Study Of High-speed Electronic Technology In QKD System And Astronomical CCD Imaging System

With the development of the seience and technology, requirements for the information acquiring and processing are improved continulusly. The progress of the electronics system makes the electronic technology developing in the high-speed direction. While in different electronic systems, the characteristics of high-speed will be affected and decided by different factors.In an analog system, the speed of signal directly reflected in rise and fall time. But with the increasing of the signal speed, the bandwidth, noise, jitter, signal-to-noise ratio of the system will more determine the speed of the whole system. In a high-speed digital system, the increasing speed of the I/O will reduce the maximum jitter of the system could sustain. To improve the system’s I/O speed, technology of reducing the jitter need to be developed. At the same time, the development of the integrated circuit has brought the chip and system to the direction of miniaturization, integration. This will bring the circuit design to the direction of low power. At this moment, to guarantee the signal-to-noise ratio of the system, the system noise must be reduced. Therefore, study various factors of limit signal speed in electronics system, develop technologys to reduce influence of adverse factors continuously, is an important way of promoting the electronic technology to develop in direction of high speed.In this thesis, the theme will be some research about high-speed and real-time data processing, high-precision and low-noise data acquisition, high-speed data storage and transmission. Some research production has been applied in the quantum key distribution system and astronomical CCD imaging system.Quantum key distribution is a new quantum information technology based on the principles of quantum mechanics. In the system of quantum mechanics, quantum key distribution scheme has been proved to be absolutely safe. Thus, in recent years, quantum key distribution has been strongly developed in the world. In this thesis, a point to point QKD system prototype for Hefei metro demonstration network of quantum communication will be designed using high-speed electronic technology. The prototype system achieves real-time quantum key distribution for the first time in China. The generation rate of quantum key reachs17kbps, at the some time real-time and encrypted voice communication has been achieved. In our QKD system, we designed an all-in-all chassis of quantum cryptography with reconfigurable scheme. Using the parallel data processing characteristics of FPGA, high-speed and real-time key extraction algorithms are completed, including sifting, error correction and privacy amplification. Thus we complete the feature of real-time key extraction which is difficult to realize by the PC software. In this thesis, electronics function mudules in the physical layer are detailed described, a ture random number generator based on FPGA is designed, the system control scheme is gived out, and the encryption algorithm and the key expansion algorithm in the key application layer are well designed. In addition, an information synchronization mechanism is designed. The quantum information between Alice and Bob is synchronized by the frame format of synchronous light. At the same time, to satisfy the large amount data cache of the quantum information encoded data, the high-speed data starage technology with using SRAM is researched.Astronomical CCD imaging systems are important observation equipments in the field of astronomical observation, and there are still no domestic self-developed high-performance astronomical imaging systems. In this thesis, a high-performance scalable general astronomical CCD imaging system is researched and designed. Now the main fertures of the initial prototype system have been completed, and the imaging function test of the CCD camera has been successfully completed.For the astronomical CCD imaging system, very low readout noise is required. Therefore the CCD noise processing technology and high precision data acquisition technology are intensive researched in the thesis. With TEC refrigerating scheme, the CCD camera can be refrigeratinged to-52.0℃when the CCD keep in working state. In order to reduce the CCD readout noise, the system uses the correlated double sampling (CDS) circuit to deal with the CCD output signal. And high precision AD conversion and data acquisition modules are designed to acquire the CCD output signal. In addition, the scalability design concept and the reconfigurable technology are adopted in system. We have designed an imaging controller with good extensible ability. The system control scheme is designed also and the system control function is completed usng FPGA and MCU combination work mode. The CCD drive schedule and the data acquisition control sequence are completed in the FPGA too. At the same time, to satisfy the request of data transmission in large CCD imaging system, high-speed optical fiber communication technology is researched. At last, we have processed a series of test for the prototype system. In the work of this thesis, we have successfully completed a real-time point to point QKD system and an astronomical CCD imaging prototype system. We use technologys of high-speed and real-time data processing, high-precision and low-noise data acquisition, high-speed data storage and transmission in the QKD system and astronomical CCD imaging system. Some research results have been obtained.The innovation of this thesis is as follows:(1) Complete the all-in-all chassis of quantum cryptography and the astronomical imaging controller with the reconfigurable and the extensible scheme. The systems have strong extensibility and reconfigurability. The QKD system can be adjusted according to the actual situation. The CCD imaing system can adapt to kinds of CCD chips with different size or type.(2) Real-time process and control technology, high-speed ture random number generate technology, the synchronization technology and high-speed data storage technology are applied in the QKD system to complete an all-in-all chassis of quantum cryptography. Real-time key extraction and control algorithms and a ture random number generator are designed and successfully applied in Hefei metroregion quantum communication network.(3) Low-noise data readout technology and high-precision ADC sampling technology are applied in astronomical imaging system. Contrapose to the characteristics of scientific CCD, noise reduction technology and high-precision data acquisition technology are studied, and the scientific CCD imaging system prototype is completed.