Atomic clock is the most accurate time and frequency standard equipment at present. In metrology, it is called frequency standard apparatus. From the point of view of application, it has a very wide market and considerable application value in aerospace, instrumentation, national defense industry and astronomy. This paper mainly introduces the application of rubidium atomic clock and its verification as a standard frequency source.

Temperature and aging drift will affect the accuracy and stability of the output frequency of the atomic clock, making the output frequency of the atomic clock unstable. Rubidium atomic clock has poor long-term performance compared with hydrogen atomic clock or cesium atomic clock. Various frequency shift mechanisms make rubidium atomic clock sensitive to many environmental factors. Besides temperature and aging drift, it also includes magnetic, pressure, impact, acceleration, vibration, radiation, electromagnetic interference, humidity, power supply, storage and reproducibility.Among these factors that affect the long-term performance of rubidium atomic clocks, the temperature is often the biggest and difficult to overcome.

The application of rubidium clock is first built into the time server as a high-precision clock source. When the satellite loses its lock, it relies on internal rubidium atomic clock for punctuality. Otherwise the time of the time server will drift drifting with the passage of time, resulting in the time server is not accurate enough. If the built-in rubidium clock, the time server can not receive a satellite in a year, the error is only about 5ms.

The built-in rubidium clock for keeping time is usually applied to some places with relatively strict requirements for punctuality accuracy, such as airports, television stations, marine bureaus, seismological bureaus and other units. Another application scenario is that the scene or the computer room can not erect the antenna, without a period of time to take out calibration time, and rely on the internal clock source for time keeping, so as to ensure the accuracy of the time.

Secondly, the common applications of atomic clocks are high precision standard frequency sources, including taming through GPS and Beidou to improve the long-term stability and accuracy of frequency signals. For example, the SYN3204 type receives satellite signals and outputs multi-channel standard 10MHz sinusoidal signals, and selects other frequency signal output. And 1PPS pulse signal and RS232 time signal.

So how to check whether the performance indicators of rubidium frequency standards are consistent with the nominal consistency? It is suggested that the relevant metrology institute be sent to the relevant metrology institutes to complete the verification and calibration according to the relevant verification regulations. What are the specific verification items? We can refer to the JJG 292-2009 rules.

Among them, boot characteristics, output signal, frequency stability and accuracy, and daily drift filtering are important detection items. The related metrology equipment includes frequency stability reference frequency standard, frequency drift rate and frequency accuracy reference frequency standard, phase noise reference frequency standard, oscilloscope, spectrum analyzer, frequency comparator, frequency difference multiplier, phase comparator, frequency divider, general counter and phase noise measurement system.

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