• A Field Monitor System of Rod-pumped Wells Based on GPRS

      Zhaodong, Xing; Yanhong, Kou; Qishan, Zhang; BeiHang University (International Foundation for Telemetering, 2004-10)
      To enhance the production management of the rod-pumped wells in the oil field, using a high performance single-chip as the processor, a field monitor system based on GPRS is researched and developed. In the paper the hardware design and software design are expatiated, the sampling frequency and determination rules for the running state are analyzed, the rational communication protocol is designed to ensure the reliable message transmission and reduce the communication fees. In the end the field monitor system is successfully implemented and verified in practice, part of data transmission result is illustrated.
    • HARDWARE DESIGN AND IMPLEMENTATION OFA MULTI-CHANNEL GPS SIMULATOR

      Yuhong, Zhu; Yanhong, Kou; Qing, Chang; Qishan, Zhang; BeiHang University (International Foundation for Telemetering, 2004-10)
      Hardware architecture and design details of a multi-channel GPS signal simulator with highly flexibility is presented, while the dynamic performance objectives and the requirements on the hardware architecture are discussed. The IF part of the simulator is implemented almost entirely in the digital domain by use of a field programmable gate array (FPGA), which mainly include C/A code generators, carrier generators, spreaders, and BPSK modulators. The results of testing the proposed simulator hardware architecture at IF with the help of a GPS receiver are presented.
    • SOFT SEAMLESS SWITCHING IN DUAL-LOOP DSP-FLL FOR RAPID ACQUISITION AND TRACKING

      Weigang, Zhao; Tingyan, Yao; Jinpei, Wu; Qishan, Zhang; BeiHang University; Wuyi University (International Foundation for Telemetering, 2004-10)
      FLL’s are extensively used for fast carrier synchronization. A common approach to meet the wide acquisition range and sufficiently small tracking error requirements is to adopt the wide or narrow band FLL loop in the acquisition and tracking modes and direct switching the loop. The paper analyze the influence of direct switching on performance, including the narrow band loop convergence, transition time etc. and propose applying the Kalman filtering theory to realize the seamless switching (SS) with time-varying loop gains between the two different loop tracking state. The SS control gains for the high dynamic digital spread spectrum receiver is derived. Simulation results for the SS compared to the direct switching demonstrate the improved performance.