| In recent years,with the frequent occurrence of disaster,people pay more and more attention to the on-site information in the emergency environment,especially in the case of earthquake relief,military operations,security inspections,etc.,a large amount of on-site information needs to be transmitted in real time and reliably.Among them,video information is an important way for people to obtain on-site conditions,because it contains a lot of information and it is intuitive.But in most emergency environments,there is no infrastructure to get timely on-site information to take countermeasures,resulting in significant losses.Therefore,it is particularly important to design a wireless image transmission system that is easy to build,independent of the public network and can transmit video in real time.Aiming at the specific application requirements in the emergency environment,a Soc-based wireless image transmission system was developed based on DVB-T2.The system mainly includes the following features.First,it does not require base station or relying on a solidified network device.Secondly,it can provide smooth,high-definition video transmission services with better user experience.In addition,it has the advantages of high bandwidth and low latency,which can meet the requirements of the emergency environment.The research content of this paper includes the following parts,design scheme of wireless image transmission system,algorithm implementation of key technologies,and building embedded system platform.Firstly,according to the characteristics of parameters simple of transmission video in the application environment,the redundant structure used to control the TV program in the original frame structure is deleted,and the parameter configuration scheme suitable for the system is developed,so the data transmission rate is effective improvement.For the problem of high complexity of BCH and LDPC algorithms,the algorithm that satisfies the system requirements and is easy to implement is selected by comparing the performance of existing algorithms and matlab simulation.In order to solve the problem of insufficient hardware resources due to the large LDPC long code check matrix,a row-column independent structured storage method is adopted to design the hardware,which effectively solves the problem of information storage and improves the speed of algorithm implementation.In order to solve the problem of low accuracy of P1 symbol correlation synchronization algorithm used in DVB-T2,related algorithms is improved,and the circuit structure of parallel cache has been implemented in hardware,which effectively improves the synchronization accuracy.Finally,the system was developed and tested on ZYNQ(XC7Z045)platform.The PS part controls the whole system through software programming,and the input of video source is controlled by UDP and DMA.The hardware development of the baseband is implemented in PL part.Through the test of embedded system platform,the system can effectively transmit and receive video data on the single development board under wireless conditions,and it meets the requirements of design. |
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