved by the U.S. Government for NWR broadcasts, are located within the larger "public service band", a VHF frequency band generally used by licensed government and public agencies and authorities for non-commercial, official two-way radio communications. The original frequency was 162.550 MHz, with 162.400 MHz added in 1970; the 162.475 MHz frequency was introduced for NWR transmission in 1975 (the use of 162.475 for several years was limited only to special cases where required to avoid channel interference, and transmitter power output was restricted to 300 watts). Honolulu NWR station KBA99 transmitted on the 169.075 MHz frequency for twelve years until it was moved to 162.550 in 1975. Many (if not most) basic weather band receivers manufactured and sold from the mid-1970s through the mid-1990s were configured to only receive the three "main" weather channels. However, for much of that period, four additional "intermediate" channels (162.425, 162.450, 162.500 and 162.525 MHz) existed to accommodate anticipated expansion but went mostly unused. Over the years, a proliferation of stations meant to ensure near-complete geographical coverage and "weather-readiness" has pushed that number solidly from three to seven. According to NOAA, by April 1985, the NWS operated "about 392 stations" with "approximately 90 percent of the nation's population...within listening range";〔 , the figure was "1025 stations" with a goal to "increase coverage to at least 95 percent". All NWR channels are available on stand-alone "weather radio" receivers that are currently sold online and in retail stores (available for prices ranging from US$20 and up), as well as on most marine VHF radio transceivers, amateur radios and digital scanners. In addition, more mainstream consumer electronics, such as clock radios, portable multi-band receivers and two-way radios (such as FRS, GMRS and CB radio), now feature the ability to also receive NWR channels. Many of the aforementioned devices also incorporate alerting capabilities. With the American digital television transition making most existing portable televisions obsolete and no longer usable and the current infant and development stage of mobile digital television, along with the need to provide a public service to their viewers and encourage the use of the NWR system, many American television station weather operations cooperate with radio manufacturers and local retail outlets to offer weather radios at discounted pricing to viewers (especially in highly tornado-prone areas), where they are often marketed as an essential safety device on par with a smoke alarm for home fires. There are two different channel numbering systems used by various weather radio manufacturers. The first is the chronological sequence that the radio frequencies were allocated to the service: 1=162.550, 2=162.400, 3=162.475, 4=162.425, 5=162.450, 6=162.500, 7=162.525. The second is in simple increasing radio frequency sequence: 1=162.400, 2=162.425, 3=162.450, 4=162.475, 5=162.500, 6=162.525, 7=162.550. As with conventional broadcast television and radio signals, it may be possible to receive more than one of the seven weather channels at a given location, dependent on factors such as the location, transmitter power, range and designated coverage area of each station. The NWS suggests that users determine which frequency (as opposed to channel) is intended for their specific location so that they are assured of receiving correct and timely information. NOAA also provides secondary weather information, usually limited to marine storm warnings for sea vessels navigating the Atlantic and Pacific Oceans, to HF band "time stations" WWV and WWVH - these shortwave radio stations continuously broadcast time signals and disseminate the "official" U.S. Government time, and are operated by Department of Commerce's National Institute of Standards and Technology (NIST). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「NOAA Weather Radio」の詳細全文を読む スポンサード リンク
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