Research And Improvement On Long Term Accumulator Sub-System Of FX Correlator

In the thesis, the principle, structure and function of the high-speed FXcorrelator of Chinese VLBI network are introduced, and the structure and function ofits long term accumulator (LTA) are dissertated in detail. The correlator ischaracterized by tremendous data to be processed with a ultra-high operation speed.It's necessary to reduce the data before processing, thus not only to decrease thequantity of data so as to shorten the time for post-processing, but also to smooth thedata so as to increase the signal-to-noise rate (SNR) to a certain extent. The task isperformed by the long term accumulator sub-system, which is the data reductionmodule of the correlator. By a review of the history and the status quo of the application of the VLBItechnology to observing and tracking of man-made space objects as well as the outerspace navigation and in consideration of the forthcoming "China's Moon ExplorationProgram", it's pointed out that the new application sets higher requirements for thelong term accumulator (LTA) of the correlator, such as shortening the integral(accumulation) time and increasing the quantity of the output data, in order toimprove the processing speed and the measurement precision. To meet the 3FX 型相关处理机长期累加器子系统的研究与改进requirements, it's necessary to improve the current LTA sub-system. By the researchand analysis on the current LTA sub-system and the related timing sequence, animprovement scheme of the sub-system is presented and a specific method toimplement the improvement is dissertated in detail. At the end of the thesis, the resultof the data processing with the improved LTA sub-system is provided, which provesthe improvement scheme of the LTA sub-system is viable and the improved LTAsub-system is of great value in practice.