Short-term Frequency Stability Measurements

As the development of science technology ,there are more and more requirement for the frequency source's stability.With the rapid developwent of electronic technology ,and the explore for radar,navigation universe flight,guided missile,etc.The demand of high precision and high stability frequency source becomes more and more urgent,such as frequency synthesizer ,quartz crystal oscillater,and atom frequency mark.Frequency stability is one of the most important characteristic of the modern exact oscillater.The measuring of the frequency's stability ,not only can confirm the performance of the oscillater ,but also drive the development of the oscillater.In the recent 30 years,the guideline of the frequency's stability advanced a large ,from 10-8 to 10-15,or more higher.There are a lot of methods to measure the frequency's stability,the task use the timing the difference of frequency method,this is the most normal method in the domain.This is a kind of comparative measurement ,use the counter as the measuring display to implement the measuring of sampling variance,we can use the electronic counter to measure the signal directly,but can't reach the high presion and high stability ,just only to 10-6 to 10-7.To improve the measuring precison ,we can use"timing the frequency difference".To enlarge theΔf ,put the signal andΔf into a frequency multiplier ,then put the signal to the counter ,and also use the strobe time T to control the sampling time.Because of the disunion of the measuring technology and the method to process data,the definitionof signal's stability characteristic and the concept are confusion ,thus the measuring method,token,the processing data and the result are also different.In 1976.2 and 1977.12,china decided to use Allan variance as the mark in time domain and use the relative frequency wave density as the mark in frequency domain.In this dissertation,the design and implementation of the measuring frequency's stability system are studiec.And the primary works in this paper are presented as follows:1. Introduced the background of this dissertation,the precept chosen and the structure schemes of the system.2. Introduced the basic theory of measuring frequency'stability,and the two parts of the token of frequency:timing domain and frequency domain.Introduced the normal methods to measuring frequency's stability,and the advantage and disadvantage of each method.3. Introduced the hardware design scheme of the system,and choose the appropriate CMOS chips,and detailed the circuitry design and realization,the chief chip module and ameliorate the whole system.4. Introduced the software of processing the data .5. Summarized and concluded the whole dissertation,pointed out future research issues and possible research directions.