Dsp-based Active Hydrogen Maser Cavity Auto-tuning System Design

Hydrogen atomic clock plays a significant role in navigation, radio astronomy,timekeeping due to its high-stability and precision. Auto-tuning of the maser cavitycompensates for cavity pulling effect, and other sources that contribute to the longterm frequency drift and hence improve the stability of the maser.In this paper, a study of theoretical analysis and design of the H-maserAutotuning systems is presented. Frequency autotuning methods are described. A newscheme is proposed based on DSP(Digital Signal Processor) and CPLD(ComplexProgramming Logic Device). This technique has the desired feature of auto-tuning thecavity with a very high sensitivity and without degrading the maser performance.The thesis is arranged as followed, First of all, the background of the research isbriefly reviewed, and the goal of the autotuning system is presented. Detailedclose-loop analysis and key IC selection is described in chapter 2. Chapter 3 gives thehardware design, we select 16bit DSP TMS320VC5402, which is powerful andhelpful to reduce the complexity of circuit board. In our experiment, we introducedthe connection circuit of 16bit SAR(Successive Aproximation Register)ADC,DACand McBSP in DSP. The software design is presented in chapter 4, we adopted C andassembly programming to realize the signal processing algorithm. The test of thesystem and the results are given in chapter 5.The work is summarized in chapter6, some improvement will be tested in the future.