U.S. Standard Frequency and Time Services
نویسندگان
چکیده
منابع مشابه
Distribution of Standard Frequency and Time Signals
This paper reviews the present methods of distributing standard frequency and time signals (SFTS), which include the use of high-frequency, low-frequency, and very-low-frequency radio signals, portable clocks, satellites, and RF cables and Lines. The range of accuracies attained with most of these systems is included along with an indication of the sources of error. Information is also included...
متن کاملTh European Frequency and Time Forum Neuchatel - 16 - 17 - 18 March 1993 Nist - 7 , the New Us Primary Frequency Standard
NIST-7, an optically pumped, cesium-beam frequency standard has replaced NBS-6 as the official US primary frequency standard. The present short-term stability of the standard, measured with respect to an active hydrogen maser, is characterized by uy(t) L 8 x i". Our first evaluation has resulted in an uncertainty of 4 x An improved servoelectronic system is being developed and this should impro...
متن کاملStudy of the Role and Performance of Islamic Association of University Students in the US and Canada (Persian Speaking) During the Time of US Embassy Takeover
One of the groups who played a valuable role during US Embassy takeover was the Islamic Association of University Students in the US and Canada (Persian speaking). Due to the importance of this issue, this article tries to answer this question: what was the role of Association of University Students in the US and Canada (Persian speaking) during the US Embassy takeover? To gather data along wit...
متن کاملReal-time damage detection of bridges using adaptive time-frequency analysis and ANN
Although traditional signal-based structural health monitoring algorithms have been successfully employed for small structures, their application for large and complex bridges has been challenging due to non-stationary signal characteristics with a high level of noise. In this paper, a promising damage detection algorithm is proposed by incorporation of adaptive signal processing and Artificial...
متن کاملDiscrete-time, discrete-frequency time-frequency representations
A discrete-time, discrete-frequency Wigner distribution is derived using a group-theoretic approach. It is based upon a study of the Heisenberg group generated by the integers mod N , which represents the group of discrete-time and discrete-frequency shifts. The resulting Wigner distribution satis es several desired properties. An example demonstrates that it is a full-band time-frequency repre...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Nature
سال: 1965
ISSN: 0028-0836,1476-4687
DOI: 10.1038/208025a0