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The Research And Implementation Of Direction Finding And Symbol Synchronization Algorithm In Airborne Assembling Communication System

Posted on:2010-08-22Degree:MasterType:Thesis
Country:ChinaCandidate:C LvFull Text:PDF
GTID:2272360278466913Subject:Communication and Information System
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Airborne operation has become absolutely necessary combat mode of country forces by its high mobility, and the fast assembling is the most important battle effectiveness and life line. At present, the assembling of the airborne is generally implemented by GPS (Global Positioning System). For the ownership and the lack of communication functions, GPS has exposed some fatal security problems in the actual, achieving the assembling system with other methods becomes the key to future battles. For this reason, this project develops an airborne assembling communication system without GPS, which implements bidirectional wireless message communication by radio direction finding as the ultimate guarantee of positioning. This thesis mainly finishes the research and implementation of radio direction finding and baseband symbol synchronization algorithm.Firstly, based on the research of existing direction finding mechanisms, combining with hand-held direction finding set’s features such as portable, weak received signal, this thesis deduces an improved Watson-watt direction finding algorithm based on orthogonal stacked loop antenna which is realized by MC3362. Base on many experiments, the fitting algorithm is given. The actual measurement results show that this solution has high direction finding precision and preferable anti-noise ability.Secondly, base on the analogue-digital mixed mode, a novel method of symbol timing recovery based on minimum mean square error criterion (MMSE) is presented. It includes the optimum acquisition mode and the tracking mode. It can complete the symbol synchronization and bit recovery at the same time, and then do the tracking adjustment of synchronization by the recovery error. Timing recovery is completely achieved with software combining with the timer of MCU. It has simple hardware scheme and finishes the symbol synchronization with limited operation resources. Simulation results show that the algorithm can catch the synchronization time in few bits, the proposed algorithm is robust to lower signal to noise ratio and deep fading channel.Finally, the joint algorithm is deduced combining orthogonal stacked loop antenna and receiver diversity. Then it is programmed in MCU by interrupt slot method after iteration. The outfield experimental results show that the direction-finding sets have many advantages such as simple operation, rapid searching and steady performance. The communication distance, bit error rate and the receiving sensitivity all achieve predicted indexes.The success of the airborne assembling communication system will greatly enhance the security standards and accelerate response capability of our airborne troop. The related techniques have many potential applications in the military and civil fields. It has broad market prospects, extensive social and economic benefit.
Keywords/Search Tags:radio direction finding, symbol synchronization, Watson-watt direction finding system, minimum mean square error criterion
PDF Full Text Request
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