The Design Of High Precision Frequency Stability Measurement System In Time Domain Based On Frequency Difference Multiplication Method

Frequency measurement technology has a long history, which includes a multi-disciplinary theory and a number of technical areas of study, in the human development of science and technology, Frequency measurement technology plays a crucial role. As the development of science technology, there are more and more requirement for the frequency technology, particularly the rapid development of electronic communications, navigation, missiles, radar, space exploration and space flight work development, The demand of high stability and high precision frequency source becomes more and more urgent, such as atom frequency mark, quartz crystal oscillator, and frequency synthesizer.Frequency stability is an important characteristic of Frequency source. In the recent30years, the index of the frequency stability is higher and higher. But it was a contradiction between the high precision and the cost of instrument, so the instruments of high precision, low cost and simple structure were very popular. The aim of us is to work over this system accord the above, the frequency stability measurement system accord with high precision, simple structure, low cost and convenient to use.The article first discusses the development of frequency stability measurement technology domestic and overseas, then introduced the frequency stability of time domain and frequency domain characterization form, and then explores five kinds of noise which influence the stability of the frequency, finally analyzes the advantages and disadvantages of various frequency stability measurements, In the article we use Frequency multiply method to measure the Frequency stability. Frequency multiply method is a comparison of measurement method, which uses counter to show the result and Realizes the variance sampling measurement. Direct frequency difference method of double frequency can not reach high precision in measurement of frequency stability and accuracy. In order to improve the measurement precision, we adopt the " timing the frequency difference", To enlarge the△f, put the signal and A/into a frequency multiplier, then put the signal to the counter. The system framework is based on this principle, The measurement system is a high precision frequency stability measure-ment system based on MCU count and single-chip microcomputer control.Then the article introduce the design of hardware modules in detail, including the choices of chip and the hardware circuit design, and give the corresponding hardware circuit diagram, at the same time, analysis the main chip. We take a series of measures to improve the stability of system and measuring precision In the hardware design process.And then the article introduces the software design of the system; the system uses the monolithic to take sample, and then display the date on LCD monitor, it can also put the date into PC.At last, the article introduces the debugging procedures and methods of the hardware, and then gives the data of the measurement system, afterwards analysis some index; the article put forward some improvement measures.