Research Of DDS Signal Source In An Atom Interferometry Gravimeter

Precisely measuring the gravity plays an important role in geophysics research,resource exploration, inertial navigation and so on. In order to realize precise measurementof the gravity acceleration g, cold atom interferometer based on atom interferometrytechnology has been built in our laboratory.My research derives from the experiment of atom interferometry. In our experiment,controlling the frequency and power of lasers depends on the signal source which is ableto realize unramped FSK and ramped FSK with high frequency resolution and stability.Although the performance of current commercial signal source is satisfactory, its size istoo large to meet the demand of our atom interferometer. Thus, it is necessary to develop anew one for optimization. As direct digital synthesizer, which can be highly integrated onchip with excellent performance, is capable to provide a sine output with high frequencyresolution, low phase noise, continuous phase while frequency modulated, we designed aprogrammable signal source which is based on DDS technology.This thesis introduces the development of the signal source in detail, including theorydescription, circuit fabrication, program design and performance testing of DDS and otherrelative experiments. The test result shows that, firstly the DDS signal source achieves afrequency resolution of μHz, a maximum output of120MHz, a phase noise level of-100dBc/Hz from100Hz to100KHz at30MHz output, and secondly it realizes unrampedFSK and ramped FSK successfully, and hence the DDS already came into practicalapplication in the experiment of atom interferometry to precisely measure g.In order to estimate the noise caused by DDS sweep in g measurement, we propose anew method based on frequency mixing to measure the stability of DDS sweep rate. Thepreliminary result shows that the stability of DDS sweep rate is1.01011@100s.