Atomic Frequency Standard Servo Circuit Design And Realization

With the development of science and technology, more and more sophisticated equipments used in laboratory, have come into people's lives. However, these equipments need accurate and stable frequency source. The development of atomic frequency standard is just meeting the requirements of measurement of time and frequency. And Rubidium atomic frequency standard (RAFS) has been applied widely because of its advantages such as simple conformation, small size, low power and price.Based on the physics package of RAFS, this dissertation mainly studies its basic theory, and the main content includes the theory of the Rubidium atomic energy level transition and the effects of spectral lamp, optical filtering bulb, microwave resonator, photosensitive tube, buffer gas, which are in the passive RAFS's physics package, and the control theory of servo loop. Through Kenschaft model's accurate simulation, this dissertation analyses the use of the method, which is modulating microwave interrogating signal, demodulating and integrating AC error signal, to control the frequency from voltage control crystal quartz oscillator (VCXO). By the simulation of the closed-loop system with Kenschaft model, this dissertation designs a general scheme about the peripheral servo circuit, divides the circuit into many function modules, such as demodulator integrated circuit, multi-frequency circuit and so on, and designs specific circuits one by one based on the function of them. At last, every part of the circuit is got together and PCB of servo circuit for the experiment is made. In the design of demodulator integrated circuit, this dissertation designs a voltage sweep circuit, which can ensure the stability of frequency control, to improve anti-interference ability of the servo circuit.Through the PCB of servo circuit and passive RAFS's physics package which is in the laboratory work together, the locking of frequency from VCXO is realized, and the 10MHz standard frequency is got.