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- WWVB is a time signal radio station near Fort Collins, Colorado and is operated by the National Institute of Standards and Technology (NIST). Most radio-controlled clocks in North America use WWVB's transmissions to set the correct time. The 70 kW ERP signal transmitted from WWVB is a continuous 60 kHz carrier wave, the frequency of which is derived from a set of atomic clocks located at the transmitter site, yielding a frequency uncertainty of less than 1 part in 1012. A one-bit-per-second time code, which is based on the IRIG "H" time code format and derived from the same set of atomic clocks, is then modulated onto the carrier wave using pulse-width modulation and amplitude-shift keying. A single complete frame of time code begins at the start of each minute, lasts one minute, and conveys the year, day of year, hour, minute, and other information as of the beginning of the minute. WWVB is co-located with WWV, a time signal station that broadcasts in both voice and time code on multiple shortwave radio frequencies. WWVB is not an acronym or abbreviation but a call sign for the radio station. While most time signals encode the local time of the broadcasting nation, the United States spans multiple time zones, so WWVB broadcasts the time in Coordinated Universal Time (UTC). Radio-controlled clocks can then apply time zone and daylight saving time offsets as needed to display local time. The time used in the broadcast is set by the NIST Time Scale, known as UTC(NIST). This time scale is the calculated average time of an ensemble of master clocks, themselves calibrated by the NIST-F1 and NIST-F2 cesium fountain atomic clocks. In 2011, NIST estimated the number of radio clocks and wristwatches equipped with a WWVB receiver at over 50 million. WWVB, along with NIST's shortwave time code-and-announcement stations WWV and WWVH, were proposed for defunding and elimination in the 2019 NIST budget. However, the final 2019 NIST budget preserved funding for the three stations. (en)
- WWVB是由美國國家標準技術研究所(NIST, National Institute of Standards and Technology)所擁有的時碼發播台,位於美國科羅拉多州科林斯堡,其姊妹站是WWV。在北美地區,當地大部分電波時鐘都使用WWVB的時碼訊號,以設定正確的時間。WWVB 擁有一個 70千瓦的有效輻射功率發射機並利用 60 千赫的頻率發射對時訊號。而WWVB的對時訊號是利用原子鐘來作訊號來源,其不確定度小於 1/1012。WWVB每一比特每秒時間代碼,這是基於的時間代碼格式,是由同一組的原子鐘產生,然後調製到使用載波脈衝寬度調變及幅移键控。而時間代碼的單一完整的幀是開始於每分鐘的開始,每一幀持續一分鐘,當中包含年份,小時,分鐘等信息。 雖然大部分授時台都是廣播該國的當地時間,但是美國跨越多個時區,所以WWVB廣播的時間訊號是協調世界時。而當地所售買的電波時鐘都可以設定為美國的四個時區及夏令時間而顯示出正確的本地時間。 在2011年,國家標準技術研究所估計超過5000萬部時鐘及手錶配備了接收WWVB的對時訊號的能力。 (zh)
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- Canada, United States, Mexico (en)
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- 1963-07-04 (xsd:date)
- July 1956 (en)
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- WWVB antenna and support towers (en)
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- WWVB是由美國國家標準技術研究所(NIST, National Institute of Standards and Technology)所擁有的時碼發播台,位於美國科羅拉多州科林斯堡,其姊妹站是WWV。在北美地區,當地大部分電波時鐘都使用WWVB的時碼訊號,以設定正確的時間。WWVB 擁有一個 70千瓦的有效輻射功率發射機並利用 60 千赫的頻率發射對時訊號。而WWVB的對時訊號是利用原子鐘來作訊號來源,其不確定度小於 1/1012。WWVB每一比特每秒時間代碼,這是基於的時間代碼格式,是由同一組的原子鐘產生,然後調製到使用載波脈衝寬度調變及幅移键控。而時間代碼的單一完整的幀是開始於每分鐘的開始,每一幀持續一分鐘,當中包含年份,小時,分鐘等信息。 雖然大部分授時台都是廣播該國的當地時間,但是美國跨越多個時區,所以WWVB廣播的時間訊號是協調世界時。而當地所售買的電波時鐘都可以設定為美國的四個時區及夏令時間而顯示出正確的本地時間。 在2011年,國家標準技術研究所估計超過5000萬部時鐘及手錶配備了接收WWVB的對時訊號的能力。 (zh)
- WWVB is a time signal radio station near Fort Collins, Colorado and is operated by the National Institute of Standards and Technology (NIST). Most radio-controlled clocks in North America use WWVB's transmissions to set the correct time. The 70 kW ERP signal transmitted from WWVB is a continuous 60 kHz carrier wave, the frequency of which is derived from a set of atomic clocks located at the transmitter site, yielding a frequency uncertainty of less than 1 part in 1012. A one-bit-per-second time code, which is based on the IRIG "H" time code format and derived from the same set of atomic clocks, is then modulated onto the carrier wave using pulse-width modulation and amplitude-shift keying. A single complete frame of time code begins at the start of each minute, lasts one minute, and conve (en)
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