Real-time Lucky Imaging System Based on USB2.0 Bus Data Listening

In order to further improve the real-time performance of the existing real-time lucky imaging system, and in the case of lucky imaging observation through the EMCCD camera with the USB2.0 interface, this paper proposes a real-time lucky imaging technology scheme based on USB2.0 bus data listening. The hardware design and digital logic design of the listening circuit have been carried out and a lucky imaging system with real-time listening, transmission, processing, dynamic update and display has been built. This system inserts the front end of the listening circuit into the USB2.0 bus connecting the camera with a PC. When the camera captures astronomical images and transfers the images to the PC via USB2.0 bus, the special USB2.0 bus data listening system realizes non-intrusive data listening on the bus. After analysis and processing, only valid astronomical image data are sent to a bottom FPGA development board, in which a FPGA lucky imaging system transplanted from an existing Ethernet-based system is embedded. When the development board receives the image data sent by the listening circuit, the embedded lucky imaging system performs image preprocessing, dynamic image selection, real-time registration and superimposition processing, and finally uses 9 adjustable thresholds to binarize high-resolution images and then outputs these images to a VGA displayer. This paper introduces the hardware, logic design method and debugging process of the listening circuit, as well as the transplantation of the lucky imaging system and the experimental situation of the whole system. The experimental results show that the implemented system can perform real-time listening, lucky imaging and dynamic update display for 10 000 frames of 512×512 pixel images continuously transmitted on the USB2.0 bus, and realize the real-time of lucky imaging technology.