Design And Realization One Kind Of GPS Disciplined High Stability Oven Controlled Crystal Oscillator

With the introduction of 5G "new infrastructure" as a national strategy,the communications market has ushered in more opportunities and challenges.In order to meet the needs of the new generation of communication systems,this thesis designs a modular oven-controlled crystal oscillator(OCXO),which combines the traditional OCXO with the GPS disciplining circuit,in order to retain the advantages of the longterm stability of the Global Positioning System's pulse per second signal(PPS)and the superiority of the OCXO's short-term stability advantage.When the satellite signal can be received,the OCXO will be locked based on the PPS and provides high-accuracy frequency and highly synchronized time information;when the GPS signal is lost,the data in the lock period are used to establish the aging and temperature model of the OCXO,in order to maintain accuracy and phase delay.This design has made many innovative improvements in the design of OCXO and disciplining circuit,which conforms to the concept of miniaturization and low cost,and is extremely competitive in the market.Modular OCXO can greatly save the research and development time of communication equipment manufacturers,and help them complete the whole design faster.The expected market prospect is broad.The main work of this thesis is as follows:1.Through the analysis of the crystal resonator and its equivalent circuit,the 43U-3rd-SC-cut-10 M crystal resonator is selected as the main oscillator component;the classification and related characteristics of the oscillation circuit are studied,and the SCCut parallel triode oscillation circuit;analyze the factors that affect the thermostatic bath,greatly improve the temperature characteristic index of the miniaturized constant temperature bath,determine the design direction,and finally complete the design of the thermostat circuit and the structure of the bath that meet the requirements.2.Briefly explained the technical basis required for designing the disciplining circuit,including GPS positioning system and time interval measurement technology;combined with the application scenarios of the designed product,conceived the overall work flow of the disciplining system;completed the lock and step by step according to the disciplining work flow in the hardware and software design of the holdover,the lock phase mainly uses time interval measurement technology,Kalman filter algorithm and the least square method.The holdover mainly models and compensates the aging and temperature characteristics of the oven-controlled crystal oscillator.3.Design single-board and batch test systems for productization to ensure the smooth progress of the test;perform performance tests on the finished products according to the index book,and analyze the key indicators and influencing factors of the oven-controlled crystal oscillator while giving the test results.Through the above work,the final modular oven-controlled crystal oscillator index has reached the temperature characteristics of the free-running phase <±3ppb/-40??85?,long-term stability <±0.2ppb/day,short-term stability <5.0ppt/1s;lock phase phase Jitter <±30ns,frequency accuracy <±1.0ppt/24 hours;holdover <±10us/24 hours index.