Vlbi Software Approach. Cluster Environment

As a radio astronomical observation technology with very high spacialresolution, Very Long Baseline Interferometry (VLBI) has been widely used in thesatellite tracking and orbit determination activities. VLBI correlator is the kerneldevice of pre-processing of VLBI. There are two kinds of correlator, hardwarecorrelator and software correlator. At present, the software correlator based on highperformance computers becomes a research emphasis in VLBI technology. Thesoftware correlator has already made a success of the deep space exploration, and itbegins to be used in astrophysics and space geodesy data processing.Increasing VLBI stations and bandwidth demands the augment of data rate.How to build a software correlator with high speed, real-time and parallel processingability becomes a highlight of VLBI technology field..At present, the cluster is the most popular architecture of the High PerformanceComputing (HPC) fields. It can solve the complicated scientific computing andintensive data processing problems. Using HPC cluster to solve researching andengineering problems is a mainstream.In first three chapters, the backgrounds of VLBI technology, and the softwarecorrelators, as well as the principle of cluster computing were presented. Then thecluster platform of the software correlator was discussed.This thesis focused on the processing method and realization of a VLBIsoftware correlator under a small cluster system. Firstly, the principle of currentsoftware correlator was presented. Secondly, a cluster system based on the currentcomputing resource was introduced. A correlation algorithm with two level parallelmodel (MPI+Pthread) was carded out in the VLBI FX software correlator. Finally,the parallel program's performance and the optimization methods were discussed.According to the research result, a VLBI software correlator running on acluster system with 3 nodes (8 CPUs in each node) was developed with the ability of4 stations, 6 baselines data correlation. Under the condition of 4 stations, thecorrelator was able to achieve 118Mbps/station data processing rate.