Circuit Design Of Real-time Acquisition And Transmission System For Infrared And Visible Light Images

Infrared imaging is based on temperature radiation imaging of target object,which reflects the object surface characteristics and temperature distribution,and is not affected by environmental factors,such us weather and light.However,the image contrast is poor,and the edges are blurred.Visible light imaging is the object surface reflection of the gray image,which can be a good response to the details of the object,but vulnerable to environmental factors.In some application scenarios,it is necessary to obtain the temperature information of the target object while obtaining the shape of the object.Therefore,simultaneous acquisition of infrared and visible dual-band image data has a good practical value.Camera Link,Gigabit Ethernet,IEEE1394 and USB are usually used in the field of image data transmission.This paper demonstrates the advantages and disadvantages of each transmission interface,and selects USB3.0 interface which is the most convenient,the most widely used and lower cost.Also,a simple and effective special image data transmission scheme is designed to realize the real-time image acquisition and transmission system of infrared and visible light.FPGA which is the control center of the system generates CMOS image sensor drive timing,and then generates a trigger signal according to the synchronization signal of infrared image,used to trigger a frame visible image data to achieve the synchronization of the two-way image.Infrared image data and visible image data are input directly to the FPGA that acts as a master.First,the FPGA buffers each row of the two images separately.Then,the buffer lines are written to the external DDR2 under the effect of the arbitration mechanism.Data are read out into the USB3.0 transfer interface when there are a frame infrared image and a frame visible image in the DDR2.By controlling the DDR2 address space of read and write,two-way image can be splitted into a frame image,and all data can be transmitted to the host computer only through a single transmission channel.Ping-pong operation is used to control data read and write by two DDR2 s.This can maintain the continuity of data flow to ensure that data is not lost.Finally,the system is tested and the results indicate that the indicators met the design requirements.