Design And Realization Of Equivalent Focal Plane Circuit Based On FPGA

Currently infrared remote sensing technology has been wildly used in the military, agriculture, meteorlogy and resource exploration fields. The development work of the infrared remote sensor has very important practical significance. The electrical system of the infrared remote sensor mainly composed of detector focal plane circuit and signal processing circuit. The test for the signal processing circuit needs the infrared detector output as input source. This paper proposed a test scheme for the signal processing ciruit, which use equivalent focal plane circuit to simulate detector output that used as the signal processing ciruit input.The equivalent focal plane circuit designed in this paper is based on FPGA. During the test of signal processing circuit, the focal plane circuit receive drive signal from the signal processing circuit and generate the corresponding infrared detector fitting signal used as the input of the signal processing circuit based on specified simulated infrared image. First of all, the function requirements of the circuit was analyzed, and the hardware was designed.The Altera's FPGA as control chip was used to complete the system control function, the CYPRESS's USB controller was used to reaceive simulated infrared image from PC, the SAMSUNG's NAND Flash and Micron's DDR2 SDRAM were respectively used as storage and buffer, the Camearalink was used to uploaded the simulated infrared image to the PC. Then the software of FPGA was designed. According to the functional requirement, the software were devided into multiple modules written by VHDL language. The designed software realized control of FPGA to peripheral devices. Finally, the paper simulated each function module and the whole system with Modesim software.The equivalent focal plane circuit can simulate the communication with signal processing and output corresponding infrared detector fitting signal according to the drive signal, the fitting signal can be outputted through 1, 4, or 8 chanels. And the circuit has 4GB Flash memeory to storage simulated infrared image, has 4Gb DDR2 cache to make the sending speed up to 640 MBPS. The circuit support USB2.0 communication procotol to update the simulated infrared image in the Flash memeroy, and support RS232 communication with PC to realize the control of the system. And the simulated infrared image used to generate the detector fitting signal can be uploaded to the PC realtime by cameralink interface to compare the image of processed and unprocessed.The circuit designed in this paper can provide necessary signal source to the signal processing circuit of infrared remote sensor when tested on the ground. It has important practical significance for the development of infrared remote sensor.