Design And Implementation Of CPT Rubidium Atomic Frequency Standard Frequency Conversion Circuit

CPT atomic frequency standard is a new generation of atomic frequencystandard. Compared with the traditional atomic frequency standard, it has theadvantages of small volume, light weight and low power consumption, so it is widelyused in many fields, for example, timing punctuality, communication and navigation,missile control, geodesy, astronomical observation and grid regulation. Passive CPTatomic frequency standard is to use electromagnetically-induced transparencyphenomenon generated by energy level transition between atoms to realize thelocking of frequency standard with high precision and high stability.The main research work of this thesis is to optimize and improve the servocontrol circuit performance of passive CPT rubidium atomic frequency standard.Compared with other atomic frequency standards, the biggest feature of passive CPTrubidium atomic frequency standard is the use of non-integer crystal oscillator insteadof the commonly used integer oscillator (5MHZ or10MHz), thus cutting down theuse of components, reducing the noise and other external interferences. And withsimple structure and convenient debugging, it can help improve the miniaturization ofatomic frequency standard.Firstly, this thesis has reviewed the development, history and present researchsituations of traditional atomic frequency standards, and elaborated on researchsituations and development achievements of CPT atomic frequency standard at homeand abroad. By setting up the mathematical model, this thesis has done quantitativeanalysis on CPT resonance phenomena, discussed the physical configuration andoperating theory of passive CPT atomic frequency standard, analyzed the mainparameter valve and designed overall plan of passive CPT atomic frequency standardsystematically. Based on this, it has introduced the servo loop equation, analyzed thephase noise of every related component in the loop, mainly discussed the factorsaffecting frequency stability in atomic frequency standard servo loop, and thenclarified that the stability-affecting factor for short-term of rubidium atomicfrequency standard is pressure control oscillator and long-term stability is mainlydecided by quantum system, frequency multiplier and servo amplifier. And then it has mainly analyzed and designed the frequency multiplier and DDS frequency synthesiscircuit. As for frequency multiplier circuit, we use the link circuit combined with bothlow frequency and high frequency, which can greatly reduce the noise in frequencycircuit, improve the performance of the whole system and meet the design indexbetter; At the same time using the ADS software simulation design has realized thefrequency doubling the band-pass filter circuit and optimize the parameters. afterfrequency multiplication, one circuit has entered the3417MHzmicrowave signalgenerated by phase step recovery diode, and the other circuit is input into the DDScontrolled by CPLD design as a reference clock source, after narrowband filter noisereduction, it can output fixed10MHzstandard frequency signal. After the actual test,the relevant index in the link has reached the early expected requirements.Finally, based on the study design, this thesis has summarized some experienceand introduced some methods for improvement and optimization on the basis of theresearch work. The scheme proposed in this thesis has reduced the use of loopcomponents, realized the signal output with high stability frequency standard andfinally reached the utility of sampling machines by continuous improving follow-upwork.