This is the basis for the well - known cesium clock, presently the standard of frequency and time.
这就是众所周知的铯原子钟的基础，它是目前的频率和时间基准。
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China digital television terrestrial broadcasting standard GB20600-2006 is based on TDS-OFDM (Time-Domain Synchronous orthogonal Frequency Division Multiplexing) systems.
A new tool that can test the clock base frequency error of energy measuring devices and provide GPS standardtime to calibrate real-time clock was introduced in this paper.