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发表于 2015-10-29 22:27:54
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Principle of operation
The OSA 3030B EUDICS frequency standard consists of a Quartz oscillator
frequency-locked to the hyperfine resonance of free Cesium atoms. The Cesium
atomic beam resonator provides an output signal which is strongly peaked around
the central frequency f0 = 9.192631770 GHz, the width of the resonance being
about 500 Hz.
The stability of the resonance frequency with time and its insensitivity to
environmental variations, especially to temperature, are the main reasons for the
long-term stability and accuracy of the Oscilloquartz Cesium standard.
In order to lock the Quartz oscillator to the atomic resonance, an interrogating
signal near f0 is derived from the output of a Quartz oscillator and RF synthesis
and fed to the atomic resonator. Under control of the microprocessor, the synthesized
frequency is switched from one side of the atomic resonance to the other.
The ouput signal is processed by a digital synchronous detector to provide a
correction signal to the voltage-controlled Quartz oscillator. The locked condition
is reached when the two frequencies are symmetric about the resonance (fi =f0). |
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