Real-time Digital Image Storage Systems Design

We discussed the design process of digital image real-time memory system and its applications in the field of scientific research in this paper.Because of high resolution rate, great amounts of pixels, enormous memory capacity is necessary, and smoothing continuous image makes high speed a must. This system realized real-time memory of high-speed data stream using several low-speed equipments. High-speed data stream of 95MB/s (peak bandwidth=100 MB/s) is divided into 4 channels and each channel is 25 MB/s. The frequency of signal is divided by 4 according to the pixel clock, and the divided frequency signal is used to control the data stream of each channel. Four XIJIE U Series 6 ST340810A IDE hard disks of 40G are used as the memory in the system. Each transmits at 55 MB/s, satisfying requirements completely. And the capacity is up to 160G, the requirements of speed and capacity are fulfilled simultaneously. The system deviated from the computer platform, its volume tends to miniaturization, therefore, it could be carried by plane and vehicle and fits remote measuring. Furthermore, IDE hard disk is considerably cheap relatively to other memories widely applied currently. This design has extremely high cost performance. During the design project of the system, the point is to resolve the interface there one data stream is divided into four. The programmable logic device (PLD) of ispLSI made by Lattice is applied. The application of Lattice development software makes it possible to integrate the interface circuits of dividing data stream into PLD and makes the delays of data and control signal consistent. Consequently the circuit gained highly stable performance and higher speed. Meanwhile if the circuit needs modification, it is unnecessary to weld PCB again, only modifying source file, recompiling and reloading are needed. Obviously the design could be more flexible and convenient.At present, the technologies of the digital signal processing and memorizing are behindhand in China and it is almost blank especially in the field of real-time memory. Therefore the digital real-time memory system is designed. The system has stable and credible performance by testing. This technology would accelerate the development of science and military technology, especially in the fields of aviation, aviation scout and high-speed data record.