Hu Zhengqun

Railway Safety Monitoring System Based on CAPS

CAPS navigation and positioning system is characterized by a unique integration of navigation and communication functions, safe and normal running of train not only need to locate the train, but also communicate back the positioning data to the monitoring center in order to protect the security command needs. We introduce CAPS positioning system which integrates satellite navigation and communication functions, design a navigation and communication monitoring system of space-earth integration for railway safety based on CAPS. Railway safety monitoring system based on CAPS plays a good supporting role in safeguarding for the railway safety system.

SIGSO Satellite Communication Resources Management

SIGSO (Slightly Inclined Geostationary-Satellite Orbit) satellite communication system has rich frequency resources. Spread spectrum communication can make up power constrained via frequency bandwidth, which can improve reliability and security of system. In this paper, we put forward a system structure and system resource management strategy and allocation method which is very suitable for SIGSO satellite communication network. The channel of satellite is defined a combination of four resources (Quad) composed of satellite, frequency, power and spread spectrum code. The frequency bandwidth is designed and resource is dynamic allocation management in processing.

A Software Design of Central Processing in Integrated System of Satellite Navigation and Communication

According to the need of an integration of satellite navigation and communication, the feedback information of terminal contains message information, picture information, voice information and navigation information, the satellite central station processing software needs to resolve, exchange and forward the communication information and resolve, storage, map matching and display processing the navigation information. We design the processing software in the center station of satellite communication, describe the system software logical architecture, software interaction of navigation application system including position monitoring and track playback, data model and systematic method in data processing center and software interactive of management system. In addition, a systematic data processing method based on the weight balance technology is proposed in this paper.

CAPS Satellite Data Push Communications System

For the application needs of CAPS (Chinese Area Positioning System) in a particular field, we design and implement the CAPS satellite data push communications system. The system mainly includes data transmission equipment in the satellite central station (document broadcast software, data packers, jammers, modulators, high power amplifier and antenna), Slightly Inclined Geo-Synchronous Orbit satellite, receiving terminal equipment (terminal antenna tracking SIGSO satellite, receiver front-end processing, receiver demodulation processing). The system has a data transfer rate of 4Mbps in satellite data push, which is well to meet the application needs in relevant field.

Study and Design of Wideband IF Down Conversion System

In a satellite communication system, for the design of receiver system. Since the characteristics of the system, we need to reduce the IF down converters count on the ground communication central station, expand the dynamic range of receiving system to make full use of satellite transponder resources. ATMega128 is used as a programmable controller, ADF4360-8 generates the local oscillator signal source, AD8343 chip is used as a frequency mixer and AD8367 is used as a VGA controller chip, which constitutes the logical architecture. We design and implement a low-distortion broadband IF down converter with multi-purpose in time division, flexible and convenient operation features.