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A weather radio service is a public broadcast service dedicated to airing continuous weather reports. In most locations, it requires a specially-designed radio capable of receiving "weather band" frequencies - when tuned to one of these channels, it receives a radio station that broadcasts both routine and emergency weather information. Many weather radio receivers are equipped with a standby alerting function - if the radio is off or tuned to another band and a severe weather bulletin is transmitted, it can automatically sound an alarm and/or switch to a pre-tuned weather channel for emergency weather information. Weather radio services may also broadcast non-weather-related emergency information, such as in the event of a natural disaster, an AMBER alert or a terrorist attack. They generally broadcast in a pre-allocated very high frequency (VHF) range using FM. Usually a dedicated weather radio receiver or radio scanner is needed for listening, although in some locations a weather radio broadcast may be retransmitted on a conventional AM or FM frequency (as well as HD Radio substations), some terrestrial television stations broadcasting in MTS stereo transmit weather radio on their second audio program (SAP) channel as well as on one of its digital subchannels (where news and weather are applicable), on local public, educational, and government access (PEG) cable TV channels or during Emergency Alert System activations for tornado warnings primarily on cable systems. ==Weather radio receivers== Weather radios are widely sold online and in retail stores that specialize in consumer electronics in Canada and the United States. Additionally, they are readily available in many supermarkets and drugstores located in the southern and midwestern U.S., which are particularly susceptible to severe weather - large portions of these regions are commonly referred to as "Tornado Alley". The price of a consumer-grade weather radio varies depending on the model and its extra features.〔url=http://www.erh.noaa.gov/okx/pdf/NWRfactsheet0307.pdf〕 Weather radios are generally sold in two varieties: home (stationary) or portable use. Portable models commonly offer specialized features that make them more useful in case of an emergency. Some models use crank power, in addition to mains electricity and batteries, in case of a power outage. Some models have a built-in flashlight and can double as a cellphone charger. Some also serve as a more general emergency radio and may include multiband and two-way communication capability. "Scanner" radios designed to continuously monitor the VHF-FM public service band are already able to receive weather channels. Historically, it was not uncommon to sell portable radios that featured AM, FM, and TV audio (VHF channels 2-13), with the weather band included some distance down the dial from TV channel 7 (after the U.S. digital TV conversion, these types of radios became mostly obsolete). One of the early consumer weather alert radios (model KH6TY) was designed and manufactured by Howard (Skip) Teller, who was issued a patent on the alerting mechanism and was instrumental in the design of the PSK31 Digipan software and hardware,〔(【引用サイトリンク】url=http://www.qsl.net/kh6ty/digipan.pdf )〕 and the Amateur radio NBEMS emergency communications system. Most receivers from the 2000s and the 2010s, and even some from the mid-1990s, are able to listen silently for weather alerts via the SAME protocol and then sound an alarm to warn the listener of impending severe weather or emergency events. SAME allows listeners to "customize" their radios to only receive alerts issued for specified geographic areas; this technological feature filters out and eliminates "nuisance" alarms for events that do not affect a listener's preset location. In the U.S., SAME locations are defined as counties (and in some instances, parishes, territories, or marine zones) and are set using preassigned six-digit FIPS county codes; in Canada, CLCs are used. Besides SAME alerting capability, modern weather radio receivers may include visual alerting elements (e.g., multicolored LED indicator lights) and allow for the use of external devices (e.g., pillow vibrators, bed shakers, strobe lights, and loud sirens, which attach via an accessory port) to alert those who are deaf or hearing impaired. Since April 2004, radio models marketed as "Public Alert-certified" must include these features and meet certain performance criteria, as specified in electronics industry standard CEA-2009.〔url=https://www.ce.org/CorporateSite/media/Standards-Media/PA_Whitepaper_9-3-08.pdf〕 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「weather radio」の詳細全文を読む スポンサード リンク
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